matthiasm@0: function [f_audio_out,timepositions_afterDegr] = degradationUnit_applyClippingAlternative(f_audio, samplingFreq, timepositions_beforeDegr, parameter)
matthiasm@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matthiasm@0: % Name: degradation_applyClippingAlternative
matthiasm@0: % Date: 2013-04
matthiasm@0: % Programmer: Sebastian Ewert
matthiasm@0: %
matthiasm@0: % Description:
matthiasm@0: % - applies clipping by over-normalising
matthiasm@0: %
matthiasm@0: % Input:
matthiasm@0: %   f_audio      - audio signal \in [-1,1]^{NxC} with C being the number of
matthiasm@0: %                  channels
matthiasm@0: %   timepositions_beforeDegr - some degradations delay the input signal. If
matthiasm@0: %                             some points in time are given via this
matthiasm@0: %                             parameter, timepositions_afterDegr will
matthiasm@0: %                             return the corresponding positions in the
matthiasm@0: %                             output. Set to [] if unavailable. Set f_audio
matthiasm@0: %                             and samplingFreq to [] to compute only
matthiasm@0: %                             timepositions_afterDegr.
matthiasm@0: %
matthiasm@0: % Input (optional): parameter
matthiasm@0: %   .clipAPercentageOfSamples = 1    - if set to zero a fixed number of
matthiasm@0: %                                      samples will be clipped
matthiasm@0: %   .parameter.percentOfSamples = 1  - used only if clipAPercentageOfSamples
matthiasm@0: %                                      is 1
matthiasm@0: %   .parameter.numSamplesClipped = 1 - used only if clipAPercentageOfSamples
matthiasm@0: %                                      is 0
matthiasm@0: %   timepositions_beforeDegr - some degradations delay the input signal. If
matthiasm@0: %                              some points in time are given via this
matthiasm@0: %                              parameter, timepositions_afterDegr will
matthiasm@0: %                              return the corresponding positions in the
matthiasm@0: %                              output
matthiasm@0: %
matthiasm@0: % Output:
matthiasm@0: %   f_audio_out  - audio output signal
matthiasm@0: %
matthiasm@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matthiasm@0: 
matthiasm@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matthiasm@0: % Audio Degradation Toolbox
matthiasm@0: %
matthiasm@0: % Centre for Digital Music, Queen Mary University of London.
matthiasm@0: % This file copyright 2013 Sebastian Ewert, Matthias Mauch and QMUL.
matthiasm@0: %    
matthiasm@0: % This program is free software; you can redistribute it and/or
matthiasm@0: % modify it under the terms of the GNU General Public License as
matthiasm@0: % published by the Free Software Foundation; either version 2 of the
matthiasm@0: % License, or (at your option) any later version.  See the file
matthiasm@0: % COPYING included with this distribution for more information.
matthiasm@0: %
matthiasm@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matthiasm@0: 
matthiasm@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matthiasm@0: % Check parameters
matthiasm@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matthiasm@0: if nargin<4
matthiasm@0:     parameter=[];
matthiasm@0: end
matthiasm@0: if nargin<3
matthiasm@0:     timepositions_beforeDegr=[];
matthiasm@0: end
matthiasm@0: if nargin<2
matthiasm@0:     error('Please specify input data');
matthiasm@0: end
matthiasm@0: 
matthiasm@0: if isfield(parameter,'clipAPercentageOfSamples')==0
matthiasm@0:     parameter.clipAPercentageOfSamples = 1;
matthiasm@0: end
matthiasm@0: if isfield(parameter,'percentOfSamples')==0
matthiasm@0:     parameter.percentOfSamples = 1;
matthiasm@0: end
matthiasm@0: if isfield(parameter,'numSamplesClipped')==0
matthiasm@0:     parameter.numSamplesClipped = 10000;
matthiasm@0: end
matthiasm@0: 
matthiasm@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matthiasm@0: % Main program
matthiasm@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matthiasm@0: 
matthiasm@0: f_audio_out = [];
matthiasm@0: if ~isempty(f_audio)
matthiasm@0:     sortedValues = sort(abs(f_audio(:)));
matthiasm@0:     numSamples = length(sortedValues);
matthiasm@0:     if parameter.clipAPercentageOfSamples
matthiasm@0:         idxStartSample = round( (1-parameter.percentOfSamples/100) * numSamples);
matthiasm@0:         divisor = min(sortedValues(idxStartSample:numSamples));
matthiasm@0:     else
matthiasm@0:         if parameter.numSamplesClipped > numSamples
matthiasm@0:             numSamplesClipped = numSamples;
matthiasm@0:         else
matthiasm@0:             numSamplesClipped = parameter.numSamplesClipped;
matthiasm@0:         end
matthiasm@0:         divisor = min(sortedValues(numSamples-numSamplesClipped+1:numSamples));
matthiasm@0:     end
matthiasm@0:     clear sortedValues
matthiasm@0:     
matthiasm@0:     divisor = max(divisor,eps);
matthiasm@0:     f_audio_out = f_audio / divisor;
matthiasm@0:     
matthiasm@0:     f_audio_out(f_audio_out < -1) = -1;
matthiasm@0:     f_audio_out(f_audio_out > 1) = 1;
matthiasm@0:     f_audio_out = f_audio_out * 0.999;
matthiasm@0:     
matthiasm@0: end
matthiasm@0: 
matthiasm@0: % This degradation does not impose a delay
matthiasm@0: timepositions_afterDegr = timepositions_beforeDegr;
matthiasm@0: 
matthiasm@0: end