Technical guide to network video. Technologies and factors to consider for the successful deployment of IP-based security surveillance and remote monitoring applications. 2 Axis’ technical guide to network video The market for network video products has grown tremendously since Axis introduced the industry’s first network camera in 1996. The rapid deployment of network video indicates an irreversible shift from old, analog video technologies as network video advances with ever more effective, innovative and easier to use products. Huge strides have been made in video quality. HDTV surveillance cameras are becoming the norm and more megapixel cameras are being introduced. There are cameras that can handle challenging lighting conditions such as low light, high contrast lighting and total darkness, enabling improved surveillance capability. Processors in cameras and video encoders are not only faster but also smarter. In addition, efficient video compression techniques as well as a new type of iris control, P-Iris, have been introduced. There are more product choices to meet a variety of needs. There are smaller, more discreet— even covert—cameras, as well as thermal network cameras. Different fields of view, from telephoto to 360° panorama, are available. Axis’ product development has also focused on easy and flexible installation. Outdoor cameras, for example, are weather-proofed right out of the box. Virtually all Axis cameras and video encoders support Power over Ethernet, which simplifies installation. Many varifocal fixed cameras (box and dome) allow the focus and angle of view to be remotely set from a computer. Many fixed cameras also have the ability to stream vertically oriented views that maximize coverage of vertical areas such as aisles and hallways. Managing cameras and video streams are being made easier. There is increased support for intelligent video functionalities. There are also video management solutions to suit every type of customer—whether it is a retail store with a few cameras or one involving hundreds of cameras at multiple sites. Products that support ONVIF can be easily integrated into systems that incorporate other ONVIF-conformant products from different manufacturers. Greater network bandwidth is becoming more commonplace, and technologies have improved to make the transmission of data over wired and wireless networks safer and more robust. Progress has also been made in storage solutions, especially for small systems. Available today are high capacity network-attached storage (NAS) solutions that provide terabytes of storage at minimal costs and memory cards that enable weeks’ worth of video to be stored in a camera or video encoder. The range of network video products is widening and the scope of their capabilities is increasing. This is reflected in the Technical Guide, which aims to provide network video users with a better understanding of the technologies and products that are available to meet their surveillance needs. 3 Table of contents 1. 1.1 1.2 1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.3.7 1.3.8 1.3.9 2. 2.1 2.1.1 2.1.2 2.1.3 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7 2.2.8 2.2.9 2.3 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7 2.4 2.4.1 2.4.2 2.4.3 2.4.4 2.4.5 2.4.6 2.5 Network video: overview, benefits and applications 7 Overview of a network video system 7 Benefits8 Applications12 Retail12 Transportation12 Banking and finance 13 City surveillance 13 Education13 Government13 Healthcare14 Industrial14 Critical infrastructure 14 Network cameras 15 What is a network camera? 15 AXIS Camera Application Platform 17 Application programming interface 18 ONVIF18 Camera features for handling difficult scenes 18 Lens’ light gathering ability (f-number) 18 Iris18 Day/night functionality 18 Infrared (IR) illuminators 19 Lightfinder technology 20 Resolution/Megapixel20 Exposure control settings 20 Wide dynamic range (WDR) 21 Thermal radiation 21 Camera features for ease of installation 22 Outdoor-ready22 Focused at delivery 22 Remote focus and zoom 22 Remote back focus 22 3-axis camera angle adjustment 22 Corridor Format 23 Pixel counter 23 Types of network cameras 24 Fixed network cameras 24 Fixed dome network cameras 24 Functionalities in multi-megapixel fixed and fixed dome cameras 25 Covert network cameras 27 PTZ network cameras 28 Thermal network cameras 31 Guidelines for selecting a network camera 33 4 3. 3.1 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.3 3.4 3.5 3.5.1 3.5.2 3.6 3.6.1 3.6.2 3.6.3 3.6.4 3.7 4. 4.1 4.1.1 4.1.2 4.2 4.3 4.4 4.5 4.6 5. 5.1 5.2 5.3 5.4 5.5 5.5.1 5.5.2 5.5.3 5.5.4 5.5.5 5.6 5.6.1 5.6.2 5.6.3 5.6.4 Camera elements 37 Video encoders 55 Environmental protection 63 Light sensitivity Lens elements Field of view Matching lens and sensor Lens mount standards for exchangeable lenses F-number and exposure Types of iris control: fixed, manual, auto, precise (P-Iris) Depth of field Removable IR-cut filter (Day/night functionality) Image sensors Image scanning techniques Interlaced scanning Progressive scanning Exposure control Exposure priority Exposure zones Dynamic range Backlight compensation Installing a network camera What is a video encoder? Video encoder components and considerations Event management and intelligent video Standalone video encoders Rack-mounted video encoders Video encoders with analog PTZ cameras Deinterlacing techniques Video decoder 37 38 38 40 41 41 42 44 45 46 48 48 48 49 49 50 50 51 51 55 56 57 58 58 59 60 60 Protection and ratings 63 External housings 64 Transparent coverings 65 Positioning a fixed camera in a housing 66 Vandal and tampering protection 66 Vandal-resistant ratings 66 Camera/housing design 66 Mounting67 Camera placement 67 Intelligent video 67 Types of mounting 68 Ceiling mounts 68 Wall mounts 68 Pole mounts 68 Parapet mounts 69 5 6. 6.1 6.2 6.3 6.4 7. 7.1 7.1.1 7.1.2 7.2 7.2.1 7.2.2 7.2.3 7.3 7.4 8. 8.1 8.2 8.3 8.3.1 8.3.2 8.3.3 8.4 8.5 8.5.1 8.5.2 8.5.3 8.6 9. 9.1 9.1.1 9.1.2 9.1.3 9.2 9.2.1 9.2.2 9.2.3 9.2.4 9.3 9.4 9.5 9.5.1 9.5.2 9.5.3 9.5.4 9.5.5 Video resolutions 71 Video compression 75 NTSC and PAL resolutions VGA resolutions Megapixel resolutions High-definition television (HDTV) resolutions 71 72 73 74 Compression basics 75 Video codec 75 Image compression vs. video compression 76 Compression formats 79 Motion JPEG 79 MPEG-479 H.264 or MPEG-4 Part 10/AVC 80 Variable and constant bit rates 81 Comparing standards 81 Audio83 Audio applications 83 Audio support and equipment 83 Audio modes 85 Simplex85 Half duplex 86 Full duplex 86 Audio detection alarm 86 Audio compression 86 Sampling frequency 87 Bit rate 87 Audio codecs 87 Audio and video synchronization 87 Network technologies 89 Local area network and Ethernet 89 Types of Ethernet networks 90 Connecting network devices and network switch 91 Power over Ethernet 92 Sending data over the Internet 95 IP addressing 96 IPv4 addresses 96 IPv6 addresses 99 Data transport protocols for network video 100 VLANs102 Quality of Service 102 Network security 104 User name and password authentication 104 IP address filtering 104 IEEE 802.1X 104 HTTPS or SSL/TLS 105 VPN (Virtual Private Network) 105 6 10. 10.1 10.2 10.2.1 10.2.2 10.2.3 10.3 10.4 11. 11.1 11.1.1 11.1.2 11.1.3 11.1.4 11.2 11.2.1 11.2.2 11.2.3 11.2.4 11.2.5 11.2.6 11.2.7 11.3 11.3.1 11.3.2 11.3.3 11.3.4 11.3.5 12. Wireless technologies 107 Video management systems 111 802.11 WLAN standards 107 WLAN security 108 WEP (Wired Equivalent Privacy) 108 Wi-Fi Protected Access 108 Recommendations109 Wireless bridges 109 Wireless mesh network 109 Types of video management solutions 111 Decentralized solution for small systems - AXIS Camera Companion 112 Hosted video solution for businesses with many small sites 113 Centralized, general client-server solution for medium-sized systems - AXIS Camera Station 114 Customized solutions for small to big systems from Axis’ partners 115 System features 115 Viewing116 Multi-streaming116 Video recording 117 Recording and storage 118 Event management and intelligent video 118 Administration and management features 121 Security123 Integrated systems 123 Point of Sale 123 Access control 124 Building management 124 Industrial control systems 125 RFID125 12.1 12.1.1 12.1.2 12.2 12.2.1 12.3 12.4 12.5 12.6 Bandwidth and storage calculations Bandwidth needs Calculating storage needs Edge storage Edge storage with SD cards or NAS Server-based storage NAS and SAN Redundant storage System configurations Bandwidth and storage considerations 127 13. Tools and resources 137 14. Axis Communications’ Academy 139 127 127 128 130 131 131 131 133 133 Chapter 1 - Network video: overview, benefits and applications 7 1. Network video: overview, benefits and applications Network video, like many other kinds of communications such as e-mail, web browsing and computer telephony, is conducted over wired or wireless IP (Internet Protocol) networks. Digital video and audio streams, as well as other data, are communicated over the same network infrastructure. Network video provides users, particularly in the security surveillance industry, with many advantages over traditional analog CCTV (closed-circuit television) systems. This chapter provides an overview of network video, as well as its benefits and applications in various industry segments. Comparisons with an analog video surveillance system are often made to provide a better understanding of the scope and potential of a digital, network video system. 1.1 Overview of a network video system Network video, often also called IP-based video surveillance or IP surveillance as it is applied in the security industry, uses a wired or wireless IP network as the backbone for transporting digital video, audio and other data. When Power over Ethernet (PoE) technology is applied, the network can also be used to carry power to network video products. A network video system allows video to be monitored and recorded from anywhere on the network, whether it is, for instance, on a local area network (LAN) or a wide area network (WAN) such as the Internet. 8 Chapter 1 - Network video: overview, benefits and applications Axis network cameras Axis video encoders PS1 NETWORK PS2 ACTIVITY 1 2 3 4 0 - FANS LOOP IP NETWORK INTERNET Power-one FNP 30 100-240 AC 50-50 Hz 4-2 A AC 0 - Power-one FNP 30 AXIS Q7900 Rack 100-240 50-50 Hz 4-2 A AC POWER POWER AXIS Q7406 Video Encoder Blade AXIS Q7406 Video Encoder Blade Computer with video management software Remote access from office/home computer with web browser Analog cameras Figure 1.1a A network video system comprises many different components, such as network cameras, video encoders and video management software. The other components including the network, storage and servers are all standard IT equipment. The core components of a network video system consist of the network camera, the video encoder (used to connect analog cameras to an IP network), the network, the server and storage, and video management software. As the network camera and the video encoder are computerbased equipment, they have capabilities that cannot be matched by an analog CCTV camera. The network camera, the video encoder and the video management software are considered the cornerstones of an IP surveillance solution. The network, the server and storage components involve standard IT equipment. The ability to use common off-the-shelf equipment is one of the main benefits of network video. Other components of a network video system include accessories, such as mountings, PoE midspans and joysticks. Each network video component is covered in more detail in other chapters. 1.2 Benefits A fully digital, network video surveillance system provides a host of benefits and advanced functionalities that cannot be provided by a traditional analog video surveillance system. The advantages include high image quality, remote accessibility, event management and intelligent video capabilities, easy integration possibilities and better scalability, flexibility and costeffectiveness. > High image quality: In a video surveillance application, high image quality is essential to be able to clearly capture an incident in progress and identify persons or objects involved. With progressive scan and HDTV/megapixel technologies, a network camera can deliver better image quality and higher resolution than an analog camera. For more on image quality, see chapters 2, 3 and 6. Chapter 1 - Network video: overview, benefits and applications 9 Image quality can also be more easily retained in a network video system than in an analog surveillance system. With today’s analog systems that use a digital video recorder (DVR) as the recording medium, many analog-to-digital conversions take place: first, analog signals are converted to digital in the camera and then back to analog for transportation; then the analog signals are digitized for recording. Captured images are degraded with every conversion between analog and digital formats and with the cabling distance. The further the analog video signals have to travel, the weaker they become. In a fully digital IP surveillance system, images from a network camera are digitized once and they stay digital with no unnecessary conversions and no image degradation due to distance traveled over a network. > Remote accessibility: Network cameras and video encoders can be configured and accessed remotely, enabling multiple, authorized users to view live and recorded video at any time and from virtually any networked location in the world. This is advantageous if users would like a third-party company, such as an alarm monitoring center or law enforcement, to also gain access to the video. > Event management and intelligent video: There is often too much video recorded and lack of time to properly analyze them. Network video products can address this problem in a few ways. Network cameras and video encoders, for instance, can be programmed to send videos for recording only when an event, whether scheduled or triggered, occurs. This would reduce the amount of uninteresting recordings. Video recordings can also be tagged with certain information called metadata to make it easier to search for and analyze videos that are of interest. Axis network video products support intelligent video functionalities (for example, video motion detection, active tampering alarm, audio detection, tripwire and third-party applications such as people counting and heat mapping). They may also provide I/O (input/output) connections to external devices such as lights. These features allow users to define the conditions or event triggers for an alarm. When an event is met, the products can automatically respond with programmed actions. Configurable actions may include video recording to one or more sites, whether local and/or off-site for security purposes; activating external devices such as alarms, lights and door position switches; and sending notification messages to users. Event management functionalities can be configured using the network video product’s web pages or using a video management software program. For more on video management, see Chapter 11. Chapter 1 - Network video: overview, benefits and applications 10 Figure 1.2a Setting up an event trigger using the network video product’s web page. > Easy, future-proof integration: Network video products based on open standards can be easily integrated into a wide array of video management systems. Video from a network camera can also be integrated into other systems such as point of sales, access control or a building management system. An analog system, on the other hand, rarely has an open interface for easy integration with other systems and applications. For more on integrated systems, see Chapter 11. > Scalability and flexibility: A network video system can grow with a user’s needs—one camera at a time, while analog systems can often only grow in steps of four or 16 at a time. IP-based systems provide a means for network video products and other types of applications to share the same wired or wireless network for communicating data. Video, audio, PTZ and I/O commands, power and other data can be carried over the same cable and any number of network video products can be added to the system without significant or costly changes to the network infrastructure. This is not the case with an analog system. In an analog video system, a dedicated cable (normally coax) must run directly from each camera to a viewing/ recording station. Separate pan/tilt/zoom (PTZ) and audio cables may also be required. Network video products can also be placed and networked from virtually any location, and the system can be as open or as closed as desired. Since a network video system is based on standard IT equipment and protocols, it can benefit from those technologies as the system grows. For instance, video can be stored on redundant servers placed in separate locations to increase reliability, and tools for automatic load sharing, network management and system maintenance can be used—none of which is possible with analog video. >Cost-effectiveness: An IP surveillance system typically has a lower total cost of ownership than a traditional analog CCTV system. An IP network infrastructure is often already in place and used for other applications within an organization, so a network video application can piggyback off the existing infrastructure. IP-based networks and wireless options are Chapter 1 - Network video: overview, benefits and applications 11 also much less expensive alternatives than traditional coaxial and fiber cabling for an analog CCTV system. In addition, digital video streams can be routed around the world using a variety of interoperable infrastructure. Management and equipment costs are also lower since back-end applications and storage run on industry standard, open systems-based servers, not on proprietary hardware such as a DVR in the case of an analog CCTV system. A network video system may also provide insights into ways of improving a business. For example, in retail applications, implementing network video analytics may help improve customer flow and enhance sales. Furthermore, network video products can support Power over Ethernet technology. PoE enables networked devices to receive power from a PoE-enabled switch or midspan through the same Ethernet cable that transports data (video). There is, therefore, no need for a power outlet right at the camera location. PoE provides substantial savings in installation costs and can increase the reliability of the system. For more on PoE, see Chapter 9. Network camera with built-in PoE 3115 Network camera without built-in PoE Uninterruptible Power Supply (UPS) PoE-enabled switch Power Ethernet Active splitter Power over Ethernet Figure 1.2b A system that uses Power over Ethernet. > Secure communication: Network video products as well as the video streams can be secured in many ways. They include user name and password authentication, IP address filtering, authentication using IEEE 802.1X, and data encryption using HTTPS (SSL/TLS) or VPN. There is no encryption capability in an analog camera and no authentication possibilities. Anyone can tap into the video or replace the signal from an analog camera with another video signal. Network video products also have the flexibility to provide multiple user access levels. For more on network security, see chapters 9 and 10. Existing analog video installations, however, can migrate to a network video system and take advantage of some of the digital benefits with the help of video encoders and such devices as Ethernet over coax adapter, which makes use of legacy coax cables. For more on video encoders and decoders, see Chapter 4. Chapter 1 - Network video: overview, benefits and applications 12 1.3 Applications Network video can be used in an almost unlimited number of applications. Most of its uses fall under security surveillance or remote monitoring of people, places, property and operations. Increasingly, network video is also being used to improve business efficiency as the number of intelligent video applications grows. The following are some typical application possibilities in key industry segments. 1.3.1 Retail Network video systems in retail stores can significantly reduce theft, improve staff security and optimize store management. A major benefit of network video is that it can be integrated with a store’s EAS (electronic article surveillance) system or a POS (point of sale) system to provide a picture and a record of shrink-related activities. The system can enable rapid detection of potential incidents, as well as any false alarms. Network video offers a high level of interoperability and gives the quickest return on investment. Network video, together with intelligent video applications, can help identify the most popular areas of a store and provide a record of consumer activity and buying behaviors that will help optimize the layout of a store or display. It can also count the number of people entering and exiting a store to help, for instance, in staff planning and show when more cash registers need to be opened because of long queues. 1.3.2 Transportation Network video helps to protect passengers, staff and assets in all modes of transport. Within public transportation, all security cameras— from stations, terminals, buses, trains and tunnels—can be connected to a security center. When an incident occurs, security operators can view live video from the relevant cameras to quickly decide on the appropriate action. At airports, network video is also becoming a tool that is used to increase the efficiency of a wide range of services in areas such as parking, retail, check-in, catering services and security control. Harbors and logistics terminals benefit from network video’s built-in detection capabilities, which can automatically alert security staff when a perimeter is breached. Network video can also be used to monitor traffic conditions to reduce congestion and enable quick response to accidents. A wide variety of Axis network cameras meet tough indoor and outdoor conditions. For onboard vehicles such as buses and trains, Axis offers network cameras that can withstand varying temperatures, humidity, dust, vibrations and vandalism. Chapter 1 - Network video: overview, benefits and applications 13 1.3.3 Banking and finance Banks have been using video surveillance for a long time, and while most installations are still analog, network video is commonly used for new and retrofit installations. This enables a bank to efficiently monitor its headquarters, branch offices and ATM machines from a central location. The system can be equipped with intelligent capabilities that automatically send alerts for ATM fraud attempts such as skimming, card jamming or cash trapping. All video can be recorded in HDTV quality, providing detailed images of persons and objects that facilitate investigations and positive identification. 1.3.4 City surveillance Network video is one of the most useful tools for fighting crime and protecting citizens. It can be used to detect and deter. The use of wireless networks has enabled effective city-wide deployment of network video. Installation costs can be greatly reduced with network cameras that offer quick and reliable installation features, including the ability to focus and configure cameras remotely over the network. The remote surveillance capabilities of network video have enabled police to respond quickly to crimes being committed in live view. 1.3.5 Education From daycare centers to universities, network video systems help to deter vandalism and increase the safety of staff and students. They allow efficient monitoring of all indoor and outdoor facilities and provide high quality images that enable positive identification of persons and objects. In addition, network cameras can generate automatic alarms. For example, if a camera is tampered with, or if there is noise or motion in a building during off hours, real-time images can be sent to security staff. Network video can also be used for remote learning, for example, for students who are unable to attend lectures in person. The system can be easily connected to an existing network infrastructure, thus keeping installation and maintenance costs down. 1.3.6 Government Network video can be used by law enforcement, military and border control. It is also an efficient means to secure all kinds of public buildings, from museums and libraries to court buildings and prisons. Cameras placed at building entrances and exits can record who comes in and out, 24 hours a day. They can be used to prevent vandalism and increase security for staff and visitors. Chapter 1 - Network video: overview, benefits and applications 14 1.3.7 Healthcare Network video enables hospitals and healthcare facilities to improve the overall safety and security of staff, patients and visitors. In case of alarms, authorized security and hospital staff can view live video from critical areas such as emergency rooms, psychiatric departments and medical supply rooms to quickly get a clear view of the situation. Network video also enables high-quality patient monitoring, remote care from specialists and remote learning. 1.3.8 Industrial Network video is not only an efficient tool to secure perimeters and premises, it can also be used to monitor and increase efficiencies in manufacturing lines, processes and logistic systems. In hazardous or cleanroom areas, remote monitoring shortens troubleshooting and response times. For industries with multiple production sites, network video can greatly reduce the amount of travel required for technical support issues. 1.3.9 Critical infrastructure Whether it is a solar plant, an electrical substation or a waste management facility, network video can help ensure safe, secure and uninterrupted activity everyday. Production data from remote sites can be enhanced with visual information. IP-based surveillance systems enable new security and business possibilities for all industry segments. Learn more from Axis case studies at www.axis.com/success_stories/ Chapter 2 - Network cameras 15 2. Network cameras A wide range of network cameras are available today to meet a variety of needs in terms of form, use, light sensitivity, resolution and environmental considerations. This chapter provides a description of what a network camera is, the different options and features that it may have, and the different types of cameras available: fixed cameras, fixed domes, covert cameras, PTZ (pan/tilt/zoom) and thermal cameras. A camera selection guide is included at the end of the chapter. For more on camera elements, see Chapter 3. 2.1 What is a network camera? A network camera, often also known as an IP camera, is used primarily to send video/audio over an IP network such as a local area network (LAN) or the Internet. A network camera enables live viewing and/or recording, either continuously, at scheduled times, on request or when triggered by an event. Video can be saved locally and/or at a remote location, and authorized access to video can be made wherever there is access to an IP network. LAN Axis network camera LAN/Internet PoE switch Computer with video management software Figure 2.1a A network camera connects directly to the network. A network camera can be described as a camera and computer combined in one unit. The main components of a network camera include a lens, an image sensor, one or several processors, and memory. The processors are used for image processing, compression, video analysis and networking functionalities. The memory is used mainly for storing the network camera’s firmware (computer program), but also to store video for shorter or longer periods of time. Chapter 2 - Network cameras 16 Like a computer, the network camera has its own IP address, is connected directly to a wired or wireless network and can be placed wherever there is a network connection. This differs from a web camera, which can only operate when it is connected to a personal computer (PC) via the USB or IEEE 1394 port, and to use it, software must be installed on the PC. A network camera provides web server, FTP (File Transfer Protocol), e-mail functionalities, and includes many other IP network and security protocols. In addition to capturing video, Axis network cameras provide event management and intelligent video functionalities such as video motion detection, audio detection, active tampering alarm and autotracking. Many network cameras also offer input/output (I/O) ports that enable connections to external devices such as motion sensors and relays (for controlling, for instance, the locking/unlocking of doors). Event management is about defining an event that is triggered either from features in the network video products or from other systems, and configuring the products or the system to automatically respond to the event by, for example, recording video, sending alert notifications and activating different devices such as doors and lights. Users can configure network video products to only record when an event is triggered. In this way, event management enables a surveillance system to more efficiently use network bandwidth and storage space. Other network camera features may include audio capabilities, built-in support for Power over Ethernet (PoE), and a memory card slot for local storage of recordings. Axis network cameras also support advanced security and network management features. Zoom puller P-Iris lens Internal microphone Memory card slot Focus puller Iris connector Power connector Figure 2.1b Front, back and underside of a network camera. Audio in Audio out Network connector PoE RS-485/422 connector I/O terminal block Chapter 2 - Network cameras 17 Network cameras can be accessed over the network by entering the product’s IP address in the Address/Location field of a computer’s web browser. Once a connection is made with the network video product, the product’s ‘start page’, along with links to the product’s configuration pages, is automatically displayed in the web browser. The built-in web pages of Axis network video products enable users to, among many things, define user access, configure camera settings, set the resolution, frame rate and compression format (H.264/Motion JPEG), as well as action rules for when an event occurs. Managing a network video product through its built-in web pages works when only a few cameras are involved in a system. For professional installations or systems with many cameras, the use of a video management solution, in combination with the cameras’ built-in web pages, is recommended. For more on video management solutions, see Chapter 11. Axis network cameras also support a host of accessories that extend the cameras’ abilities. For example, network cameras can be connected to a fiber optic network using a media converter switch or to coax cables using an Ethernet over coax adapter with support for Power over Ethernet. 2.1.1 AXIS Camera Application Platform Most Axis network video products support AXIS Camera Application Platform, which enables compatible applications—typically intelligent video applications—that are accessible from Axis’ website to be downloaded to the products. It allows the products to boost their intelligent video capabilities with applications either from Axis or from third-party suppliers of video analytics. An example of such an application is AXIS Cross Line Detection, which is a tripwire application that detects and triggers an event when moving objects cross a virtual line. Figure 2.1c AXIS Cross Line Detection is well suited for many situations, including video monitoring of building entrances, loading docks and parking lots. Chapter 2 - Network cameras 18 2.1.2 Application programming interface All Axis network video products have an application programming interface (API) called VAPIX®. VAPIX enables developers to easily integrate Axis video products and their built-in functionalities in software solutions. VAPIX also enables an Axis camera with an upgraded firmware to be backward compatible with, for example, an existing video management system. 