Model: LT-101-USB LT-101 For USB
LT-101 For USB
Copyright © 2014 Enciris Technologies, SAS.
Other companies’ product names that may be used in this document are for identification purposes only and may be trademarks of their respective companies.
The LT-101-USB is an HD video capture module that compresses HDTV video in realtime without using the host computer’s CPU resources.
The module is attached via USB to a host system.
This board captures video from both analog and digital HD and SD video sources via DVI,
RGB, VGA, component, S-video, or composite connectors. In addition to external video sources, the LT-101-USB can compress from host internal video sources such as files or
DirectShow devices including USB and
FireWire cameras. An HD/SD-SDI daughter board option is available.
The LT-101-USB compresses video in compliance with the H.264 or the VC-1 standard.
This high performance board can compress
1080p/i at up to 30 frames per second (fps).
2048x2048 can be compressed at 15fps. At lower resolutions the maximum compression frame rate increases. If the frame rate is higher than the board can handle, frame decimation can be enabled allowing high frame rate source to be acquired at then compressed at a lower frame rate.
Compressed bitrates can vary between
64Kbit/s and 80Mbit/s depending on resolution, frame rate and quality desired.
An uncompressed/raw video capture function is also available for simultaneous snapshots or continuous uncompressed video acquisition.
The sections below introduce the many elements of the LT-101-USB board and detail their features and operation.
• VC-1/SMPTE-421M advanced profile level 3 video compression
• H.264 High Profile up to the level 5.1
• I or IP encoding with variable GOP size
• VBR (variable) bitrate control
• 1024x512 motion vector search range covered
• Bitrates from 64Kbit/s to 80Mbit/s
• 1 frame maximum latency (can be reduced to a few milliseconds under special circumstances)
• ASF/MPEG-TS container formats
• DVI, VGA, RGB, component, S-video, composite video inputs
• Optional HD/SD-SDI input
• USB host bus interface
• Simultaneous uncompressed video capture
• 2 channel audio capture
• Synchronized audio/video acquisition
• Advanced hardware deinterlacing
• Frame rate reduction feature available
• Video downscaling prior to compression
• Smoothing filter prior to compression
• Text overlay prior to compression
• Bitrate reduction via monochrome mode when color is not needed
• Synchronization to external events
• Extensive Motion statistics for all frames
• Windows XP/Vista drivers
• DirectShow support as well as simple SDK
• Linux support
• Mac OS X support
• Solaris support
• HDTV capture and storage
• Digital video recorders
• Video Medical systems
• Endoscopy DVR
• Video surveillance systems
• Internet broadcasting
• Video over LAN
• Inspection systems
INPUT VIDEO AND AUDIO CONNECTIONS
Many different video and audio sources are supported by the LT-101-USB. The physical connectors are shown below.
The DVI connector serves as an integrated analog component (YUV/YPrPb), RGB, RGBHV,
VGA, and DVI-A as well as a digital DVI-D and HDMI compatible video input. To accommodate the numerous video sources various low cost, off the shelf, or passive cable adapters might be required. However, the video signaling remains compliant with the mentioned inputs.
The BNC to the left shows the optional HD-SDI/SD-SDI connector.
The table on the following page summarizes the many possible input configurations and please refer the document “LT-101 Input Formats” for an up to date list of all the video resolution and graphics modes supported.
Audio/Video Input Features
HD/SD-SDI 1 Audio Jack
SDI 75 ohm BNC
S-Video 5-pin Mini-DIN
RGB via BNC (separate syncs)
RGB via BNC (sync on green)
RGB via RCA
YUV via BNC
YUV via RCA
● ● ●
Line level audio
Digital Audio embedded with video
1. Requires purchase of SDI option.
2. RCA to BNC adapter required.
3. BNC to VGA cable and VGA to DVI adapter required.
4. YUV/RCA to DVI adapter required.
5. VGA to DVI adapter required.
6. HDMI to DVI adapter required
7. HDCP not supported.
8. 3.5mm stereo jack. Optional RCA jack to 3.5mm plug cable available.
9. 3.5mm stereo jack. Microphone bias available (jumper setting required – see installation manual)
10. Under development. HDMI/SDI audio embedded in video stream. Multichannel audio: only L/R extracted.
HOST BUS CONNECTIVITY
The LT-101-USB module is connected to the USB host computer using a standard USB cable.
