Question

I’m trying to extract individual frames from a video.

ffmpeg -i face_source.wmv face_sourceframes/image%03d.jpg

is almost working just fine. The first six or so appear perfect (have roughly 30kB file size), but then they continuously degrade (e.g. 23kB, 17kB, etc.) until all frames are 11kB. Of course, these frames are pixelated and not desired.

I tried forcing a bitrate with the -b option. ffmpeg tells me this about the inupt video:

  Duration: 00:00:10.07, start: 0.000000, bitrate: 781 kb/s

So I set bitrate, first using -b 781k, and then, just to be safe, also tried doubling it, to -b 1562k. Neither of these options made any apparent difference in the output.

Any help would be appreciated! Thank you!

Answer 1

Try setting the quantizer with the -qscale option using a value between 1-31: 1 is best quality and 31 is worst.

That should help if it indeed is trying to do some rate control.

However, it could be that your input video is itself of bad quality? Try playing it and checking. I suspect that is the case.