2.1.3 ONVIF Most of Axis’ network video products are ONVIF conformant. ONVIF, which is a global, open industry forum founded by Axis, Bosch and Sony in 2008, works to standardize the network interface of network video products of different manufacturers to ensure greater interoperability. It gives users the flexibility to use ONVIF conformant products from different manufacturers in a multi-vendor network video system. ONVIF has rapidly gained momentum and is today endorsed by the majority of the world’s largest manufacturers of IP video products. ONVIF now has more than 400 member companies involved. For more information, visit www.onvif.org 2.2 Camera features for handling difficult scenes Security cameras face many challenges that affect their ability to provide quality video for effective surveillance. Scenes may have changing and wide ranging light levels, and conditions such as complete darkness, haze and smoke may present problems to getting usable video. To address these scenarios, cameras may be equipped with a variety of features (see list below) that are important to consider as they have an impact on image quality. 2.2.1 Lens’ light gathering ability (f-number) Camera lenses with a small f-number have better light gathering ability. In general, the smaller the f-number, the better its performance in low-light settings. Sometimes a higher f-number is preferable for handling some types of lighting. A camera’s light sensitivity depends not only on its lens, but also on the image sensor and image processing. More details on lenses and image sensors are covered in Chapter 3. 2.2.2 Iris Lenses with a manually adjustable iris are suitable for scenes with a constant light level. For scenes with changing light levels, an automatically adjustable iris (DC-iris/P-Iris) is recommended to provide the right level of exposure. Cameras with P-Iris enable better iris control for optimal image quality in all lighting conditions. More details are covered in Chapter 3. 2.2.3 Day/night functionality A network camera with day/night functionality has an automatically removable infrared-cut filter. The filter is on during daytime, enabling the camera to produce colors as the human eye sees them. At night, the filter is removed to enable the camera to take advantage of near infrared light and produce good quality, black and white images. This is one way of extending a network camera’s usefulness in low-light conditions. Chapter 2 - Network cameras 19 Figure 2.2a At left, an image in Day mode. At right, an image in Night mode. 2.2.4 Infrared (IR) illuminators In low light or complete darkness, built-in IR LEDs in a camera or a separately installed infrared illuminator will strengthen a camera’s ability to use near infrared light to deliver quality black and white images. Near infrared light from the moon, street lamps or IR illuminators is not visible to the human eye, but a camera’s image sensor can detect it. (Near infrared light is just beyond the visible part of the light spectrum and has longer wavelengths than visible light.) IR illuminators provide different illumination distances. The illumination with built-in IR LEDs in Axis cameras can be adjusted to match the viewing angle and can be activated automatically in darkness, upon an event or on request from a user. Axis cameras with built-in IR LEDs simplify installation and provide a cost-effective option. External IR illuminators, meanwhile, give installers the flexibility to choose the IR illuminator—for instance, a long range one—and place the light where it is needed and not necessarily at the same location as the camera. Figure 2.2b At left, Night mode image without the use of IR illuminators (whereby the camera made use of the small amount of light coming underneath a door in the left-hand corner of the room). At right, Night mode image with IR illuminators. Chapter 2 - Network cameras 20 2.2.5 Lightfinder technology Cameras with Axis’ Lightfinder technology have extreme light sensitivity. Such cameras can deliver color images in as little light as 0.18 lux or lower. This is achieved through the optimal selection of the image sensor and lens, Axis’ image processing know-how and in-house ASIC chip development. For more details, see the Lightfinder white paper at www.axis.com/corporate/ corp/tech_papers.htm Figure 2.2c Scene (with 0.4 lux of illumination at the back wall) shown at left using a camera that has switched over to Night mode, and at right using a camera with Lightfinder technology, which is still functioning in Day mode, providing a color image and details such as the box on the floor at the back wall. 2.2.6 Resolution/Megapixel A camera’s resolution is defined by the number of pixels in an image provided by an image sensor.Depending on the lens used, the resolution can mean either more details in an image or a wider field of view to cover a larger area of a scene. Cameras with megapixel sensors offer images with one million or more pixels. When using a wide viewing angle, it can provide a wider area of coverage than a non-megapixel camera. When using a narrow viewing angle, it can enable viewers to see greater details, which would be helpful in identifying people and objects. Cameras supporting HDTV 720p (1280x720 pixels) and HDTV 1080p (1920x1080 pixels), which are approximately 1 and 2 megapixels, respectively, are gaining popularity since they follow standards that guarantee full frame rate, high color fidelity and a 16:9 aspect ratio. For more details about image sensors and resolution, see Chapter 3 and 6, respectively. 2.2.7 Exposure control settings When the level of lighting changes, Axis cameras automatically adjust to ensure optimal exposure. The cameras also give users the option of modifying various exposure control settings in challenging situations. For example, in low light situations, users can increase gain to enable more details to be seen. The downside is that noise may be more visible. In low light, users can also increase the exposure time to get a brighter image but this may lead to smearing of moving objects. Exposure zones may also be available, enabling users to set the area of an image that should be more properly exposed. Backlight compensation is another technique that can be used in a camera to enable objects in dark areas to be visible against a very bright background (e.g., in front of a window/entrance). Chapter 2 - Network cameras 21 2.2.8 Wide dynamic range (WDR) For surveillance scenes with very bright and dark areas, such as at entrance doors in a retail/ office environment, entrance way to an indoor parking garage or tunnel, or at train platforms, a camera with wide dynamic range may provide the best solution. WDR cameras often incorporate an image sensor that takes different exposures of a scene (e.g., a short exposure for very bright areas and long exposure for dark areas) and combine them into one image, enabling objects in both bright and dark areas of a scene to be visible. For more details, see the WDR white paper at www.axis.com/corporate/corp/tech_papers.htm Figure 2.2d At left, image from a conventional camera. At right, image with a WDR camera. 2.2.9 Thermal radiation Besides the use of sunlight, artificial light and near infrared light, there is thermal radiation, which can be used to generate images. A thermal network camera requires no light source. Instead it detects thermal radiation emitted from every object with a temperature above zero degrees Kelvin. The hotter the object, the greater the radiation. Greater temperature differences produce higher contrast thermal images. Thermal network cameras can be used to detect subjects in complete darkness or under other challenging conditions such as smoke or light fog, or when subjects are hiding in shadows or obscured by a complex background. Such cameras are also not blinded by strong lights. Thermal cameras are ideal for detection purposes and can be used to complement conventional cameras to enhance the effectiveness of a surveillance system. Figure 2.2e At left, image from a conventional camera. At right, image from a thermal camera. Chapter 2 - Network cameras 22 2.3 Camera features for ease of installation Axis network cameras incorporate features that make the products easy to install and use, as well as more reliable by minimizing installation errors. They include the following. 2.3.1 Outdoor-ready Outdoor-ready products are ready right out of the box for installation outdoors. No separate housing is required. The products are designed to meet a range of operating temperatures and offer protection against dust, rain and snow. Some even meet military standards for operation in harsh climates. 2.3.2 Focused at delivery To make installation quicker and simpler, Axis cameras with a fixed focal lens are focused at the factory, which eliminates the need to focus them at the installation site. This is possible since fixed focal cameras with a wide or mid-range field of view usually have a wide depth of field (the range where near and far objects are in focus). For an explanation about focal length, f-number and depth of field, see Chapter 3. 2.3.3 Remote focus and zoom A varifocal camera with remote focus and zoom eliminates the need for manual focusing and field of view adjustment at the camera location. The camera, together with the lens motor, allows the focus and viewing angle to be remotely controlled and adjusted from a computer on the network. 2.3.4 Remote back focus A CS-mount varifocal camera with remote back focus allows the focus to be fine-tuned remotely from a computer by enabling the image sensor to move. This functionality works even with optional lenses. 2.3.5 3-axis camera angle adjustment Axis’ fixed dome cameras are designed with a 3-axis camera angle adjustment that allows the lens holder (comprising the lens and image sensor) to pan, tilt and rotate. This enables the cameras to be mounted on a wall or ceiling. Users can then easily adjust the cameras’ direction and level the image. The flexibility of the camera adjustment, together with the ability to rotate the image using the cameras’ web page, enables users to get vertically oriented video streams (Axis’ Corridor Format). Figure 2.3a 3-axis camera angle adjustment. Chapter 2 - Network cameras 23 2.3.6 Corridor Format Axis’ Corridor Format enables a fixed/fixed dome camera to provide a vertically oriented video stream. The vertical format optimizes the coverage of areas such as corridors, hallways and aisles, maximizing image quality while eliminating bandwidth and storage waste. It enables, for example, HDTV network cameras to deliver video with a 9:16 aspect ratio. With a fixed dome, it is achieved first by rotating the 3-axis lens 90° (or with a fixed camera, by positioning it on its side), and then rotating the video image back 90° in the camera’s web page. Figure 2.3b A display of camera views using Axis’ Corridor Format. 2.3.7 Pixel counter Axis’ pixel counter helps ensure that the video resolution has sufficient video quality to meet goals such as facial identification. It can be used to verify that the pixel resolution of an object fulfills regulatory or customer requirements. Figure 2.3c Axis’ pixel counter is a visual aid shaped as a frame with a corresponding counter to show the box’s width and height. The pixel counter helps verify, for instance, that the pixel resolution of a face is enough for facial identification. Chapter 2 - Network cameras 24 2.4 Types of network cameras Network cameras can be classified in terms of whether they are designed for indoor use only or for indoor and outdoor use. An outdoor camera requires an external, protective housing unless the camera design already incorporates a protective enclosure. For more on environmental protection, see Chapter 5. Network cameras, whether for indoor or outdoor use, can be further categorized into fixed, fixed dome, covert, PTZ and thermal network cameras. 2.4.1 Fixed network cameras Figure 2.4a Fixed network cameras, including models with features such as wireless, built-in IR illuminators, HDTV/multi-megapixel, WDR, Lightfinder, outdoor-ready and vandal-resistant design. A fixed network camera is a camera that has a fixed viewing direction once it is mounted. It may come with a fixed, varifocal or motorized zoom lens, and the lens may be exchangeable on some cameras. A fixed camera is the traditional camera type where the camera and the direction in which it is pointing are clearly visible. This type of camera represents the best choice in applications where it is advantageous to make the camera very noticeable. Fixed cameras can be installed in protective enclosures. Axis’ outdoor fixed cameras come pre-installed in housings. Fixed cameras can also be mounted on a pan/tilt motor for greater viewing flexibility. 2.4.2 Fixed dome network cameras Figure 2.4b Fixed dome network cameras, including models with features such as panoramic view, HDTV/multimegapixel, built-in IR illuminators, WDR, Lightfinder, outdoor-ready and vandal-resistant design. A fixed dome network camera is a fixed camera in a dome design. It may come with a fixed, varifocal or motorized zoom lens, and the lens may be exchangeable on some cameras. Chapter 2 - Network cameras 25 The camera can be directed to point in any direction. Its main benefit lies in its discreet, non-obtrusive design, as well as in the fact that it is hard to see in which direction the camera is pointing. The camera is also tamper resistant. Axis’ fixed dome cameras provide different types and levels of protection such as vandal- and dust-resistance, and IP66 and NEMA 4X ratings for outdoor installations. The cameras can be mounted on a wall, ceiling or pole. A fixed dome with a wide-angle lens and a megapixel sensor that provides a 360° field of view is often known as a panoramic or 360° camera. Figure 2.4c An Axis 5-megapixel 360° fixed dome camera offers multiple viewing modes such as 360° overview, panorama, view area with digital PTZ and quad view. 2.4.3 Functionalities in multi-megapixel fixed and fixed dome cameras Multi-megapixel fixed and fixed dome cameras are becoming more common. While the multimegapixel resolution offers advantages, as described earlier, it also presents challenges to bandwidth and storage requirements. However, functionalities have been developed to use such cameras in innovative ways that help reduce bandwidth and storage needs. Some functionalities that Axis’ multi-megapixel cameras can support are described over on the next page. Chapter 2 - Network cameras 26 > Digital PTZ: Since a multi-megapixel camera can cover a large area, the camera may enable digital pan/tilt/zoom capability with preset positions. > AXIS Digital Autotracking: This application, when installed in an Axis multi-megapixel camera, aims to reduce bandwidth and storage requirements particularly in low-traffic surveillance situations where it is unnecessary to continuously send the camera’s full view at maximum resolution. AXIS Digital Autotracking enables the camera to automatically detect movement its field of view and stream the part of the view where there is activity. The cropped viewing area zeroes in on and follows moving objects with no loss in image quality. As the application will not lock on a single object, the view can “zoom out” to cover moving objects in different areas of the camera’s field of view, ensuring that no incidents are missed. When there is no movement, a scaled-down overview of the camera’s full view is streamed. While the size of the video streams is reduced, the video quality of zoomed-in views is maintained using the camera’s original pixel resolution. Depending on the scenario, AXIS Digital Autotracking—in SVGA (800x600) resolution at 30 frames per second—can reduce bandwidth/storage use by approximately 90% compared with a continuous 2-megapixel video stream at 30 frames per second. Correspondingly, a digital autotracking stream in VGA (640x480) at 12 frames per second can reduce by approximately 95% compared with a continuous 5-megapixel videostream at 12 frames per second. Figure 2.4d At left, a scaled down 5-megapixel image. At right, AXIS Digital Autotracking provides a cropped VGA view—with no loss in image quality—of the area where there is activity. > Multi-view streaming: This functionality allows several cropped view areas from a multi megapixel camera to be streamed simultaneously, simulating up to eight virtual cameras. Each stream can be individually configured. The streams, for instance, can be sent at different frame rates for live viewing or recording. Multi-view streaming gives users the ability to reduce bandwidth and storage use while being able to cover a large area with just one camera. Chapter 2 - Network cameras 27 Figure 2.4e One multi-megapixel camera. Full overview enabling cropped view areas. Multiple virtual camera views (up to eight views possible). 2.4.4 Covert network cameras Covert cameras are designed to blend into the environment and be virtually impossible to discover. They can be placed at eye-level at entrances or integrated into things such as ATM machines for discreet or covert surveillance. They can enable close-up shots for identification purposes or overview surveillance. Tampering risks are also reduced. Using a pin-hole lens, Axis’ indoor/outdoor covert network cameras provide resolutions of up to 1 MP, including HDTV 720p, and come pre-mounted with an Ethernet cable for both power and data. The cameras are ideal for use in retail stores, banks and hospitals. Main unit with various connectors Sensor unit (lens and image sensor) Figure 2.4f Covert cameras, such as an AXIS P12 Network Camera pictured above, blend easily into a variety of environments. The sensor unit can be integrated into very small spaces, such as behind a thin metal sheet in a doorway, behind any wall, in an ATM machine or in a special casing. The main unit can be placed up to 8 m (26 ft.) away. Figure 2.4g Covert cameras in AXIS P85 Network Camera Series, which are pre-mounted for eye-level placement, provide discreet surveillance and the best angle of view for facial identification compared with ceiling-mounted cameras. Chapter 2 - Network cameras 28 2.4.5 PTZ network cameras Figure 2.4h PTZ network cameras including HDTV and outdoor-ready models, as well as (at far right) a dual PTZ camera that combines both a visual (conventional) and thermal camera in one unit for mission-critical surveillance. A PTZ camera provides pan, tilt and zoom functions (using manual or automatic control), enabling wide area coverage and great details when zooming in. An Axis PTZ camera usually has the ability to pan 360°, tilt 180° or 220°, and is often equipped with a zoom lens. (A zoom lens provides an optical zoom that maintains image resolution, as opposed to a digital zoom, which enlarges an image with loss in image quality.) PTZ commands are sent over the same network cable as for video transmission (no need for RS-485 wires as is the case with an analog PTZ camera). PTZ cameras with support for Power over Ethernet (PoE/PoE+/High PoE) also do not require separate power cables, unlike an analog PTZ camera. PTZ cameras can come in various form factors; the most common is a PTZ dome, which is ideal for use in discreet installations due to its design, mounting (particularly in indoor, drop-ceiling mounts), and difficulty in seeing the camera’s viewing angle. In outdoor installations, the cameras are usually mounted on poles or walls of a building. In operations with live monitoring, PTZ cameras can be used to follow a person or object, and zoom in for closer inspection. In unmanned operations, automatic guard tour on PTZ cameras can be used to monitor different areas of a scene. In guard tour mode, one PTZ network camera can cover an area where many fixed network cameras would be needed. The main drawback is that only one location can be monitored at any given time. Axis’ high-end PTZ domes offer high-speed endless pan, tilt and zoom, and provide mechanical robustness for continuous operation in guard tour mode. PTZ domes with a mechanical stop incorporate Axis’ Auto-flip functionality to enable them to pan 360°. 29 Chapter 2 - Network cameras 0.75:1 Figure 2.4i At left, wide view and at right, 20x zoomed-in view with an HDTV 1080p PTZ dome, enabling texts on the cargo ship to be read 1.6 km (1 mile) away from the camera. 0.75:1 Figure 2.4j At left, wide view and at right, 20x zoomed-in view with an HDTV 1080p PTZ dome, enabling the license plate to be read 275 m (900 ft.) away from the camera. It is worth noting that an HDTV camera with a lower zoom factor may be able to provide the same level of detail in zoomed-in views as a lower resolution camera with a higher zoom. This was illustrated when comparing an 18x zoom, HDTV 720p Axis camera with a 4CIF, 36x zoom camera. For details, see whitepaper on 18x vs. 36x zoom at www.axis.com/corporate/corp/ tech_papers.htm PTZ domes are not limited to high-end installations. Using Axis’ palm-sized, ceiling-mount PTZ cameras, price-sensitive installations such as retail stores have the flexibility to easily change where the cameras are pointing and use them as tools to improve store management as well as secure premises. Another innovative product from Axis combines an HDTV PTZ dome camera with a wide-angle lens converter that provides a 360° field of view. AXIS P5544 PTZ Dome Network Camera can switch between a 360° field of view for overview surveillance, and pan, tilt and zoom in with a separate lens for close-up views in HDTV resolution and with no loss in image quality. This kind of camera is ideal for live monitoring applications. Chapter 2 - Network cameras 30 Figure 2.4k With the ability to cover a 360° field of view and mechanically pan, tilt and zoom in with no loss in image quality, AXIS P5544 can cover an area more than 950 m² (10,000 sq. ft.). The above left image shows the live view in Overview mode (with a digital magnifier in the corner) and at right, the zoomed-in view in Normal mode. Some of the features that can be incorporated in a PTZ camera include: > 3D privacy masking. 3D privacy masking, which is supported in most Axis PTZ cameras, enables selected areas of a scene to be blocked or masked from viewing and recording. It allows masking to be maintained even as the camera’s field of view changes through panning, tilting and zooming since the masking moves with the camera’s coordinate system. Figure 2.4l With built-in privacy masking (gray rectangles in image), the camera can guarantee privacy for areas that should not be covered by a surveillance application. > E-flip. When a PTZ camera is mounted on a ceiling and is used to follow a person in, for example, a retail store, there will be situations when a person will pass just under the camera. When following through on the person, images would be seen upside down without the E-flip functionality. E-flip electronically rotates images 180° in such cases. It is performed automatically and will not be noticed by an operator. > Preset positions/guard tour. PTZ cameras enable a number of preset positions, normally between 20 and 100, to be programmed. Once the preset positions have been set in the camera, it is very quick for the operator to go from one position to the next. In guard tour mode, the camera can be programmed to automatically move from one preset position to the next in a pre-determined order or at random. Normally up to 20 guard tours can be set up and activated during different times of the day. Chapter 2 - Network cameras 31 > Tour recording. The tour recording functionality in PTZ cameras enables easy setup of an automatic tour using a device such as a joystick to record an operator’s pan/tilt/zoom movements and length of time spent at each point of interest. The tour can then be actvated at a touch of a button or at a scheduled time. > Autotracking. Autotracking is an intelligent video functionality that will automatically detect a moving person or vehicle and follow it within the camera’s area of coverage. Auto tracking is particularly beneficial in unmanned video surveillance situations where the occasional presence of people or vehicles requires special attention. The functionality cuts down substantially the cost of a surveillance system since fewer cameras are needed to cover a scene. It also increases the effectiveness of the solution since it allows a PTZ camera to record areas of a scene with activity. > Advanced/Active Gatekeeper. Advanced Gatekeeper enables an Axis PTZ camera to pan, tilt and zoom in to a preset position when motion is detected in a pre-defined area and return to home position after a set time. When this is combined with the ability to continue to track the detected object, the function is called Active Gatekeeper. > Electronic image stabilization (EIS). In outdoor installations, PTZ cameras with zoom factors above 20x are sensitive to vibrations and motion caused by traffic or wind. EIS helps reduce the affects of vibration in a video. In addition to getting more useful video, EIS will reduce the file size of the compressed image and thereby save valuable storage space. 2.4.6 Thermal network cameras Figure 2.4m Indoor and outdoor thermal network cameras, as well as (at far right) a dual PTZ camera that combines both a visual (conventional) and thermal camera in one unit for mission-critical surveillance. Thermal network cameras create images based on heat that radiates from all objects. Images are generally produced in black and white but can be artificially colored to make it easier to distinguish different shades. Thermal images are best when there are great temperature differences in a scene; the hotter an object, the brighter it is in a thermal image. Chapter 2 - Network cameras 32 Thermal cameras are ideal for detecting people, objects and incidents in shadows, complete darkness or in other challenging conditions such as smoke and dust. The cameras are used primarily to detect suspicious activities as thermal images do not enable reliable identification. They, therefore, complement and support conventional network cameras in a surveillance installation. Thermal cameras can be used for perimeter or area protection, providing a powerful and costeffective alternative to radio frequency intruder detection, electrified fences and flood lights. In the dark, they provide discreet surveillance since there is no need for artificial light. In public areas, thermal cameras can help secure dangerous or off-limit areas such as tunnels, railway tracks and bridges. Indoor uses include building security and emergency management, enabling humans to be detected inside a building, whether after business hours or during emergencies such as a fire. Thermal cameras are often used in high security buildings and areas such as nuclear power plants, prisons, airports, pipelines and sensitive railway sections. A thermal camera requires special optics since regular glass will block the thermal radiation. Most thermal camera lenses are made using germanium, which enables infrared light and thermal radiation to pass through. How much or how far away a thermal camera can “see” or detect depends on the lens. A wide-angle lens enables a thermal camera to have a wider field of view, but a shorter detection range than a telephoto lens, which provides a longer detection range with a narrower field of view. A thermal camera also requires a special, more expensive image sensor. Detectors used for thermal imaging can be broadly divided into two types: uncooled thermal image sensors and cooled thermal image sensors. Sensors in uncooled thermal cameras operate at or close to the ambient temperature and operate between 8 µm and 14 µm in the long-wave infrared range. Uncooled sensors are based often on microbolometer technology. Uncooled thermal image sensors are smaller and less expensive than cooled image sensors. Hence, an uncooled thermal camera is more affordably priced. Such cameras also have a longer life span. Cooled thermal image sensors are usually contained in a vacuum-sealed case and cooled to temperatures as low as -210 °C (-346 °F) to reduce noise created by their own thermal radiation at higher temperatures. It allows the sensors to operate in the mid-wave infrared band, approx. 3 to 5 µm (hot pink band in the image on the next page), which provides better spatial resolution and higher thermal contrast since such sensors can distinguish smaller temperature differences and produce crisp, high resolution images. The disadvantages of such detectors are that they are bulky, expensive, energy-consuming and the coolers must be rebuilt every 8,000 to 10,000 hours. A thermal camera’s sensitivity to infrared radiation is expressed as its NETD value (Noise Equivalent Temperature Difference). The lower the NETD value, the better the sensitivity to infrared radiation. Chapter 2 - Network cameras 33 Micrometers (µm) -2 0.01(10 ) 3.00 Middle Infrared 0.70 104 5.50 Shortwave Visible -4 10 Ultraviolet 1.50 Infrared Near Infrared X-rays 0.40 Thermal Infrared Microwave 3 10 (1 mm) Radio/TV waves 106 (1 m) Figure 2.4n Conventional cameras work in the range of visible light, i.e. with wavelengths between approximately 0.4–0.7 μm. Thermal cameras, on the other hand, are designed to detect radiation in the much broader infrared spectrum, up to around 14 μm (the distances in the spectrum above are not according to scale). Thermal imaging technologies, which were originally developed for military use, are regulated. In order for a thermal camera to be freely exported, the maximum frame rate cannot exceed 9 frames per second (fps). Thermal cameras with a frame rate of up to 60 fps can be sold within the EU, Norway, Switzerland, Canada, U.S.A., Japan, Australia and New Zealand on the condition that the buyer is registered and can be traced. 