What Exactly is DV Compression?

greenspun.com : LUSENET : Editing DV Films : One Thread

Hi, I'm new to the forum. I thought I'd start with a question that has puzzled me for a while. What exactly in the name, and type, of compression used in the DV / DVCAM / DVC-PRO format? What Codec family is it most closely related to (if that is the right way to express it)? My initial research indicates that is an algorithm similar to JPEP, but at a fixed, or constant, compression rate of 5:1. And because the compression is fixed, then the resolution is also fixed at 720 x 480 (4:1:1) for NTSC and 720 x 576 (4:2:0) for PAL. Unlike MPEG compression and the like, it is an "intraframe" system, meaning all the compression is within each frame, and not between adjacent frames. Furthermore, it has a fixed 25Mbits/sec video data rate, and when it comes to likes of FireWire throughput, it has a fixed transfer rate of 3.6MB/sec which must be sustained. I guess this is a case where the name of the format and the name of the Codec are, for all intends and purposes, the same? Does this sound right? Does anyone have any words of wisdom here? And on a similar note, what is the compression system used by Avid, and other similar, high-end, NLE editing systems?

-- Peter Gray (peter@jkor.com), May 22, 1999

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