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MelBands extends BaseAlgorithm
in package

MelBands

Inputs:

[vector_real] spectrum - the audio spectrum

Outputs:

[vector_real] bands - the energy in mel bands

Parameters:

highFrequencyBound: real ∈ [0,inf) (default = 22050) an upper-bound limit for the frequencies to be included in the bands

inputSize: integer ∈ (1,inf) (default = 1025) the size of the spectrum

log: bool ∈ {true,false} (default = false) compute log-energies (log2 (1 + energy))

lowFrequencyBound: real ∈ [0,inf) (default = 0) a lower-bound limit for the frequencies to be included in the bands

normalize: string ∈ {unit_sum,unit_tri,unit_max} (default = "unit_sum") spectrum bin weights to use for each mel band: 'unit_max' to make each mel band vertex equal to 1, 'unit_sum' to make each mel band area equal to 1 summing the actual weights of spectrum bins, 'unit_area' to make each triangle mel band area equal to 1 normalizing the weights of each triangle by its bandwidth

numberBands: integer ∈ (1,inf) (default = 24) the number of output bands

sampleRate: real ∈ (0,inf) (default = 44100) the sample rate

type: string ∈ {magnitude,power} (default = "power") 'power' to output squared units, 'magnitude' to keep it as the input

warpingFormula: string ∈ {slaneyMel,htkMel} (default = "htkMel") The scale implementation type: 'htkMel' scale from the HTK toolkit [2, 3] (default) or 'slaneyMel' scale from the Auditory toolbox [4]

weighting: string ∈ {warping,linear} (default = "warping") type of weighting function for determining triangle area

Description:

This algorithm computes energy in mel bands of a spectrum. It applies a frequency-domain filterbank (MFCC FB-40, [1]), which consists of equal area triangular filters spaced according to the mel scale. The filterbank is normalized in such a way that the sum of coefficients for every filter equals one. It is recommended that the input "spectrum" be calculated by the Spectrum algorithm.

It is required that parameter "highMelFrequencyBound" not be larger than the Nyquist frequency, but must be larger than the parameter, "lowMelFrequencyBound". Also, The input spectrum must contain at least two elements. If any of these requirements are violated, an exception is thrown.

Note: an exception will be thrown in the case when the number of spectrum bins (FFT size) is insufficient to compute the specified number of mel bands: in such cases the start and end bin of a band can be the same bin or adjacent bins, which will result in zero energy when summing bins for that band. Use zero padding to increase the number of spectrum bins in these cases.

References: [1] T. Ganchev, N. Fakotakis, and G. Kokkinakis, "Comparative evaluation of various MFCC implementations on the speaker verification task," in International Conference on Speach and Computer (SPECOM’05), 2005, vol. 1, pp. 191–194.

[2] Mel-frequency cepstrum - Wikipedia, the free encyclopedia, http://en.wikipedia.org/wiki/Mel_frequency_cepstral_coefficient

[3] Young, S. J., Evermann, G., Gales, M. J. F., Hain, T., Kershaw, D., Liu, X., … Woodland, P. C. (2009). The HTK Book (for HTK Version 3.4). Construction, (July 2000), 384, https://doi.org/http://htk.eng.cam.ac.uk

[4] Slaney, M. Auditory Toolbox: A MATLAB Toolbox for Auditory Modeling Work. Technical Report, version 2, Interval Research Corporation, 1998.

Category: Spectral 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 = 'MelBands'

$category

protected string $category = 'Spectral'

$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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