2.5 Guidelines for selecting a network camera With the variety of network cameras available, it is useful to have some guidelines when selecting a network camera. > Define the surveillance goal: overview or high detail, and detection, recognition or identification. Overview images aim to view a scene in general or view the general movements of people. High detail images are important for identification of persons or objects (e.g., face or license plate recognition, point-of-sales monitoring). The surveillance goal will determine the field of view, the placement of the camera, and the type of camera/ lens required. For more on lenses, see Chapter 3. > Area of coverage. For a given location, determine the number of interest areas, how much of these areas should be covered and whether the areas are located relatively close to each other or spread far apart. The area will determine the type of camera and number of cameras required. - Megapixel/HDTV or lower resolution. For instance, if there are two, relatively small areas of interest that are close to each other, an HDTV/megapixel camera with a wide-angle lens can be used instead of two lower resolution cameras. - Fixed or PTZ. An area may be covered by several fixed/fixed dome cameras or a few PTZ cameras. Consider that a PTZ camera with a high optical zoom can provide highly detailed images and survey a large area. A conventional PTZ camera Chapter 2 - Network cameras 34 may provide a brief view of one part of its area of coverage at a time, while a fixed camera will be able to provide full coverage of its area all the time. The special PTZ dome with the additional 360° field of view provides a middle ground where full, wide area coverage can be provided when pan/tilt/zoom is not used. To make full use of a PTZ camera, an operator is required or an automatic tour needs to be set up. > Indoor or outdoor environment. - Light sensitivity and lighting requirements. Cameras come with different light sensitivities. There are two factors that purchasers can look at: one is the lowest f-number on the camera lens (the lower the number, the more light sensitive it is); the other is the lux specification (the lower, the better). The lux specification takes into account the combined performance of several factors such as the lens, image sensor and image processing. (Keep in mind that lux measurements on network cameras are not comparable among different network video product vendors as there is no industry standard for measuring light sensitivity.) In outdoor environments, consider the use of day/night cameras. Day/night cameras with Axis’ Lightfinder technology have extended light sensitivity, providing color information even in dark environments. Meanwhile, cameras with built-in IR LEDs, or with external IR illuminators, help enhance black and white video in low light and will also provide usable video in completely dark conditions. If adding external light through the use of a normal lamp or an IR illuminator is not an option, consider the use of thermal cameras for detection in complete darkness. In scenes with backlight (e.g., an indoor camera pointing at a window or door) or scenes with a combination of very bright and dark areas, repositioning the camera may be an answer to getting better video quality. If such scenarios are unavoidable, consider cameras with wide dynamic range (WDR). A good WDR surveillance camera can deliver images that capture details in both well-lit and dark areas. - Protection. If the camera is to be placed outdoors or in environments that require protection, select cameras with the appropriate specifications, such as IP51/52 for indoor cameras, IP66 and NEMA 4X for outdoor cameras, IK08/10 for vandal/impactresistance, and operating temperatures that are suitable for the environment. Specialized, external housings are also available. For more on environmental protection, see Chapter 5. > Overt or covert surveillance. This will help in selecting the cameras, as well as the type of housing and mount, that offer a non-discreet or discreet installation. Chapter 2 - Network cameras 35 Other important feature considerations that may be required of a camera include: >Resolution. For applications that require detailed images, HDTV/megapixel cameras may be the best option. For more on megapixel resolution, see Chapter 6. >Compression. Axis’ latest network video products support H.264 and Motion JPEG video compression formats. H.264 offers the greatest savings in bandwidth and storage. For more on compression, see Chapter 7. >Audio. If audio is required, consider whether one- or two-way audio is needed. An Axis net work camera with audio support comes with a built-in microphone and/or an input for an external microphone and a speaker or a line out for external speakers. For more on audio, see Chapter 8. > Event management and intelligent video. Event management is often configured using a video management software program. Event management is enhanced with the use of input/ output ports and intelligent video functionalities in a network video product. Making recordings based on event triggers from input ports and/or intelligent video features in a network video product saves on bandwidth and storage use, and allows operators to take care of more cameras since not all cameras require live monitoring unless an alarm/event takes place. For more on event management functions, see Chapter 11. > Edge storage. Edge storage allows an Axis network video product to create, control and manage recordings either locally on a memory card or to network shares on a network-attached storage (NAS) or file server. Many Axis network video products have a built-in SD card slot or a micro version of it. When integrated with video management software, edge storage can provide an easy video management solution for systems with a few cameras at a site. For mission-critical installations, at remote locations or in mobile situations, edge storage can help create a more robust and flexible video surveillance system. For more on video management functions, see Chapter 11. > Networking functionalities. Considerations include PoE; HTTPS encryption for encrypting video streams before they are sent over the network; IP address filtering, which gives or denies access rights to defined IP addresses; IEEE 802.1X to control access to a network; IPv6; Quality of Service to prioritize traffic over a network; and wireless functionality. For more on networking and security technologies, see Chapter 9. > Open interface and application software. A network video product with an open interface enables better integration possibilities with other systems. It is also important that the product is supported by a good selection of application software, and management software that enable easy installation and upgrades of network video products. Axis products are supported by a variety of video management software and intelligent video applications from Axis and more than 1,000 of its Application Development Partners. For more on video management systems, see Chapter 11. Chapter 2 - Network cameras 36 Another important consideration, outside of the network camera itself, is the selection of the network video product vendor. Since needs grow and change, the vendor should be seen as a partner, and a long-term one. This means that it is important to select a vendor that offers a full product line of network video products and accessories that can meet the needs now and well into the future. The vendor should also provide innovation, support, upgrades and product path for the long term. Once a decision has been made as to the required camera, it is a good idea to purchase one and test its quality before setting out to order quantities of it. Chapter 3 - Camera elements 37 3. Camera elements There are a number of camera elements that have an impact on image quality and the field of view and are, therefore, important to understand when choosing a network camera. The elements include the light sensitivity of a camera, the type of lens, type of image sensor and scanning technique, as well as image processing functionalities—all of which are discussed in this chapter. Some guidelines on installation considerations are also provided at the end. 3.1 Light sensitivity A network camera’s light sensitivity is defined mainly by the lens and image sensor, which are discussed in the following sections. Light sensitivity is often specified in terms of lux, which corresponds to an illuminance level at which a camera produces an acceptable image. The lower the lux specification, the better light sensitivity the camera has. Normally, at least 200 lux is needed to illuminate an object so that a good quality image can be obtained. In general, the more light on the subject, the better the image. With too little light, focusing will be difficult and the image will be noisy and/or dark. Illuminance Lighting condition 100,000 lux Strong sunlight 10,000 lux Full daylight 500 lux Office light 100 lux Poorly lit room Table 3.1a Examples of different levels of illuminance. Different light conditions offer different illuminance. Many natural scenes have fairly complex illumination, with both shadows and highlights that give different lux readings in different parts of a scene. It is important, therefore, to keep in mind that one lux reading does not indicate the light condition for a scene as a whole. Chapter 3 - Camera elements 38 Many manufacturers specify the minimum level of illumination needed for a network camera to produce an acceptable image. While such specifications are helpful in making light sensitivity comparisons for cameras produced by the same manufacturer, it may not be helpful to use such numbers to compare cameras from different manufacturers. This is because different manufacturers use different methods and have different criteria for what is an acceptable image. To properly compare the low light performance of two different cameras, the cameras should be placed side by side and be viewing a moving object in low light. To capture good quality images in low light or nighttime conditions, Axis provides a variety of solutions. They include cameras with day/night functionality, which takes advantage of nearinfrared light to produce quality black and white video; day/night cameras with Axis’ Lightfinder technology, which enables color video in very little light; and day/night cameras with built-in infrared (IR) LED or an external IR illuminator to enhance the quality of black and white video in low light or complete darkness. A thermal camera, which makes use of infrared radiation from objects (i.e. longer wavelengths than visible light), is also another alternative for detection in complete darkness or in challenging lighting conditions. For more about Lightfinder technology, cameras with built-in IR LED and thermal cameras, see Chapter 2. More information on IR illuminators can be found on Axis’ website at www.axis.com/products/cam_irillum. For more on day/ night functionality, see Section 3.3. 3.2 Lens elements A lens or lens assembly on a network camera performs several functions. They include: > Defining the field of view; that is, defining how much of a scene and level of detail are to be captured. > Controlling the amount of light passing through to the image sensor so that an image is correctly exposed. > Focusing by adjusting either elements within the lens assembly or the distance between the lens assembly and the image sensor. 3.2.1 Field of view A consideration to take into account when selecting a camera is the field of view required; that is, the area of coverage. The field of view is determined by the focal length of the lens and the size of the image sensor. A lens’ focal length is defined as the distance between the center of a single lens or a specific point in a complicated lens assembly and the point where all the light rays converge to a point (normally the camera’s image sensor). The longer the focal length, the narrower the field of view. Chapter 3 - Camera elements 39 The fastest way to find out what focal length lens is required for a desired field of view is to use a rotating lens calculator or an online lens calculator (www.axis.com/tools), both of which are available from Axis. The size of a network camera’s image sensor, typically 1/4”, 1/3” and 1/2”, must also be used in the calculation. The field of view can be classified into three types: > Normal view: offering the same field of view as the human eye. >Telephoto: a narrower field of view, providing, in general, finer details than a human eye can deliver. A telephoto lens is used when the surveillance object is either small or located far away from the camera. A telephoto lens generally has less light gathering capability than a normal lens. > Wide angle: a larger field of view with less detail than in normal view. A wide-angle lens generally provides good depth of field and fair, low-light performance. Wide-angle lenses produce geometrical distortions such as “fish-eye” and barrel effects. Figure 3.2a Different fields of view: wide-angle view (at left); normal view (middle); telephoto (at right). Figure 3.2b Network camera lenses with different focal lengths: wide-angle (at left); normal (middle); telephoto (at right). Chapter 3 - Camera elements 40 There are three main types of lenses: > Fixed lens: Such a lens offers a focal length that is fixed; that is, only one field of view (either normal, telephoto or wide angle). A common focal length of a fixed network camera lens is 3 mm. > Varifocal lens: This type of lens offers a range of focal lengths, and hence, different fields of view. The field of view can be adjusted manually or by a motor. Whenever the field of view is changed, the user has to refocus the lens. Varifocal lenses for network cameras often provide focal lengths that range from 3 mm to 8 mm. > Zoom lens: Zoom lenses are like varifocal lenses in that they enable the user to select different fields of view. However, with zoom lenses, there is no need to refocus the lens if the field of view is changed. Focus can be maintained within a range of focal lengths, for example, 5.1 mm to 51 mm. Lens adjustments can be either manual or motorized for remote control. When a lens states, for example, 10x-zoom capability, it is referring to the ratio between the lens’ longest and shortest focal length. 3.2.2 Matching lens and sensor If a network camera comes with an exchangeable lens, it is important to select a lens suitable for the camera. A lens made for a 1/2-inch image sensor will be large enough for 1/2-inch, 1/3inch and 1/4-inch image sensors, but not for a 2/3-inch image sensor. If a lens is made for a smaller image sensor than the one that is actually fitted inside the camera, the image will have black corners (see left-hand illustration in Figure 3.2c below). If a lens is made for a larger image sensor than the one that is actually fitted inside the camera, the field of view will be smaller than the lens’ capability since part of the information will be “lost” outside the image sensor (see right-hand illustration in Figure 3.2c). 1/3” 1/3” 1/3” 1/4” lens 1/3” lens 1/2” lens Figure 3.2c Examples of different lenses mounted onto a 1/3-inch image sensor. When replacing a lens on a megapixel camera, a high quality lens is required since megapixel sensors have pixels that are much smaller than those on a VGA sensor (640x480 pixels). It is best to match the lens resolution to the camera resolution in order to fully use the camera’s capability as well as other aspects of the lens. Note that lenses may be tailored to a specific camera type in order to reach maximum performance. Axis’ optional lenses are selected with this in mind. Chapter 3 - Camera elements 41 3.2.3 Lens mount standards for exchangeable lenses When changing a lens, it is also important to know what type of lens mount the network camera has. The lens mount is the interface that connects the lens to the camera body. There are three main mounting standards for exchangeable lenses on Axis network cameras: CS, C and M12. CS and C mounts are used on fixed cameras, while M12 is used on lenses for fixed dome cameras. CS and C mount both have a 1-inch thread and they look the same. What differs is the distance from the lenses to the sensor when fitted on the camera. With CS mount, the distance between the sensor and the lens should be 12.5 mm. With C mount, the distance should be 17.526 mm. It is possible to mount a C-mount lens to a CS-mount camera body by using a 5 mm spacer (C/CS adapter ring). If it is impossible to focus a camera, it is likely that the wrong type of lens is used. An M12 lens has a metric M12 thread with a 0.5 mm pitch. 3.2.4 F-number and exposure In low-light situations, particularly in indoor environments, an important factor to look for in a network camera is the lens’ light-gathering ability. This can be determined by the lens’ f-number, also known as f-stop. An f-number defines how much light can pass through a lens. An f-number is the ratio of the lens’ focal length to the diameter of the aperture or iris as seen from the front of the lens—normally referred to as the entrance pupil; that is, f-number = focal length/aperture. The smaller the f-number (either short focal length relative to the aperture, or large aperture relative to the focal length), the better the lens’ light gathering ability; that is, more light can pass through the lens to the image sensor. In low-light situations, a smaller f-number generally produces a better image quality. (There may be some sensors, however, that may not be able to take advantage of a lower f-number in low-light situations due to the way they are designed.) A higher f-number, on the other hand, increases the depth of field, which is explained in Section 3.2.6. F-numbers are sometimes expressed as F/x. The slash indicates division. An F/4 means the entrance pupil is equal to the focal length divided by 4; so if a camera has a lens with a focal length of 8 mm, light must pass through an entrance pupil that is 2 mm in diameter. While lenses with automatically adjustable iris have a range of f-numbers, often only the maximum light gathering end of the range (smallest f-number) is specified. A lens’ light-gathering ability or f-number, and the exposure time (that is, the length of time an image sensor is exposed to light) are the two main elements that control how much light an image sensor receives. A third element, the gain, is an amplifier that is used to make the image brighter. However, increasing the gain also increases the level of noise (graininess) in an image, so adjusting the exposure time or iris opening is preferred. For more on exposure control, see Section 3.6. Chapter 3 - Camera elements 42 3.2.5 Types of iris control: fixed, manual, auto, precise (P-Iris) The ability to control a camera’s iris opening plays an important role in image quality. An iris is used to maintain the optimum light level to the image sensor so that images are properly exposed. The iris can also be used to control the depth of field, which is explained in more detail in Section 3.2.6. Iris control can be fixed or adjustable, and adjustable iris lenses can be manual or automatic. Automatic iris lenses can further be classified as either auto iris or P-Iris lenses. Fixed iris With fixed iris lenses, the iris opening cannot be adjusted and is fixed at a certain f-number. The camera can compensate for changes in the level of light by adjusting the exposure time or using gain. Manual iris With manual iris lenses, the iris can be adjusted by turning a ring on the lens to open or close the iris. This is not convenient in environments with changing light conditions, such as in outdoor surveillance applications. Auto iris (DC and video) There are two types of auto iris lenses: DC iris and video iris. Both use a galvanometer to automatically adjust the iris opening in response to changes in light levels. Both also use an analog signal (often analog video signal) to control the iris opening. The difference between the two is where the circuitry to convert the analog signal into control signals is located. In a DC-iris lens, the circuit resides inside the camera; in a video iris, it is inside the lens. In bright situations, a camera with an auto iris lens can be affected by diffraction and blurring when an iris opening becomes too small. This problem is especially prominent in megapixel and HDTV cameras since the pixels in the image sensors are smaller than lower resolution cameras. Therefore, the image quality is more dependent on getting the right iris opening (aperture). In order to optimize image quality, a camera needs to have control over the position of the iris opening. The problem with an auto iris lens is that this control cannot be made available to the camera or user. P-Iris P-Iris is an automatic, precise iris control first developed by Axis and Kowa Company of Japan. It involves a P-Iris lens and specialized software that optimize image quality. The system is designed to address the shortcomings of an auto-iris lens. P-Iris provides improvements in contrast, clarity, resolution and depth of field. Having good depth of field— where objects at different distances from the camera are in focus simultaneously—is important in the video monitoring of, for example, a long corridor or parking lot. Chapter 3 - Camera elements Old technology 43 P-Iris Figure 3.2d The P-Iris image (at right) provides greater depth of field. Old technology (cropped view) P-Iris (cropped view) Figure 3.2e The P-Iris image (at right) provides higher contrast. In bright situations, P-Iris limits the closing of the iris to avoid blurring (diffraction) caused when the iris opening becomes too small. This can typically happen in cameras that use DCiris lenses in combination with megapixel sensors that have small pixels. Being able to avoid diffraction and at the same time benefit from an automatically controlled iris is highly valued in outdoor video surveillance applications. A P-Iris lens uses a motor that allows the position of the iris opening to be precisely controlled. Together with software that is configured to optimize the performance of the lens and image sensor, P-Iris automatically provides the best iris position for optimal image quality in all lighting conditions. Chapter 3 - Camera elements 44 In an Axis network camera with P-Iris, the camera’s web page provides a scale of f-numbers that ranges between the widest and smallest iris opening. This feature enables the user to adjust the preferred iris position, which is the iris position used by the automatic control for most lighting conditions. Figure 3.2f P-Iris enables the user to adjust the preferred iris position for most lighting conditions. P-Iris allows fixed network cameras to reach a new level of performance in image quality. The advanced iris control is especially beneficial for megapixel/HDTV cameras and demanding video surveillance applications. 3.2.6 Depth of field A criterion that may be important to a video surveillance application is depth of field. Depth of field refers to the distance in front of and beyond the point of focus where objects appear to be sharp simultaneously. Depth of field may be important, for instance, in monitoring a parking lot, where there may be a need to identify license plates of cars at 20, 30 and 50 meters (60, 90 and 150 feet) away. Depth of field is affected by four factors: focal length, f-number, distance of the camera to the subject, and the circle of confusion, which is a measurement of how carefully an image is viewed. A long focal length, a large entrance pupil, a short distance between the camera and the subject or a close-up view will limit the depth of field. Figure 3.2g Depth of field: Imagine a line of people standing behind each other. If the focus is in the middle of the line, the depth of field makes it possible to identify the faces of all in front and behind the mid-point more than 15 m (45 ft.) away. Chapter 3 - Camera elements 45 Figure 3.2h Iris opening and depth of field. The above illustration is an example of the depth of field for different f-numbers with a focal distance of 2 m (7 ft.). A large f-number (smaller iris opening) enables objects to be in focus over a longer range. (Depending on the pixel size, very small iris openings may blur an image due to diffraction.) 3.3 Removable IR-cut filter (Day/night functionality) In many cameras, there is an automatically removable infrared-cut filter that sits behind a camera lens, and in front of the image sensor. The role of an IR-cut filter is to filter out infrared light to enable cameras to produce colors that the human eye sees. However, if the filter is removed under low light or nighttime conditions, the camera’s sensor is able to take advantage of near-infrared light and deliver black and white images even when there is not enough visible light. Solenoid Night filter Image sensor Optical holder Front guard Day filter Figure 3.3a Illustration and photo of the IR-cut (day/night) filter on the optical holder, which in this camera, slides sideways on the back side of the front guard to use the red-hued filter during the day and the clear part during the night. Near-infrared light, which spans from 0.7 micrometers (μm) up to about 1.0 μm, is beyond what the human eye can see, but most camera sensors can detect it and make use of it. Chapter 3 - Camera elements 46 B/W mode Color mode Visible light Near-IR light 1.0 Relative response 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Wavelength (μm) Kelvin 10,000 7,000 5,600 3,200 2,860 (color temperature) Figure 3.3b The graph shows how an image sensor responds to visible and near-IR light. Near-IR light spans the 0.7 μm to 1.0 μm range. Cameras with a removable IR-cut filter have day/night functionality as they deliver color video during daytime, and during nighttime, black and white video, which reduces the image noise. They have applications in low-light video surveillance situations, covert surveillance and in environments that restrict the use of artificial light. An IR illuminator that provides near-infrared light can also be used in conjunction with a day/night camera to further enhance the camera’s ability to produce high-quality video in low-light or complete darkness. Day/night cameras with built-in IR illuminators are also available. Figure 3.3c At left, external IR illuminators; at right, two cameras with built-in IR illuminators. 3.4 Image sensors As light passes through a lens, it is focused on the camera’s image sensor. An image sensor is made up of many photosites and each photosite corresponds to a picture element (more commonly known as “pixel”) on an image sensor. Each pixel on an image sensor registers the amount of light it is exposed to and converts it into a corresponding number of electrons. The brighter the light, the more electrons are generated. Chapter 3 - Camera elements 47 When building a camera, there are two main technologies that can be used for the camera’s image sensor: >CMOS (complementary metal-oxide semiconductor) >CCD (charge-coupled device) Figure 3.4a Images sensors: CMOS (at left); CCD (at right). CMOS sensors are developing at a much faster pace than CCDs. The quality of CMOS sensors has undergone dramatic improvements and they are today well suited for delivering highperformance multi-megapixel video. Compared with CCD sensors, CMOS sensors enable more integration possibilities and functions, and have a faster readout, which is advantageous when high-resolution images are required. They also have lower power dissipation at the chip level and a smaller system size. CMOS sensors lower the total cost for cameras since they contain all the logics needed to build cameras around them. Megapixel CMOS sensors are more widely available and are often less expensive than megapixel CCD sensors. The megapixel sensors that are generally used in video surveillance cameras have smaller size pixels than lower resolution sensors. For this reason, megapixel sensors were known to be less light sensitive than lower resolution sensors. However, advancements in CMOS technology make it possible for newer megapixel sensors (and hence, new multi-megapixel cameras) to match the light sensitivity of many lower resolution sensors and cameras. While megapixel sensors with larger pixel sizes are available, they are not often used in video surveillance cameras due to the limited availability of lenses that match them. Image sensors with wide dynamic range are also making it possible to introduce cameras that can simultaneously show objects in very bright and dark areas of a scene. CCD sensors, which employ a technology that was specifically developed for the camera industry, have been in use since the 1970s and still present some benefits at moderate resolutions and video speed. CCD sensors, however, are often more expensive and more complex to incorporate into a camera. A CCD can also consume much more power than an equivalent CMOS sensor. For details, see the white paper on image sensors at www.axis.com/corporate/corp/tech_papers.htm Chapter 3 - Camera elements 48 3.5 Image scanning techniques Interlaced scanning and progressive scanning are the two techniques available today for reading and displaying information produced by image sensors. Network cameras can make use of either scanning technique. Analog cameras can only make use of the interlaced scanning technique for transferring images over a coaxial cable and for displaying them on analog monitors. 3.5.1 Interlaced scanning When an image from an interlaced image sensor is produced, two fields of lines are generated: a field displaying the odd lines, and a second field displaying the even lines. However, to create the odd field, information from both the odd and even lines on a sensor is combined. The same goes for the even field, where information from both the even and odd lines is combined to form an image on every other line. When transmitting an interlaced image, only half the number of lines (alternating between odd and even lines) of an image is sent at a time, which reduces the use of bandwidth by half. The monitor, for example, a traditional TV, must also use the interlaced technique. First the odd lines and then the even lines of an image are displayed and then refreshed alternately at 25/50 (PAL) or 30/60 (NTSC) frames per second so that the human visual system interprets them as complete images. All analog video formats and some modern HDTV formats are interlaced. Although the interlacing technique creates artifacts or distortions as a result of ‘missing’ data, they are not very noticeable on an interlaced monitor. However, when interlaced video is shown on progressive scan monitors such as computer monitors, which scan lines of an image consecutively, the artifacts become noticeable. The artifacts, which can be seen as “tearing”, are caused by the slight delay between odd and even line refreshes as only half the lines keep up with a moving image while the other half waits to be refreshed. It is especially noticeable when the video is stopped and a freeze frame of the video is analyzed. 3.5.2 Progressive scanning With a progressive scan image sensor, values are obtained for each pixel on the sensor and each line of image data is scanned sequentially, producing a full frame image. In other words, captured images are not split into separate fields as with interlaced scanning. With progressive scan, an entire image frame is sent over a network and when displayed on a progressive scan computer monitor, each line of an image is put on the screen one at a time in perfect order. Moving objects are, therefore, better presented on computer screens using the progressive scan technique. In a video surveillance application, it can be critical in viewing details of a moving subject (e.g., a person running away). Virtually all Axis network cameras use the progressive scan technique. Chapter 3 - Camera elements 1st field: Odd lines 2nd field: Even lines Freeze frame on moving dot [17/20 ms (NTSC/PAL) later] using interlaced scanning 49 Freeze frame on moving dot using progressive scan Figure 3.5a At left, an interlaced scan image shown on a progressive (computer) monitor. At right, a progressive scan image on a computer monitor. Figure 3.5b At left, a full-sized JPEG image (704x576 pixels) from an analog camera using interlaced scanning. At right, a full-sized JPEG image (640x480 pixels) from an Axis network camera using progressive scan technology. Both cameras used the same type of lens and the speed of the car was the same at 20 km/h (15 mph). The background is clear in both images. However, the driver is clearly visible only in the image using progressive scan technology. 3.6 Exposure control As mentioned earlier, exposure time has an effect on images and users can change the settings related to exposure in a number of ways. The most important ones—exposure priority, exposure zones, dynamic range and backlight compensation—are explained in this section. 