On Wed, Nov 28, 2001 at 11:08:35PM -0800, Billy Biggs wrote: > Brian J. Murrell (v4l@xxxxxxxxxxxxxxx): > > > > One thing I wrote is a simple prediction-based codec. It's fast > > > enough for lossless realtime encoding, but the files it writes are > > > massive > > > > 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. > Yeah, well, the v4l api sucks. Do you mean that to include v4l2 as well or specifically v4l1? > Doing what you request should be > pretty trivial, I thought so. > but it seems like a waste to me. The linux scene could > benefit more from a userspace video capture library that can also do > things like colourspace conversion and chroma resampling for webcams and > stuff (and also for live capture). I'd rather work towards that. Fair enough. > Having a few sample clips in a lossless format (like my codec) would > be useful then. Right! 'Cept that when you want to compare v4l[2] capture apps you need to feed them in via the v4l[2] api. Not all (indeed probably less than more) capture apps can read from a file as well. > I can see about posting up some of the samples I use, > but it sucks since they're all in about the 1-gig size range. I could believe it. > Is that what you meant? Half way. Like I said above, they need to be fed through the API though. b. -- Brian J. Murrell
