How to check Number of channels of a sound file and convert stereo file in mono in MATLAB

I want to check whether the .wav file is stereo or mono.If it is stereo, convert in mono using MATLAB.How to proceed

Answer 1

[Geoff Hayes]

Hemangi - try using audioread as

 myWavFile = 'some.wav';
 [y,Fs] = audioread(myWavFile);

From audioread y output argument, y will be an m-by-n matrix, where m is the number of audio samples read and n is the number of audio channels in the file. So if n is greater than one, then you have multiple channels.

Answer 2

[Jan]

And a conversion to mono:

yMono = sum(y, 2) / size(y, 2);

Answer 3

[JoshuaT]

A couple of points:

1) Taking the average of the channels is not usually recommended for mixing down to stereo. Instead, it is common to sum the two channels but normalize them according to the absolute value of the maximum peak in either channel (https://en.wikipedia.org/wiki/Audio_normalization).

2) Hemanji appears to be asking to conditionally mix the stereo down. That is, the sound file may already be mono in which case we would get an error if we try to mix it down.

An example script that accomplishes all of this might look like this:

[x,fs] = audioread('myWavFile.wav');

[m, n] = size(x); %gives dimensions of array where n is the number of stereo channels

if n == 2

y = x(:, 1) + x(:, 2); %sum(y, 2) also accomplishes this

peakAmp = max(abs(y));

y = y/peakAmp;

% check the L/R channels for orig. peak Amplitudes

peakL = max(abs(x(:, 1)));

peakR = max(abs(x(:, 2)));

maxPeak = max([peakL peakR]);

%apply x's original peak amplitude to the normalized mono mixdown

y = y*maxPeak;

else

y = x; %it is stereo so we will return it as is (e.g., for additional processing)

end

[vaibhav gaur]

hello joshua, I came across the audioread function in my assignment and cant understand what does the channel mean here. can you please elaborate.