How Much To CompressUltimately the picture quality you're left with after lossy compression depend on which of these techniques you use, and how. Formats for distribution, like DVD, typically use all of them because they're not intended for editing. On the other hand, DV was designed with editing in mind, so every frame is an I frame. This means you can do anything you want with that frame, even remove it completely, and the surrounding frames won't be affected except for later frames having a different time code.
Bitrate ConsiderationsOther than format requirements for standalone players, the most important consideration for most encoding is bitrate. Bitrate determines that maximum quality you can get from a given format, and may sometimes be the determing factor in what format is appropriate. Final video size will always be constant for a given bitrate, but quality will vary by format and usually by specific encoder software or hardware. The same bitrate that would be acceptable for one format (1000kbps at 720x480 MPEG-4) might look horrible in another (1000kbps at 720x480 MPEG-2).
v1.0 2007.08.31 Original version by Rich Fiscus
v1.0.1 2007.11.16 Added links to additional DVF guides by Rich Fiscus
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Written by: Rich Fiscus