68 lines
2.5 KiB
Scheme
68 lines
2.5 KiB
Scheme
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;; (compander input control thresh slopeBelow slopeAbove clampTime relaxTime)
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;; Compressor, expander, limiter, gate, ducker. General purpose
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;; dynamics processor.
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;; input: The signal to be compressed / expanded / gated.
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;; control: The signal whose amplitude determines the gain applied to
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;; the input signal. Often the same as in (for standard
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;; gating or compression) but should be different for
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;; ducking.
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;; thresh: Control signal amplitude threshold, which determines the
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;; break point between slopeBelow and slopeAbove. Usually
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;; 0..1. The control signal amplitude is calculated using RMS.
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;; slopeBelow: slope of the amplitude curve below the threshold. If
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;; this slope > 1.0, the amplitude will drop off more
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;; quickly the softer the control signal gets when the
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;; control signal is close to 0 amplitude, the output
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;; should be exactly zero -- hence, noise gating. Values <
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;; 1.0 are possible, but it means that a very low-level
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;; control signal will cause the input signal to be
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;; amplified, which would raise the noise floor.
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;; slopeAbove: Same thing, but above the threshold. Values < 1.0
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;; achieve compression (louder signals are attenuated) >
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;; 1.0, you get expansion (louder signals are made even
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;; louder). For 3:1 compression, you would use a value of
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;; 1/3 here.
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;; clampTime: The amount of time it takes for the amplitude adjustment
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;; to kick in fully. This is usually pretty small, not much
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;; more than 10 milliseconds (the default value).
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;; relaxTime: The amount of time for the amplitude adjustment to be
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;; released. Usually a bit longer than clampTime if both
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;; times are too short, you can get some (possibly
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;; unwanted) artifacts.
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;; Example signal to process.
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(define z
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(mul (decay2 (mul (impulse ar 8 0) (mul (lf-saw kr 0.3 0) 0.3)) 0.001 0.3)
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(mix (pulse ar (mce2 80 81) 0.3))))
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(audition (out 0 z))
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;; Noise gate
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(let ((x (mouse-x kr 0.01 1 0 0.1)))
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(audition (out 0 (mce2 z (compander z z x 10 1 0.01 0.01)))))
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;; Compressor
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(let ((x (mouse-x kr 0.01 1 0 0.1)))
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(audition (out 0 (mce2 z (compander z z x 1 0.5 0.01 0.01)))))
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;; limiter
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(let ((x (mouse-x kr 0.01 1 0 0.1)))
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(audition (out 0 (mce2 z (compander z z x 1 0.1 0.01 0.01)))))
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;; Sustainer
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(let ((x (mouse-x kr 0.01 1 0 0.1)))
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(audition (out 0 (mce2 z (compander z z x 0.1 1.0 0.01 0.01)))))
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