The LT-101-USB does not rely on the host processor for video compression. The host processor does however use the processor for low CPU usage activities such as audio compression, audio/video multiplexing and data transfer. For an acquisition only system that does not play or decode compressed or uncompressed audio/video streams, such as a small multimedia server, a 500MHz CPU with 64MB RAM should suffice. If stream decoding is involved, as would be typically required by a DVR or a system with video preview, a 2GHz processor would be recommended especially for HD video.
For further information see the LT-101-USB hardware installation manual.
The LT-101-USB is comprised of several functional elements. Their operation as well as their function is described in this section. The diagram below shows the various elements and their interconnections.
The video front-end can accept captured video at rates of over 150 megapixels per second.
This allows for the acquisition of high resolution and frame rate data such as WUXGA
(1920x1200) at 60 frames per second.
It must be noted that the compression engine is limited to processing about 63 megapixels per second. Consequently, either the scaling unit or the frame rate decimator must be activated when the input pixel rate exceeds the 63 megapixels per second limit in order to reduce the pixel rate. If the acquisition rate is too high the driver will report an acquisition overflow error. When using the auto-setup capabilities the LT-101-USB will automatically activate the frame rate decimator if required.
In addition to the external video inputs the LT-101-USB can also take uncompressed video from the host system. In this configuration the LT-101-USB can perform as a compression co-processor relieving the host CPU resources. However, due to the bandwidth requirements involved in sending uncompressed video to the LT-101-USB this not a
recommended mode of operation. See the LT-101-PCI or LT-101-PCIE as these are more suitable for co-processing applications.
The LT-101-USB allows for the adjustment of hue, saturation, brightness and contrast in real-time.
FRAME RATE DECIMATOR UNIT
The LT-101-USB has a flexible frame rate decimator that reduces the frame rate of incoming video to an arbitrary value. This is primarily used to reduce the frame rate for high resolution images to meet the requirements of the compression engine but can also be used to reduce the amount of compressed or uncompressed data. At this time there is only a single frame rate decimator unit for both the compressed and uncompressed video paths.
If scaling is needed, the LT-101-USB incorporates a scaling unit that allows the user to reduce the image size to any smaller size than the original resolution. This is primarily used to reduce either or both compressed or uncompressed video bandwidth.
In order to have full frame rate uncompressed video data transferred to the host system it may be necessary to reduce the image size. If the size of a very high resolution image is not reduced, the acquisition frame rate will automatically drop to meet the host bus (your PC) bandwidth limitations. This is particularly noticeable when attempting to transfer uncompressed HD over USB.
This unit performs uses an adaptive de-interlacing algorithm to convert interlaced images to progressive images for compression or uncompressed capture. Saw tooth effects are removed, even for high motion interlaced video, without affecting detail.
NOISE REDUCTION FILTER
A pre-compression filter can be enabled to help remove noise and some high frequency components and thus improve the video compression quality. This filter may reduce some image sharpness and its usage should be determined experimentally.
RAW/UNCOMPRESSED VIDEO CAPTURE UNIT
The LT-101-USB can simultaneously capture compressed and uncompressed video. The uncompressed video capture unit uses double buffering to allow for efficient video acquisition.
If your host bus or processor does not have sufficient performance to transfer video data at the uncompressed rate, the capture unit cleanly drops frames to meet your host system’s limitations. This effectively limits your capture frame rate. This is particularly noticeable when attempting to transfer uncompressed HD vide over USB or a poorly performing PCI bus.
Text overlay is available to the compressed video path. The overlay is applied prior to compression and can be used to place a date/time stamp, watermark, or identification label.
The user can arbitrarily place four 16 character text windows within the video frame. If long strings are required, the windows can be placed side by side.
VIDEO COMPRESSION ENGINE
The video compression engine is designed for high quality low latency video compression and is capable of processing up to 247,000 (16x16 pixels) macroblocks, or over 63 megapixels, per second.
Low latency is achieved by beginning compression during the acquisition of the frame itself.
Compressed video for the current frame becomes available after about eight macroblock rows have been acquired. This equates to a latency of about 3ms for 1080p video.
Compressed data can be transferred to the host as soon as there are 2048 (default value) bytes in the buffer. In systems that are using frame based processing (e.g. DirectShow) it is usually more efficient to wait until a whole frame is available before transferring it to the host. Frame based systems have inherently a latency of at least one frame.
