SebastianEwert@28: function computeMeanSpectralEnvelope(audiofile, fftLength)
SebastianEwert@28: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
SebastianEwert@28: % Audio Degradation Toolbox
SebastianEwert@28: %
SebastianEwert@28: % Centre for Digital Music, Queen Mary University of London.
SebastianEwert@28: % This file copyright 2013 Sebastian Ewert, Matthias Mauch and QMUL.
SebastianEwert@28: %    
SebastianEwert@28: % This program is free software; you can redistribute it and/or
SebastianEwert@28: % modify it under the terms of the GNU General Public License as
SebastianEwert@28: % published by the Free Software Foundation; either version 2 of the
SebastianEwert@28: % License, or (at your option) any later version.  See the file
SebastianEwert@28: % COPYING included with this distribution for more information.
SebastianEwert@28: %
SebastianEwert@28: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
SebastianEwert@28: 
SebastianEwert@28: [f_audio,samplingFreq]=wavread(audiofile);
SebastianEwert@28: 
SebastianEwert@28: % compute mean spectral vector for f_audio
SebastianEwert@28: [destMagFreqResp, destMagFreqResp_freqs] = internal_computeMeanSpectralVector(f_audio,samplingFreq,fftLength);
SebastianEwert@28: destMagFreqResp = internal_standardizeMagFreqResp(destMagFreqResp);
SebastianEwert@28: 
SebastianEwert@28: outputFilename = [audiofile(1:end-4),'_specEnv'];
SebastianEwert@28: save(outputFilename,'destMagFreqResp','destMagFreqResp_freqs')
SebastianEwert@28: 
SebastianEwert@28: end
SebastianEwert@28: 
SebastianEwert@28: 
SebastianEwert@28: function [f_meanmagspec_db,freqs] = internal_computeMeanSpectralVector(f_audio,fs,fftLength)
SebastianEwert@28: 
SebastianEwert@28: f_audio = mean(f_audio,2);
SebastianEwert@28: 
SebastianEwert@28: [f_spec,freqs,time] = spectrogram(f_audio,hanning(fftLength),fftLength/2,fftLength,fs);
SebastianEwert@28: 
SebastianEwert@28: f_magspec_db = 20 * log10(abs(f_spec));
SebastianEwert@28: 
SebastianEwert@28: f_magspec_db(:,isinf(sum(abs(f_magspec_db),1))) = []; % ignore rows with -inf/inf entries
SebastianEwert@28: 
SebastianEwert@28: f_meanmagspec_db = mean(f_magspec_db,2);
SebastianEwert@28: 
SebastianEwert@28: end
SebastianEwert@28: 
SebastianEwert@28: function magFreqResp = internal_standardizeMagFreqResp(magFreqResp)
SebastianEwert@28: 
SebastianEwert@28: maxRobust = max(magFreqResp(~isinf(magFreqResp)));
SebastianEwert@28: 
SebastianEwert@28: magFreqResp = magFreqResp - maxRobust;
SebastianEwert@28: 
SebastianEwert@28: magFreqResp(magFreqResp > 0) = 0;  % remaining positive inf
SebastianEwert@28: magFreqResp(magFreqResp < -80) = -80;  % remaining positive inf
SebastianEwert@28: 
SebastianEwert@28: end
SebastianEwert@28: