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):
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?