Brian J. Murrell (d16c258a5ec634f3b48cfcf86d3f0fdb@xxxxxxxxxxxxxxx): > > > What's the storage rate in terms of bytes/sec.? > > > > I get on average 50-60% compression from raw Y'CbCr images. > > > > So, say you downsample to 4:2:0, and you're capturing > > 525/59.94-style video. Each frame uncompressed is (720*480*12/8) == > > 518400 bytes. So, I compress down to about 260000 bytes on average > > per frame. > > Wow, that is 26GB/H. Well, that's assuming you want full-frame lossless. Probably more realistic to do some subsampling horizontally and somewhat mimic VHS. For example, when recording from VHS sources, I use 352x480 or 360x480. If we still only use 4:2:0 chroma sampling, that gives about 253440 bytes per uncompressed frame, so only 128000 bytes per compressed frame or so. At 29.97fps that's only 13GB/H. With audio I usually get about 15GB/H before compressing to MPEG2 or what not. If you use RTJPEG compression, you can get this to about 10G/H or so. An 80GB drive would then get you about 8 hours of video which you can record and view in real time. Not too bad without any hardware compression. Too bad about the quality though. 30GB/H would be ideal if you're going to recompress to MPEG2 on a DVD-R, I think. It surprises me that I had to write my own recorder to be able to record full-frame video without dropping frames. :( Doesn't anyone else care about quality? > > Yeah, well, the v4l api sucks. > > Do you mean that to include v4l2 as well or specifically v4l1? I'm not too happy with either, but I can probably live with v4l2. -- Billy Biggs vektor@xxxxxxxxxxxx
