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I am working on a small neural network project and I am very new to Matlab.

I have about 400 short wav files, which have to be read, and then combined into a matrix data set. I was not able to find any information on how to be able to load all the wav files into Matlab so that it stores each file with a different name.

My questions are:

  • Is it possible to batch process the wav files in Matlab to have each vector stored as a separate data?
  • What would be the procedure of populating the matrix with the processed wav file vectors, given that they are of different dimensions (lengths)?
marsei
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nanachan
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1 Answers1

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This solution makes use of cell arrays, {...}, that can handle data of different dimensions, sizes and even types. Here, Y will store the .wav sampled data and FS the sampled rate of all the audio files in a directory.

% create some data (write waves)
load handel.mat;                  %predifined sound in matlab stored in .mat
audiowrite('handel1.wav',y,Fs);   %write the first wave file
audiowrite('handel2.wav',y,Fs);   %write the second
clear y Fs                        %clear the data


% reading section
filedir = dir('*.wav');           %list the current folder content for .wav file
Y = cell(1,length(filedir));      %pre-allocate Y in memory (edit from @ Werner)
FS = Y;                           %pre-allocate FS in memory (edit from @ Werner)
for ii = 1:length(filedir)        %loop through the file names

    %read the .wav file and store them in cell arrays
    [Y{ii,1}, FS{ii,1}] = audioread(filedir(ii).name);  

end

You can access the data with

for ind_wav = 1:length(Y)
    wav_data = Y{ind_wav,1};
end
marsei
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    Also indicate him to preallocate the cell array: `Y = cell(1,length(filedir)); FS = Y;` – Werner Sep 12 '13 at 20:35
  • thanks a lot! Now I have wav_data file which has all the signal values, however i am not sure about the next step : I need to create a matrix which is 400 rows(the number of audio files) by the vector size of the longest audio file. Finding the size of the longest audio file is not an issue, but in the wav_data we have 1 big vector, which i need to somehow re-wrap into the matrix mentioned above. – nanachan Sep 12 '13 at 20:57
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    please see http://stackoverflow.com/questions/6210495/how-to-combine-vectors-of-different-length-in-a-cell-array-into-matrix-in-matlab – marsei Sep 12 '13 at 21:39
  • @Magla - thank you so much for the link! Now i have achieved what i needed for this part! – nanachan Sep 12 '13 at 22:46