one solution would certainly be to throw money at the problem, i.e.: - get more HD space - get a faster/more CPU(s) - shell out for an mpeg2 encoder card
you probably don't want to do that though. but it's rather obvious that encoding twice will prove to take quite a hit on quality, because you can't really compress binary data losslessly (unless there's some sweet algorithm for YUV, i don't know). Otherwise, I'd suggest the HD solution, since harddrive space is becoming cheaper and cheaper. I recently bought a 60GB drive for $120 (or something) so that might be an option. Or, just get a second drive. Otherwise, I don't think there is a solution to your problem. Marcel (the unknowledgable one) Trevor Boicey wrote: > Iposted this to the mjpeg list but it might be worth >discussing here as well: > >===== > > This question might take a bit of explaining, so bear with me. > > Like a lot of the world it seems, I have a linux box that >is working as a PVR. > > It's a celeron-500 with a 30G disk, a bt848 card, lirc receiver, >and some software that I've crufted up that basically calls >other apps to encode, save, play, etc. according to a >simple scheduler and a remote-control menu. Probably >what a lot of people here have running. > > Up to now, I've been using mp1e to record in real time >directly to the file I wanted to keep. So I'd run mp1e >with a VCD-sized frame, a suitable bit rate, and that would >be the file that I would later watch. > > However, the more I use it, the more I realize that even >given a high bitrate mp1e still doesn't look very good, and >being a real-time encoder, I don't really blame it. It looks >horrible at 500kbps, acceptable at 1Mbps, but doesn't seem >to get any better looking even at 5Mbps or more at the same >resolution. > > It sounds like to get the best quality file, I would >capture directly in YUV format and then recompress it >later with mjpeg to get my video files. > > Enter mjpeg... > > The problem with this is that I sometimes need to record >2-3 hours a night, and I don't have nearly enough disk >space to record 2-3 hours of YUV data. > > So... I've been experimenting with this: > >- Recording with mp1e at 640x480 (v4l size) at a fairly >high bitrate of about 5Mbps. The goal is to get as few >compression artifacts as possible at this stage but still to >be able to record a busy evening's stuff with only 4-5G of >scratch space. > >- After taping, recompressing the video with mjpeg, this seems to work >decently well at a reasonable 3-4 fps. > >cat $1_large.mpg > | mpeg2dec -s -o YUVh > | nice -n 20 yuvdenoise > | mpeg2enc -4 1 -2 1 -s -f 1 -o $1_temp.m1v > > This produces acceptable results. I lose a few gigs when I tape >but overnight scripts recompress the video and I get the space >back. I leave about 4G free at all times so I have about 26G >to store programs and the system is happy. > > The quality is fairly watchable and better overall than >straight mp1e was even at twice the bitrate. However, there >still are some visual funnies that are very likely the effect >of double-compressing, and I am looking at ways to improve >the final quality. > > Is there a better method of doing what I am trying to do? > > Basically what I could use is something that can do real >time capture with the highest possible quality in say, 2G per >hour of video. (an order of magnitude more than mpeg1 but >an order of magnitude less than straight YUV) > > Then I could postprocess down to VCD in the wee hours with >mjpeg. > > Ideas? Suggestions? > > _______________________________________________ Video4linux-list mailing list [EMAIL PROTECTED] https://listman.redhat.com/mailman/listinfo/video4linux-list
