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‎+librosa/istft.m‎

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function varargout = istft(Y,varargin)
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% librosa.istft Inverse Short-time Fourier transform.
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%
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% This function matches the istft function from Librosa (tested for
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% version 0.9.2). Parameter defaults are identical to the Librosa
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% function.
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%
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% X = librosa.istft(Y) returns the inverse short-time Fourier transform
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% (istft) of Y.
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%
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% X = librosa.istft(S, FFTLength=NFFT) specifies the FFT length used to
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% calculate the stft.
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%
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% X = librosa.istft(S, Window=win) specifies the window used to compute
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% the stft.
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%
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% X = librosa.istft(S, HopLength=H) specifies the hop length.
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%
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% X = librosa.istft(S, Center=center) specifies if the signal was
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% centered.
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%
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% S = librosa.istft(X, GenerateMATLABCode=true) generates and opens an
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% untitled file containing code that implements the code of librosa.istft
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% using the MATLAB function istft.
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%
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% % EXAMPLE:
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% % Compute the istft of a real signal using the overlap-add method.
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% fs = 10240;
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% t = 0:1/fs:0.5-1/fs;
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% x = 5*sin(2*pi*t*10);
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% win = hamming(512,'periodic');
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% S = librosa.stft(x,'Window',win,'HopLength',numel(win)-384,...
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% 'FFTLength',1024);
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% X = librosa.istft(S,'Window',win,'HopLength',numel(win)-384,...
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% 'FFTLength',1024);
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%
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% % Plot original and resynthesized signals.
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% plot(1:numel(x),x,1:size(X,1),X,'-.')
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% axis tight
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% xlabel('Time bins')
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% ylabel('Amplitude (V)')
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% title('Original and Reconstructed Signal')
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% legend('Original','Reconstructed')
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% Copyright 2022 The MathWorks, Inc.
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%% Validate input signal
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validateattributes(Y,{'single','double'},...
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{'nonempty','3d'}, ...
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'librosa.istft','Y')
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%% Parse function parameters
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p = inputParser;
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addRequired(p,'Y');
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validFFTLength = @(x) isnumeric(x) && isscalar(x) && (x > 0) && floor(x)==x;
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addParameter(p,'FFTLength',2048,validFFTLength);
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validHopLength = @(x) isnumeric(x) && isscalar(x) && (x > 0) && floor(x)==x;
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addParameter(p,'HopLength',2048,validHopLength);
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validWindowLength = @(x) isnumeric(x) && isscalar(x) && (x > 0) && floor(x)==x;
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addParameter(p,'WindowLength',2048,validWindowLength);
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validWindow = @(x) ischar(x) || isstring(x) || isvector(x) && isreal(x) &&isfloat(x);
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addParameter(p,'Window',hann(2048,'periodic'),validWindow);
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validCenter = @(x)isscalar(x) && (isnumeric(x)||islogical(x));
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addParameter(p,'Center',true,validCenter);
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validLength = @(x) isnumeric(x) && isscalar(x) && (x > 0) && floor(x)==x;
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addParameter(p,'Length',true,validLength);
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validCodegen = @(x)isscalar(x) && (isnumeric(x)||islogical(x));
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addParameter(p,'GenerateMATLABCode',false,validCodegen);
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parse(p,Y,varargin{:});
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FFTLength = p.Results.FFTLength;
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center = p.Results.Center;
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% Reconcile Window and WindowLength specifications, similar to Librosa
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% function
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if ismember('WindowLength',p.UsingDefaults)
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if ismember('Window',p.UsingDefaults)
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winlen = FFTLength;
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else
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win = p.Results.Window;
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if ischar(win) || isstring(win)
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winlen = FFTLength;
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else
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winlen = numel(win);
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end
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end
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else
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winlen = p.Results.WindowLength;
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end
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if ismember('Window',p.UsingDefaults)
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win = hann(winlen,'periodic');
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else
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win = p.Results.Window;
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if ischar(win) || isstring(win)
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win = sprintf('%s(%d)',win,winlen);
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win = eval(win);
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end
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end
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if (numel(win) ~= winlen)
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error('Window size mismatch')
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end
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if ismember('HopLength',p.UsingDefaults)
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hopLength = floor(numel(win)/4);
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else
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hopLength = p.Results.HopLength;
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end
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lengthSpecified = ~ismember('Length',p.UsingDefaults);
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len = p.Results.Length;
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if numel(win)<FFTLength
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L = FFTLength-numel(win);
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L2 = floor(L/2);
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win = win(:);
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win = [zeros(L2,1); win; zeros(FFTLength-L2-numel(win),1)];
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end
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if p.Results.GenerateMATLABCode
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strWriter = StringWriter;
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else
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strWriter = librosa.utils.StringWriter;
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end
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if lengthSpecified
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strWriter.addcr('%s\n%% Adjust length.','%%');
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if center
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padded_length = len + FFTLength;
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strWriter.addcr('padLength = %d+%d;',len,FFTLength);
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else
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padded_length = len;
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strWriter.addcr('padLength = %d;',len);
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end
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n_frames = min(size(Y,2),ceil(padded_length/hopLength));
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Y = Y(:,1:n_frames,:);
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strWriter.addcr('numFrames = min(size(Y,2),ceil(padLength/%d));',hopLength);
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strWriter.addcr('Y = Y(:,1:numFrames,:)');
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end
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y = istft(Y,Window=win,...
