Recently I wanted to try out the Webm codecs VP8 and VP9 but when I ran ffmpeg
to encode a H.264 MP4 file into one of the other two codecs, I realized that the encoding is (by almost an order of magnitude) slower.
A 1080p30 video from H.264 to VP9 at 3 MBit/s is being encoded at around 6-7 fps while the same video encodes at around 40 fps to H.264. I used the libvpx-vp9
codec in ffmpeg
for the VP9 format. I am getting the same results for VP8 and Theora too.
Can someone explain to me why VP9 is so much slower? I tried a different machine which gave me similar resullts using Handbrake.