FILTERBANKREASSIGN - Reassign filterbank spectrogram

Usage

sr = filterbankreassign(s,tgrad,fgrad,a,cfreq);
sr = filterbankreassign(s,tgrad,fgrad,a,g);
[sr,repos,Lc] = filterbankreassign(...);

Input parameters

Output parameters

Description

filterbankreassign(s,tgrad,fgrad,a,cfreq) will reassign the values of the filterbank spectrogram s using the group delay fgrad and instantaneous frequency tgrad. The time-frequency sampling pattern is determined from the time steps a and the center frequencies cfreq.

filterbankreassign(s,tgrad,fgrad,a,g) will do the same thing except the center frequencies are estimated from a set of filters g.

[sr,repos,Lc]=filterbankreassign(...) does the same thing, but in addition returns a vector of subband lengths Lc (Lc = cellfun(@numel,s)) and cell array repos with sum(Lc) elements. Each element corresponds to a single coefficient obtained by cell2mat(sr) and it is a vector of indices identifying coefficients from cell2mat(s) assigned to the particular time-frequency position.

The arguments s, tgrad and fgrad must be cell-arrays of vectors of the same lengths. Arguments a and cfreq or g must have the same number of elements as the cell arrays with coefficients.

Examples:

This example shows how to reassign a ERB filterbank spectrogram:

% Genrate 3 chirps 1 second long
L = 44100; fs = 44100; l = 0:L-1;

f = sin(2*pi*(l/35+(l/300).^2)) + ...
    sin(2*pi*(l/10+(l/300).^2)) + ...
    sin(2*pi*(l/5-(l/450).^2));
f = 0.7*f';

% Create ERB filterbank
[g,a,fc]=erbfilters(fs,L,'fractional','spacing',1/12,'warped');

% Compute phase gradient
[tgrad,fgrad,cs,c]=filterbankphasegrad(f,g,a);
% Do the reassignment
sr=filterbankreassign(cs,tgrad,fgrad,a,cent_freqs(fs,fc));
figure(1); subplot(211);
plotfilterbank(cs,a,fc,fs,60);
title('ERBlet spectrogram of 3 chirps');
subplot(212);
plotfilterbank(sr,a,fc,fs,60);
title('Reassigned ERBlet spectrogram of 3 chirps');