3.6.1 Exposure priority Bright environments require shorter exposure time. Low-light conditions require longer exposure time so that the image sensor can receive more light and thereby, improve image quality. However, increasing the exposure time also increases motion blur and lowers the total frame rate since a longer time is required to expose each image frame. In low-light conditions, Axis network cameras enable users to prioritize video quality in terms of either movement or low noise (graininess). When rapid movement or when a high frame rate is required, a shorter exposure time/fast shutter speed is recommended, but image quality may be reduced. Chapter 3 - Camera elements 50 When low noise is prioritized, the gain (amplification) should be kept as low as possible to improve image quality, but frame rate may be reduced as a result. Keep in mind that in dark conditions, setting a low gain can result in a very dark image. A large gain value makes it possible to observe a dark scene, but with increased noise. Figure 3.6a A camera’s web page with options for setting, among other things, exposure in low-light conditions. 3.6.2 Exposure zones Besides dealing with limited areas of high illumination, a network camera’s automatic exposure must also decide what area of an image should determine the exposure value. For instance, the foreground (usually the bottom section of an image) may hold more important information than the background; for example, the sky (usually the top section of an image). The less important areas of a scene should not determine the overall exposure. In many Axis network cameras, the user is able to use exposure zones to select the area of a scene—center, left, right, top or bottom—that should be more correctly exposed. 3.6.3 Dynamic range Dynamic range, as it relates to light, is the ratio between the largest and smallest illumination values. Many scenes have high dynamic range, with areas that are very bright and very dark. This is a problem for standard cameras, which have limited dynamic range. In such scenes or in backlight situations where a person is in front of a bright window, a typical camera will produce an image where objects in the dark areas will hardly be visible. To increase a camera’s dynamic range and enable objects in dark and light areas to be seen, various techniques can be applied. Exposure can be controlled and tone mapping can be used to increase the gain in dark areas. Chapter 3 - Camera elements 51 Figure 3.6b Above are two images of the same scene but the image on the right better handles the dynamic range in the scene since details in both the bright and dark areas are visible. 3.6.4 Backlight compensation While a camera’s automatic exposure tries to get the brightness of an image to appear as the human eye would see a scene, it can be easily fooled. Strong backlight can cause objects in the foreground to be dark. Network cameras with backlight compensation strive to ignore limited areas of high illumination, just as if they were not present. It enables objects in the foreground to be seen, although the bright areas will be overexposed. 3.7 Installing a network camera Once a network camera has been purchased, the way it is installed is just as important. Below are some recommendations on how to best achieve high-quality video surveillance based on camera positioning and environmental considerations. > Surveillance objective and camera positioning. If the aim is to get an overview of an area to be able to track the movement of people or objects, make sure a camera that is suitable for the task is placed in a position that achieves the objective. If the intention is to be able to identify a person or object, the camera must be positioned or focused in a way that will capture the level of detail needed for identification purposes. Axis’ pixel counter functionality, which is available in most Axis cameras, can be used to verify that the pixel resolution of an object fulfills regulatory or customer requirements, for example, for facial identification. If a surveillance scene benefits more from a vertically oriented view, installing a camera with Axis’ Corridor Format will be advantageous. Cameras with varifocal lenses also enable the field of view to be adjusted, so be sure to make the necessary adjustments and refocus to optimize the view. Local police authorities may also be able to provide guidelines on how best to position a camera. See Chapter 2 for more information on features such as Corridor Format and pixel counter. Chapter 3 - Camera elements 52 > Use lots of light or add light if needed. It is normally easy and cost-effective to add strong lamps in both indoor and outdoor situations to provide the necessary light conditions for capturing good images. > Avoid pointing the camera toward the sun as it will “blind” the camera and can reduce the performance of the image sensor. If possible, position the camera with the sun shining from behind the camera. > Avoid backlight. This problem typically occurs when attempting to capture an object in front of a window. To avoid this problem, reposition the camera or use curtains and close blinds if possible. If it is not possible to reposition the camera, add frontal lighting. Cameras with support for wide dynamic range are better at handling a backlight scenario. > Reduce the dynamic range of the scene. In outdoor environments, viewing too much sky results in too high a dynamic range. If the camera does not support wide dynamic range, a solution is to mount the camera high above the ground, using a pole if needed. > Adjust camera settings. It may be necessary at times to adjust settings for white balance, brightness and sharpness to obtain an optimal image. In low light situations, users must also prioritize either frame rate or image quality. Prior to mounting a camera, it is advisable to test it first. Where the distance between the camera and the surveillance object, and the size of the object are known or can be approximated, setting the field of view on a varifocal lens and roughly focusing it can be done prior to installing it. Once the camera is installed, aspects such as the field of view, focus and other settings can be fine-tuned. Axis network camera PoE AXIS T8412 Installation Display Figure 3.7a A battery-powered handheld display device, such as the AXIS T8414 Installation Display, can be helpful at the installation site for fine-tuning a camera’s settings. The AXIS T8414 connects to and powers up the camera and gives installers an easier alternative than the use of a laptop, which may be awkward to work with when installing a camera while on a ladder or sky lift. Chapter 3 - Camera elements > 53 Legal considerations. Video surveillance can be restricted or prohibited by laws that vary from country to country. It is advisable to check the laws in the local region before installing a video surveillance system. It may be necessary, for instance, to register or get a license for video surveillance, particularly in public areas. Signage may be required. Video recordings may require time and date stamping. There may be rules regulating how long video should be retained. Audio recordings may or may not be permitted. Chapter 3 - Camera elements 54 Chapter 4 - Video encoders 55 4. Video encoders Video encoders enable an existing analog CCTV video surveillance system to be integrated with a network video system. Video encoders play a significant role in installations where many analog cameras are to be maintained. This chapter provides an overview on video encoders and describes the different types of video encoders that are available. A brief discussion on deinterlacing techniques is also included, in addition to a section on video decoders. 4.1 What is a video encoder? A video encoder makes it possible for an analog CCTV system to migrate to a network video system. It enables users to gain the benefits of network video without having to discard existing analog equipment such as analog CCTV cameras and coaxial cabling. A video encoder connects to an analog video camera via a coaxial cable and converts analog video signals into digital video streams that are then sent over a wired or wireless IP-based network (e.g., LAN, WLAN or Internet). To view and/or record the digital video, computer monitors and PCs can be used instead of DVRs or VCRs and analog monitors. Remote access from office/home computer with web browser Axis network cameras Axis video encoders PS1 NETWORK ACTIVITY 1 2 3 LOOP PS2 4 FANS 0 - INTERNET Power-one FNP 30 100-240 AC 50-50 Hz 4-2 A AC 0 - Power-one FNP 30 AXIS Q7900 Rack 100-240 50-50 Hz 4-2 A AC POWER POWER AXIS Q7406 Video Encoder Blade AXIS Q7406 Video Encoder Blade Analog cameras Computer with video management software Network video decoder and video wall Figure 4.1a An illustration of how analog video cameras and analog monitors can be integrated with a network video system using video encoders and decoders. Chapter 4 - Video encoders 56 By using video encoders, analog video cameras of all types, such as fixed, indoor/outdoor, dome, pan/tilt/zoom, and specialty cameras such as microscope cameras can be remotely accessed and controlled over an IP network. A video encoder also offers other benefits such as event management and intelligent video functionalities, as well as advanced security measures. It may also incorporate a memory card slot for storing recordings locally. A video encoder also provides scalability and ease of integration with other security systems. Analog input Audio Ethernet (PoE) Memory card I/O RS-485 RS-422 Power Figure 4.1b A four-channel, standalone video encoder with audio, I/O (input/output) ports for controlling external devices such as sensors and alarms, serial ports (RS-422/RS-485) for controlling PTZ analog cameras, Ethernet connection with Power over Ethernet support and a memory card slot for local storage of recordings. 4.1.1 Video encoder components and considerations Axis video encoders offer many of the same functions that are available in network cameras. Some of the main components of a video encoder include: > Analog video input for connecting an analog camera using a coaxial cable. > Processor for running the video encoder’s operating system, for networking and security functionalities, for encoding analog video using various compression formats and for video analysis. The processor determines the performance of a video encoder, normally measured in frames per second in the highest resolution. Advanced video encoders can provide full frame rate (30 frames per second with NTSC-based analog cameras or 25 frames per second with PAL-based analog cameras) in the highest resolution for every video channel. Axis video encoders also have auto sensing to automatically recognize if the incoming analog video signal is an NTSC or PAL standard. For more on NTSC and PAL resolutions, see Chapter 6. > Memory for storing the firmware (computer program) using Flash, as well as buffering of video sequences (using RAM). > Memory card slot that enables recordings to be locally stored on a memory card. > Ethernet/Power over Ethernet port to connect to an IP network for sending and receiving Chapter 4 - Video encoders 57 data, and for powering the unit and the attached camera if Power over Ethernet is supported. For more on Power over Ethernet, see Chapter 9. >Serial port (RS-232/RS-422/RS-485) often used for controlling the pan/tilt/zoom functionality of an analog PTZ camera. > Input/output ports for connecting external devices; for example, sensors to detect an alarm event, and relays to activate, for instance, lights in response to an event. > Audio in for connecting a microphone or line-in equipment and audio out for connecting to speakers. When selecting a video encoder, key considerations for professional systems are reliability and quality. Other considerations include the number of supported analog channels, image quality, compression formats, resolution, frame rate and features such as pan/tilt/zoom support, audio, event management, intelligent video, Power over Ethernet and security functionalities. Figure 4.1c IP66-rated protective enclosure for video encoders. Meeting environmental requirements may also be a consideration if the video encoder must withstand such conditions as vibration, shock and extreme temperatures. In such cases, a protective enclosure or a rugged video encoder should be considered. 4.1.2 Event management and intelligent video One of the main benefits of Axis video encoders is the ability to provide event management and intelligent video functionalities—capabilities that cannot be provided in an analog video system. Built-in intelligent video features such as multi-window video motion detection, audio detection and active tampering alarm, as well as input ports for external sensors, enable a network video surveillance system to be constantly on guard to detect an event. Once an event is detected, the system can automatically respond with actions that may include video recording, sending alerts such as e-mails and SMS, activating lights, opening/closing doors and sounding alarms. For more on event management and intelligent video, see Chapter 11. Chapter 4 - Video encoders 58 4.2 Standalone video encoders Figure 4.2a Standalone video encoders ranging from one channel up to 16 channels, including a rugged version. The most common type of video encoders is the standalone version, which offers one or multichannel connections to analog cameras. A multi-channel video encoder is ideal in situations where there are several analog cameras located in a remote facility or a place that is a fair distance from a central monitoring room. Through the multi-channel video encoder, video signals from the remote cameras can then share the same network cabling, thereby reducing cabling costs. In situations where investments have been made in analog cameras but coaxial cables have not yet been installed, it is best to use and position standalone video encoders close to the analog cameras. It reduces installation costs as it eliminates the need to run new coaxial cables to a central location since the video can be sent over an Ethernet network. It also eliminates the loss in image quality that would occur if video were to be sent over long distances through coaxial cables. With coaxial cables, the video quality decreases the further the signals have to travel. A video encoder produces digital images, so there is no reduction in image quality due to the distance traveled by a digital video stream. Figure 4.2b An illustration of how a single-channel video encoder can be positioned next to an analog camera in a camera housing. 4.3 Rack-mounted video encoders Rack-mounted video encoders are beneficial in instances where there are many analog cameras with coaxial cables running to a dedicated control room. They enable many analog cameras to be connected and managed from one rack in a central location. A rack allows a number of different video encoder blades to be mounted and thereby offers a flexible and Chapter 4 - Video encoders 59 expandable, high-density solution. A video encoder blade may support one, four or six analog cameras. A blade can be seen as a video encoder without a casing, although it cannot function on its own since it has to be mounted in a rack to operate. Figure 4.3a Video encoder blades and racks supporting various numbers of analog cameras and features. When the AXIS Q7900 Rack (far right) is fully outfitted with 6-channel video encoder blades, it can connect to as many as 84 analog cameras. Axis video encoder racks support features such as hot swapping of blades; that is, blades can be removed or installed without having to power down the rack. The racks also provide serial communication and input/output ports for each video encoder blade, in addition to a common power supply and shared Ethernet network connection(s). 4.4 Video encoders with analog PTZ cameras In a network video system, pan/tilt/zoom commands from a control board are carried over the same IP network as for video transmission and are forwarded to the analog PTZ camera through the video encoder’s serial port (RS-232/RS-422/RS-485). Video encoders, therefore, enable analog PTZ cameras to be controlled over long distances, even through the Internet. (In an analog CCTV system, each PTZ camera would require separate and dedicated serial wiring from the control board—with joystick and other control buttons—all the way to the camera.) To control a specific PTZ camera, a driver must be uploaded to the video encoder. Many manufacturers of video encoders provide PTZ drivers for most analog PTZ cameras. A PTZ driver can also be installed on the PC that runs the video management software program if the video encoder’s serial port is set up as a serial server that simply passes on the commands. RS-485 twisted pair I/O IO AUD 1 OUT IN Coax Cable Analog dome camera Video encoder 2 3 4 5 6 IP NETWORK PC workstation Joystick Figure 4.4a An analog PTZ dome camera can be controlled via the video encoder’s serial port (e.g., RS-485), making it possible to remotely control it over an IP network. Chapter 4 - Video encoders 60 The most commonly used serial port for controlling PTZ functions is RS-485. One of the benefits that RS-485 allows is the possibility to control multiple PTZ cameras using twisted pair cables in a daisy chain connection from one dome camera to the next. The maximum distance of an RS-485 cable, without using a repeater, is 1,200 m (4,000 ft.). 4.5 Deinterlacing techniques Video from analog cameras is designed to be viewed on analog monitors such as traditional TV sets, which use a technique called interlaced scanning. With interlaced scanning, two consecutive interlaced fields of lines are shown to form an image. When such video is shown on a computer screen, which uses a different technique called progressive scanning, interlacing effects (i.e., tearing or comb effect) from moving objects can be seen. In order to reduce the unwanted interlacing effects, different deinterlacing techniques can be employed. In advanced Axis video encoders, users can choose between two different deinterlacing techniques: adaptive interpolation and blending. Figure 4.5a At left, a close-up of an interlaced image shown on a computer screen; at right, the same interlaced image with deinterlacing technique applied. Adaptive interpolation offers the best image quality. The technique involves using only one of the two consecutive fields and using interpolation to create the other field of lines to form a full image. Blending involves merging two consecutive fields and displaying them as one image so that all fields are present. The image is then filtered to smooth out the motion artifacts or ‘comb effect’ caused by the fact that the two fields were captured at slightly different times. The blending technique is not as processor intensive as adaptive interpolation. 4.6 Video decoder Axis’ video decoders enable digital or analog monitors to connect to and display live video from Axis network cameras and video encoders. The video decoders can decode digital video and audio coming from video encoders or network cameras into analog signals, which can then be used by analog monitors, such as traditional TV sets, and video switches. The video decoders can also provide high-quality, digital outputs on LCD screens. They are ideal for use with a public view monitor, and in large and small surveillance systems. The video decoders have the ability to Chapter 4 - Video encoders 61 decode and display video from many cameras sequentially; that is, decoding and showing video from one camera for some seconds before changing to another and so on. They also have autoconnect on alarm, which will automatically display alarm-triggered video. In situations where only live video display is required, such as with a public view monitor at a store entrance, a video decoder offers a more cost-effective solution than connecting a monitor to the network via a PC. A video decoder can also complement a video management system by helping to offload the main server from decoding digital streams simply for display purposes. Another common application for a video decoder is to use it in an analog-to-digital-to-analog configuration for transporting video over long distances. The quality of digital video is not affected by the distance traveled, which is not the case when sending analog signals over long distances. The only downside may be some level of latency, from 100 ms to a few seconds, depending on the distance and the quality of the network between the end points. I/O AUD IO 1 2 3 4 5 6 OUT IN Analog camera Axis video encoder Axis video decoder Analog monitor Figure 4.6a A video encoder and video decoder can be used to transport video over long distances, from an analog camera to an analog monitor. Chapter 4 - Video encoders 62 Chapter 5 - Environmental protection 63 5. Environmental protection Surveillance cameras are often placed in environments that are very demanding. Cameras, video encoders and certain accessories may require protection from rain, hot and cold environments, dust, corrosive substances, vibrations and vandalism. Various methods may be used to meet such environmental challenges. The sections below cover such topics as environmental protection, external housings, coverings, positioning of fixed cameras in enclosures, vandal and tampering protection, and types of mounting. 5.1 Protection and ratings The main environmental threats to a network video product—particularly one that is installed outdoors—are cold, heat, water, dust and snow. Today, many indoor and outdoor Axis network video products are designed to meet environmental challenges—right out of the box—and do not require separate housings. This results in a more compact camera/video encoder and an easier installation process. For example, Axis cameras that are designed to operate in temperatures up to 75 °C (167 °F) are very compact, even with a built-in active cooling system. A camera design can also ensure reliability and maintenance of a camera’s lifetime, especially under extreme operating conditions. For instance, some of Axis’ fixed and PTZ dome cameras incorporate Arctic Temperature Control, which allows the cameras to start-up in temperatures as low as -40 °C/°F without causing extra wear and tear on the cameras. The control enables different elements in the camera unit to receive power at different times. Some Axis fixed domes without Arctic Temperature Control can also start up at -40 °C/°F and send video immediately. The level of protection provided by enclosures, whether built-in or separate from the network video product, is often indicated by classifications set by such standards as IP, NEMA and IK ratings. IP stands for Ingress Protection (also sometimes known as International Protection) and is applicable worldwide. NEMA stands for National Electrical Manufacturers Association and is applicable in the U.S. IK ratings pertain to external mechanical impacts and are applicable internationally. Chapter 5 - Environmental protection 64 Figure 5.1a From left, a rugged camera designed to meet the special environment of a bus, an outdoor-ready fixed dome, an outdoor fixed camera with Arctic Temperature Control, a PTZ dome with built-in active cooling, as well as a rugged video encoder. The most common environmental ratings for Axis’ indoor products are IP42, IP51 and IP52, which provide resistance against dust and humidity/dripping water. Axis’ outdoor products usually have IP66 and NEMA 4X ratings. IP66 ensures protection against dust, rain and powerful water jets. NEMA 4X ensures protection not only against dust, rain, and hose-directed water, but also snow, corrosion and damage from the external build-up of ice. Some Axis cameras that are designed for extreme environments also meet the U.S. military’s MIL-STD-810G standard for high temperature, temperature shock, radiation, salt fog and sand. For vandal-resistant products, IK08 and IK10 are the most common ratings for resistance against impact. More on IP ratings can be found here: www.axis.com/products/cam_housing/ip66.htm In situations where cameras may be exposed to acids, such as in the food industry, housings made of stainless steel are required. Special enclosures may also be required for aesthetic considerations. Some specialized housings can be pressurized, submersible and bulletproofed. When a camera is to be installed in a potentially explosive environment, other standards—such as IECEx, which is a global certification, and ATEX, a European certification—come into play. 5.2 External housings In instances where the demands of the environment are beyond a network video product’s operating conditions, external enclosures are required. Housings come in different sizes and qualities and with different features. There may be camera housings with heaters and fans (blowers) to accommodate changing temperatures. Some housings also have peripherals such as antennas for wireless applications. An external antenna is only required if the housing is made of metal. A wireless camera inside a plastic housing will work without the use of an external antenna. In outdoor installations, special enclosures may also be required for video encoders and accessories such as I/O audio modules and video decoders. Critical system equipment such as power supply, midspan and switch may also require protection from weather and vandalism. Chapter 5 - Environmental protection 65 Housings are made of either metal or plastic. When selecting an enclosure, several things need to be considered, including: > > > > > > > Easy access to the network video product Mounting brackets Clear or smoked dome cover (for dome camera housings) Cable management Temperature and other ratings (consider the need for heater, fan and sunshield) Power supply (12 V, 24 V, 110 V, 230 V, PoE etc.) Level of vandal resistance Figure 5.2a Outdoor-ready, vandal-resistant cabinets for protecting such equipment as power supply and switches, as well as providing a place to mount the Axis cameras. At far right, an outdoor-ready enclosure for video encoders, I/O audio modules and video decoders. 5.3 Transparent coverings The “window” or transparent covering of an enclosure is usually made of acrylic (PMMA) or polycarbonate plastic. As windows act like optical lenses, they should be of high quality to minimize its effect on image quality. When there are built-in imperfections in the clear material, clarity is compromised. Higher demands are placed on the windows of housings for PTZ cameras. Not only do the windows have to be specially shaped in the form of a bubble, but they must also have high clarity since imperfections such as dirt particles can be magnified, particularly when cameras with high resolution and zoom factors are installed. In addition, if the thickness of the window is uneven, a straight line may appear curved in the resulting image. A high-quality dome cover should have very little impact on image quality, irrespective of the camera’s zoom level and lens position. The thickness of a dome cover can be increased to withstand heavy blows, but the thicker a covering is, the higher the chances of imperfections. Increased thickness may also create unwanted reflections and refraction of light. Therefore, thicker coverings should meet higher requirements if the effect on image quality is to be minimized. Chapter 5 - Environmental protection 66 A variety of dome coverings are available, including clear and smoked versions. While smoked versions enable a more discreet installation, they also act much like sunglasses do in reducing the amount of light available to the camera. It will, therefore, have an effect on the camera’s light sensitivity. 5.4 Positioning a fixed camera in a housing When installing a fixed camera in an enclosure, it is important that the lens of the camera is positioned right up against the window to prevent any glare. Otherwise, reflections from the camera and the background will appear in the image. To reduce reflection, special coatings can be applied on any glass used in front of the lens. Today, Axis’ outdoor fixed cameras are delivered pre-mounted in an outdoor housing, which saves on installation time and prevents errors. Glass n tio ec fl Re Glass GOOD n tio ec fl Re BAD Figure 5.4a When installing a camera behind a glass, correct positioning of the camera becomes important to avoid reflections. 5.5 Vandal and tampering protection In some surveillance applications, cameras are at risk of hostile and violent attacks. While a camera or housing can never guarantee 100% protection from destructive behavior in every situation, vandalism can be mitigated by considering various aspects: camera/housing design, mounting, placement and use of intelligent video functionalities. 5.5.1 Vandal-resistant ratings Vandal or impact resistance can be indicated by the IK rating on a camera or housing. IK ratings specify the degree of protection that enclosures of electrical equipment can provide against external mechanical impacts. For example, an IK10 rating means the product can withstand 20 joules of impact, which is equivalent to a drop of a 5-kg object from a height of 40 cm. 5.5.2 Camera/housing design The shape of the housing or camera is an important factor. A housing or a traditional fixed camera that protrudes from a wall or ceiling is more vulnerable to attacks (e.g., kicking or hitting) than more discreetly designed housings or casings for a fixed dome or PTZ camera. The smooth, Chapter 5 - Environmental protection 67 rounded covering of a fixed dome or a ceiling-mounted PTZ dome makes it more difficult, for example, to block the camera’s view by trying to hang a piece of clothing over the camera. The more a housing or camera blends into an environment or is disguised as something other than a camera—for example, an outdoor light—the better the protection against vandalism. Figure 5.5a Examples of vandal-resistant cameras and housings 5.5.3 Mounting The way cameras and housings are mounted is also important. As mentioned earlier, a traditional fixed network camera or a PTZ camera whose mount protrudes from a wall or ceiling is more vulnerable to attacks. How the cabling to a camera is mounted is also an important consideration. Maximum protection is provided when the cable is pulled directly through the wall or ceiling behind the camera. In this way, there are no visible cables to tamper with. If this is not possible, a conduit should be used to protect cables from attacks. 