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OverlapLength=numel(win)-hopLength,...
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FFTLength=FFTLength,...
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FrequencyRange="onesided");
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strWriter.addcr('%s\n%% Compute ISTFT.','%%');
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strWriter.addcr('y = istft(Y, Window=%s,...',mat2str(win(:),32));
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strWriter.addcr('OverlapLength=%d,...',numel(win)-hopLength);
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strWriter.addcr('FFTLength=%d,...',FFTLength);
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strWriter.addcr('FrequencyRange="onesided");');
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if ~lengthSpecified
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if center
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strWriter.addcr('%s\n%% STFT was centered.','%%');
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L = floor(FFTLength/2);
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y = y(L+1:size(y,1)-L,:);
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strWriter.addcr('L = floor(%d/2);',FFTLength);
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strWriter.addcr('y = y(L+1:size(y,1)-L,:);',FFTLength);
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end
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else
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if center
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strWriter.addcr('%s\n%% STFT was centered.','%%');
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L = floor(FFTLength/2);
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strWriter.addcr('L = floor(%d/2);',FFTLength);
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y = y(L+1:L+len,:);
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strWriter.addcr('y = y(L+1:L+%d,:);',len);
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else
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y = y(1:len,:);
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strWriter.addcr('y = y(1:%d,:);',len);
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end
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end
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varargout{1} = y;
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varargout{2} = strWriter.char;
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generateMATLABCode = p.Results.GenerateMATLABCode;
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if generateMATLABCode
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footer = sprintf('%% _Generated by MATLAB (R) and Audio Toolbox on %s_', string(datetime("now")));
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strWriter.addcr('\n%s\n%s','%%',footer);
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matlab.internal.liveeditor.openAsLiveCode(strWriter.char)
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end

‎+librosa/mel.m‎

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function varargout = mel(varargin)
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% librosa.stft Design Mel filter bank
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%
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% This function matches the mel function from Librosa (tested for
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% version 0.9.2). Parameter defaults are identical to the Librosa
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% function.
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%
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% FB = librosa.mel(SampleRate=fs) returns a frequency-domain
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% Mel filter bank, filterBank. fs is the input sample rate, in Hz.
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%
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% FB = librosa.mel(FFTLength=NFFT) specifies the FFT length.
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%
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% FB = librosa.mel(NumBands=NUMBANDS) specifies the number of bands in
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% the filter bank.
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%
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% FB = librosa.mel(Fmin=FMIN) specifies the lowest frequency (in Hz).
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%
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% FB = librosa.mel(Fmax=FMAX) specifies the highest frequency (in Hz).
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%
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% FB = librosa.mel(Normalization=NORM) specifies the type of filter bank
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% normalization.
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%
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% FB = librosa.mel(HTK=FLAG) specifies what type of Mel scaling is used.
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% If FLAG is true, HTK scaling is used. If FLAG is false, Slaney scaling
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% is used. This function only supports HTK scaling, which is the
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% non-default of the Librosa function. Set HTK=true in the function call.
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%
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% FB = librosa.mel(GenerateMATLABCode=true) generates and opens an
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% untitled file containing code that implements the code of librosa.mel
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% using the MATLAB function designAuditoryFilterBank.
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%
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% % Example:
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% % Design an auditory filter bank and use it to compute a mel
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% % spectrogram.
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%
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% [audioIn,fs] = audioread("Counting-16-44p1-mono-15secs.wav");
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%
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% % Compute spectrogram
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% win = hann(1024,"periodic");
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% [~,F,T,S] = spectrogram(audioIn,win,512,1024,fs,"onesided");
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%
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% % Design auditory filter bank
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% filterBank = librosa.mel(SampleRate=fs,FFTLength=1024, ...
