b@4: function prepare2listen(foldername)
b@4: % PREPARE2LISTEN batch processes all audio files in a folder to prepare for
b@4: % a listening test, by 
b@4: % - making sure everything is at the same sampling rate and bit depth;
b@4: % - removing subsequent zeros at the start and the end;
b@4: % - ensuring none of the files are equal to each other; 
b@4: % - clipping the desired region from the file; 
b@4: % - adding a fade in and fade out; and
b@4: % - setting the loudness at a predefined value. 
b@4: % It then saves the result in a folder within the audio folder. 
b@0: %
b@0: % by Brecht De Man at Centre for Digital Music, 5 June 2013
b@0: 
b@4:     % PARAMETERS
b@4:     newfolder   = 'fragments';
b@4:     fs          = 96000;    % Hz
b@4:     bitdepth    = 24; 
b@8:     starttime   = 76;  % SR1 88; SR2 76      % seconds
b@8:     endtime     = 152; % SR1 142;  SR2 152    % seconds
b@4:     fadetime    = 1;        % seconds
b@6:     format      = 'wav';
b@4:     slash       = '/';
b@4:     
b@6:     target_loudness = -23;  % dBLU (https://tech.ebu.ch/loudness)
b@5:     
b@6:     tic;                                    % measure time
b@6:     list = dir([foldername '/*.' format]);  % get files
b@4:     
b@4:     % remove hidden files from list, and copy to new folder
b@4:     % see http://www.mathworks.co.uk/matlabcentral/newsreader/view_thread/258220
b@6:     newfoldername = [foldername slash newfolder]; % within original folder
b@6:     if ~exist(newfoldername, 'dir')   % if it doesn't exist yet
b@6:         mkdir(foldername, newfolder); % make newfolder within folder
b@6:     end
b@4:     for k = length(list):-1:1
b@4:         fname = list(k).name;
b@4:         if fname(1) == '.'
b@4:             list(k) = [];
b@4:         else
b@4:             copyfile([foldername slash list(k).name], ...
b@4:                 [newfoldername slash list(k).name]);
b@4:         end
b@4:     end
b@4:     
b@4:     % set at same sampling rate and bit depth
b@12:     %disp(['-- Ensuring audio is at ' num2str(fs) 'Hz / ' ...
b@6:         num2str(bitdepth) ' bit...']);
b@12:     %batchresample(newfoldername, fs, bitdepth); 
b@6:     % NOTE: clipfade(...) also tests sampling rate, but does not resample
b@6:     
b@6:     % find doubles
b@6:     disp('-- Checking for doubles...');
b@6:     finddouble(newfoldername);
b@4:     
b@4:     % strip zeros off beginning and end
b@6:     disp('-- Stripping off leading and trailing zeros...');
b@4:     stripzeros(newfoldername); 
b@4:     
b@6:     % align all audio files
b@6:     disp('-- Aligning audio files...');
b@6:     autoalign(newfoldername); 
b@4:     
b@4:     % clip and fade desired fragments
b@6:     startmin = floor(starttime/60);
b@6:     startsec = mod(starttime, 60);
b@6:     endmin   = floor(endtime/60);
b@6:     endsec   = mod(endtime, 60);
b@6:     disp(['-- Fading in (' num2str(fadetime) 's) at ' num2str(startmin) ...
b@6:         ':' num2str(startsec) ', fading out (' num2str(fadetime) 's) at '...
b@6:         num2str(endmin) ':' num2str(endsec) '...']);
b@5:     clipfade(newfoldername, starttime, endtime, fadetime, fs, bitdepth); 
b@0: 
b@5:     % open files and calculate their loudness, then adjust
b@6:     disp(['-- Setting each file at ' num2str(target_loudness) 'dBLU ...']);
b@4:     for i = 1:length(list)
b@5:         disp([newfoldername slash list(i).name]); % DEBUG
b@6:         audio = audioread([newfoldername slash list(i).name]);
b@5:         initial_loudness   = getloudness( audio, fs, 'ITU', 0); 
b@5:         
b@5:         % calculate difference in loudness
b@5:         difference_loudness = target_loudness - initial_loudness; 
b@5:         
b@5:         % write back with adjusted loudness
b@6:         newaudio = 10^(difference_loudness/20) .* audio;
b@5:         audiowrite([newfoldername slash list(i).name],...
b@6:             newaudio, fs, 'BitsPerSample', bitdepth);
b@4:     end
b@6:     
b@6:     elapsed_time = toc;
b@6:     disp(['prepare2listen took ' num2str(elapsed_time) ...
b@6:         ' seconds on folder ' foldername]); 
b@0: end