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I have two sound samples (.WAV) and I want to find the difference between them. I've read about this subject and I know that I should use FFT to do such a thing.

Unfortunately, I can't find a way to do the actual calculation. I am searching for a PHP library or directions on how to make this calculation with PHP.

I tried googling this question and no related solutions came up.

mjk
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user1396033
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    If you are not finding PHP lib, you can always search for a Java one and just run a java command from your PHP script :) – Radoslav Georgiev Dec 25 '12 at 19:04
  • Java or C or anything else, really. PHP doesn't really do sound processing. – Charles Dec 25 '12 at 22:48
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    You can do the same math in PHP as you can any other language. There just won't always be some pre-built library for you. In any case, what do you mean by "difference between them"? That's a very ambiguous statement. What are you trying to do? If you really wanted the difference, you could just subject PCM sample values from each other... but I suspect that's not what you want. – Brad Dec 25 '12 at 23:14
  • I tried to look for java libs, let me clerfiy my question, the clients sends a 5 sec file to the server and the server should output a number that tells me how much the two sounds are similar. – user1396033 Dec 26 '12 at 07:23
  • There is no obvious thing that is meant by "difference between two sound samples", and the most obvious thing, subtracting them, you probably don't want. **You need to better define your question.** Do you want to identify which are exactly the same sound files, but played at different times and volumes? Or the same song, maybe by different bands? Or the same species, say to differentiate whales vs sparrows? – tom10 Dec 28 '12 at 01:17

3 Answers3

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PHP lib to handle audio files: ffmpeg-php
PHP lib for computing Fast Fourier Transform (FFT): fft

CSᵠ
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The subject you are looking for might be sound fingerprinting, sometimes done by 2D pattern matching of sets of MFCC vectors computed from the audio data of interest.

hotpaw2
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There are so many things you have to care of when finding the differences between audio files that writing an own libary for php is hard.

Why don't you use Audacity for audio analysis?

Max
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