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• avcodec/decode : copy the output parameters from the last bsf in the chain back to...

  27 juillet 2018, par James Almer

  avcodec/decode : copy the output parameters from the last bsf in the chain back to the AVCodecContext
  Certain AVCodecParameters, like the contents of the extradata, may be changed
  
  by the init() function of any of the bitstream filters in the chain.
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/decode.c

• avcodec/rv30 : put the rpr check back in init with the max vs bits bug fixed

  4 janvier 2014, par Michael Niedermayer

  avcodec/rv30 : put the rpr check back in init with the max vs bits bug fixed
  Its usefull to know immediatly if extradata is wrong and not just when later
  
  the decoder tries to use it.
  This check was removed by : a6a2282c25abe43e352010a7c3fbc92994c0bc1c
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/rv30.c

• FFmpeg massive data loss when writing large data and swapping segments

  25 avril 2023, par Bohdan Petrenko

  I have an ffmpeg process running which continiously writes audio data to two 30 seconds (for testing, I'm actually planning to use 5 minutes) segments. The problem is that when I write some audio data with length more than size of two segments (60 seconds), 8-17 seconds of audio is lost. Here is how I run FFmpeg and write data :

  


      _ffmpeg = Process.Start(new ProcessStartInfo
    {
        FileName = "ffmpeg",
        Arguments = 
            $"-y -f s16le -ar 48000 -ac {Channels} -i pipe:0 -c:a libmp3lame -f segment -segment_time {BufferDuration} -segment_format mp3 -segment_wrap 2 -reset_timestamps 1 -segment_list \"{_segmentListPath}\" \"{segmentName}\"",
        UseShellExecute = false,
        RedirectStandardInput = true
    })!;
    // Channels is usually 1, BufferDuration is 30


  


  And here is how I write data :

  


  public async Task WriteSilenceAsync(int amount)
{
    if (amount > _size) amount = _size; // _size is 48000 * 1 * 2 * 30 * 2 = 5760000 (size of 1 minute of audio)
    
    var silence = _silenceBuffer.AsMemory(0, amount);
    await _ffmpeg.StandardInput.BaseStream.WriteAsync(silence);
}


  


  I tried to change the ffmpeg parameters and ways I write data. But I haven't found the solution.

  


  I'm sure that the problem is caused by ffmpeg segments, because if I disable segmenting and write audio to a single file, there are no problems with data loss or audio missmatch. I also sure that amount of silence to add in WriteSilenceAsync() method is calculated right. I'm not sure if the problem appears with data length more than 30 seconds but less then 1 minute, but I think it doesn't.

  


  I don't know how to solve this problem and would be glad to see any suggestions or solutions.