Description:
The Compressor module weakens the input signal when it goes above a specified threshold which effectively reduces the dynamic range of the signal. The aim of the audio object is to remap the dynamic range of an audio signal to a smaller range in such a way that the volume of loud sounds over a certain threshold is reduced while quiet sounds remain unaffected.
The number of audio channels it can process is configurable in the SFD and each channel has its own set of specifications. The number of channels and maximum delay are the configurable parameters in the SFD.
The compressor has only one operating mode and does not expose any variables to control.
The AO supports in-place computation based on the core type.
In the GTT, the Compressor exposes the following parameters for each channel of the Compressor:
Tuning Parameters:
| Parameter Name | Data type | Default Value | Range of values | Note |
| Compressor Threshold | Float | -30 | -120 to 0 dB | Level of the compressor activation |
| Attack Time | Float | 0.02 s | 0.001 s to 0.5 s | Time needed to compress signal to the target value. The signal level is reduced by 6dB in this duration. |
| Release Time | Float | 0.05 s | 0.001 s to 0.5 s | Time needed to restore original level of the signal (by 6dB) after its return below threshold. |
| RMS smooth filter coefficient | Float | 0.8 | 0 to 1 | Coefficient of the RMS filter used for calculating RMS level of input signal |
| Compression ratio | Float | 3 | 1 to 100 | Amount of compression applied to signal when its level is above threshold |
| Knee width/ Soft Knee | Float | 3 dB | 0 dB to 120 dB | The half width of smooth transition band around threshold point |
| Make-up (after) gain | Float | 0 dB | -128 dB to 20 dB | Value of additional gain applied to the output signal |
| Noise gate threshold | Float | -128 dB | -128 dB to 20 dB | Level of the noise gate activation |
| Bypass | ULong | 0 |
0 – disabled 1 – enabled |
When this value is equal one the compressor is transparent |
| Delay (Look ahead buffer) | Float | 0 s | 0 s to Max LookAhead | Amount of time that the input signal is delayed |
| LP Coefficient a1 | Float | 0 | 0 to 1 | Antialiasing filter’s a1 coefficient |
| LP Coefficient b0 | Float | 0 | 0 to 1 | Antialiasing filter’s b0 coefficient |
| LP Coefficient b1 | Float | 0 | 0 to 1 | Antialiasing filter’s b1 coefficient |
| Noise gate bypass | ULong | 0 | 0, 1 | To bypass noise gate functionality completely. When set to 1, noise gating is disabled |
Streaming:
- Attenuation (Implemented in U Release and is streamable) – Indicates the amount of the computed attenuation when the compressor is active.
- Range 0 to 128 dB, Default value – 0dB.