apt install normalize-audio
normalize-audio -bv *.mp3
normalize-audio --help
Usage: normalize-audio [OPTION]... [FILE]...
Normalize volume of multiple audio files
-a, --amplitude=AMP normalize the volume to the target amplitude
AMP [default -12dBFS]
-b, --batch batch mode: get average of all levels, and
use one adjustment, based on the average
level, for all files
--clipping turn off limiter; do clipping instead
--fractions display levels as fractions of maximum
amplitude instead of decibels
-g, --gain=ADJ don't compute levels, just apply adjustment
ADJ to the files. Use the suffix "dB"
to indicate a gain in decibels.
-l, --limiter=LEV limit all samples above LEV [default -6dBFS]
-m, --mix mix mode: get average of all levels, and
normalize volume of each file to the
average
-n, --no-adjust compute and display the volume adjustment,
but don't apply it to any of the files
--peak adjust by peak level instead of using
loudness analysis
-q, --quiet quiet (decrease verbosity to zero)
-t, --average-threshold=T when computing average level, ignore any
levels more than T decibels from average
-T, --adjust-threshold=T don't bother applying any adjustment smaller
than T decibels
-v, --verbose increase verbosity
-w, --output-bitwidth=W force adjusted files to have W-bit samples
-V, --version display version information and exit
-h, --help display this help and exit
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