Caption
A textual representation of the audio information in a video program. Captions are usually intended for the hearing impaired, and therefore include additional text to identify the person speaking, offscreen sounds, and so on.



Capture
Also called Cap or Capping - To capture video or TV/Satellite signals to disk.



CBR
Constant Bit Rate - the bitrate is the same at any part of a single video or audio stream. VCD standard MPEG video and audio are constant bit rate as are most MP3 standalone audio files. Also see VBR (variable bit rate).  



Chapter
A DVD 'Chapter' (somewhat confusingly referred to as a 'Part' in the parlence of DVD authors) is generally a logical segment of a Title such as a scene in a film or one interview in a set of cast interviews. There can be up to 999 Chapters in one DVD Title. dvd.sourceforge.net



Chroma bug
The basic "Chroma Bug" manifests itself as streaky or spiky horizontal lines running through the chroma channel, most notably on diagonal edges. As mentioned above, this problem has been around for a long time. It's only just now being noticed largely because one needs a good high-resolution display, such as a front projector and a six foot projection screen, to really see the problem clearly. In addition, the increasingly common use of large progressive displays has really allowed people to get up close to the screen and see every artifact magnified in great detail. Problems that might have gone unnoticed on a 20 inch interlaced TV suddenly hit you in the face. With the advent of relatively high resolution media like DVD, people are starting to compare the video image to the original film image, not to other forms of TV. And suddenly strange problems that people accepted in a TV picture, but would never be allowed on film, look out of place. The Chroma Bug is one of the most visible artifacts around, but because it's specific to MPEG and 4:2:0 encoding, there was nothing written about it until very recently. http://www.hometheaterhifi.com/volume_8 ... -2001.html



Chroma Key
The Chroma Key process is based on the Luminance key. In a luminance key, everything in the image over (or under) a set brightness level is "keyed"out and replaced by either another image, or a color from a color generator. Also known as Blue Screen Compositing, the Chroma Key Process was made famous by films such as star wars where spacecraft miniatures were composited onto starfield backgrounds.



Chroma noise
Chroma noise affects areas of colour in the image. Instead of being clean, even areas of colour, chroma noise makes colours look grainy due to random noise being inserted into the colour signal. Chroma noise seems to particularly affect blue, although it can potentially be seen in any large expanse of a single colour. Chroma noise is pretty much exclusively an artefact of analogue video processing, and it is very rare to see it in modern, all-digital transfers. Increased MPEG macro-blocking artefacts are a potential side-effect of chroma noise, as the MPEG encoder attempts to encode the extra spurious random noise, leaving less bits for actual picture information.



Closed GOP
When encoding MPEG video, a Open GOP is one that uses no referenced pictures from the previous GOP at the current GOP boundary. For example the GOP is closed when it starts with an I Frame and subsequent B Frames do not rely on I or P frames from the previous GOP. Also see Open GOP.



Codec
An acronym for "compression/deccompression", a codec is an algorithm or specialized computer program that encodes or reduces the number of bytes consumed by large files and programs. Files encoded with a specific codec require the same codec for decoding. Some codecs you may encounter in computer video production are Divx, MPEG-1, MPEG-2, Xivd, DV type 1 and type 2 for video and MP3 for audio.



Composite Video
An analog video signal in which the luma and chroma components are combined (by frequency multiplexing), along with sync and burst. Also called CVBS. Most televisions and VCRs have composite video connectors, which are usually colored yellow.



Compression
The process of removing redundancies in digital data to reduce the amount that must be stored or transmitted. Lossless compression removes only enough redundancy so that the original data can be recreated exactly as it was. Lossy compression sacrifices additional data to achieve greater compression.



Convert
To change from one form into another. In video obviously it is to change one form of video into another. For example, many people like to convert divx to MPEG, quicktime to AVI, etc. Conversions to a final format is called encoding.

Crop
To cut away pieces of a video stream without rendering; similar to cutting a picture with scissors.

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