comparison functions/fe_funcs/mel_matrix.m @ 0:2fadb31a9d55 tip

Import code by Vuegen et al

+function [M,fCen,Mfull]=mel_matrix(fs,NbCh,Nfft,warp,fhigh,flow)
+% [M,fCen,Mfull]=mel_matrix(fs,NbCh,Nfft,warp,fhigh)
+% returns Nfft/2+1 - by - NbCh matrix of triangular weights
+% NbCh filterbanks linearly spaced on a MEL scale till fhigh
+% warp: default 1.0
+% fhigh: default=fs/2
+% Mfull: matrix without truncation to Nfft/2+1 points
+
+if nargin<4,
+    warp=1;
+end
+if nargin<5,
+    fhigh=fs/2;
+end
+
+LowMel=2595 * log10(1+flow/700);
+NyqMel=2595 * log10(1+fhigh/700);
+
+StartMel=LowMel + (0:NbCh-1)/(NbCh+1)*(NyqMel-LowMel);
+fCen=warp*700*(10.^(StartMel/2595)-1);
+StartBin=round(Nfft/fs*fCen)+1;
+
+EndMel=LowMel + (2:NbCh+1)/(NbCh+1)*(NyqMel-LowMel);
+EndBin=round(warp*Nfft/fs*700*(10.^(EndMel/2595)-1))+1;
+
+TotLen=EndBin-StartBin+1;
+
+LowLen=[StartBin(2:NbCh) EndBin(NbCh-1)]-StartBin+1;
+HiLen=TotLen-LowLen+1;
+
+M=sparse([],[],[],ceil(warp*Nfft/2+1),NbCh,sum(TotLen));
+for k=1:NbCh,
+    M(StartBin(k):StartBin(k)+LowLen(k)-1,k)=(1:LowLen(k))'/LowLen(k);
+    M(EndBin(k)-HiLen(k)+1:EndBin(k),k)=(HiLen(k):-1:1)'/HiLen(k);
+end
+%TotWeight=sum(M,1);
+Mfull=M;
+M=M(1:Nfft/2+1,:);
+%WeightSum=full([sum(M,1);TotWeight]);