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SNR extends BaseAlgorithm
in package

SNR

Inputs:

[vector_real] frame - the input audio frame

Outputs:

[real] instantSNR - SNR value for the the current frame [real] averagedSNR - averaged SNR through an Exponential Moving Average filter [vector_real] spectralSNR - instant SNR for each frequency bin

Parameters:

MAAlpha: real ∈ [0,1] (default = 0.949999988079) Alpha coefficient for the EMA SNR estimation [2]

MMSEAlpha: real ∈ [0,1] (default = 0.980000019073) Alpha coefficient for the MMSE estimation [1].

NoiseAlpha: real ∈ [0,1] (default = 0.899999976158) Alpha coefficient for the EMA noise estimation [2]

frameSize: integer ∈ (1,inf) (default = 512) the size of the input frame

noiseThreshold: real ∈ (-inf,0] (default = -40) Threshold to detect frames without signal

sampleRate: real ∈ (0,inf) (default = 44100) the sampling rate of the audio signal [Hz]

useBroadbadNoiseCorrection: bool ∈ {true,false} (default = true) flag to apply the -10 * log10(BW) broadband noise correction factor

Description:

This algorithm computes the SNR of the input audio in a frame-wise manner.

The algorithm assumes that:

  • The noise is gaussian.
  • There is a region of noise (without signal) at the beginning of the stream in order to estimate the PSD of the noise [1].

Once the noise PSD is estimated, the algorithm relies on the Ephraim-Malah [2] recursion to estimate the SNR for each frequency bin.

The algorithm also returns an overall (a single value for the whole spectrum) SNR estimation and an averaged overall SNR estimation using Exponential Moving Average filtering.

This algorithm throws a warning if less than 15 frames are used to estimate the noise PSD.

References:

  1. Vaseghi, S. V. (2008). Advanced digital signal processing and noise reduction. John Wiley & Sons. Page 336.

  2. Ephraim, Y., & Malah, D. (1984). Speech enhancement using a minimum-mean square error short-time spectral amplitude estimator. IEEE Transactions on acoustics, speech, and signal processing, 32(6), 1109-1121.

Category: Standard Mode: standard

Table of Contents

Properties

$algorithmName  : string
$category  : string
$essentia  : EssentiaFFI
$mode  : string
$parameters  : array<string|int, mixed>
$algorithmHandle  : CData|null
$configured  : bool

Methods

__construct()  : mixed
__destruct()  : mixed
compute()  : array<string|int, mixed>
getAlgorithmName()  : string
getCategory()  : string
getMode()  : string
getParameters()  : array<string|int, mixed>
setParameter()  : self
configure()  : void
isValidParameter()  : bool
validateInput()  : void
cleanupAlgorithm()  : void
configureAlgorithmParameters()  : void
estimateOutputSize()  : int
executeAlgorithm()  : array<string|int, mixed>
executeGenericAlgorithm()  : array<string|int, mixed>
executeSpecificAlgorithm()  : array<string|int, mixed>
getAlgorithmCreateFunction()  : string
getValidParameters()  : array<string|int, mixed>
initializeAlgorithm()  : void
prepareInput()  : mixed
processOutput()  : array<string|int, mixed>
processRhythmOutput()  : array<string|int, mixed>
processSpectralOutput()  : array<string|int, mixed>
processStatsOutput()  : array<string|int, mixed>
processTemporalOutput()  : array<string|int, mixed>
processTonalOutput()  : array<string|int, mixed>
setAlgorithmParameter()  : void
setArrayParameter()  : void
validateAlgorithmInput()  : void

Properties

$algorithmName

protected string $algorithmName = 'SNR'

$category

protected string $category = 'Standard'

$mode

protected string $mode = 'standard'

$parameters

protected array<string|int, mixed> $parameters = []

$algorithmHandle

private CData|null $algorithmHandle = null

$configured

private bool $configured = false

Methods

__construct()

public __construct([array<string|int, mixed> $parameters = [] ]) : mixed
Parameters
$parameters : array<string|int, mixed> = []