There are three primary components to the compression engine. The first is the motion estimation block. The second is the H.264/VC-1 bitstream generation block. And the third is the bitrate control block. The features of the three blocks are described below.
• MOTION ESTIMATION
The motion estimation block uses an advanced algorithm that gives very high quality block matching with a large search range. The search range is 1024 horizontally and 512 vertically.
• H.264VC-1 BITSTREAM GENERATOR
The LT-101-USB produces an H.264 High Profile level 5.1 or a VC-1/SMPTE-421M advanced profile level 3 compliant bitstream.
The video can be encoded either as I-frame only or as IP GOP structures. The number of
P-frames per I-frame (GOP length) is programmable. The GOP length can vary from 1 (i.e.
I-frame only) to 4095.
The user can reset the GOP counter on the fly when an I-frame is required. This is useful if the GOP structure is long and an entry point into the stream is needed with minimal delay.
Skip frames are supported to reduced bandwidth while the input video stream remain static. If the current image varies imperceptibly from the previous image, it is not compressed and a skip- code is sent to effectively inform the decoder to repeat the previous image.
• BITRATE CONTROL
The bitrate control system uses a VBR (variable bitrate) algorithm. Bitrates can vary from
64Kbits/s to 80MBits/s. The actual bitrate range will depend on resolution and frame rate. Obtaining very low bitrates on high resolution/frame rate video or very high bitrate on low resolution/frame rate video is generally not possible.
In cases where the compressed video is not evacuated from the LT-101-USB sufficiently rapidly, the bitrate control system will automatically reduce the programmed bitrate to prevent buffer overflow. If this action is not sufficient, the system will begin the insertion of forced skip frames until the situation is rectified. Once the buffer level has returned to a normal level the programmed bitrate is reactivated. This feature is useful when sending data over a poorly performing network where the bandwidth is suddenly reduced.
It must be noted that compression latency increases as the compressed video buffer level grows. Low latency systems the data must be evacuated efficiently.
Complete (down to quarter pel) motion vectors for each macroblock are available and can be obtained from the compression engine. These motion vectors (giving magnitude and direction) indicate the motion that has occurred between two consecutive frames with macroblock granularity. As a result of our advanced motion estimation algorithm, the vectors generated by the LT-101 tend to reflect true motion. Consequently, interested users can use our motion vectors as a basis for implementing an advanced motion detection
system. Less sophisticated, but more commonly used, algorithms produce vectors that do not necessarily represent true motion.
Incoming audio from the analog to digital converter (A/D), HDMI source, or SDI source is normalized to 16-bit stereo (2-channel) audio and then forwarded to audio synchronization unit by this block.
AUDIO SYNCHRONIZATION UNIT
This unit synchronizes the audio captured by the LT-101-USB to the video. This is done to ensure that the audio does not drift with respect to the video and cause poor lip-sync. Audio leaving this unit can be safely multiplexed with video without the need to resample.
AUDIO COMPRESSION (SOFTWARE)
Audio compression is done on the host processor and not in the LT-101-USB hardware. The associated SDK allows for AAC or WMA compression. Uncompressed audio can also be accessed. The audio compression tools are included in the driver/SDK package that comes with the LT-101-USB.
AUDIO/VIDEO MULTIPLEXER (SOFTWARE)
The multiplexing of audio and video is done by the host processor and not by the LT-101-
USB hardware. The video elementary stream and compressed audio stream are combined into a single MPEG-TS/ASF (.wmv) stream by this unit. The MPEG-TS/ASF can then be saved to a file or sent over a network.
The table below gives our current driver support for the LT-101-USB. Contact us if you have a special driver requirement.
Windows XP 1
Windows Vista 32 1
Windows Vista 64 2
Supported Driver Features
Windows 7 3
OS X Snow Leopard
Other OS X 86 8
1 Release candidates available
2 Beta available
3 Beta available soon (Q4/2009)
4 Not tested. Source code provided. Contributions welcome.
5 Under development. Contributions welcome.
6 Beta available
Beta available soon (Q4/2009)
8 Under development, will depend on need.
Video4Linux Quick Time
To contact us for further information on this or any other Enciris Product:
22, Avenue de l’Europe
Tel: +33 (0)5 81 18 01 12
Email: [email protected]
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project