Codec: Difference between revisions

Revision as of 18:22, 18 September 2005

Revision as of 16:11, 28 September 2005

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Most codecs are [[lossy]], in order to get a reasonably small file size. There are [[lossless]] codecs as well, but for most purposes the almost imperceptible increase in quality is not worth the considerable increase in data size. The main exception is if the data will undergo more processing in the future, in which case the repeated lossy encoding would damage the eventual quality too much.

Many [[multimedia]] data streams need to contain both [[Sound|audio]] and [[video]] data, and often some form of [[Metadata (computing)|metadata]] that permits synchronization of the audio and video. Each of these three streams may be handled by different programs, processes, or hardware; but for the multimedia data stream to be useful in stored or transmitted form, they must be [[Encapsulation|encapsulated]] together. This function is carried out byin a [[video filecontainer format]] (or container), such as [[MPEG|*.mpg]], [[AVI|*.avi]], [[QuickTime|*.mov]], [[MPEG-4 Part 14|*.mp4]], [[RealMedia|*.rm]], [[Ogg|*.ogg]] or [[TTA|*.tta]]. Some of these formats are limited to containing streams conforming to a small fixed set of codecs, while others are intended to be more general purpose.

An [[endec]] is a similar (but ''not'' identical) concept for [[hardware]].