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• FFmpeg outputs errors when encoding 32 bit float pcm file to an mp3 [closed]

  23 mars 2024, par Lazolv

  I am trying to :

  


  


  1. Record audio from my microphone on Windows 10 following this guide

     


  


  2. Encode gotten PCM file using FFmpeg 6.0

     


  


  


  I figured out that the audio data recorded is in stereo 32 bit floating point little endian format with frequency of 48000 Hz. The audio is supposed to be 3 hand claps and importing them in Audacity as raw data with specified format works just fine.

  


  But using ffmpeg -f f32le -ar 48000 -ac 2 -i MicAudio.pcm MicAudio.mp3 outputs the following error :

  


  Assertion failed: cod_info->part2_3_length <= MAX_BITS_PER_CHANNEL, file ../../lame-3.100/libmp3lame/quantize.c, line 2044


  


  Also, despite Audacity being able to correctly play my audio, when trying to export it as MP3 causes Audacity to crash, while exporting as WAV outputs a working wave file.
I don't think the problem is in my code because if it was I wouldn't be able to import it in Audacity at all.

  


  The PCM file itself

  


  Just found out its closed LOL. I guess FFmpeg isn't about programming or software development ! It's sad that this question wasn't considired opinion based :(

  


• pyav - cannot save stream as mono

  3 août 2022, par Zvika

  I'm trying to use pyav to convert arbitrary audio file to a low quality, mono, wave file.

  


  I almost managed to do it, but it's stereo, and I couldn't find how to make it mono. Furthermore, I think I made some mistake here, as I had to repeat the rate in the output_container.add_stream and in the AudioResampler - it seems redundant, and I can't understand what would happen if those numbers won't match.

  


  My code is :

  


      import av
    
    input_file = 'some.mp3'
    output_file = 'new.wav'
    
    rate = 22000
    
    output_container = av.open(output_file, 'w')

    # can I tell `output_stream` to just use `resampler`'s info?
    # or, if not, how can I tell it to have only 1 channel?
    output_stream = output_container.add_stream('pcm_u8', rate)  
    
    resampler = av.audio.resampler.AudioResampler('u8p', 'mono', rate)
    
    input_container = av.open(input_file)
    for frame in input_container.decode(audio=0):
        out_frames = resampler.resample(frame)
        for out_frame in out_frames:
            for packet in output_stream.encode(out_frame):
                output_container.mux(packet)
    output_container.close()


  


  And not related to my main question, but any comments regarding my code, or pointing out mistakes, are welcomed. I hardly could find usage examples to use a reference, and PyAV API documentation isn't very detailed...

  


• threads : Check w32threads dependencies at the configure stage

  18 décembre 2013, par Diego Biurrun

  threads : Check w32threads dependencies at the configure stage
  Also add warning comment about threading implementations without matching
  
  atomics implementation to the atomics fallback implementation.
  

  • [DH] configure
  • [DH] libavutil/atomic.c