Lesson 8-Video
Lesson 8-Video
Overview
 Using video.
 How video works?
 Broadcast video standards.
 Analog video.
Overview
 Digital video.
 Video recording and tape formats.
 Shooting and editing video.
 Optimizing video files for CD-ROM.
Using Video
 Video is an excellent tool for delivering multimedia.
 Video places the highest performance demand on computer
and its memory and storage.
 Digital video has replaced analog as the method of choice
for making and delivering video for multimedia.
Using Video
 Digital video device produces excellent finished products at
a fraction of the cost of analog.
 Digital video eliminates the image-degrading analog-todigital conversion.
 Many digital video sources exist, but getting the rights can
be difficult, time-consuming, and expensive.
How Video Works
 Light reflected from an object through the camera’s lens is
converted into electronic signal by charge-coupled device
(CCD).
 This electronic signal contains three channels of color
information and synchronization pulses (sync).
 Several video standards exist that deal with the amount of
separation between the components of the signal.
Broadcast Video Standards
National Television Standards Committee (NTSC):
 These standards define a method for encoding information into
electronic signal that creates a television picture.
 It has screen resolution of 525 horizontal scan lines and a scan
rate of 30 frames per second.
Broadcast Video Standards
Phase Alternate Line (PAL) and Sequential Color and
Memory (SECAM):
 PAL has a screen resolution of 625 horizontal lines and a
scan rate of 25 frames per second.
 SECAM has a screen resolution of 625 horizontal lines and
is a 50 Hz system.
 SECAM differs from NTSC and PAL color systems in its basic
technology and broadcast method.
Broadcast Video Standards
Advanced Television Systems Committee (ATSC) Digital
Television (DTV):
 This digital standard provides TV stations with sufficient
bandwidth to present four or five Standard Television (STV)
signals or one High Definition TV (HDTV) signal.
 This standard allows for transmission of data to computers
and for new Advanced TV (ATV) interactive services.
Analog Video
Overscan and the safe title area:
 Analog television sets remain the most widely installed
platforms for delivering and viewing video.
 Overscan occurs when an image is larger than the standard TV
screen.
Analog Video
Overscan and the safe title area (continued):
 Underscan occurs when computer monitors display a smaller
image on picture tube.
 The safe title area is where the image will not be affected by
overscanning, even in the worst conditions.
Analog Video
Video color:
 Television sets use composite input. Hence colors are less pure
and less accurate than computers using RGB component.
 NTSC television uses a limited color palette and restricted
luminance (brightness) levels and black levels.
Analog Video
Video color (continued):
 Some colors generated by a computer that display fine on a
RGB monitor may be illegal for display on a NTSC TV.
 While producing a multimedia project, consider whether it will
be played on a RGB monitor or a conventional television set.
Analog Video
Interlacing effects:
 In television, the electron beam makes two passes on the
screen while drawing a single video frame.
 It first lays down all the odd-numbered lines, and then all the
even-numbered lines, hence they are interlaced.
 While capturing images from a video signal, they can be
filtered through a de-interlacing filter provided by image-
editing applications.
Analog Video
Text and titles for television and taking care of analog tapes:
 Titles for video productions can be created with an analog
character generator.
 Computers can create titles digitally using video and imageediting software.
 New tapes should always be fast-forwarded to the end and
then rewound, to ensure even tape tension.
Digital Video
 Video clip stored on any mass-storage device can be played
back on a computer’s monitor without special hardware.
 Setting up a production environment for making digital
video, requires some hardware specifications.
 Some specifications include computer with FireWire
connection and cables, fast processor, plenty of RAM, fast
and big hard disk.
Digital Video
 Digital video architecture.
 Digital video compression.
Digital Video Architecture
 Digital video architecture consists of a format for encoding
and playing back video files by a computer.
 Architecture includes a player that can recognize and play
files created for that format.
Digital Video Compression
 Digital video compression schemes or codecs is the
algorithm used to compress (code) a video for delivery.
 The codec then decodes the compressed video in real-time
for fast playback.
 Streaming audio and video starts playback as soon as
enough data has transferred to the user’s computer to
sustain this playback.
Digital Video Compression
 MPEG is a real-time video compression algorithm.
 MPEG-4 includes numerous multimedia capabilities and is a
preferred standard.
 MPEG-7 (or Multimedia Content Description Interface)
integrates information about motion video elements with
their use.
Video Recording and Tape
Formats
 Composite analog video.
 Component analog video.
 Composite digital.
 Component digital.
 ATSC digital TV.
Composite Analog Video
 Composite video combines the luminance and chroma
information from the video signal.
 Composite video produces lowest quality video and is most
susceptible to generation loss.
 Generation loss is the loss of quality that occurs while
moving from original footage to editing master to copy.
Component Analog Video
 Component video separates the luminance and chroma
information.
 It improves the quality of the video and decreases
generation loss.
 In S-video, color and luminance information are kept on
two separate tracks (Y/C) to improve the picture quality.
 Betacam is a new portable professional video format which
lays the signal on the tape in three component channels.
Composite Digital
 Composite digital recording formats combine the luminance
and chroma information.
 They sample the incoming waveforms and encode the
information in binary (0/1) digital code.
 It improves color and image resolution and eliminates
generation loss.
Component Digital
 Component digital formats add the advantages of
component signals to digital recording.
 D-1 component digital format is an uncompressed format
which has a very high quality image.
 It uses a 19 mm (3/4-inch) tape in order to save data.
 Several other digital component formats are DCT, Digital
Betacam, DV format, DVCPRO, and DVCAM formats.
ATSC Digital TV
 These standards provide for digital STV and HDTV
recordings that can be broadcast by digital TV transmitters
to digital TV receivers.
 ATSC standards also provide for enhanced TV bringing the
interactivity of multimedia and the Web to broadcast
television.
Shooting and Editing Video
 Import video and sound at the highest resolution and with
the least amount of compression possible.
 Resolution should be reduced and footage must be
compressed later according to the requirements.
 A steady shooting platform should always be used.
Shooting and Editing Video
 Good and even lighting is extremely important.
 Blue screen in digital video editing applications is a popular
technique for making multimedia.
 Wide panoramic shots and camera motion should be
avoided when shooting for a small computer window on
CD-ROM or the Web.
Optimizing Video Files for CDROM
 CD-ROMs provide an excellent distribution medium for
computer-based video.
 When preparing video for CD-ROM distribution, interleave
the audio track(s) with the video track.
 Key frames should be used every 10 to 15 frames and the
size of the video window must be kept small.
 The Sorenson codec is optimized for CD-ROM playback.
Summary
 Digital video method is used for making and delivering
video for multimedia.
 Charge-coupled device (CCD) converts the light that has
been reflected from an object through the camera’s lens.
Summary
 Various video standards are NTSC, PAL, SECAM, and ATSC
DTV.
 Categories of video standards are composite analog,
component analog, composite digital, and component
digital.
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