This version (18 May 2021 08:58) was approved by John Joseph.The Previously approved version (15 Jan 2021 04:23) is available.
Table of Contents
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Limiter
Description
The Limiter block computes the RMS level of the incoming audio signal and attempts to prevent it from exceeding the threshold by automatically reducing it's gain.
Targets Supported
| Name | ADSP-214xx | ADSP-215xx/SC5xx | ADAU145x/146x |
|---|---|---|---|
| —————————————- | —————————- | ——————————-- | —————————- |
| Limiter | B | B | S |
Pins
Input
| Name | Type | Description |
|---|---|---|
| ————————————— | —————————— | ———————————————— |
| Input | Audio | Input channel |
Output
| Name | Type | Description |
|---|---|---|
| ———————————————— | —————————— | ————————————————————————————- |
| Output | Audio | Output channel |
| ActiveInactive | Control | Pin outputs 1 indicates the limiter is active and 0 indicates the limiter is inactive.This essentially shows if the input signal has exceeded the threshold or not. The number is an unsigned integer format |
| LimitingRatio | Control | Value representing the current gain factor being applied to the input audio signal |
Configurable Parameters
| GUI Parameter Name | Default Value | Range | Function Description |
|---|---|---|---|
| ———————————————- | —————————- | ————————————- | —————————————————————- |
| RMSTC | 50 dB/s | 1 to 10000 dB/s | Controls the tracking rate of the RMS-approximation calculation used to track the input level. |
| Decay | 12 dB/s | 5 to 23 dB/s | Controls the rate at which the signal compression ratio will subside after the input signal level has dropped below the limiter threshold. Larger values result in longer decays, with 23 never recovering to the original gain |
| Threshold | 1 dB | -24 to +24 dB | Sets the threshold point. If the input signal's approximated RMS level exceeds the threshold point, the limiter will apply compression in order to prevent the signal from exceeding that level. This threshold level does not need to be an integer; its resolution can be set in steps of less than 0.01 dB. A full-scale sine wave is a level of -3 dB, due to the RMS measurement |
DSP Parameters
| Parameter Name | Description | ADSP-214xx/SC5xx/215xx | ADAU145x/146x |
|---|---|---|---|
| —————————— | ——————————————————————————- | ——————————————- | ———————————————- |
| RMSTC | Time constant for RMS calculation | Float | 8.24 format |
| Decay | Decay value | Float | 8.24 format |
| Threshold | limiter threshold | Float | 8.24 format |
DSP Parameter Computation
Decay = 1/10^(Decay/(10 * (FS + 0.000001)))
Where FS is the sampling rate
resources/tools-software/sigmastudiov2/modules/dynamicsprocessors/limiter.txt · Last modified: 12 May 2021 09:35 by John Joseph