de.sciss.fscape.modules.ModLimiter.md Maven / Gradle / Ivy

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Bringing FScape v1 modules to the next generation

There is a newer version: 3.15.6

# Limiter

This module applies a single band brick-wall limiter to a sound file.

## Parameters

_Input:_ Sound file to be limited.

_Output:_ Destination sound file.

_Boost:_ Gain applied to the input before entering the limiting stage.

_Ceiling:_ Absolute output ceiling in decibels full-scale.

_Attack:_ Attack time specified as the point where the gain control envelope rises above 0.1%.

_Release:_ Release time specified as the point where the gain control envelope falls below 0.1%.

_Synchronize Channels:_ If checked (default), all channels of a multi-channel file will be affected 
by the same amount of limiting, taking the maximum limiting factor across the channels. If not 
checked, the gain control of each channel is independent.

## Notes

This algorithm is as follows: For each successive input sample, a cumulative attenuation gain is 
calculated, projecting an exponential envelope whose maximum corresponds to this gain onto this 
cumulative gain buffer. As a result, there is no notion of a sustained limiting or hold segment, 
but instead the control envelope is automatically smoothed out. The default time constants emphasize 
loudness, for a more punchy sound increase these values by a factor of five to ten.

The higher the time parameters, the less the distortion products. For example, limiting a sustained 
full scale 220.5 Hz sine wave with 6 dB boost, produces a third harmonic of strength around -72 dB 
compared to the fundamental when using the default values of 20ms/200ms. Increasing these values 
to 200ms/2000ms, the third harmonic appears at around -108 dB (aka inaudible). With the latter 
setting, a sine tone of 110.25 Hz has a third harmonic as low as -86 dB.