Audio nomalization with ffmpeg using loudnorm (ebur128) filter

Source: https://developers.google.com/actions/tools/audio-loudness

 

  • ./ffmpeg -i /path/to/input.wav -af loudnorm=I=-16:TP=-1.5:LRA=11:print_format=summary -f null -
    

    This instructs FFmpeg to measure the audio values of your media file without creating an output file. You will get a series of values presented as follows:

    Input Integrated:    -27.2 LUFS
    Input True Peak:     -14.4 dBTP
    Input LRA:             0.1 LU
    Input Threshold:     -37.7 LUFS
    
    Output Integrated:   -15.5 LUFS
    Output True Peak:     -2.7 dBTP
    Output LRA:            0.0 LU
    Output Threshold:    -26.2 LUFS
    
    Normalization Type:   Dynamic
    Target Offset:        -0.5 LU
    

    The sample values above indicate important information about the incoming media. For instance, the Input Integrated value shown indicates audio that is too loud. The Output Integrated value is much closer to -16.0. Both the Input True Peak and Input LRA, or loudness range, values are higher than our provided ceilings and will be reduced in the normalized version. Finally, the Target Offset represents the offset gain used in the output.

  • Run a second pass of the loudnorm filter, supplying the values from step 1 as “measured” values in the loudnorm options.
    ./ffmpeg -i /path/to/input.wav -af loudnorm=I=-16:TP=-1.5:LRA=11:measured_I=-27.2:measured_TP=-14.4:measured_LRA=0.1:measured_thresh=-37.7:offset=-0.7:linear=true:print_format=summary output.wav

 

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