Overview
DSP Concepts proprietary Single-Channel Noise Reduction Gain Calculator. For version 4
Discussion
This module calculates gain coefficients for single-channel noise reduction. It is part of the SCNRv4 design.
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The timeAlphaPrioriMs parameter controls the recursive averaging parameter in the SNR calculation. The default value is 250ms. Higher values mean more smoothing, resulting in a lower risk of musical noise, but a higher risk of distorting onset transients.
Type Definition
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typedef struct _ModuleSCNRv4GainCalculator
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
FLOAT32 prioriSnrScaler1Gain; // Scaler gain.
FLOAT32 prioriSnrScaler2Gain; // Scaler gain.
FLOAT32 timeAlphaPrioriMs; // Averaging time for a-priori SNR computation, in ms.
FLOAT32 minGaindB; // Minimum gain (maximum reduction) per subband, in dB.
FLOAT32 smoothOctave; // Number of octaves for cross-bin logarithmic smoothing.
FLOAT32 postSnrClipAsymUpper; // Asymmetric-clip upper limit.
FLOAT32 prioriSnrClipAsymUpper; // Asymmetric-clip upper limit.
FLOAT32 gainCalcLogScaleGain; // Scale Offset gain.
FLOAT32 smoothStartFreq; // Start frequency for cross-bin smoothing.
FLOAT32* aAPrioriFb; // A-priori SNR estimation feedback line.
FLOAT32* aPrioriSnrDelay; // Block Delay single-block delay buffer.
INT32* aSmoothStartIdx; // Starting index for the averaging process.
INT32* aSmoothEndIdx; // Ending index for the averaging process.
FLOAT32* aSmoothOneOverN; // Precomputed 1/N for averaging.
} ModuleSCNRv4GainCalculatorClass; |
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
prioriSnrScaler1Gain | float | derived | 0 | 1 | Unrestricted | |
prioriSnrScaler2Gain | float | derived | 0 | 1 | Unrestricted | |
timeAlphaPrioriMs | float | parameter | 0 | 250 | 0:1000000 | ms |
minGaindB | float | parameter | 0 | -12 | -30:0 | dB |
smoothOctave | float | parameter | 0 | 0.1 | 0:1 | |
postSnrClipAsymUpper | float | const | 1 | 1000000 | Unrestricted | |
prioriSnrClipAsymUpper | float | const | 1 | 10000 | Unrestricted | |
gainCalcLogScaleGain | float | const | 1 | 0.033333 | Unrestricted | |
smoothStartFreq | float | const | 1 | 0 | Unrestricted | |
aAPrioriFb | float* | state | 1 | [1 x 32] | Unrestricted | |
aPrioriSnrDelay | float* | state | 1 | [1 x 32] | Unrestricted | |
aSmoothStartIdx | int* | derived | 1 | [32 x 1] | Unrestricted | |
aSmoothEndIdx | int* | derived | 1 | [32 x 1] | Unrestricted | |
aSmoothOneOverN | float* | derived | 1 | [32 x 1] | Unrestricted |
Pins
Input Pins
Name: Yk
Description: Input signal power
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Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out
Description: Output signal
Data type: float
Scratch Pins
Channel count: 1
Block size: 33
Sample rate: 48000
MATLAB Usage
File Name: scnrv4_gain_calculator_module.m
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