5.5.4 Camera placement Camera placement is also an important factor in deterring vandalism. By placing a camera out of reach on high walls or in the ceiling, many spur-of-the-moment attacks can be prevented. The downside may be the angle of view, which to some extent can be compensated by selecting a different lens. 5.5.5 Intelligent video Axis’ active tampering alarm feature helps protect cameras against vandalism. It can detect if a camera has been redirected, obscured or tampered with, and can send alarms to operators. This is especially useful in installations with hundreds of cameras in demanding environments where keeping track of the proper functioning of all cameras is difficult. It is also useful in situations where no live viewing takes place and operators can be notified when cameras have been tampered with. Chapter 5 - Environmental protection 68 5.6 Types of mounting Cameras need to be placed in all kinds of locations and this requires a large number of variations in the type of mounting. Wall/Pole Corner Pendant Kit Parapet Ceiling Figure 5.6a Examples of mounting accessories 5.6.1 Ceiling mounts Ceiling mounts are mainly used in indoor installations. The enclosure itself can be: > A surface mount: mounted directly on the surface of a ceiling and, therefore, completely visible > A drop-ceiling mount: mounted inside the ceiling with only parts of a camera and housing (usually the clear dome cover) visible > A pendant mount: hung from a ceiling like a pendant 5.6.2 Wall mounts Wall mounts are often used to mount cameras inside or outside a building. The housing is connected to an arm, which is mounted on a wall. Advanced mounts have an inside cable gland to protect the cable. To install an enclosure at a corner of a building, a normal wall mount, together with an additional corner adapter, can be used. 5.6.3 Pole mounts A pole mount is often used together with a PTZ camera in locations such as a parking lot. This type of mount usually takes into consideration the impact of wind. The dimensions of the pole and the mount itself should be designed to minimize vibrations. Cables are often enclosed inside the pole and outlets must be properly sealed. Some PTZ cameras have built-in electronic image stabilization to limit the effects of wind and vibrations. Chapter 5 - Environmental protection 69 5.6.4 Parapet mounts Parapet mounts are used for roof-mounted housings or to raise the camera for a better angle of view. Axis provides an online tool that can help users identify the right housing and mounting accessories needed. Visit www.axis.com/products/video/accessories/configurator/ Chapter 5 - Environmental protection 70 Chapter 6 - Video resolutions 71 6. Video resolutions Video resolution in an analog or digital world is similar, but there are some important differences in how it is defined. In analog video, an image consists of lines or TV-lines since analog video technology is derived from the television industry. In a digital system, an image is made up of square pixels. The sections below describe the different resolutions that network video can provide. They include NTSC, PAL, VGA, megapixel and HDTV. 6.1 NTSC and PAL resolutions NTSC (National Television System Committee) and PAL (Phase Alternating Line) resolutions are analog video standards. They are relevant to network video since video encoders provide such resolutions when they digitize signals from analog cameras. Older Axis PTZ network cameras also provide NTSC and PAL resolutions since such cameras include an NTSC/PAL-compatible camera block (which incorporates the camera sensor with integrated lens that enables zoom, autofocus and auto-iris functions) made for analog video cameras, in conjunction with a builtin video encoder board. Both NTSC and PAL standards originate from the television industry. NTSC has a resolution of 480 scan lines and uses a refresh rate of 60 interlaced fields per second (or 30 full frames per second). The naming convention for this standard is 480i60, which defines the number of lines, type of scan (“i” stands for interlaced scanning) and refresh rate. PAL has a resolution with 576 scan lines and uses a refresh rate of 50 interlaced fields per second (or 25 full frames per second). The naming convention for this standard is 576i50. The total amount of information per second is the same in both standards. When analog video is digitized, the maximum amount of pixels that can be created is based on the number of TV lines available to be digitized. The maximum size of a digitized image is typically D1 and the most commonly used resolution is 4CIF. Chapter 6 - Video resolutions 72 D1 720 x 576 D1 720 x 480 When shown on a computer screen, digitized analog video may show interlacing effects such as tearing and shapes may be off slightly since the pixels generated may not conform to the square pixels on the computer screen. Interlacing effects can be reduced using deinterlacing techniques (see Chapter 4.5). Correction for the aspect ratio (the ratio of the width of an image to its height) can be applied to video before it is displayed to ensure, for instance, that a circle in an analog video remains a circle when shown on a computer screen. 4CIF 704 x 480 4CIF 704 x 576 2CIF 704 x 288 2CIF 704 x 240 CIF 352 x 288 CIF 352 x 240 QCIF 176 x 120 QCIF 176 x 144 Figure 6.1a At left, different NTSC image resolutions. At right, different PAL image resolutions.. 6.2 VGA resolutions 4CIF 704 x 480 VGA 640 x 480 SVGA 800 x 600 With 100% digital systems based on network cameras, resolutions that are derived from the computer industry and that are standardized worldwide can be provided, allowing for better flexibility. The limitations of NTSC and PAL become irrelevant. VGA (Video Graphics Array) is a graphics display system for PCs originally developed by IBM. The resolution is defined as 640x480 pixels. Axis cameras today offer resolutions greater than that. They include SVGA (Super VGA), which is 800x600 pixels, and HDTV and multi-megapixel resolutions, which are explained further in the following sections. HDTV 720p 1280 x 720 1 MP 1280 x 800 2 MP / HDTV 1080 1920 x 1080 ~2 MP 1600 x 1200 3 MP 2048 x 1536 5 MP 2592 x 1944 Figure 6.2a Common resolutions in Axis products. Chapter 6 - Video resolutions 73 6.3 Megapixel resolutions A network camera that offers megapixel resolution uses a megapixel sensor to deliver an image that contains one million or more pixels. The more pixels a sensor has, the greater the potential it has for capturing finer details and for producing a higher quality image. Megapixel network cameras can be used to allow users to see more details (ideal for identification of people and objects) or to view a larger area of a scene. This benefit is an important consideration in video surveillance applications. Megapixel resolution is one area in which network cameras excel over analog cameras. The maximum resolution a conventional analog camera can provide after the video signal has been digitized in a digital video recorder or a video encoder is D1, which is 720x480 pixels (NTSC) or 720x576 pixels (PAL). The D1 resolution corresponds to a maximum of 414,720 pixels or 0.4 megapixel. By comparison, a common megapixel format of 1280x1024 pixels gives a 1.3-megapixel resolution. This is more than 3 times the resolution that can be provided by analog CCTV cameras. Megapixel resolution also provides a greater degree of flexibility in terms of being able to provide images with different aspect ratios. A conventional TV monitor displays an image with an aspect ratio of 4:3. Axis megapixel network cameras can offer the same ratio, as well as others, such as 16:9. The advantage of a 16:9 aspect ratio is that unimportant details, usually located in the upper and lower part of a conventional-sized image, are not present and therefore, bandwidth and storage requirements can be reduced. 4:3 16:9 Figure 6.3a Illustration of 4:3 and 16:9 aspect ratios. Chapter 6 - Video resolutions 74 6.4 High-definition television (HDTV) resolutions The video industry has embraced HDTV formats and today, HDTV is prevalent. HDTV provides up to five times higher resolution than standard analog TV. HDTV also has better color fidelity (i.e., how true colors are to reality) and a 16:9 format. Defined by SMPTE (Society of Motion Picture and Television Engineers), the two most important HDTV standards are SMPTE 296M and SMPTE 274M. SMPTE 296M (HDTV 720p) defines a resolution of 1280x720 pixels with high color fidelity in a 16:9 format using progressive scanning at 25/30 hertz (Hz), which corresponds to 25 or 30 frames per second depending on the country, and at 50/60 Hz (50/60 frames per second). Countries using 25/50 Hz frequencies include those in Europe, many in Asia and Africa, Australia, and some in South America such as Argentina. Countries using 30/60 Hz include those in North and Central America, as well as South Korea, Brazil and Saudi Arabia. Some countries like Japan use 25/50 Hz and 30/60 Hz. SMPTE 274M (HDTV 1080) defines a resolution of 1920x1080 pixels with high color fidelity in a 16:9 format using either interlaced (represented by an “i” as in HDTV 1080i) or progressive scanning (represented by a “p” as in HDTV 1080p) at 25/30 Hz and 50/60Hz. A camera that complies with the SMPTE standards indicates adherence to HDTV quality and should provide all the benefits of HDTV in resolution, color fidelity and frame rate. The HDTV standard is based on square pixels—similar to computer screens, so HDTV video from network video products can be shown on either HDTV screens or standard computer monitors. With progressive scan HDTV video, no conversion or deinterlacing technique needs to be applied when the video is to be processed by a computer or displayed on a computer screen. Chapter 7 - Video compression 75 7. Video compression Video compression technologies are about reducing and removing redundant video data so that a digital video file can be effectively sent over a network and stored on computer disks. With efficient compression techniques, a significant reduction in file size can be achieved with little or no adverse effect on the video quality. The quality, however, can be affected if the file size is further lowered by raising the compression level for a given compression technique. Different compression technologies, both proprietary and industry standards, are available. Most network video vendors today use standard compression techniques. Standards are important in ensuring compatibility and interoperability. They are particularly relevant to video compression since video may be used for different purposes and, in some video surveillance applications, needs to be viewable many years from the recording date. By deploying standards, end users are able to pick and choose from different vendors, rather than be tied to one supplier when designing a video surveillance system. Axis uses mostly two video compression standards: H.264 and Motion JPEG. H.264 is the latest and most efficient video compression standard. The use of MPEG-4 Part 2 (or simply referred to as MPEG-4) is being phased out. This chapter covers the basics of compression and provides a description of the compression standards mentioned earlier. 7.1 Compression basics 7.1.1 Video codec The process of compression involves applying an algorithm to the source video to create a compressed file that is ready for transmission or storage. To play the compressed file, an inverse algorithm called decompression is applied to produce a video that shows virtually the same content as the original source video. The time it takes to compress, send, decompress and display Chapter 7 - Video compression 76 a file is called latency. The more advanced the compression algorithm, the higher the latency. A pair of algorithms that works together is called a video codec (encoder/decoder). Video codecs of different standards are normally not compatible with each other; that is, video content that is compressed using one standard cannot be decompressed with a different standard. For instance, an MPEG-4 Part 2 decoder will not work with an H.264 encoder. This is simply because one algorithm cannot correctly decode the output from another algorithm but it is possible to implement many different algorithms in the same software or hardware, which would then enable multiple formats to coexist. 7.1.2 Image compression vs. video compression Different compression standards utilize different methods of reducing data, and hence, results differ in bit rate, quality and latency. Compression algorithms fall into two types: image compression and video compression. Image compression uses intraframe coding technology. Data is reduced within an image frame simply by removing unnecessary information that may not be noticeable to the human eye. Motion JPEG is an example of such a compression standard. Images in a Motion JPEG sequence are coded or compressed as individual JPEG images. Figure 7.1a With the Motion JPEG format, the three images in the above sequence are coded and sent as separate unique images (I-frames) with no dependencies on each other. Video compression algorithms such as H.264 and MPEG-4 use interframe prediction to reduce video data between a series of frames. This involves techniques such as difference coding, where one frame is compared with a reference frame and only pixels that have changed with respect to the reference frame are coded. In this way, the number of pixel values that is coded and sent is reduced. When such an encoded sequence is displayed, the images appear as in the original video sequence. Chapter 7 - Video compression 77 Figure 7.1b With difference coding, only the first image (I-frame) is coded in its entirety. In the two following images (P-frames), references are made to the first picture for the static elements, i.e., the house. Only the moving parts, i.e., the running man, are coded using motion vectors, thus reducing the amount of information that is sent and stored. Other techniques such as block-based motion compensation can be applied to further reduce the data. Block-based motion compensation takes into account that much of what makes up a new frame in a video sequence can be found in an earlier frame, but perhaps in a different location. This technique divides a frame into a series of macroblocks (blocks of pixels). Block by block, a new frame can be composed or ‘predicted’ by looking for a matching block in a reference frame. If a match is found, the encoder codes the position where the matching block is to be found in the reference frame. Coding the motion vector, as it is called, takes up fewer bits than if the actual content of a block were to be coded. Search window Matching block Motion vector Earlier reference frame Target block P-frame Figure 7.1c Illustration of block-based motion compensation. With interframe prediction, each frame in a sequence of images is classified as a certain type of Chapter 7 - Video compression 78 frame, such as an I-frame, P-frame or B-frame. An I-frame, or intra frame, is a self-contained frame that can be independently decoded without any reference to other images. The first image in a video sequence is always an I-frame. I-frames are needed as starting points for new viewers or resynchronization points if the transmitted bit stream is damaged. I-frames can be used to implement fast-forward, rewind and other random access functions. An encoder will automatically insert I-frames at regular intervals or on demand if new clients are expected to join in viewing a stream. The drawback of I-frames is that they consume many more bits, but on the other hand, they do not generate many artifacts, which are caused by missing data. A P-frame, which stands for predictive inter frame, makes references to parts of earlier I and/or P frame(s) to code the frame. P-frames usually require fewer bits than I-frames, but a drawback is that they are very sensitive to transmission errors because of the complex dependency on earlier P and/or I frames. A B-frame, or bi-predictive inter frame, is a frame that makes references to both an earlier reference frame and a future frame. Using B-frames increases latency. I B B P B B P B B I B B P Figure 7.1d A typical sequence with I-, B- and P-frames. A P-frame may only reference preceding I- or P-frames, while a B-frame may reference both preceding and succeeding I- or P-frames. When a video decoder restores a video by decoding the bit stream frame by frame, decoding must always start with an I-frame. P-frames and B-frames, if used, must be decoded together with the reference frame(s). Axis network video products allow users to set the GOV (group of video) length, which determines how many P-frames should be sent before another I-frame is sent. By decreasing the frequency of I-frames (having longer GOV), the bit rate can be reduced. However, if there is congestion on the network, the video quality may decline. Besides difference coding and motion compensation, other advanced methods can be employed to further reduce data and improve video quality. H.264, for example, supports advanced techni- Chapter 7 - Video compression 79 ques that include prediction schemes for encoding I-frames, improved motion compensation down to sub-pixel accuracy, and an in-loop deblocking filter to smooth block edges (artifacts). For more information on H.264 techniques, see Axis’ white paper on H.264 at www.axis.com/ corporate/corp/tech_papers.htm 7.2 Compression formats 7.2.1 Motion JPEG Motion JPEG or M-JPEG is a digital video sequence that is made up of a series of individual JPEG images. (JPEG stands for Joint Photographic Experts Group.) When 16 image frames or more are shown per second, the viewer perceives motion video. Full motion video is perceived at 25 (50 Hz) or 30 (60 Hz) frames per second. One of the advantages of Motion JPEG is that each image in a video sequence can have the same guaranteed quality that is determined by the compression level chosen for the network camera or video encoder. The higher the compression level, the lower the file size and image quality. In some situations, such as in low light or when a scene becomes complex, the image file size may become quite large and use more bandwidth and storage space. To prevent an increase in the bandwidth and storage used, Axis network video products allow the user to set a maximum file size for an image frame. Since there is no dependency between the frames in Motion JPEG, a Motion JPEG video is robust, meaning that if one frame is dropped during transmission, the rest of the video will not be affected. Motion JPEG is an unlicensed standard. It has broad compatibility and may be needed when integrating with systems that support only Motion JPEG. It is also popular in applications where individual frames in a video sequence are required—for example, for analysis—and where lower frame rates, typically 5 frames per second or lower, are used. The main disadvantage of Motion JPEG is that it makes no use of any video compression techniques to reduce the data since it is a series of still, complete images. The result is that it has a relatively high bit rate or low compression ratio for the delivered quality compared with video compression standards such as H.264 and MPEG-4. 7.2.2 MPEG-4 When MPEG-4 is mentioned in video surveillance applications, it is usually referring to MPEG-4 Part 2, also known as MPEG-4 Visual. Like all MPEG (Moving Picture Experts Group) standards, it is a licensed standard, so users must pay a license fee per monitoring station. MPEG-4 has, in most applications, been replaced by the more efficient H.264 compression. Chapter 7 - Video compression 80 7.2.3 H.264 or MPEG-4 Part 10/AVC H.264, also known as MPEG-4 Part 10/AVC for Advanced Video Coding, is the latest MPEG standard for video encoding and is the current video standard of choice. This is because an H.264 encoder can, without compromising image quality, reduce the size of a digital video file by more than 80% compared with the Motion JPEG format and as much as 50% more than with the MPEG-4 Part 2 standard. This means that much less network bandwidth and storage space are required for a video file. Or seen another way, much higher video quality can be achieved for a given bit rate. H.264 was jointly defined by standardization organizations in the telecommunications (ITU-T’s Video Coding Experts Group) and IT industries (ISO/IEC Moving Picture Experts Group). It is the most widely adopted standard. H.264 helps accelerate the adoption of megapixel/HDTV cameras since the highly efficient compression technology can reduce the large file sizes and bit rates generated without compromising image quality. There are tradeoffs, however. While H.264 provides savings in network bandwidth and storage costs, it requires higher performance network cameras and monitoring stations. The Baseline Profile for H.264 uses only I- and P- frames, while the Main Profile may also use B-frames in addition to I- and P-frames. Axis’ network video products use the H.264 Baseline or Main Profile. The Baseline Profile allows network video products to have low latency. In video products with more powerful processors, Axis uses the Main Profile without B-frames to enable higher compression and at the same time low latency and maintained video quality. Using Axis’ Main Profile H.264 compression, VGA-sized video streams are reduced by 10% to 15% and HDTV-sized video streams are reduced by 15% to 20%, compared with Axis’ Baseline Profile H.264 compression. H.264 profile comparison 500,000 Baseline Main 400,000 Bit rate 300,000 200,000 100,000 0 0 500 1,000 Time 1,500 2,000 2,500 3,000 Figure 7.2a While maintaining the same quality, Axis’ Main Profile H.264 compression generates fewer bits per second than with its Baseline Profile H.264 compression. Chapter 7 - Video compression 81 7.3 Variable and constant bit rates With MPEG-4 and H.264, users can allow an encoded video stream to have a variable or a constant bit rate. The optimal selection depends on the application and network infrastructure. With VBR (variable bit rate), a predefined level of image quality can be maintained regardless of motion or the lack of it in a scene. This means that bandwidth use will increase when there is a lot of activity in a scene and will decrease when there is no motion. This is often desirable in video surveillance applications where there is a need for high quality, particularly if there is motion in a scene. Since the bit rate may vary, even when an average target bit rate is defined, the network infrastructure (available bandwidth) must be able to accommodate high throughputs. With limited bandwidth available, the recommended mode is normally CBR (constant bit rate) as this mode generates a constant bit rate that can be predefined by a user. The disadvantage with CBR is that when there is, for instance, increased activity in a scene that results in a bit rate that is higher than the target rate, the restriction to keep the bit rate constant leads to a lower image quality and frame rate. Axis network video products allow the user to prioritize either the image quality or the frame rate if the bit rate rises above the target bit rate. 7.4 Comparing standards When comparing the performance of MPEG standards such as MPEG-4 and H.264, it is impor-tant to note that results may vary between encoders that use the same standard. This is because the designer of an encoder can choose to implement different sets of tools defined by a standard. As long as the output of an encoder conforms to a standard’s format and decoder, it is possible to make different implementations. An MPEG standard, therefore, cannot guarantee a given bit rate or quality, and comparisons cannot be properly made without first defining how the standards are implemented in an encoder. A decoder, unlike an encoder, must implement all the required parts of a standard in order to decode a compliant bit stream. A standard specifies exactly how a decompression algorithm should restore every bit of a compressed video. The graph on the following page provides a bit rate comparison, given the same level of image quality, among the following video standards: Motion JPEG, MPEG-4 Part 2 (no motion compensation), MPEG-4 Part 2 (with motion compensation) and H.264 (Baseline Profile). Chapter 7 - Video compression 82 Figure 7.4a Axis’ Baseline Profile H.264 compression generated up to 50% fewer bits per second for a sample video sequence than an MPEG-4 compression with motion compensation. The H.264 compression was at least three times more efficient than an MPEG-4 compression with no motion compensation and at least six times more efficient than with Motion JPEG. Chapter 8 - Audio 83 8. Audio While the use of audio in video surveillance systems is still not widespread, having audio can enhance a system’s ability to detect and interpret events, as well as enable audio communication over an IP network. The use of audio, however, can be restricted in some countries, so it is a good idea to check with local authorities. Topics covered in this chapter include application scenarios, audio equipment, audio modes, audio detection alarm, audio compression and audio/ video synchronization. 8.1 Audio applications Having audio as an integrated part of a video surveillance system can be an invaluable addition to a system’s ability to detect and interpret events and emergency situations. The ability of audio to cover a 360° area enables a video surveillance system to extend its coverage beyond a camera’s field of view. It can instruct a PTZ camera (or alert the operator of one) to visually verify an audio alarm. Audio can also be used to provide users with the ability to not only listen in on an area, but also communicate orders or requests to visitors or intruders. For instance, if a person in a camera’s field of view demonstrates suspicious behavior, such as loitering near a bank machine, or is seen to be entering a restricted area, a remote security guard can send a verbal warning to the person. In a situation where a person has been injured, being able to remotely communicate with and notify the victim that help is on the way can also be beneficial. Access control—that is, a remote ‘doorman’ at an entrance—is another area of application. Other applications include a remote helpdesk situation (e.g., an unmanned parking garage), and video conferencing. An audiovisual surveillance system increases the effectiveness of a security or remote monitoring solution by enhancing a remote user’s ability to receive and communicate information. 8.2 Audio support and equipment Audio support can be more easily implemented in a network video system than in an analog CCTV system. In an analog system, separate audio and video cables must be installed from endpoint to endpoint; that is, from the camera and microphone location to the viewing/recording Chapter 8 - Audio 84 location. If the distance between the microphone and the station is too long, balanced audio equipment must be used, which increases installation costs and difficulty. In a network video system, a network camera with audio support processes the audio and sends both audio and video over the same network cable for monitoring and/or recording. This eliminates the need for extra cabling, and makes synchronizing the audio and video much easier. AUDIO Stream IP NETWORK VIDEO Stream Recording/monitoring Figure 8.2a A network video system with integrated audio support. Audio and video streams are sent over the same network cable. AUDIO Stream I/O AUD IO 1 2 3 4 5 6 IP NETWORK OUT IN Analog camera Video encoder VIDEO Stream Recording/monitoring Figure 8.2b Some video encoders have built-in audio, making it possible to add audio even if analog cameras are used in an installation. Figure 8.2c An example of an Axis omnidirectional condenser microphone. A network camera or video encoder with an integrated audio functionality often provides a built-in microphone, and/or mic-in/line-in jack. With mic-in/line-in support, users have the option of using another type or quality of microphone than the one that is built into the camera or Chapter 8 - Audio 85 video encoder. It also enables the network video product to connect to more than one microphone, and the microphone can be located some distance away from the camera. The microphone should always be placed as close as possible to the source of the sound to reduce noise. In two-way, full-duplex mode, a microphone should face away and be placed some distance from a speaker to reduce feedback from the speaker. Many Axis network video products do not come with a built-in speaker. An active speaker—a speaker with a built-in amplifier—can be connected directly to a network video product with audio support. If a speaker does not have a built-in amplifier, it must first connect to an amplifier, which is then connected to a network camera/video encoder. To minimize disturbance and noise, always use a shielded audio cable and avoid running the cable near power cables and cables carrying high frequency switching signals. Audio cables should also be kept as short as possible. If a long audio cable is required, balanced audio equipment— that is, cable, amplifier and microphone that are all balanced—should be used to reduce noise. 8.3 Audio modes Depending on the application, there may be a need to send audio in only one direction or both directions, which can be done either simultaneously or in one direction at a time. There are three basic modes of audio communication: simplex, half duplex and full duplex. 8.3.1 Simplex Audio sent by camera LAN/WAN Loudspeaker Video sent by camera PC Network camera Microphone Figure 8.3a In simplex mode, audio is sent in one direction only. In this case, audio is sent by the camera to the operator. Applications include remote monitoring and video surveillance.. Audio sent by operator LAN/WAN Microphone Video sent by camera PC Network camera Loudspeaker Figure 8.3b In this example of a simplex mode, audio is sent by the operator to the camera. It can be used, for instance, to provide spoken instructions to a person seen on the camera or to scare a potential car thief away from a parking lot. Chapter 8 - Audio 86 8.3.2 Half duplex Loudspeaker Audio sent by operator Audio sent by camera LAN/WAN Video sent by camera Headphones PC Network camera Microphone Figure 8.3c In half-duplex mode, audio is sent in both directions, but only one party at a time can send. This is similar to a walkie-talkie. 8.3.3 Full duplex Loudspeaker Full duplex audio sent and received by operator LAN/WAN Video sent by camera Headphones PC Network camera Microphone Figure 8.3d In full-duplex mode, audio is sent to and from the operator simultaneously. This mode of communication is similar to a telephone conversation. Full duplex requires that the client PC has a sound card with support for full-duplex audio. 8.4 Audio detection alarm Audio detection alarm can be used as a complement to video motion detection since it can react to events in areas too dark for the video motion detection functionality to work properly. It can also be used to detect activity in areas outside of the camera’s view. When sounds, such as the breaking of a window or voices in a room, are detected, they can trigger a network camera to send and record video and audio, send e-mail or other alerts, and activate external devices such as alarms. Similarly, alarm inputs such as motion detection and door contacts can be used to trigger video and audio recordings. In a PTZ camera, audio detection can trigger the camera to automatically turn to a preset location such as a specific window. 8.5 Audio compression Analog audio signals must be converted into digital audio through a sampling process and then compressed to reduce the size for efficient transmission and storage. The conversion and compression is done using an audio codec, an algorithm that codes and decodes audio data. Chapter 8 - Audio 87 8.5.1 Sampling frequency There are many different audio codecs supporting different sampling frequencies and levels of compression. Sampling frequency refers to the number of times per second a sample of an analog audio signal is taken and is defined in hertz (Hz). In general, the higher the sampling frequency, the better the audio quality and the greater the bandwidth and storage needs. 8.5.2 Bit rate The bit rate is an important setting in audio since it determines the level of compression and, thereby, the quality of the audio. In general, the higher the compression level (the lower the bit rate), the lower the audio quality. The differences in the audio quality of codecs may be particularly noticeable at high compression levels (low bit rates), but not at low compression levels (high bit rates). Higher compression levels may also introduce more latency or delay, but they enable greater savings in bandwidth and storage. The bit rates most often selected with audio codecs are between 32 kbit/s and 64 kbit/s. Audio bit rates, as with video bit rates, are an important consideration to take into account when calculating total bandwidth and storage requirements. 