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1 function [M,fCen,Mfull]=mel_matrix(fs,NbCh,Nfft,warp,fhigh,flow)
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2 % [M,fCen,Mfull]=mel_matrix(fs,NbCh,Nfft,warp,fhigh)
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3 % returns Nfft/2+1 - by - NbCh matrix of triangular weights
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4 % NbCh filterbanks linearly spaced on a MEL scale till fhigh
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5 % warp: default 1.0
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6 % fhigh: default=fs/2
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7 % Mfull: matrix without truncation to Nfft/2+1 points
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8
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9 if nargin<4,
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10 warp=1;
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11 end
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12 if nargin<5,
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13 fhigh=fs/2;
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14 end
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15
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16 LowMel=2595 * log10(1+flow/700);
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17 NyqMel=2595 * log10(1+fhigh/700);
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18
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19 StartMel=LowMel + (0:NbCh-1)/(NbCh+1)*(NyqMel-LowMel);
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20 fCen=warp*700*(10.^(StartMel/2595)-1);
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21 StartBin=round(Nfft/fs*fCen)+1;
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22
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23 EndMel=LowMel + (2:NbCh+1)/(NbCh+1)*(NyqMel-LowMel);
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24 EndBin=round(warp*Nfft/fs*700*(10.^(EndMel/2595)-1))+1;
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25
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26 TotLen=EndBin-StartBin+1;
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27
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28 LowLen=[StartBin(2:NbCh) EndBin(NbCh-1)]-StartBin+1;
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29 HiLen=TotLen-LowLen+1;
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30
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31 M=sparse([],[],[],ceil(warp*Nfft/2+1),NbCh,sum(TotLen));
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32 for k=1:NbCh,
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33 M(StartBin(k):StartBin(k)+LowLen(k)-1,k)=(1:LowLen(k))'/LowLen(k);
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34 M(EndBin(k)-HiLen(k)+1:EndBin(k),k)=(HiLen(k):-1:1)'/HiLen(k);
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35 end
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36 %TotWeight=sum(M,1);
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37 Mfull=M;
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38 M=M(1:Nfft/2+1,:);
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39 %WeightSum=full([sum(M,1);TotWeight]); |