__destruct()

public __destruct() : mixed

compute()

public compute(mixed $input) : array<string|int, mixed>
Parameters
$input : mixed
Return values
array<string|int, mixed>

getAlgorithmName()

public getAlgorithmName() : string
Return values
string

getCategory()

public getCategory() : string
Return values
string

getParameters()

public getParameters() : array<string|int, mixed>
Return values
array<string|int, mixed>

setParameter()

public setParameter(string $key, mixed $value) : self
Parameters
$key : string
$value : mixed
Return values
self

configure()

protected configure(array<string|int, mixed> $parameters) : void
Parameters
$parameters : array<string|int, mixed>

isValidParameter()

protected isValidParameter(string $parameter) : bool
Parameters
$parameter : string
Return values
bool

validateInput()

protected validateInput(mixed $input, string $expectedType) : void
Parameters
$input : mixed
$expectedType : string

cleanupAlgorithm()

private cleanupAlgorithm() : void

configureAlgorithmParameters()

private configureAlgorithmParameters() : void

estimateOutputSize()

private estimateOutputSize(mixed $input) : int
Parameters
$input : mixed
Return values
int

executeAlgorithm()

private executeAlgorithm(mixed $input) : array<string|int, mixed>
Parameters
$input : mixed
Return values
array<string|int, mixed>

executeGenericAlgorithm()

private executeGenericAlgorithm(FFI $ffi, mixed $input) : array<string|int, mixed>
Parameters
$ffi : FFI
$input : mixed
Return values
array<string|int, mixed>

executeSpecificAlgorithm()

private executeSpecificAlgorithm(FFI $ffi, mixed $input) : array<string|int, mixed>
Parameters
$ffi : FFI
$input : mixed
Return values
array<string|int, mixed>

getAlgorithmCreateFunction()

private getAlgorithmCreateFunction() : string
Return values
string

getValidParameters()

private getValidParameters() : array<string|int, mixed>
Return values
array<string|int, mixed>

initializeAlgorithm()

private initializeAlgorithm() : void

prepareInput()

private prepareInput(mixed $input) : mixed
Parameters
$input : mixed

processOutput()

private processOutput(array<string|int, mixed> $result) : array<string|int, mixed>
Parameters
$result : array<string|int, mixed>
Return values
array<string|int, mixed>

processRhythmOutput()

private processRhythmOutput(array<string|int, mixed> $result) : array<string|int, mixed>
Parameters
$result : array<string|int, mixed>
Return values
array<string|int, mixed>

processSpectralOutput()

private processSpectralOutput(array<string|int, mixed> $result) : array<string|int, mixed>
Parameters
$result : array<string|int, mixed>
Return values
array<string|int, mixed>

processStatsOutput()

private processStatsOutput(array<string|int, mixed> $result) : array<string|int, mixed>
Parameters
$result : array<string|int, mixed>
Return values
array<string|int, mixed>

processTemporalOutput()

private processTemporalOutput(array<string|int, mixed> $result) : array<string|int, mixed>
Parameters
$result : array<string|int, mixed>
Return values
array<string|int, mixed>

processTonalOutput()

private processTonalOutput(array<string|int, mixed> $result) : array<string|int, mixed>
Parameters
$result : array<string|int, mixed>
Return values
array<string|int, mixed>

setAlgorithmParameter()

private setAlgorithmParameter(FFI $ffi, string $key, mixed $value) : void
Parameters
$ffi : FFI
$key : string
$value : mixed

setArrayParameter()

private setArrayParameter(FFI $ffi, string $key, array<string|int, mixed> $value) : void
Parameters
$ffi : FFI
$key : string
$value : array<string|int, mixed>

validateAlgorithmInput()

private validateAlgorithmInput(mixed $input) : void
Parameters
$input : mixed 

        

        
    




    

    

                                

                

                                
    

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