8.5.3 Audio codecs Axis network video products support three audio codecs. The first is AAC-LC (Advanced Audio Coding - Low Complexity), also known as MPEG-4 AAC, which requires a license. AAC-LC, particularly at a sampling rate of 16 kHz or higher and at a bit rate of 64 kbit/s or more, is the recommended codec to use when the best possible audio quality is required. The other two codecs are G.711 and G.726, which are non-licensed ITU-T standards. They have lower delay and requires less computing power than AAC-LC. G.711 and G.726 are speech codecs that are primarily used in telephony and have low audio quality. Both have a sampling rate of 8 kHz. G.711 has a bit rate of 64 kbit/s. Axis’ G.726 implementation supports 24 and 32 kbit/s. With G.711, Axis’ products support only µ-law, which is one of two sound compression algorithms in the G.711 standard. When using G.711, it is important that the client also uses the µ-law compression. 8.6 Audio and video synchronization Synchronization of audio and video data is handled by a media player (a computer software program used for playing back multimedia files) or by a multimedia framework such as Microsoft DirectX, which is a collection of application programming interfaces that handles multimedia files. Audio and video are sent over a network as two separate packet streams. In order for the client or player to perfectly synchronize the audio and video streams, the audio and video packets must be time-stamped. The timestamping of video packets using Motion JPEG compression may not always be supported in a network camera. If this is the case and if it is important to have Chapter 8 - Audio 88 synchronized video and audio, the video format to choose is MPEG-4 or H.264 since such video streams, along with the audio stream, are sent using RTP (Real-time Transport Protocol), which timestamps the video and audio packets. There are many situations, however, where synchronized audio is less important or even undesirable; for example, if audio is to be monitored but not recorded. Chapter 9 - Network technologies 89 9. Network technologies Different network technologies are used to support and provide the many benefits of a network video system. This chapter begins with a discussion about the local area network, in particular, Ethernet networks and the components that support it. The use of Power over Ethernet is also covered. Internet communication is then addressed with discussions on IP (Internet Protocol) addressing—what they are and how they work, including how network video products can be accessed over the Internet. An overview of the data transport protocols used in network video is also provided. Other areas covered in the chapter include virtual local area networks and Quality of Service, and the different ways of securing communication over IP networks. For more on wireless technologies, see Chapter 10. 9.1 Local area network and Ethernet A local area network (LAN) is a group of computers that are connected together in a localized area to communicate with one another and share resources such as printers. Data is sent in the form of packets, and to regulate the transmission of the packets, different technologies can be used. The most widely used LAN technology is Ethernet and it is specified in a standard called IEEE 802.3. (Other types of LAN networking technologies include token ring and FDDI.) Today Ethernet uses a star topology in which the individual nodes (devices) are networked with one another via active networking equipment such as switches. The number of networked devices in a LAN can range from two to several thousand. The physical transmission medium for a wired LAN involves cables, mainly twisted pair or fiber optics. A twisted pair cable consists of eight wires, forming four pairs of twisted copper wires and is used with RJ45 plugs and sockets. The maximum cable length of a twisted pair is 100 m (328 ft.) while for fiber, the maximum length ranges from 10 km to 70 km (6 miles to 43 miles), depending on the type of fiber. Depending on the type of twisted pair or fiber optic cables used, data rates today can range from 100 Mbit/s to 100,000 Mbit/s. Chapter 9 - Network technologies 90 Figure 9.1a Twisted pair cabling includes four pairs of twisted wires, normally connected to a RJ45 plug at the end. A rule of thumb is to always build a network with greater capacity than is currently required. To future-proof a network, it is a good idea to design a network such that only 30% of its capacity is used. Since more and more applications are running over networks today, higher and higher network performance is required. While network switches (discussed below) are easy to upgrade after a few years, cabling is normally much more difficult to replace. 9.1.1 Types of Ethernet networks Below are the most common types of Ethernet networks in the video surveillance industry. Fast Ethernet Fast Ethernet refers to an Ethernet network that can transfer data at a rate of 100 Mbit/s. It can be based on a twisted pair or fiber optic cable. (The older 10 Mbit/s Ethernet is still installed and used, but such networks do not provide the necessary bandwidth for some network video applications.) Most devices that are connected to a network, such as a laptop or a network camera, are equipped with a 10BASE-T/100BASE-TX Ethernet interface, most commonly called a 10/100 interface, which supports both 10 Mbit/s and Fast Ethernet. The type of twisted pair cable that supports Fast Ethernet is called a Cat-5 cable. Gigabit Ethernet Gigabit Ethernet, which can also be based on a twisted pair or fiber optic cable, delivers a data rate of 1,000 Mbit/s (1 Gbit/s) and is now more commonly used than Fast Ethernet. 1 or 10 Gbit/s Ethernet may be necessary for the backbone network that connects many network cameras. The type of twisted pair cable that supports Gigabit Ethernet is a Cat-5e cable, where all four pairs of twisted wires in the cable are used to achieve the high data rates. Cat-5e or higher cable categories are recommended for network video systems. Most interfaces are backwards compatible with 10 and 100 Mbit/s Ethernet and are commonly called 10/100/1000 interfaces. Chapter 9 - Network technologies 91 For transmission over longer distances, fiber cables such as 1000BASE-SX (up to 550 m/1804 ft.) and 1000BASE-LX (up to 550 m with multimode optical fibers and 5,000 m or 3 miles with single-mode fibers) can be used. Figure 9.1b Longer distances can be bridged using fiber optic cables. Fiber is typically used in the backbone of a network. 10 Gigabit Ethernet 10 Gigabit Ethernet delivers a data rate of 10 Gbit/s (10,000 Mbit/s), and a fiber optic or twisted pair cable can be used. 10GBASE-LX4, 10GBASE-ER and 10GBASE-SR based on an optical fiber cable can be used to bridge distances of up to 10 km (6 miles). With a twisted pair solution, a very high quality cable (Cat-6a or Cat-7) is required. 10 Gbit/s Ethernet is mainly used for backbones in high-end applications that require high data rates. 9.1.2 Connecting network devices and network switch When only two devices need to communicate directly with one another via a twisted pair cable, a so-called crossover cable may be needed. The crossover cable simply crosses the transmission pair on one end of the cable with the receiving pair on the other end and vice versa. Since many devices have network interfaces that automatically detect such cases, a regular network cable may be used. To network multiple devices in a LAN, network equipment such as a network switch is required. When using a network switch, a regular network cable is used. The main function of a network switch is to forward data from one device to another on the same network. It does it in an efficient manner since data can be directed from one device to another without affecting other devices on the same network. A network switch works by registering the MAC (Media Access Control) addresses of all devices that are connected to it. (Each networking device has a unique MAC address, which is made up of a series of numbers and letters in hexadecimal notation and is set by the manufacturer. The address is often found on the product label.) When a network switch receives data, it forwards it only to the port that is connected to the device with the appropriate destination MAC address. Chapter 9 - Network technologies 92 Network switches typically indicate their performance in per port rates and in backplane or internal rates (both in bit rates and in packets per second). The port rates indicate the maximum rates on specific ports. This means that the speed of a switch, for example 100 Mbit/s, is often the performance of each port. Figure 9.1c With a network switch, data transfer is managed very efficiently as data traffic can be directed from one device to another without affecting any other ports on the switch. A network switch normally supports different data rates simultaneously. The most common rates used to be 10/100 Mbit/s, supporting the 10 Mbit/s and Fast Ethernet standards. Today, network switches often have 10/100/1000 interfaces, thus supporting 10 Mbit/s, Fast Ethernet and Gigabit Ethernet simultaneously. The transfer rate and mode between a port on a switch and a connected device are normally determined through auto-negotiation, whereby the highest common data rate and best transfer mode are used. A network switch also allows a connected device to function in full-duplex mode—that is, send and receive data at the same time, resulting in increased performance. Network switches may come with different features or functions. Some switches include the function of a router (see Section 9.2). A switch may also support Power over Ethernet or Quality of Service (see Section 9.4), which controls how much bandwidth is used by different applications. 9.1.3 Power over Ethernet Power over Ethernet (PoE) provides the option of supplying devices connected to an Ethernet network with power using the same cable as for data communication. Power over Ethernet is widely used to power IP phones, wireless access points and network cameras in a LAN. The main benefit of PoE is the inherent cost savings. Hiring a certified electrician and installing a separate power line are not needed. This is advantageous, particularly in difficult-to-reach areas. The fact that no power cable has to be installed can save, depending on the camera location, up to a few hundred dollars per camera. Having PoE also makes it easier to move a camera to a new location, or add cameras to a video surveillance system. Chapter 9 - Network technologies 93 Additionally, PoE can make a video system more secure. A video surveillance system with PoE can be powered from the server room, which is often backed up with a UPS (Uninterruptible Power Supply). This means that the video surveillance system can be operational even during a power outage. Due to the benefits of PoE, it is recommended for use with as many devices as possible. The power available from the PoE-enabled switch or midspan should be sufficient for the connected devices and the devices should support power classification. These are explained in more detail in the sections below. 802.3af standard, PoE+ and High PoE Most PoE devices today conform to the IEEE 802.3af standard, which was published in 2003. The IEEE 802.3af standard uses standard Cat-5 or higher cables, and ensures that data transfer is not affected. In the standard, the device that supplies the power is referred to as the power sourcing equipment (PSE). This can be a PoE-enabled switch or midspan. The device that receives the power is referred to as a powered device (PD). The functionality is normally built into a network device like a network camera, or provided in a standalone splitter (see section below). Backward compatibility to non PoE-compatible network devices is guaranteed. The standard includes a method for automatically identifying if a device supports PoE, and only when that is confirmed will power be supplied to the device. This also means that the Ethernet cable that is connected to a PoE switch will not supply any power if it is not connected to a PoE-enabled device. This eliminates the risk of getting an electrical shock when installing or rewiring a network. In a twisted pair cable, there are four pairs of twisted wires. PoE can use either the two ‘spare’ wire pairs, or overlay the current on the wire pairs used for data transmission. Switches with built-in PoE often supply electricity through the two pairs of wires used for transferring data, while midspans normally use the two spare pairs. A PD supports both options. According to IEEE 802.3af, a PSE provides a voltage of 48 V DC with a maximum power of 15.4 W per port. Considering that power loss takes place on a twisted pair cable, only 12.95 W is guaranteed for a PD. The IEEE 802.3af standard specifies various performance categories for PDs. PSE such as switches and midspans normally supply a certain amount of power, typically 300 W to 500 W. On a 48-port switch, that would mean 6 W to 10 W per port if all ports are connected to devices that use PoE. Unless the PDs support power classification, a full 15.4 W must be reserved for each port that uses PoE, which means a switch with 300 W can only supply power on 20 of the 48 ports. However, if all devices let the switch know that they are Class 1 devices, the 300 W will be enough to supply power to all 48 ports. Chapter 9 - Network technologies 94 Class Minimum power level at PSE Maximum power level used by PD Usage 0 15.4 W 0.44 W - 12.95 W default 1 4.0 W 0.44 W - 3.84 W optional 2 7.0 W 3.84 W - 6.49 W optional 3 15.4 W 6.49 W - 12.95 W optional 4 30 W 12.95 W - 25.5 W Table 9.1a Power classifications according to IEEE 802.3af and IEEE 802.3at. Most fixed network cameras can receive power via PoE using the IEEE 802.3af standard and are normally identified as Class 1 or 2 devices. Another PoE standard is IEEE 802.3at, also known as PoE+. Using PoE+, the power limit is raised to at least 30 W via two pairs of wires from a PSE. For power requirements that are higher than the PoE+ standard, Axis uses the term, High PoE. With High PoE, the power limits are raised to at least 60 W via four pairs of wires and 51 W is guaranteed for power over Ethernet. PoE+ and High PoE midspans and splitters can be used for devices such as PTZ cameras with motor control, as well as cameras with heaters and fans, which require more power than can be delivered by the IEEE 802.3af standard. For PoE+ and High PoE, the use of at least a Cat-5e or higher cable is recommended. Midspans and splitters Midspans and splitters (also known as active splitters) are equipment that enable an existing network to support Power over Ethernet. Uninterruptible Power Supply (UPS) 3115 Network camera with built-in PoE Network camera without built-in PoE Network switch Midspan Power Ethernet Active splitter Power over Ethernet Figure 9.1d An existing system can be upgraded with PoE functionality using a midspan and splitter. Chapter 9 - Network technologies 95 The midspan, which adds power to an Ethernet cable, is placed between the network switch and the powered devices. To ensure that data transfer is not affected, it is important to keep in mind that the maximum distance between the source of the data (e.g., switch) and the network video products is not more than 100 m (328 ft.). This means that the midspan and active splitter(s) must be placed within the distance of 100 m. A splitter is used to split the power and data in an Ethernet cable into two separate cables, which can then be connected to a device that has no built-in support for PoE. Since PoE or PoE+ only supplies 48 V DC, another function of the splitter is to step down the voltage to the appropriate level for the device; for example, 12 V or 5 V. 9.2 Sending data over the Internet To send data between a device on one local area network to another device on another LAN, a standard way of communicating is required since local area networks may use different types of technologies. This need led to the development of IP addressing and the many IP-based protocols for communicating over the Internet, which is a global system of interconnected computer networks. Before IP addressing is discussed, some of the basic elements of Internet communication such as routers, firewalls and Internet service providers are covered below. Routers To forward data packages from one LAN to another LAN via the Internet, a networking equipment called a network router must be used. A router routes information from one network to another based on IP addresses. It forwards only data packages that are to be sent to another network. A router is most commonly used for connecting a local network to the Internet. Traditionally, routers were referred to as gateways. Firewalls A firewall is designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks that are connected to the Internet. Messages entering or leaving the Internet pass through the firewall, which examines each message, and blocks those that do not meet the specified security criteria. Internet connections In order to connect a LAN to the Internet, a network connection via an Internet service provider (ISP) must be established. When connecting to the Internet, terms such as upstream and downstream are used. Upstream describes the transfer rate (bandwidth) with which data can be uploaded from the device to the Internet; for instance, when video is sent from a network camera. Downstream is the transfer speed for downloading files; for instance, when video is received by a monitoring PC. In most scenarios—for example, a laptop that is connected to the Internet— Chapter 9 - Network technologies 96 the download speed from the Internet is the most important to consider. In a network video application with a network camera at a remote site, the upstream speed is more relevant since data (video) from the network camera will be uploaded to the Internet. Internet technologies with asymmetrical bandwidth such as ADSL (Asymmetric Digital Subscriber Line) may not be suitable for network video applications since their upstream data rate may be too low. 9.2.1 IP addressing Any device that wants to communicate with other devices via the Internet must have a unique and appropriate IP address. IP addresses are used to identify the sending and receiving devices. There are currently two IP versions: IP version 4 (IPv4) and IP version 6 (IPv6). The main difference between the two is that the length of an IPv6 address is longer (128 bits compared with 32 bits for an IPv4 address). IPv4 addresses are most commonly used today. 9.2.2 IPv4 addresses IPv4 addresses are grouped into four blocks, and each block is separated by a dot. Each block represents a number between 0 and 255; for example, 192.168.12.23. Certain blocks of IPv4 addresses have been reserved exclusively for private use. These private IP addresses are 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255 and 192.168.0.0 to 192.168.255.255. Such addresses can only be used on private networks and are not allowed to be forwarded through a router to the Internet. All devices that want to communicate over the Internet must have its own individual, public IP address. A public IP address is an address allocated by an Internet service provider. An ISP can allocate either a dynamic IP address, which can change during a session, or a static address, which normally comes with an additional monthly fee. Ports A port number defines a particular service or application so that the receiving server (e.g., network camera) will know how to process the incoming data. When a computer sends data tied to a specific application, it usually automatically adds the port number to an IP address without the user’s knowledge. Port numbers can range from 0 to 65535. Certain applications use port numbers that are pre-assigned to them by the Internet Assigned Numbers Authority (IANA). For example, a web service via HTTP is typically mapped to port 80 on a network camera. Setting IPv4 addresses In order for a network camera or video encoder to work in an IP network, an IP address must be assigned to it. Setting an IPv4 address for an Axis network video product can be done mainly in two ways: automatically using DHCP (Dynamic Host Configuration Protocol) and manually. Manual setting can be done in two ways. One is to use the network video product’s web page Chapter 9 - Network technologies 97 to enter the static IP address, the subnet mask, as well as the IP addresses of the default router, the DNS (Domain Name System) server and the NTP (Network Time Protocol) server for synchronizing the time of the network video product. The second way is to use a management software tool such as AXIS Camera Management. DHCP manages a pool of IP addresses, which it can assign dynamically to a network camera/ video encoder. The DHCP function is often performed by a broadband router. The broadband router in turn is typically connected to the Internet and gets its public IP address from an Internet service provider. Using a dynamic IP address means that the IP address for a network device may change from day to day. With dynamic IP addresses, it is recommended that users register a domain name (e.g., www.mycamera.com) for the network video product at a dynamic DNS server, which can always tie the domain name for the product to any IP address that is currently assigned to it. (A domain name can be registered using some of the popular dynamic DNS sites such as www.dyndns.org. Axis also offers its own called AXIS Internet Dynamic DNS Service at www.axiscam.net, which is accessible from an Axis network video product’s web page.) Using DHCP to set an IPv4 address works as follows. When a network video product comes online, it sends a query requesting configuration from a DHCP server. The DHCP server replies with the configuration requested by the network video product. This normally includes the IP address, the subnet mask, and IP addresses for the router, DNS server and NTP server. The network video product first verifies that the offered IP address is not already in use on the local network, assigns the address to itself and can then update a dynamic DNS server with its current IP address so that users can access the product using a domain name. With AXIS Camera Management, the software can automatically find and set IP addresses and show the connection status. The software can also be used to assign static, private IP addresses for Axis network video products. This is recommended when using video management software to access network video products. In a network video system with potentially hundreds of cameras, a software program such as AXIS Camera Management is necessary in order to effectively manage the system. For more on video management, see Chapter 11. NAT (Network address translation) When a network device with a private IP address wants to send information via the Internet, it must do so using a router that supports NAT. Using this technique, the router can translate a private IP address into a public IP address without the sending host’s knowledge. Port forwarding To access cameras that are located on a private LAN via the Internet, the public IP address of the router should be used together with the corresponding port number for the network video product on the private network. Chapter 9 - Network technologies 98 Since a web service via HTTP is typically mapped to port 80, what happens when there are several network video products using port 80 for HTTP in a private network? Instead of changing the default HTTP port number for each network video product, a router can be configured to associate a unique HTTP port number to a particular network video product’s IP address and default HTTP port. This is a process called port forwarding. Port forwarding works as follows. Incoming data packets reach the router via the router’s public (external) IP address and a specific port number. The router is configured to forward any data coming into a predefined port number to a specific device on the private network side of the router. The router replaces the router address with the private address of the device and forwards the data to the device. The reverse happens with outgoing data packets. The router replaces the private IP address of the device with the router’s public IP address before the data is sent out over the Internet. For the external client, it looks like its communicating with the router when in fact the sent packets originate from the device on the private network. Port mapping in the router External IP address of router 126.96.36.199 188.8.131.52 184.108.40.206 External port Internal IP address of network device 8028 192.168.10.11 8030 192.168.10.12 8032 192.168.10.13 Internal port 80 80 80 192.168.10.11 Port 80 HTTP Request URL: http://220.127.116.11:8032 192.168.10.12 Port 80 INTERNET 18.104.22.168 Router 192.168.10.13 Port 80 Figure 9.2a Thanks to port forwarding in the router, network cameras with private IP addresses on a local network can be accessed over the Internet. In this illustration, the router knows to forward data (request) coming into port 8032 to a network camera with a private IP address of 192.168.10.13 port 80. The network camera can then begin to send video. Port forwarding is traditionally done by first configuring the router. Different routers have different ways of doing port forwarding and there are websites such as www.portforward.com that offer step-by-step instruction for different routers. Usually port forwarding involves bringing up the router’s interface using an Internet browser, and entering the public (external) IP address of the router and a unique port number that is then mapped to the internal IP address of the specific network video product and its port number for the application. Chapter 9 - Network technologies 99 To make the task of port forwarding easier, Axis offers the NAT traversal feature in its network video products. NAT traversal will, when enabled, attempt to configure port mapping in a NAT router on the network using UPnP. On the network video product’s web page, users can manually enter the IP address of the NAT router. If a router is not manually specified, then the network video product will automatically search for NAT routers on the network and select the default router. In addition, NAT traversal will automatically select an HTTP port if none is manually entered. Figure 9.2b Axis network video products enable port forwarding to be set using NAT traversal. 9.2.3 IPv6 addresses An IPv6 address is written in hexadecimal notation with colons subdividing the address into eight blocks of 16 bits each; for example, 2001:0da8:65b4:05d3:1315:7c1f:0461:7847 The major advantages of IPv6, apart from the availability of a huge number of IP addresses, include enabling a device to automatically configure its IP address using its MAC address. For communication over the Internet, the host requests and receives from the router the necessary prefix of the public address block and additional information. The prefix and host’s suffix is Chapter 9 - Network technologies 100 then used, so DHCP for IP address allocation and manual setting of IP addresses are no longer required with IPv6. Port forwarding is also no longer needed. Other benefits of IPv6 include renumbering to simplify switching entire corporate networks between providers, faster routing, point-to-point encryption according to IPSec, and connectivity using the same address in changing networks (Mobile IPv6). An IPv6 address is enclosed in square brackets in a URL and a specific port can be addressed in the following way: http://[2001:0da8:65b4:05d3:1315:7c1f:0461:7847]:8081/ Setting an IPv6 address for an Axis network video product is as simple as checking a box to enable IPv6 in the product. The product will then receive an IPv6 address according to the configuration in the network router. 9.2.4 Data transport protocols for network video The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) are the IP-based protocols used for sending data. These transport protocols act as carriers for many other protocols. For example, HTTP (Hyper Text Transfer Protocol), which is used to browse web pages on servers around the world using the Internet, is carried by TCP. TCP provides a reliable, connection-based transmission channel. It ensures that data sent from one end is received on the other. TCP’s reliability through retransmission may introduce significant delays. In general, TCP is used when reliable communication is preferred over transport latency. UDP is a connectionless protocol and does not guarantee the delivery of data sent, thus leaving the whole control mechanism and error-checking to the application itself. UDP provides no transmissions of lost data and, therefore, does not introduce further delays. Chapter 9 - Network technologies Protocol FTP (File Transfer Protocol) SMTP (Send Mail Transfer Protocol HTTP (Hyper Text Transfer Protocol HTTPS (Hypertext Transfer Protocol over Secure Socket Layer) Transport protocol TCP TCP TCP TCP 101 Port Common usage Network video usage 21 Transfer of files over the Internet/intranets Transfer of images or video from a network camera/video encoder to an FTP server or to an application 25 Protocol for sending e-mail messages A network camera/video encoder can send images or alarm notifications using its built-in e-mail client. 80 Used to browse the web, i.e. to retrieve web pages from web servers The most common way to transfer video from a network camera/ video encoder where the network video device essentially works as a web server making the video available for the requesting user or application server. 443 Used to access web pages securely using encryption technology Secure transmission of video from network cameras/video encoders. A common way of transmitting H.264/MPEG-based network video, and for synchronizing video and audio since RTP provides sequential numbering and timestamping of data packets, which enable the data packets to be reassembled in the correct sequence. Transmission can be either unicast or multicast. RTP (Real Time Protocol) UDP/TCP Not defined RTP standardized packet format for delivering audio and video over the Internet— often used in streaming media systems or video conferencing RTSP (Real Time Streaming Protocol) TCP 554 Used to set up and control multimedia sessions over RTP Table 9.2a Common TCP/IP protocols and ports used for network video. Chapter 9 - Network technologies 102 9.3 VLANs When a network video system is designed, there is often a desire to keep the network separate from other networks, both for security as well as performance reasons. At first glance, the obvious choice would be to build a separate network. While the design would be simplified, the cost of purchasing, installing and maintaining the network would often be higher than using a technology called virtual local area network (VLAN). VLAN is a technology for virtually segmenting networks, a functionality that is supported by most network switches. It can be achieved by dividing network users into logical groups. Only users in a specific group are capable of exchanging data or accessing certain resources on the network. If a network video system is segmented into a VLAN, only the servers located on that VLAN can access the network cameras. VLANs provide a flexible and more cost-efficient solution than a separate network. The primary protocol used when configuring VLANs is IEEE 802.1Q, which tags each frame or packet with extra bytes to indicate which virtual network the packet belongs to. VLAN 30 VLAN 20 VLAN 20 VLAN 30 Figure 9.3a In this illustration, VLANs are set up over several switches. First, each of the two different LANs are segmented into VLAN 20 and VLAN 30. The links between the switches transport data from different VLANs. Only members of the same VLAN are able to exchange data, either within the same network or over different networks. VLANs can be used to separate a video network from an office network. 