120 lines
2.8 KiB
Matlab
120 lines
2.8 KiB
Matlab
function logmmse(filename,outfile)
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%
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% Implements the logMMSE algorithm [1].
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%
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% Usage: logmmse(noisyFile, outputFile)
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%
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% infile - noisy speech file in .wav format
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% outputFile - enhanced output file in .wav format
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%
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%
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% Example call: logmmse('sp04_babble_sn10.wav','out_log.wav');
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%
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% References:
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% [1] Ephraim, Y. and Malah, D. (1985). Speech enhancement using a minimum
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% mean-square error log-spectral amplitude estimator. IEEE Trans. Acoust.,
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% Speech, Signal Process., ASSP-23(2), 443-445.
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%
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% Authors: Philipos C. Loizou
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%
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% Copyright (c) 2006 by Philipos C. Loizou
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% $Revision: 0.0 $ $Date: 10/09/2006 $
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%-------------------------------------------------------------------------
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if nargin<2
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fprintf('Usage: logmmse(noisyfile.wav,outFile.wav) \n\n');
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return;
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end
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[x, Srate, bits]= wavread( filename); %nsdata is a column vector
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% =============== Initialize variables ===============
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len=floor(20*Srate/1000); % Frame size in samples
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if rem(len,2)==1, len=len+1; end;
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PERC=50; % window overlap in percent of frame size
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len1=floor(len*PERC/100);
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len2=len-len1;
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win=hamming(len); % define window
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% Noise magnitude calculations - assuming that the first 6 frames is
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% noise/silence
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nFFT=2*len;
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noise_mean=zeros(nFFT,1);
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j=1;
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for m=1:6
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noise_mean=noise_mean+abs(fft(win.*x(j:j+len-1),nFFT));
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j=j+len;
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end
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noise_mu=noise_mean/6;
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noise_mu2=noise_mu.^2;
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%--- allocate memory and initialize various variables
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x_old=zeros(len1,1);
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Nframes=floor(length(x)/len2)-floor(len/len2);
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xfinal=zeros(Nframes*len2,1);
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%=============================== Start Processing =======================================================
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%
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k=1;
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aa=0.98;
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mu=0.98;
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eta=0.15;
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ksi_min=10^(-25/10);
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for n=1:Nframes
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insign=win.*x(k:k+len-1);
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spec=fft(insign,nFFT);
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sig=abs(spec); % compute the magnitude
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sig2=sig.^2;
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gammak=min(sig2./noise_mu2,40); % limit post SNR to avoid overflows
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if n==1
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ksi=aa+(1-aa)*max(gammak-1,0);
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else
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ksi=aa*Xk_prev./noise_mu2 + (1-aa)*max(gammak-1,0); % a priori SNR
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ksi=max(ksi_min,ksi); % limit ksi to -25 dB
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end
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log_sigma_k= gammak.* ksi./ (1+ ksi)- log(1+ ksi);
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vad_decision= sum(log_sigma_k)/ len;
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if (vad_decision< eta)
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% noise only frame found
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noise_mu2= mu* noise_mu2+ (1- mu)* sig2;
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end
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% ===end of vad===
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A=ksi./(1+ksi); % Log-MMSE estimator
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vk=A.*gammak;
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ei_vk=0.5*expint(vk);
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hw=A.*exp(ei_vk);
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sig=sig.*hw;
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Xk_prev=sig.^2;
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xi_w= ifft( hw .* spec,nFFT);
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xi_w= real( xi_w);
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xfinal(k:k+ len2-1)= x_old+ xi_w(1:len1);
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x_old= xi_w(len1+ 1: len);
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k=k+len2;
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end
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wavwrite(xfinal,Srate,16,outfile);
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