AVI compression

[fatdom]

Hi,

I have a couple of questions that have been bugging me for a while,

When a video file is compressed is the original information there in it's entirety, i.e. are compressed AVIs similar to zip files in that all of the original information can be obtained.

Also what are the advantages/disadvantages of VBR and CBR (for VCD and SVCD encoding)

thanks in advance, Dom.

[Dave B]

There are two types of video compression - lossless and lossy.

A lossless compression algorithm will compress the video so that all the original information can be extracted. This is similar to the way a zip file works. A good example of a lossless codec is HuffyUV. HuffyUV can compress a video stream to about a fourth of it's original size.

A lossy algorithm will (usually) compress video to a much higher ratio than a lossless algorithm. MPEG-1, MPEG-2, MJPEG and DivX are all examples of a lossy algorithm. The more you compress the video, the more quality you lose.

[Dave B]

For a good explanation of VBR, CBR and CQ encoding methods follow this link. (Thanks Kwag)
http://www.tecoltd.com/enctest/concepts.htm