9.4 Quality of Service Since different applications—for example, telephone, e-mail and surveillance video—may be using the same IP network, there is a need to control how network resources are shared to fulfill the requirements of each service. One solution is to let network routers and switches operate differently on different kinds of services (voice, data, and video) as traffic passes through the network. By using Quality of Service (QoS), different network applications can co-exist on the same network without consuming each other’s bandwidth. Chapter 9 - Network technologies 103 The term, Quality of Service, refers to a number of technologies such as Differentiated Service Codepoint (DSCP), which can identify the type of data in a data packet and so divide the packets into traffic classes that can be prioritized for forwarding. The main benefits of a QoS-aware network include the ability to prioritize traffic to allow critical flows to be served before flows with lesser priority, and greater reliability in a network by controlling the amount of bandwidth an application may use and thus controlling bandwidth competition between applications. An example of where QoS can be used is with PTZ commands to guarantee fast camera responses to movement requests. The prerequisite for the use of QoS within a video network is that all switches, routers and network video products must support QoS. PC 3 PC 1 FTP Router 1 100 Mbit 100 Mbit Switch 1 Camera 1 Video Router 2 FTP 10 Mbit Switch 2 PC 2 Video 100 Mbit Camera 2 Figure 9.4a Ordinary (non-QoS aware) network. In this example, PC1 is watching two video streams from cameras 1 and 2, with each camera streaming at 2.5 Mbit/s. Suddenly, PC2 starts a file transfer from PC3. In this scenario, the File Transfer Protocol (FTP) will try to use the full 10 Mbit/s capacity between the routers 1 and 2, while the video streams will try to maintain their total of 5 Mbit/s. The amount of bandwidth given to the surveillance system can no longer be guaranteed and the video frame rate will probably be reduced. At worst, the FTP traffic will consume all the available bandwidth. PC 3 PC 1 FTP Router 1 100 Mbit Switch 1 Camera 1 Video Router 2 FTP HTTP 2 3 Video 5 100 Mbit 10 Mbit Switch 2 PC 2 100 Mbit Camera 2 Figure 9.4b QoS aware network. Here, Router 1 has been configured to use up to 5 Mbit/s of the available 10 Mbit/s for streaming video. FTP traffic is allowed to use 2 Mbit/s, and HTTP and all other traffic can use a maximum of 3 Mbit/s. Using this division, video streams will always have the necessary bandwidth available. File transfers are considered less important and get less bandwidth, but there will still be bandwidth available for web browsing and other traffic. Note that these maximums only apply when there is congestion on the network. If there is unused bandwidth available, this can be used by any type of traffic. Chapter 9 - Network technologies 104 9.5 Network security There are different levels of security when it comes to securing information being sent over IP networks. The first is authentication and authorization. The user or device identifies itself to the network and the remote end by a user name and password, which are then verified before the device is allowed into the system. Added security can be achieved by encrypting the data to prevent others from using or reading the data. Common methods are SSL/TLS (also known as HTTPS), VPN and WEP or WPA in wireless networks. (For more on wireless security, see Chapter 10.) The use of encryption may slow down communications, depending on the kind of implementation and encryption used. 9.5.1 User name and password authentication Using user name and password authentication is the most basic method of protecting data on an IP network and may be sufficient where high levels of security are not required, or where the video network is segmented off from the main network and unauthorized users would not have physical access to the video network. The passwords can be encrypted or unencrypted when they are sent; the former provides the best security. Axis network video products provide multi-level password protection. Three levels are available: Administrator (full access to all functionalities), Operator (access to all functionalities except the configuration pages), Viewer (access only to live video). 9.5.2 IP address filtering Axis network video products provide IP address filtering, which gives or denies access rights to defined IP addresses. A typical configuration is to configure the network cameras to allow only the IP address of the server that is hosting the video management software to access the network video products. 9.5.3 IEEE 802.1X Many Axis network video products support IEEE 802.1X, which is a method used to protect a network from connecting with unauthorized devices. IEEE 802.1X establishes a point-to-point connection or prevents access from the LAN port if authentication fails. IEEE 802.1X prevents what is called “port hijacking”; that is, when an unauthorized computer gets access to a network by getting to a network jack inside or outside a building. IEEE 802.1X is useful in network video applications since network cameras are often located in public spaces where an openly accessible network jack can pose a security risk. In today’s enterprise networks, IEEE 802.1X is becoming a basic requirement for anything that is connected to a network. In a network video system, IEEE 802.1X can work as follows: 1) A network camera that is configured for IEEE 802.1X sends a request for network access to a switch or access point; 2) the switch or access point forwards the query to an authentication server; for instance, a RADIUS (remote authentication dial-in user service) server such as a Microsoft Internet Authentication Chapter 9 - Network technologies 105 Service server; 3) if authentication is successful, the server instructs the switch or access point to open the port to allow data from the network camera to pass through the switch and be sent over the network. 1 Supplicant (Network camera) 2 Authenticator (Switch) 3 Authentication Server (RADIUS) or other LAN resources Figure 9.5a IEEE 802.1X enables port-based security and involves a supplicant (e.g., a network camera), an authenticator (e.g., a switch) and an authentication server. Step 1: network access is requested; step 2: query forwarded to an authentication server; step 3: authentication is successful and the switch is instructed to allow the network camera to send data over the network. 9.5.4 HTTPS or SSL/TLS HTTPS (Hyper Text Transfer Protocol Secure) is a secure communication method that sends HTTP inside a Secure Socket Layer (SSL) or Transport Layer Security (TLS) connection. It means that the HTTP and the data itself are encrypted. Many Axis network video products have built-in support for HTTPS, which makes it possible for video to be securely viewed using a web browser. To enable an Axis network camera or video encoder to communicate over HTTPS, a digital certificate and an asymmetric key pair must be installed in the Axis product. The key pair is generated by the Axis product. The certificate can either be generated and self-signed by the Axis product, or issued by a certificate authority. With HTTPS, the certificate is used for authentication and encryption. This means that the certificate allows a web browser to verify the identity of the camera or video encoder, and it enables the communication to be encrypted using keys that are generated by public-key cryptography. 9.5.5 VPN (Virtual Private Network) With VPN, a secure “tunnel” between two communicating devices can be created, enabling safe and secure communication over the Internet. In such a set up, the original packet, including the data and its header, which may contain information such as the source and destination addresses, the type of information being sent, the packet number in the sequence of packets and the packet length, is encrypted. The encrypted packet is then encapsulated in another packet that shows only the IP addresses of the two communicating devices (i.e., routers). This set up protects the traffic and its contents from unauthorized access, and only devices with the correct “key” Chapter 9 - Network technologies 106 will be able to work within the VPN. Network devices between the client and the server will not be able to access or view the data. SSL/TLS encryption DATA VPN tunnel PACKET Secure Non-secure Figure 9.5b The difference between SSL/TLS and VPN is that in SSL/TLS only the actual data of a packet is encrypted. With VPN, the entire packet can be encrypted and encapsulated to create a secure “tunnel”. Both technologies can be used in parallel, but it is not recommended since each technology will add overhead and decrease the performance of the system. Chapter 10 - Wireless technologies 107 10. Wireless technologies For video surveillance applications, wireless technology offers a flexible, costefficient and quick way to deploy cameras, particularly over a large area as in a parking lot or a city center surveillance application. There would be no need to pull a cable through the ground. In older, protected buildings, wireless technology may be the only alternative if standard Ethernet cables may not be installed. Axis offers cameras with built-in wireless support. Network cameras without built-in wireless technology can still be integrated into a wireless network if a wireless bridge is used. 10.1 802.11 WLAN standards The most common set of standards for wireless local area networks (WLAN) is IEEE 802.11. While there are also other standards as well as proprietary technologies, the benefit of 802.11 wireless standards is that they all operate in a license-free spectrum, which means there is no license fee associated with setting up and operating the network. The most relevant amendments of the standards for Axis products are 802.11b, 802.11g and 802.11n. 802.11b, which was approved in 1999, operates in the 2.4 GHz range and provides data rates up to 11 Mbit/s. 802.11g, which was approved in 2003, operates in the 2.4 GHz range and provides data rates of up to 54 Mbit/s. WLAN products are usually 802.11b/g compliant. Most wireless products today support 802.11n, which was approved in 2009 and which operates in the 2.4 GHz or 5 GHz band. Depending on what features in the standard are implemented, 802.11n enables a maximum data rate of between 65 Mbit/s and 600 Mbit/s. Data rates, in practice, can be much lower than the theoretical maximums. The forthcoming IEEE 802.11ac standard, which will operate in the 5 GHz band, aims for even higher data rates. When setting up a wireless network, the bandwidth capacity of the access point and the bandwidth requirements of the network devices should be considered. In general, the useful data throughput supported by a particular WLAN standard is about half the bit rate stipulated by a standard due to signaling and protocol overhead. With network cameras that support 802.11g, no more than four to five of such cameras should be connected to a wireless access point. Chapter 10 - Wireless technologies 108 10.2 WLAN security Due to the nature of wireless communications, anyone with a wireless device that is present within the area covered by a wireless network can share the network and intercept data being transferred over it unless the network is secured. To prevent unauthorized access to the data transferred and to the network, some security technologies such as WEP and WPA/WPA2 have been developed to prevent unauthorized access and encrypt data sent over the network. 10.2.1WEP (Wired Equivalent Privacy) WEP was designed to prevent people without the correct key from accessing the network. It is, however, not a recommended security technology due to its weaknesses such as keys that are relatively short and the ease of reconstructing the keys from a relatively small amount of intercepted traffic. 10.2.2Wi-Fi Protected Access Wi-Fi Protected Access (WPA™) and its successor Wi-Fi Protected Access II (WPA2™) are based on IEEE 802.11i standard. They significantly increase wireless security by addressing the shortcomings in WEP. WPA-Personal, also known as WPA-/WPA2–PSK (Pre-shared key), is designed for small networks and does not require an authentication server. With WPA-Personal (WPA-/WPA2-PSK), Axis’ wireless cameras use a PSK to authenticate with the access point. The key can be entered either as a 256 bit number — expressed as 64 hexadecimal digits (0 to 9, A to F) — or a passphrase using 8 to 63 ASCII characters. Long passphrases must be used to circumvent weaknesses with this security method. Meanwhile, WPA-/WPA2-Enterprise is designed for large networks and requires an authentication server with the use of IEEE 802.1X. See Chapter 9 for more on IEEE 802.1X. To simplify the process of configuring WLAN and connecting to an access point, some Axis wireless cameras support a WLAN pairing mechanism that is compatible with Wi-Fi Protected Setup™ push-button configuration. It involves a WLAN pairing button on the camera and an access point with a push button configuration (PBC) button. When the buttons on both the camera and the access point are pressed within a 120 second time frame, the devices will automatically discover each other and agree on a configuration. The WLAN pairing function should be disabled once the camera is installed to prevent someone with physical access to the camera from connecting the camera to a rogue access point. Chapter 10 - Wireless technologies 109 Figure 10.2a Some Axis wireless cameras support a WLAN pairing mechanism that is compatible with Wi-Fi Protected Setup™ protocol, which simplifies the process of configuring security on wireless networks. 10.2.3Recommendations Some security guidelines when using wireless cameras for surveillance: > Enable the user/password login in the cameras. > Use WPA/WPA2 and a passphrase with at least 20 random characters in a mixed combination of lower and uppercase letters, special characters and numbers. > Enable the encryption (HTTPS) in the wireless router/cameras. This should be done before the keys or credentials are set for the WLAN to prevent anyone from seeing the keys as they are sent to/configured in the camera. 10.3 Wireless bridges Some solutions may use other standards than the dominating IEEE 802.11, providing increased performance and much longer distances in combination with very high security. Two commonly used technologies are microwave and laser, which can be used to connect buildings or sites with a point-to-point high-speed data link. 10.4 Wireless mesh network A wireless mesh network is a common solution for city center video surveillance applications where hundreds of cameras, together with mesh routers and gateways, may be involved. Such a network is characterized by several connection nodes that serve to receive, send as well as relay data, providing individual and redundant connection paths between one another. Keeping the latency down is important in applications such as live video and particularly in cases where PTZ cameras are used. Chapter 10 - Wireless technologies 110 Chapter 11 - Video management systems 111 11. Video management systems An important aspect of a video surveillance system is managing video for live viewing, recording, playback and storage, in addition to managing the network video products. If the system consists of only one or a few cameras, viewing and some basic video recording can be managed via the built-in web pages of the network cameras and video encoders. When the system consists of more than a few cameras, using a network video management system—as well as the products’ built-in web pages in some cases—is recommended. Today, several hundred different video management systems are available, based on different hardware and software platforms that cover different operating systems (Windows, UNIX, Linux and Mac OS), market segments and languages. Axis offers decentralized and centralized solutions for Windows, with support for different languages and remote access to live viewing and recording using a laptop, an iPhone/iPad or an Android-based smartphone with Internet access. Furthermore, the company’s network of Application Development Partners offers solutions for any system type, size or complexity. The sections below provide a description of Axis’ video management solutions, system features, as well as integration possibilities with other systems such as point of sale or building management. 11.1 Types of video management solutions Video management solutions involve a combination of hardware and software platforms that may be set up in different ways. Recording, for example, can be done either decentrally at many camera locations, hosted or centrally at one location. PC-based solutions offer flexibility and maximum performance for the specific design of the system, with the ability to add functionality, such as increased or external storage, firewalls, virus protection and intelligent video applications. Chapter 11 - Video management systems 112 Solutions are often tailored to the number of cameras supported. For smaller systems with less demanding video management requirements, solutions with limited functionality are ideal. The scalability of most video management software, in terms of the number of cameras and frames per second that can be supported, is in most cases limited by the hardware capacity rather than the software. Storing video files puts strains on the storage hardware because it may be required to operate on a continual basis, as opposed to only during normal business hours. In addition, video by nature generates large amounts of data, which put high demands on the storage solution. For more on servers and storage, see Chapter 12. 11.1.1Decentralized solution for small systems - AXIS Camera Companion For end users who want a simple solution for viewing and recording video even in HDTV, Axis provides AXIS Camera Companion. It supports one to 16 cameras per site—ideal for retail stores, offices and hotels. It is a decentralized video management solution that enables recordings to be stored on a SD/SDHC/SDXC memory card in an Axis camera or video encoder. It enables live viewing, playback of recordings, video exporting and recording settings to be made remotely from any location with Internet access. AXIS Camera Companion allows end users with a few site installations to access each site individually. Figure 11.1a AXIS Camera Companion’s live view involving four cameras (at left); playback view with recording timeline (at right). The free AXIS Camera Companion software client only needs to be used at installation for configuring and uploading settings in the network video products. Once the network video products are configured, the products operate independently without the need for a central PC server or DVR. Since recordings take place locally in the video products without the use of any network, network failure would not disrupt any recording. Network bandwidth would only be used when live viewing or playback is required. Using the default settings of motion-based recording, HDTV 720p resolution and 15 frames per second, a 64 GB SDXC card can record more than a month of video. Chapter 11 - Video management systems 113 INTERNET Figure 11.1b At left, an AXIS Camera Companion setup involving cameras with memory cards, PoE switch, router (for wireless and for Internet access), laptop and smartphone. At right, viewing on a smartphone. 11.1.2Hosted video solution for businesses with many small sites Hosted video offers a hassle-free monitoring solution over the Internet for end users. It usually involves a subscription to a monitoring service provider, such as a security integrator or an alarm monitoring center that also provides services such as guards, and supports other business areas such as cash protection. With Axis’ hosted video solution, end users’ investments are limited to the Axis camera or video encoder and an Internet connection. There is no need to maintain the recording and monitoring station locally. Using a web browser on a computer or smartphone, an authorized user can connect to a service portal on the Internet to access live or recorded video. The service is enabled by a network of hosting providers that uses AXIS Video Hosting System (AVHS) software, which makes it easy for security integrators and alarm monitoring centers to offer video monitoring services over the Internet. The solution is suitable for systems with a limited number of cameras per site in single or multiple locations and is ideal for retailers such as convenience stores, gas stations, banks and small offices. Customer site VIDEO SERVICE PROVIDER Axis network cameras Network-attached storage AVHS server and storage INTERNET Router/Switch End customer Figure 11.1c An AXIS Video Hosting System setup with video recording saved off-site. End customers access live view and recordings by logging in to the service provider’s portal. Chapter 11 - Video management systems 114 11.1.3Centralized, general client-server solution for medium-sized systems AXIS Camera Station AXIS Camera Station offers advanced video management functionalities, providing a complete monitoring and recording system for up to 100 cameras per server. The software is ideal for retail shops, hotels and schools with more than 10 cameras and a locally connected, standard PC for running the software. It offers easy installation and setup with automatic camera discovery, a powerful Configuration Wizard and efficient management of Axis network video products. Details about supported system features are described in Section 11.2. By using a Windows client-server software, AXIS Camera Station is a centralized solution that requires the video management software to run continuously on an on-site computer for management and recording functions. Recordings are made on the local network, either on the same computer where the AXIS Camera Station software is installed or on separate storage devices. A client software is provided and can be installed on any computer for viewing, playback and administration functions, which can be done either on-site or remotely via the Internet. As multi-site functionality is supported, the client enables users to access cameras that are supported by different AXIS Camera Station servers. This makes it possible to manage video at many remote sites or in a large system. AXIS Camera Station offers an open API (Application Programming Interface) for integration with other systems such as point of sale, access control, tracking (e.g., radio-frequency identification), building management and industrial control. When video is integrated, information from other systems can be used to trigger functions such as event-based recordings in the network video system, and vice versa. In addition, users can benefit from having a common interface for managing different systems. Chapter 11 - Video management systems Viewing, Playback and Administration AXIS Camera Station Client software Viewing, Playback and Administration Remote access via AXIS Camera Station Client software Analog cameras Coax cables Network switch IP NETWORK Axis video encoder 115 INTERNET Broadband router Axis network cameras AXIS Camera Station software Viewing, Playback Administration and Background Service RECORDING DATABASE Figure 11.1d A network video surveillance system based on an open, PC server platform with AXIS Camera Station video management software. 11.1.4Customized solutions for small to big systems from Axis’ partners Axis works with more than 800 Application Development Partners globally to ensure tightly integrated software solutions that support Axis network video products. The partners provide a range of customized software solutions. Such solutions may offer optimized features and advanced functionalities, tailored features for a specific industry segment or country-focused solutions. There are also solutions that support more than 1000 cameras and multiple brands of network video products. To find compatible applications, see www.axis.com/partner/adp 11.2 System features A video management system can support many different features. Some of the more common ones are listed below: > > > > > > Simultaneous viewing of video from multiple cameras Recording of video and audio Event management functions including intelligent video such as video motion detection Camera administration and management Search options and playback User access control and activity (audit) logging Chapter 11 - Video management systems 116 11.2.1Viewing A key function of a video management system is enabling live and recorded video to be viewed in efficient and user-friendly ways. Most video management software applications enable multiple users to view in different modes such as split view (to view different cameras at the same time), full screen or camera sequence (where views from different cameras are displayed automatically, one after the other). Menu Toolbar Recording indicator Links to workspaces View groups Audio and PTZ controls Alarm log Figure 11.2a AXIS Camera Station’s live view screen. 11.2.2Multi-streaming Software such as AXIS Camera Station supports Axis network video products’ multi-streaming capability. Multiple video streams from a network camera or video encoder can be individually configured with different frame rates, compression formats and resolutions, and sent to different recipients simultaneously. This capability optimizes the use of network bandwidth. INTERNET Analog camera Remote recording/ viewing at medium frame rate and medium resolution Local recording/ viewing at full frame rate and high resolution Video encoder INTERNET Viewing with a mobile telephone at medium frame rate and low resolution Figure 11.2b Multiple, individually configurable video streams enable different frame rate video and resolution to be sent to different recipients. Chapter 11 - Video management systems 117 11.2.3Video recording With video management software such as AXIS Camera Station, video can be recorded manually, continuously and on trigger (by an event/alarm). Continuous and triggered recordings can be scheduled to run at selected times during each day of the week. Continuous recording normally uses more disk space than an event-triggered recording. An event-triggered recording may be activated by, for example, video motion detection or external inputs through a camera’s or video encoder’s input port. With scheduled recordings, timetables for both continuous and event-triggered recordings can be set. Figure 11.2c Scheduled recording settings with a combination of continuous and event-triggered recordings applied using AXIS Camera Station video management software. The quality of the recordings can be determined by selecting the video format (e.g., H.264, MPEG-4, Motion JPEG), resolution, compression level and frame rate. These parameters will affect the amount of bandwidth used, as well as the amount of storage space required. Network video products may have varying frame rate capabilities depending on the resolution. Recording and/or viewing at full frame rate (considered as 25 frames per second in 50 Hz and 30 frames per second in 60 Hz) on all cameras at all times is more than what is required for most applications. Frame rates under normal conditions can be set lower—for example, one to four frames per second—to dramatically decrease storage requirements. In the event of an alarm—for instance, if video motion detection or an external sensor is triggered—a separate stream with a higher recording frame rate can be sent. Chapter 11 - Video management systems 118 11.2.4Recording and storage Most video management software use the standard Windows file system for storage, so any system drive or network share can be used for storing video. A video management software program may enable more than one level of storage; for instance, recordings are made on a primary hard drive (the local hard disk) and archiving takes place on either local disks, network-attached drive or remote hard drive. Users may be able to specify how long images should remain on the primary hard drive before they are automatically deleted or moved to the archive drive. Users may also be able to prevent event-triggered video from being deleted automatically by specially marking or locking them in the system. 11.2.5Event management and intelligent video Event management is about identifying or creating an event that is triggered by inputs, whether from built-in features in the network video products or from other systems such as point-ofsale terminals or intelligent video software. The network video surveillance system can then be configured to automatically respond to the event by, for example, recording video, sending alert notifications and activating different devices such as doors and lights. Event management and intelligent video functionalities can work together to enable a video surveillance system to more efficiently use network bandwidth and storage space. Live camera monitoring is not required all the time since alert notifications to operators can be sent when an event occurs. All configured responses can be activated automatically, improving response times. Event management helps operators cover more cameras. Both event management and intelligent video functionalities can be built-in and conducted in a network video product or in a video management software program. It can also be handled by both in the sense that a video management software program can take advantage of an intelligent video functionality that is built into a network video product. For instance, the intelligent video functionality, such as video motion detection and camera tampering, can be performed by the network video product and flagged to the management software program for further actions to be taken. This process offers a number of benefits: > It enables a more efficient use of bandwidth and storage space since there is no need for a camera to continuously send video to a video management server for analysis of any potential events. Analysis takes place at the network video product and video streams are sent for recording and/or viewing only when an event occurs. > It does not require the video management server to have a fast processing capability, thereby providing some cost-savings. Conducting intelligent video algorithms is CPU (central processing unit) intensive. Chapter 11 - Video management systems > 119 Scalability can be achieved. If a server were to perform intelligent video algorithms, only a few cameras can be managed at any given time. Having the intelligent functionality “at the edge”, that is, in the network camera or video encoder, enables a fast response time and a very large number of cameras to be managed proactively. PIR detector Computer with video management software IP NETWORK Axis network camera Alarm siren Home Office INTERNET Video recording server Mobile telephone Relay Figure 11.2d Event management and intelligent video enable a surveillance system to be constantly on guard in analyzing inputs to detect an event. Once an event is detected, the system can automatically respond with actions such as video recording and sending alerts. Event triggers An event can be scheduled or triggered. Events can be triggered by, for example: > Input port(s): The input port(s) on a network camera or video encoder can be connected to external devices such as a motion sensor, PIR (passive infrared detection that detects motion based on heat emission), a door contact or glass break detector (detects change in air pres sure). The range of devices that can be connected to a network video product’s input port is almost infinite. The basic rule is that any device that can toggle between an open and closed circuit can be connected to a network camera or a video encoder. > Manual trigger: An operator can make use of buttons to manually trigger an event. > Video motion detection: When a camera detects certain movement in a camera’s motion detection window, an event can be triggered. Video motion detection (VMD) defines an activity in a scene by analyzing image data and differences in a series of images. With VMD, motion can be detected in any part of a camera’s view. Users can configure an “included” window (a specific area in a camera’s view where motion is to be detected), and an “excluded” window (an area within an “included” window that should be ignored). Chapter 11 - Video management systems 120 Figure 11.2e Setting video motion detection in AXIS Camera Station video management software. >Tampering: This feature, which allows a camera to detect when it has been intentionally covered, moved or is no longer in focus, can be used to trigger an event. > Audio detection: This enables a camera with built-in audio support to trigger an event if it detects audio below or above a certain threshold. For more on audio detection, see Chapter 8. > Failover recording: This means that images can be temporarily stored on a memory card in a network camera/video encoder in case of network failure. When the network connection is restored and the system returns to normal operation, the video management system can retrieve and merge local video recordings seamlessly. This ensures that the user gets uninterrupted video recordings. The functionality provides increased system reliability and safeguards system operation. >Temperature: If the temperature rises or falls outside of the operating range of a camera, an event can be triggered. Applications that are compatible with the AXIS Camera Application Platform can also be used as triggers. See Chapter 2 for more information about AXIS Camera Application Platform. Chapter 11 - Video management systems 121 Responses Network video products or a video management software program can be configured to respond to events all the time or at certain set times. When an event is triggered, some of the common responses that can be configured include the following: > Upload images or recording of video streams to specified location(s) with a specified compression format and at a certain frame rate. > Activate output port: The output port(s) on a network camera or video encoder can be connected to external devices such as alarms and door relay for controlling the locking/ unlocking of doors. > Send e-mail notification: This notifies users that an event has occurred. An image can also be attached in the e-mail. > Send HTTP/TCP notification: This is an alert to a video management system, which can then, for example, initiate recordings. > Go to a PTZ preset: This feature may be available with PTZ cameras. The camera can be directed to point to a specified position such as a window when an event takes place, or start guard tour or autotracking. > Send an SMS (Short Message Service) with text information about the alarm or an MMS (Multimedia Messaging Service) with an image showing the event. > Activate an audio alert on the video management system. > Enable on-screen pop-up, showing views from a camera where an event has been activated. > Show procedures that the operator should follow. In addition, pre-alarm and post-alarm image buffers can be set, enabling a network video product to send a set length and frame rate of video captured before and after an event is triggered. This can be beneficial in helping to provide a more complete picture of an event. 