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% NumBands=16,Normalization="None", HTK=true);
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%
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% % Visualize filter bank
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% plot(F,filterBank.')
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% grid on
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% title("Mel Filter Bank")
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% xlabel("Frequency (Hz)")
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%
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% % Compute mel spectrogram
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% SMel = filterBank*S;
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% Copyright 2022 The MathWorks, Inc.
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%% Parse function parameters
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p = inputParser;
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validFFTLength = @(x) isnumeric(x) && isscalar(x) && (x > 0) && floor(x)==x;
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addParameter(p,'FFTLength',2048,validFFTLength);
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validSampleRate = @(x) isnumeric(x) && isscalar(x) && (x>0);
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addParameter(p,'SampleRate',22050,validSampleRate);
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validNumBands = @(x) isnumeric(x) && isscalar(x) && (x > 0) && floor(x)==x;
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addParameter(p,'NumBands',128,validNumBands);
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validFmin = @(x) isnumeric(x) && isscalar(x) && (x>0);
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addParameter(p,'Fmin',0,validFmin);
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validFmax = @(x) isnumeric(x) && isscalar(x) && (x>0);
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addParameter(p,'Fmax',8000,validFmax);
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validHTK = @(x)isscalar(x) && (isnumeric(x)||islogical(x));
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addParameter(p,'HTK',false,validHTK);
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validNorm = @(x) (isnumeric(x) && isscalar(x)) || (ismember(char(x),{'Slaney','None'}));
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addParameter(p,'Normalization','Slaney',validNorm);
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validCodegen = @(x)isscalar(x) && (isnumeric(x)||islogical(x));
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addParameter(p,'GenerateMATLABCode',false,validCodegen);
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parse(p,varargin{:});
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if ismember('Fmax',p.UsingDefaults)
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fmax = p.Results.SampleRate/2;
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else
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fmax = min(p.Results.SampleRate/2,p.Results.Fmax);
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end
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if ~p.Results.HTK
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error('Slaney scaling is not supported. Set HTK to true.');
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end
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norm = p.Results.Normalization;
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customNorm = false;
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switch norm
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case 'None'
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norm = 'none';
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case 'Slaney'
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norm = 'bandwidth';
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otherwise
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norm = 'none';
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customNorm = true;
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end
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if p.Results.GenerateMATLABCode
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strWriter = StringWriter;
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else
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strWriter = librosa.utils.StringWriter;
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end
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strWriter.addcr('%s\n%% Construct filter bank.','%%');
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filterBank = designAuditoryFilterBank(p.Results.SampleRate,...
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"FrequencyScale","mel",...
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"FFTLength",p.Results.FFTLength,...
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"NumBands",p.Results.NumBands,...
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"FrequencyRange",[p.Results.Fmin fmax],...
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"Normalization",norm,...
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"OneSided",true,...
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"FilterBankDesignDomain","linear");
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strWriter.addcr('filterBank = designAuditoryFilterBank(%f,...',p.Results.SampleRate);
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strWriter.addcr('FrequencyScale="mel",...');
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strWriter.addcr('FFTLength=%d,...',p.Results.FFTLength);
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strWriter.addcr('NumBands=%d,...',p.Results.NumBands);
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strWriter.addcr('FrequencyRange=[%f %f],...',p.Results.Fmin,fmax);
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strWriter.addcr('Normalization=''%s'',...',norm);
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strWriter.addcr('OneSided=true,...');
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strWriter.addcr('FilterBankDesignDomain="linear");');
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if customNorm
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n = p.Results.Normalization;
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strWriter.addcr('%s\n%% Normalize filter bank.','%%');
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if ~isequal(n,-Inf)
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val = vecnorm(filterBank,n,2);
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strWriter.addcr('n = vecnorm(filterBank,%f,2);',p.Results.Normalization);
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filterBank = filterBank./val;
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strWriter.addcr('filterBank = filterBank./n;');
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end
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end
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varargout{1} = filterBank;
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varargout{2} = strWriter.char;
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if p.Results.GenerateMATLABCode
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footer = sprintf('%% _Generated by MATLAB (R) and Audio Toolbox on %s_', string(datetime("now")));
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strWriter.addcr('\n%s\n%s','%%',footer);
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matlab.internal.liveeditor.openAsLiveCode(strWriter.char)
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end
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end

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