class:: CompanderD
summary:: Compressor, expander, limiter, gate, ducker.
related:: Classes/Amplitude, Classes/Compander, Classes/Normalizer, Classes/Limiter
categories::  UGens>Dynamics


Description::

CompanderD passes the signal directly to the control input, but
adds a delay to the process input so that the lag in the gain clamping
will not lag the attacks in the input sound.


classmethods::

method::ar

argument::in
The signal to be compressed / expanded / gated.

argument::thresh
Control signal amplitude threshold, which determines the break point between slopeBelow and slopeAbove. Usually 0..1. The control signal amplitude is calculated using RMS.

argument::slopeBelow
Slope of the amplitude curve below the threshold. If this slope > 1.0, the amplitude will drop off more quickly the softer the control signal gets; when the control signal is close to 0 amplitude, the output should be exactly zero -- hence, noise gating. Values < 1.0 are possible, but it means that a very low-level control signal will cause the input signal to be amplified, which would raise the noise floor.

argument::slopeAbove
Same thing, but above the threshold. Values < 1.0 achieve compression (louder signals are attenuated); > 1.0, you get expansion (louder signals are made even louder). For 3:1 compression, you would use a value of 1/3 here.

argument::clampTime
The amount of time it takes for the amplitude adjustment to kick in fully. This is usually pretty small, not much more than 10 milliseconds (the default value). I often set it as low as 2 milliseconds (0.002).

argument::relaxTime
The amount of time for the amplitude adjustment to be released. Usually a bit longer than clampTime; if both times are too short, you can get some (possibly unwanted) artifacts.

argument::mul
Output will be multiplied by this value.

argument::add
This value will be added to the output.

Discussion::
If any of this is confusing, see http://en.wikipedia.org/wiki/Audio_level_compression