Name
Mcompand -- multi-band compression/expansion/limiting
Synopsis
mcompand "attack1,decay1{,attack2,decay2} [soft-knee-dB:]in-dB1
    [,out-dB1]{,in-dB2,out-dB2}[gain [initial-volume-dB [delay]]]"
    {crossover-freq[k]"attack1,..."}
Function
The multi-band compander is similar to the single-band compander but the audio is first divided into bands using Linkwitz-Riley cross-over filters and a separately specifiable compander run on each band. See the compand effect for the definition of its parameters. Compand parameters are specified between double quotes and the crossover frequency for that band is given by crossover-freq; these can be repeated to create multiple bands.

For example, the following (one long) command shows how multiband companding is typically used in FM radio:

 
gain -3 sinc 8000- 29 100 mcompand
"0.005,0.1 -47,-40,-34,-34,-17,-33" 100
"0.003,0.05 -47,-40,-34,-34,-17,-33" 400
"0.000625,0.0125 -47,-40,-34,-34,-15,-33" 1600
"0.0001,0.025 -47,-40,-34,-34,-31,-31,-0,-30" 6400
"0,0.025 -38,-31,-28,-28,-0,-25"
gain 15 highpass 22 highpass 22 sinc -n 255 -b 16 -17500
gain 9 lowpass -1 17801

See also compand for a single-band companding effect.

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