I'm testing vp9 codec for the web video platform, and cannot get a satisfactory quality for one movie. This is very dark film encoding with vp9 generates ugly circles. This is the original frame (I made it brighter a bit):

orignal frame

And VP9 encoded (brighter): vp9 encoded

With h264 codec the result is good, close to the original.

I tried single pass, 2-passes, constant quality etc, everything, and only with "-lossless 1" option the result is fine (but the file size is large). Results on the picture I get with:

ffmpeg -i org.mp4 -an -c:v libvpx-vp9 -b:v 10M -threads 8 -crf 25 -speed 2 -y "out.webm"

Original file is encoded with h264, very high bitrate.

Do you know any secret parameter which could improve the quality?

  • Try using -crf 18 not 25 and avoid using -speed option
    – user36820
    Nov 17 '21 at 15:49

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