I have a low quality, but playable .webm video. It was recorded from a webrtc live stream that seems to have been on a bad connection. There are not many video frames and the audio cuts out for a moment. I am trying to convert the video to .mp4 with the following command:

avconv -i foo.webm -strict experimental -movflags faststart foo.mp4

I get this error repeated at least 100x:

[opus @ 0x268d7a0] LBRR frames present; this is unsupported
[opus @ 0x268d7a0] Error decoding a SILK frame.
[opus @ 0x268d7a0] Error decoding an Opus frame.

The resulting .mp4 video is even significantly worse than the .webm video. The audio cuts out for good and there are even less video frames. Is there a way to get this video to convert more accurately in spite of the issue it is encountering?

  • Can you post a copy of the low quality webm file here: datafilehost.com ? Mar 31, 2016 at 12:17
  • 1
    @andrew.46 Sure thing! datafilehost.com/d/a797e52e
    – m59
    Mar 31, 2016 at 17:02
  • Sorry, I could not fix this file with any of the tools I have at hand :(. Apr 1, 2016 at 0:17
  • @andrew.46 Thanks for trying! My interest isn't so much in fixing that particular file as it is having some fallback command for files like this in the future. It seems like if it happened once, it will happen again. Unfortunately, iOS won't play mp4, so I can't just use the webm video when this happens. It will make my application unreliable.
    – m59
    Apr 1, 2016 at 0:38
  • Almost all serious decoders / encoders use parts of FFmpeg and this error is currently unfixable with this... Apr 1, 2016 at 9:04

1 Answer 1


You might want to check https://groups.google.com/forum/#!topic/kurento/-csxDrMgLnE for the answer : basically the built-on OPUS support in ffmpeg is not perfect but libopus does a better job for situations like that so simply add -acodec libopus in front of your input and that should do the trick (it does for me).

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