Source: http://k.ylo.ph/2016/04/04/loudnorm.html (Credits: email@example.com | Source discovered by Mulvya)
./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 Integratedvalue shown indicates audio that is too loud. The
Output Integratedvalue is much closer to -16.0. Both the
Input True Peakand
Input LRA, or loudness range, values are higher than our provided ceilings and will be reduced in the normalized version. Finally, the
Target Offsetrepresents 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