11.2.6Administration and management features All video management software applications provide the ability to add and configure basic camera settings, frame rate, resolution and compression format, but some also include more advanced functionalities, such as camera discovery and complete device management. The larger a video surveillance system becomes, the more important it is to be able to efficiently manage networked devices. Chapter 11 - Video management systems 122 Software programs that help simplify the management of network cameras and video encoders in an installation often provide the following functionalities: > > > > > > Locating and showing the connection status of video devices on the network Setting IP addresses Configuring single or multiple units Managing firmware upgrades of multiple units Managing user access rights Providing a configuration sheet, which enables users to obtain, in one place, an overview of all camera and recording configurations Figure 11.2f AXIS Camera Management software makes it easy to find, install and configure network video products. Chapter 11 - Video management systems 123 11.2.7Security An important part of video management is security. A network video product or video management software should enable the following possibilities: > Define/set authorized users > Set passwords and have the ability to encrypt passwords > Define/set different user-access levels, for example: - Administrator: access to all functionalities (In the AXIS Camera Station software, for instance, an administrator can select which cameras and functionalities a user may have access to.) - Operator: access to all functionalities except for certain configuration pages - Viewer: access only to live video from selected cameras > Support IEEE 802.1X to prevent unauthorized network access. See Chapter 9 for more on IEEE 802.1X and network security. 11.3 Integrated systems When video is integrated with other systems such as point-of-sale and building management, information from other systems can be used to trigger functions such as event-based recordings in the network video system, and vice versa. In addition, users can benefit from having a common interface for managing different systems. 11.3.1Point of Sale The introduction of network video in retail environments has made the integration of video with point-of-sale (POS) systems easier. The integration enables all cash register transactions to be linked to actual video of the transactions. It helps catch and prevent fraud and theft from employees and customers. POS exceptions such as returns, manually entered values, line corrections, transaction cancellations, co-worker purchases, discounts, specially tagged items, exchanges and refunds can be visually verified with the captured video. A POS system with integrated video surveillance makes it easier to find and verify suspicious activities. Event-based recordings can be applied. For instance, a POS transaction or exception, or the opening of a cash register drawer, can be used to trigger a camera to record and tag the recording. The scene prior to and following an event can be captured using pre- and post-event recording buffers. Event-based recordings increase the quality of the recorded material, as well as reduce storage requirements and the amount of time needed to search for incidents. Chapter 11 - Video management systems 124 Figure 11.3a An example of a POS system integrated with video surveillance. This screenshot displays the receipt together with video clips of the event. Picture courtesy of Milestone Systems. 11.3.2Access control Integrating a video management system with a facility’s access control system allows for facility and room access to be logged with video. For example, video can be captured at all doors when someone enters or exits a facility. This allows for visual verification when exceptional events occur. In addition, identification of tailgating events can also be made. Tailgating occurs when, for instance, the person who swipes his/her access card knowingly or unknowingly enables others to gain entry without having to swipe a card. 11.3.3Building management Video can be integrated into a building management system (BMS) that controls a number of systems ranging from heating, ventilation and air conditioning (HVAC) to security, safety, energy and fire alarm systems. The following are some application examples: > An equipment failure alarm can trigger a camera to show video to an operator, in addition to activating alarms at the BMS. > A fire alarm system can trigger a camera to monitor exit doors and begin recording for security purposes. This makes it possible for first responders and building managers to assess the situation at all emergency exits in real time and focus their efforts where they are needed the most. Chapter 11 - Video management systems 125 > Intelligent video can be used to detect reverse flow of people into a building due to an open or unsecured door from events such as evacuations. > Automatic video alerts can be sent when someone enters a restricted area or room. > Information from the video motion detection functionality of a camera that is located in a meeting room can be used with lighting and heating systems to turn the light and heat off once the room is vacated, thereby saving energy. 11.3.4Industrial control systems Remote visual verification is often beneficial and required in complex industrial automation systems. By having access to network video using the same interface as for monitoring a process, an operator does not have to leave the control panel to visually check on part of a process. In addition, when an operation malfunctions, the network camera can be triggered to send images. In some sensitive clean-room processes, or in facilities with dangerous chemicals, video surveillance is the only way to have visual access to a process. The same goes for electrical grid systems with substations in remote locations. 11.3.5RFID Tracking systems that involve RFID (radio-frequency identification) or similar methods are used in many applications to keep track of items. For example, tagged items in a store can be tracked together with video footage to prevent theft or provide evidence. Another example is luggage handling at airports whereby RFID can be used to track the luggage and direct it to the correct destination. If it is integrated with video surveillance, there is visual evidence when luggage is lost or damaged, and search routines can be optimized. Chapter 11 - Video management systems 126 Chapter 12 - Bandwidth and storage considerations 127 12. Bandwidth and storage considerations Network bandwidth and storage requirements are important considerations when designing a video surveillance system. The factors include the number of cameras, the image resolution used, the compression type and ratio, frame rates and scene complexity. This chapter provides some guidelines on designing a system, along with information on storage solutions and various system configurations. 12.1 Bandwidth and storage calculations Network video products utilize network bandwidth and storage space based on their configuration. As mentioned earlier, this depends on the following: > > > > > > > > > Number of cameras Continuous or event-triggered recording Edge recording in the camera/video encoder, server-based recording or a combination Number of hours per day the camera will be recording Frames per second Image resolution Video compression type: H.264, MPEG-4, Motion JPEG Scenery: Image complexity (e.g., gray wall or a forest), lighting conditions and amount of motion (e.g., office environment or crowded train stations) How long data must be stored 12.1.1Bandwidth needs In a small surveillance system involving fewer than 10 cameras, a basic 100-megabit (Mbit) network switch can be used without having to consider bandwidth limitations. Most companies can implement a surveillance system of this size using their existing network. When implementing 10 or more cameras, the network load can be estimated using a few rules of thumb: > > A camera that is configured to deliver high-quality images at high frame rates will use approx. 2 to 3 Mbit/s of the available network bandwidth. With more than 12 to 15 cameras, consider using a switch with a gigabit backbone. If a gigabit-supporting switch is used, the server that runs the video management software should have a gigabit network adapter installed. Chapter 12 - Bandwidth and storage considerations 128 Technologies that enable the management of bandwidth consumption include the use of VLANs on a switched network, Quality of Service and event-triggered recordings. For more on these topics, see chapters 9 and 11. 12.1.2Calculating storage needs One of the factors affecting storage requirements is the type of video compression used. The H.264 compression format is by far the most efficient video compression technique available today. Without compromising image quality, an H.264 encoder can reduce the size of a digital video file by more than 80% compared with the Motion JPEG format. This means much less network bandwidth and storage space are required for an H.264 video file. Sample storage calculations for the two compression formats, H.264 and Motion JPEG, are provided in the tables below. Because of a number of variables that affect average bit rate levels, calculations are not so clear-cut for H.264. With Motion JPEG, there is a clear formula because Motion JPEG consists of one individual file for each image. Storage requirements for Motion JPEG recordings vary depending on the frame rate, resolution and level of compression. H.264 calculation: Approx. bit rate / 8(bits in a byte) x 3600s = KB per hour / 1000 = MB per hour MB per hour x hours of operation per day / 1000 = GB per day GB per day x requested period of storage = Storage need Resolution Frames per second Bit rate (Mbit/s) GB/hour Hours of operation GB/day 4CIFv 5 0.569 0.26 8 2.1 12 1.07 0.48 8 3.9 24 1.65 0.74 8 5.9 30 1.88 0.84 8 6.7 5 1.70 0.76 8 6.1 12 3.23 1.46 8 11.7 24 4.93 2.22 8 17.8 30 5.61 2.52 8 20.2 5 3.82 1.72 8 13.8 12 7.28 3.28 8 26.2 24 11.1 5.00 8 40 30 12.6 5.68 8 45.4 HDTV 720p HDTV 1080p Table 12.1a The figures above are based on continuous recording with lots of motion in a scene, e.g., at a station. With fewer changes in a scene, the figures can be 20% lower. The amount of motion in a scene can have a big impact on the amount of storage required. Chapter 12 - Bandwidth and storage considerations 129 Motion JPEG calculation: Image size x frames per second x 3600s = Kilobyte (KB) per hour/1000 = Megabyte (MB) per hour MB per hour x hours of operation per day / 1000 = Gigabyte (GB) per day GB per day x requested period of storage = Storage need Resolution Frames per second Bit rate (Mbit/s) GB/hour Hours of operation GB/day 4CIF 5 1.84 0.83 8 6.64 12 4.39 1.98 8 15.1 24 8.75 3.94 8 31.5 30 10.9 4.91 8 39.3 5 5.30 2.38 8 19.0 12 12.6 5.67 8 45.4 24 25.2 11.3 8 90.4 30 31.5 14.2 8 114 5 11.9 5.36 8 42.9 12 28.5 12.8 8 102 24 56.7 25.5 8 204 30 70.8 31.9 8 255 HDTV 720p HDTV 1080p Table 12.1c The figures above are based on continuous recording with lots of motion in a scene, e.g. at a station. With fewer changes in a scene, the figures can be 20% lower. The amount of motion in a scene can have a big impact on the amount of storage required. A helpful tool in estimating requirements for bandwidth and storage is the AXIS Design Tool, which is accessible from the following web address: www.axis.com/products/video/design_tool/ Figure 12.1a AXIS Design Tool includes advanced project management functionality that enables bandwidth and storage to be calculated for a large and complex system. Chapter 12 - Bandwidth and storage considerations 130 12.2 Edge storage Edge storage—sometimes referred to as local storage or onboard recording—is a concept in Axis network cameras and video encoders that allows network video products to create, control and manage recordings locally on an SD (Secure Digital) memory card, network-attached storage (NAS) or file server. Edge storage enables the possibility to design flexible and reliable recording solutions. They include increased system reliability, high-quality video in low bandwidth installations, recording for remote and mobile surveillance, and integration with video management software. AXIS Camera Companion is an example of a video management system based on edge storage, whereby all video is recorded on the memory card in the network camera or video encoder and the need for central storage is eliminated. A 64 GB SDXC card can record more than a month of video using motion-based recording with HDTV 720p resolution and 15 frames per second. For more information on AXIS Camera Companion, see Chapter 11. Edge storage can work as a complement to central storage. It can record video locally when the central system is not available, or continuously record in parallel. When used together with video management software such as AXIS Camera Station, failover recordings can be handled. This means that missing video clips from network disruptions or central system maintenance can be retrieved later from the camera and merged with the central storage, ensuring the user gets uninterrupted video recordings. System redundancy example Video GAP Edge storage video merged after failure Figure 12.2a Edge storage for redundancy (failover recording). Additionally, edge storage can improve video forensics for systems with low network bandwidth where video cannot be streamed at the highest quality. By supporting low bandwidth monitoring with high-quality local recordings, users can optimize bandwidth limitations and still retrieve high-quality video from incidents for detailed investigation. Edge storage can also be used to manage recordings in remote locations and other installations where there is intermittent or no network availability. On trains and other rail bound vehicles, edge storage can be used to first record video onboard and then transfer to the central system when the vehicle stops at a depot. Chapter 12 - Bandwidth and storage considerations 131 12.2.1Edge storage with SD cards or NAS There are pros and cons of using SD cards or NAS for edge storage. (More details on NAS are provided in Section 12.4 below.) The following are some considerations: > > > > > > > SD cards are easier to deploy and configure than NAS. SD cards are limited in storage compared with NAS. NAS can store terabytes of data. SD cards can be tampered with if reachable by authorized persons. A NAS can be located in a place that is secured. SD cards are resilient to single point of failure. If the NAS or its connection is disrupted, multiple cameras will be affected. The expected lifespan of the disk in a NAS is longer than an SD card’s. The NAS can also have RAID configuration. See Section 12.5 for more on RAID. SD cards may be costly to replace if the camera is mounted in hard-to-reach places such as on a pole or wall more than 4.5 m (15 ft.) off the ground. NAS is the only edge storage option for cameras without an SD card slot. 12.3 Server-based storage Server-based storage involves a PC server that is connected locally to the network video products for video management and recording. The server would run a video management software application that records video to either the local hard disk (called a direct-attached storage) or to a NAS. Depending on a PC server’s central processing unit (CPU), network card and internal RAM (Random Access Memory), a server can handle a certain number of cameras, frames per second and image sizes. Most PCs can hold several hard disks, and each disk can be up to several terabytes. With the AXIS Camera Station video management software, for instance, one hard disk is suitable for storing recordings from up to 15 cameras when using H.264, or between 8 and 10 cameras when using Motion JPEG. 12.4 NAS and SAN When the amount of stored data and management requirements exceed the limitations of a direct-attached storage, a network-attached storage or storage area network (SAN) allows for increased storage space, flexibility and recoverability. Chapter 12 - Bandwidth and storage considerations 132 Network-attached storage Axis network cameras Network switch, broadband router or corporate firewall Computer server with video management software Figure 12.4a Network-attached storage NAS provides a single storage device that is directly attached to a LAN and offers shared storage to all clients on the network. A NAS device is simple to install and easy to administer, providing a low-cost storage solution. However, it provides limited throughput for incoming data because it has only one network connection, which can become problematic in high-performance systems. SANs are high-speed, special-purpose networks for storage, typically connected to one or more servers via fiber. Users can access any of the storage devices on the SAN through the servers, and the storage is scalable to hundreds of terabytes. Centralized storage reduces administration and provides a high-performance, flexible storage system for use in multi-server environments. Fibre Channel technology is commonly used to provide data transfers up to 16 Gbit/s and to allow large amounts of data to be stored with a high level of redundancy. TCP/IP LAN Server Fiber channel Server Server Server Fiber channel Fiber channel switch Tape RAID disk array RAID disk array Figure 12.4b A SAN architecture where storage devices are tied together and the servers share the storage capacity. Chapter 12 - Bandwidth and storage considerations 133 12.5 Redundant storage SAN systems build redundancy into the storage device. Redundancy in a storage system allows video, or any other data, to be saved simultaneously in more than one location. This provides a backup for recovering video if a portion of the storage system becomes unreadable. There are a number of options for providing this added storage layer in an IP surveillance system, including a Redundant Array of Independent Disks (RAID), data replication, server clustering and multiple video recipients. RAID. RAID is a method of arranging standard, off-the-shelf hard drives such that the operating system sees them as one large hard disk. A RAID setup spans data over multiple hard disk drives with enough redundancy so that data can be recovered if one disk fails. There are different levels of RAID, ranging from practically no redundancy to a full-mirrored solution in which there is no disruption and no loss of data in the event of a hard disk failure. Data replication. This is a common feature in many network operating systems. File servers in a network are configured to replicate data among each other, providing a backup if one server fails. Figure 12.5a Data replication. Server clustering. A common server clustering method is to have two servers work with the same storage device, such as a RAID system. When one server fails, the other identically configured server takes over. These servers can even share the same IP address, which makes the so-called “fail-over” completely transparent for users. Multiple video recipients. A common method to ensure disaster recovery and off-site storage in network video is to simultaneously send the video to two different servers in separate locations. These servers can be equipped with RAID, work in clusters, or replicate their data with servers even further away. This is an especially useful approach when surveillance systems are in hazardous or not easily accessible areas, such as in mass-transit installations or industrial facilities. 12.6 System configurations Small system Using an edge storage solution such as AXIS Camera Companion, users can manage video recordings on memory cards for up to 16 cameras/video encoders. Since all video is stored on the edge, there is no need to have dedicated recording equipment such as a server running during operation, making the system very simple. Chapter 12 - Bandwidth and storage considerations 134 Router INTERNET Switch Figure 12.6a A small system using an edge storage solution such as AXIS Camera Companion. Hosted video system In a hosted video setup (often referred to as cloud computing), the system requirements are handled by a hosting provider and a video service provider such as a security integrator or alarm monitoring center, which in turn provides end users with access to live and recorded video over the Internet. In an AXIS Video Hosting System (AVHS) setup, the AVHS software is installed on a hosting provider’s server that serves as both a web and recording server. Together with the OneClick Camera Connection feature that is supported in Axis network video products, it is easy to install cameras/encoders to the system regardless of the Internet service provider, routers and firewall settings. The solution supports up to 10 cameras per site in single or multiple locations. Customer site VIDEO SERVICE PROVIDER Axis network cameras Network-attached storage AVHS server and storage INTERNET Router/Switch End customer Figure 12.6b A hosted video system involving a hosting provider with its server farm, a video service provider that provides security services, and cameras/video encoders at the site to be monitored. End users gain access to videos by logging on to an Internet site. Chapter 12 - Bandwidth and storage considerations 135 Medium system A typical, medium-sized installation has a server with additional storage attached to it. The storage is usually configured with RAID in order to increase performance and reliability. The videos are normally viewed and managed from a client rather than from the recording server itself. IP NETWORK Application and storage server Workstation client (optional) RAID storage (optional) Figure 12.6c A medium system. Large centralized system A large-sized installation requires high performance and reliability in order to manage the large amount of data and bandwidth. This requires multiple servers with dedicated tasks. A master server controls the system and decides what kind of video is stored at what storage server. As there are dedicated storage servers, it is possible to do load balancing. In such a setup, it is also possible to scale up the system by adding more storage servers when needed and do maintenance without bringing down the entire system. IP NETWORK Surveillance workstations Master server 1 Master server 2 Figure 12.6d A large centralized system. Storage server 1 Storage server 2 Chapter 12 - Bandwidth and storage considerations 136 Large distributed system When multiple sites require surveillance with centralized management, distributed recording systems may be used. Each site records and stores the video from local cameras. The master controller can view and manage recordings at each site. Workstation IP NETWORK LAN, WAN, INTERNET Storage server RAID Surveillance workstations Workstation Storage server RAID Figure 12.6e A large distributed system. Chapter 13 - Tools and resources 137 13. Tools and resources Axis offers a variety of tools and information resources to help design IP surveillance systems. Many are accessible from the Axis website: www. axis.com/tools Axis Product Selector This tool helps you select the right cameras or video encoders for your project. A version of this tool, AXIS Guide iPhone app, is available for use on iPhone, iPod Touch and iPad. Chapter 13 - Tools and resources 138 Axis Accessory Selector Tool This tool helps you pick the right housing, bracket and power accessory for the cameras in your project. AXIS Camera Companion Buyers Tool Pick the cameras, storage and networking devices you need for a small surveillance system with this user-friendly tool. Axis Lens Calculator Use the Axis Lens Calculator to easily establish for a specific camera the optimal camera placement and required focal length for a particular scene size and resolution. AXIS Design Tool Estimate the storage and network bandwidth needs for your system. This tool lets you experiment with viewing, recording and compression options for each camera. Axis Coverage Shapes for Microsoft Visio This tool visualizes the coverage of cameras in a layout drawing to help you ensure that all critical areas are covered. Axis Camera Families for Autodesk® Revit® Design surveillance systems based on Axis cameras directly in your Autodesk Revit 3D CAD building layout. Axis’ innovative Revit security camera families provide 3D camera models to illustrate what the camera setup will look like in reality and which areas the surveillance system will cover once installed. Intelligent Network Video: Understanding modern surveillance systems This 390-page hardcover book is authored by Fredrik Nilsson and Axis Communications. It represents the first resource to provide detailed coverage of advanced digital networking and intelligent video capabilities. The book is available for purchase through Amazon, Barnes & Noble and CRC Press, or contact your local Axis office. Chapter 14 - Axis Communications’ Academy 139 14. Axis Communications’ Academy Building your strengths in network video. At Axis Communications, we understand that your business success depends on continually building your strengths and staying on top of the latest technology to offer your customers the very best. We have designed Axis Communications’ Academy to work with every facet of your business, providing training, tools and quick reference help for everything your customers expect you to be an expert in—as well as the things they don’t even know they need yet. Whether you need instant help with a specific customer situation or comprehensive training to reach your long-term business goals, Axis Communications’ Academy has what you need, when you need it. From sales and system design to installation, configuration and ongoing customer care. Choose from a wide range of online tools and training as well as interactive classes and seminars. > Classroom training > Online courses > Business seminars >Webinars > Tutorials and guides > System design tools > Axis Certification Program For more information, visit Axis’ Learning Center at www.axis.com/academy 60870/EN/R1/1411 About Axis Communications Axis offers intelligent security solutions that enable a smarter, safer world. As the global market leader in network video, Axis is driving the industry by continually launching innovative network products based on an open platform - delivering high value to customers through a global partner network. Axis has long-term relationships with partners and provides them with knowledge and ground-breaking network products in existing and new markets. Axis has more than 1,800 dedicated employees in more than 40 countries around the world, supported by a network of over 70,000 partners across 179 countries. Founded in 1984, Axis is a Sweden-based company listed on NASDAQ Stockholm under the ticker AXIS. For more information about Axis, please visit our website www.axis.com. ©2006-2014 AXIS COMMUNICATIONS, AXIS, ETRAX, ARTPEC and VAPIX are registered trademarks or trademark applications of Axis AB in various jurisdictions. All other company names and products are trademarks or registered trademarks of their respective companies. Microsoft and Windows are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries. Mac OS, iPad, iPhone and iPod are trademarks or registered trademarks of Apple Inc. in the United States and/or other countries. SMPTE is a registered trademark or trademark of Society of Motion Picture and Television Engineers, Inc. in the United States and/or other countries. The UPnP® Certification Word and Logo Mark and the UPnP ForumSM Word and Logo Mark are trademarks or registered trademarks of UPnP Forum. SD, SDHC and SDXC are trademarks or registered trademarks of SD-3C, LLC in the United States, other countries or both. Wi-Fi Protected Access®, Wi-Fi Protected Setup™, WPA™ and WPA2™, are registered trademarks or trademarks of the Wi-Fi Alliance. Autodesk and Revit are registered trademarks or trademarks of Autodesk, Inc., and/or its subsidiaries and/or affiliates in the USA and/or other countries. Some Axis products include software developed by the OpenSSL Project for use in the OpenSSL Toolkit (www.openssl.org), and cryptographic software written by Eric Young ([email protected]).
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