[Libav-user] Huge bit rate for VP9 while encoding WebM (libvpx-vp9, vorbis)

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[Libav-user] Huge bit rate for VP9 while encoding WebM (libvpx-vp9, vorbis)

Leandro Moreira
Hi there,

I'm writing a mini-book/tutorial on how to use FFmpeg/libav as a library and on the third chapter I created a transcoder/transmuxer that I tested for h264->h265, mpeg4->mpeg-ts and it looked fine... but when I tried to use it to produce a WebM (VP9, Vorbis) I noticed the following issues:
  • huge final bit rate 190 Mb/s
  • weird fps 60.145
  • warning messages during encoding process [libvorbis @ 0x243c040] more samples than frame size (avcodec_encode_audio2)
Do you have any idea why this is happening? =( I took inspiration from the FFmpeg API documentation/examples and command-line source code to create this example. If you want to test for yourself here is how:

git clone https://github.com/leandromoreira/ffmpeg-libav-tutorial.git
cd ffmpeg

# edit so you'll be using WebM streaming parameters https://github.com/leandromoreira/ffmpeg-libav-tutorial/blob/master/3_transcoding.c#L302

# make sure to have docker installed
make run_transcoding

# if you want to check the final media file
mediainfo bunny_1s_gop
ffprobe bunny_1s_gop

Thank you

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