Question

I am trying to write a program where i have to read a wav file, extract some features from it and save them and then go and pick the next file repeat the same procedure. the number of wave files to be picked are more than 100. Can someone help me how to read wavfiles one after another. (say the files are named e1.wav,e2.wav and so on). someone please help me

Answer 1

The dir command is quite helpful here. It either displays the whole content of a directory but you can also specify a glob to just return a sub-set of files, e.g. dir('*.wav'). This returns an struct-array containing file information such as name, date, bytes, isdir and so on.

To get started, try the following:

filelist = dir('*.wav');
for file = filelist
    fprintf('Processing %s\n', file.name);
    fid = fopen(file.name);
    % Do something here with your file.
    fclose(fid);
end

Edit 1: Change the double-quotes to single-quotes (thx to user1540393).

Edit 2 (Suggested by amro): If a processing result has to be stored per file,
I often use the following pattern. I usually pre-allocate an array, a struct array or
a cell array of the same size as the filelist. Then I use an integer index to iterate
over the file list, which I can also use to write the output. If the information to be
stored is homogeneous (e.g. one scalar per file), use an array or a struct array.
However, if the information differs from file to file (e.g. vectors or matrices of different size) use a cell array instead.

An example using an ordinary array:

filelist = dir('*.wav');
% Pre-allocate an array to store some per-file information.
result = zeros(size(filelist));
for index = 1 : length(filelist)
    fprintf('Processing %s\n', filelist(index).name);
    % Read the sample rate Fs and store it.
    [y, Fs] = wavread(filelist(index).name);
    result(index) = Fs;
end
% result(1) .. result(N) contain the sample rates of each file.

An example using a cell array:

filelist = dir('*.wav');
% Pre-allocate a cell array to store some per-file information.
result = cell(size(filelist));
for index = 1 : length(filelist)
    fprintf('Processing %s\n', filelist(index).name);
    % Read the data of the WAV file and store it.
    y = wavread(filelist(index).name);
    result{index} = y;
end
% result{1} .. result{N} contain the data of the WAV files.