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matlabaudiooctavesox

Taking the left and right channels of two wav files and joining them into one separate stereo file

I have two stereo wav files that I would like to take the left channel of the first audio file and take the right channel of the second audio file and join them into one new wave file.

Here's an image of what I'm trying to do.

http://i.imgur.com/Rwe5jWHl.jpg

I know I can read files into matlab / octave and get the separate left right channels with the code below:

[imported_sig_1, fs_rate, nbitsraw] = wavread(strcat('/tmp/01a.wav'));
imported_sig_L=imported_sig_1(:,1)';

[imported_sig_2, fs_rate, nbitsraw] = wavread(strcat('/tmp/02a.wav'));
imported_sig_R=imported_sig_2(:,2)';

I can then write the new channels that I want out using the code

wavwrite([(imported_sig_L)' (imported_sig_R)'] ,fs_rate,16,'newfile.wav'); %

The problem I'm running into is the time it takes to import the file and size of the array the wave files take up. The files I'm importing are about 1-4 hours long and it takes a while to import and it takes a lot of memory in the array is there away around importing the full file and then exporting them?

I'm using octave 3.8.1 on Ubuntu 14.04 which is like matlab but I also have access to sox

Solution

  • I assume the bottleneck is your hard drive and your system has sufficient memory to keep all thee files in memory at the same time. If so you won't gain an speed reading only one channel. With a 16 bit wav your HDD would have to skip 2 bytes, read 2 bytes, skip 2 bytes, read 2 bytes... For such a read operation it is much faster to copy the full file into the memory and remove the unwanted channels afterwards.