On Tue, Apr 06, 2010 at 02:47:52PM +0100, Steve Fosdick wrote: > On Tue, 6 Apr 2010 13:55:38 +0200 > Josef Wolf <jw at raven.inka.de> wrote: [ ... ] > 1. Some form of decimation, i.e. reduce the number of pixels in each > frame or reduce the colour depth. > 2. Capture to MJPEG, i.e. where each frame is encoded as a JPEG image > but no inter-frame coding is done. I think I'd go with option 2. So for the grab I use following command: streamer -i composite1 -b 64 -s 768x576 -n pal -f mjpeg -j 100 -r 25 -F stereo -o file.avi This gives about 650MB per minute. BTW: when I use S-Video input, I get only black-white :-( > I reckon the factor by which CPUs have got faster these last ten years > is much greater than the factor by which disk I/O has got faster so it > may be worth trying to see if it is possible to encode direct to your > final format in real time. I'd prefer two-pass encoding for better quality, so direct capture+encode would not work anyway. > > BTW: I've seen various resolution recommendations for PAL varying from > > 384x288 to 768x576. What is the correct setting? > > In the output from a PAL VHS machine there should be 625 scan lines, > only 576 of which would normally be visible. As the output is analogue > there isn't an number of pixels to be applied to the horizontal axis > but as the aspect ratio is 4:3 you could go for the same level of > detail in both directions and set the horizontal to 768. > > For the original VHS the video bandwidth is only 3Mhz so the 768 > horizontal resolution may be overkill - the Wikipedia article suggests > 480 pixels may be sufficient. But don't I need 768 to keep aspect ratio? Some howtos suggest 720 for DVD. Won't this break aspect? I'd like to encode into avi, but in such a way that I can create DVDs from that file without reencoding. Here is how I currently do the encoding: mencoder infile.avi -vf yadif=0 -mc 0 -noskip -ovc lavc -lavcopts \ vcodec=mpeg4:trell:nr=400:vqscale=10:mbd=2:scplx_mask=0.2:turbo:vpass=1 \ -nosound -o /dev/null mencoder infile.avi -vf yadif=0 -mc 0 -noskip -ovc lavc -lavcopts \ vcodec=mpeg4:trell:nr=400:vqscale=10:mbd=2:scplx_mask=0.2:vpass=2 \ -oac mp3lame -lameopts preset=standard:mode=2 -o outfile.avi This seems to give reasonable results. Any suggestions for improvement?
