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mfcc​

mfcc(
    @dcttype 2
    @highfrequencybound 11000
    @inputsize 1025
    @liftering 0
    @logtype 'dbamp'
    @lowfrequencybound 0
    @normalize 'unit_sum'
    @numberbands 40
    @numbercoefficients 13
    @samplerate 44100
    @silencethreshold 0.0000
    @type 'power'
    @warpingformula 'htkmel'
    @weighting 'warping'
    @mode 0
) -> llll

Generates audio descriptor to compute the mel-frequency cepstrum coefficients of a buffer's spectrum. As there is no standard implementation, the MFCC-FB40 is used by default. See analyze.

The resulting buffer will be updated with the following keys:

  • mfcc_bands
  • mfcc
info

mfcc is a mirror implementation of the same algorithm in the Essentia library. For more details on the algorithm, please check the Essentia Algorithms reference.

Arguments​

  • @dcttype [int]: DCT type. (default: 2).
  • @highfrequencybound [int/float]: upper bound of the frequency range, in Hz. (default: 11000).
  • @inputsize [int]: size of input spectrum. (default: 1025).
  • @liftering [int]: liftering coefficient. Use 0 to bypass it. (default: 0).
  • @logtype [symbol]: logarithmic compression type. (default: 'dbamp').
    • 'natural'
    • 'dbpow'
    • 'dbamp'
    • 'log'
  • @lowfrequencybound [float]: lower bound of the frequency range, in Hz. (default: 0).
  • @normalize [symbol]: spectrum bin weights to use for each mel band. (default: 'unit_sum').
    • 'unit_sum'
    • 'unit_tri'
    • 'unit_max'
  • @numberbands [int]: number of mel-bands in the filter. (default: 40).
  • @numbercoefficients [int]: number of output mel coefficients. (default: 13).
  • @samplerate [int]: sampling rate of the audio signal, in Hz. (default: 44100).
  • @silencethreshold [int/float]: silence threshold for computing log-energy bands. (default: 0.0000).
  • @type [symbol]: use magnitude or power spectrum. (default: 'power').
    • 'magnitude'
    • 'power'
  • @warpingformula [symbol]: scale implementation type. (default: 'htkmel').
    • 'slaneymel'
    • 'htkmel'
  • @weighting [symbol]: type of weighting function for determining triangle area. (default: 'warping').
    • 'warping'
    • 'linear'
  • @mode [int]: analysis mode. (default: 0).
    • 0: global
    • 1: time series
    • 2: time-tagged time series
    • 3: buffer

Output​

mfcc descriptor [llll]

Usage​

mfcc is meant to be used with the analyze function:

$buffer = importaudio('singing.wav'); ## input buffer
$descr = mfcc(); ## generate mfcc audio descriptor
$buffer.inspect('before analysis');
$buffer = $buffer.analyze($descr); ## apply analysis
$buffer.inspect('after analysis')