Description:
Compand (compress and/or expand) the dynamic range of the audio.
<attack> and <release> determine the time over which the instantaneous level of the input signal is averaged to determine its volume; <attack> refers to increases in volume and <release> refers to decreases. For most situations, <attack> should be smaller than <release> because the human ear is more sensitive to sudden increases rather than decreases in audio levels. Typical values are 0.3,0.8 seconds.
<transferfunction> is a breakpoint function describing compression/expansion over the dynamic range of the input signal.
<softknee> will round the points at where adjacent line segments on the transfer function meet by the specified amount.
<makeup-gain> is an additional gain in dB to be applied at all points on the transfer function which allows easy adjustment of the overall gain.
<minvolume> permits the user to supply a nominal level initially, so that, for example, a very large gain is not applied to initial signal levels before the companding action has begun to operate: it is quite probable that in such an event, the output would be severely clipped while the compander gain properly adjusts itself.
<lookahead> is a delay in seconds. The input signal is analysed immediately to control the compander, but it is delayed before being fed to the volume adjuster. Specifying a delay approximately equal to the attack/release times allows the compander to effectively operate in a 'predictive' rather than a reactive mode.
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