Audio Volume Manipulation

Changing volume

To change the audio volume, you may use FFmpeg's ​volume audio filter.

If we want our volume to be half of the input volume:

ffmpeg -i input.wav -filter:a "volume=0.5" output.wav

150% of current volume:

ffmpeg -i input.wav -filter:a "volume=1.5" output.wav

You can also use decibel measures:

ffmpeg -i input.wav -filter:a "volume=10dB" output.wav

Peak and RMS Normalization

To normalize the volume to a given peak or RMS level, the file first has to be analyzed using the volumedetect filter:

ffmpeg -i input.wav -filter:a volumedetect -f null /dev/null

Read the output values from the command line log:

[Parsed_volumedetect_0 @ 0x7f8ba1c121a0] mean_volume: -16.0 dB
[Parsed_volumedetect_0 @ 0x7f8ba1c121a0] max_volume: -5.0 dB
...

... then calculate the required offset, and use the volume filter as shown above.

To automate this process and run it on multiple files (including video), you can also use the ​ffmpeg-normalize Python script via pip install ffmpeg-normalize. For the supported options, see ffmpeg-normalize -h.

Loudness Normalization

If you want to normalize the (perceived) loudness of the file, use the ​loudnorm filter, which implements the EBU R128 algorithm:

ffmpeg -i input.wav -filter:a loudnorm output.wav

This is recommended for most applications, as it will lead to a more uniform loudness level compared to simple peak-based normalization.