How do you reverse a wav file? - wav

Question

I want to reverse a wav file. I am not sure how to do this however. I have read that you need to reverse the sample stream instead of the byte stream, but I am not sure what people mean by this. Thanks for the help!

Answer 1

A nice way to get some kind of soud manipulation going is to use the Python language + Pygame -
Pygame allows you to read the contents of a .wav file into a value array with 5 or 6 lines of program - in total. The Python language allow you to revese that with a simple expression, and you will need more 2 or 3 function calls to pygame to either save the wav file or play it back.
You cna get the latest Python at http://www.python.org , and them look for instructions on how to install modules with pip - at which point you woill be able to install pygame. Then, learn some Python basics if you don't already know, and follow Pygame's documentations at:
https://www.pygame.org/docs/ref/sndarray.html

Answer 2

That's right, you need to reverse the samples and not the bytes.
Here's a brief summary from this tutorial.
Grab the bytes after the metadata (usually at index 44).
Reverse the samples by using a for loop:
private static byte[] ReverseTheForwardsArrayWithOnlyAudioData(int bytesPerSample, byte[] forwardsArrayWithOnlyAudioData)
{
int length = forwardsArrayWithOnlyAudioData.Length;
byte[] reversedArrayWithOnlyAudioData = new byte[length];
int sampleIdentifier = 0;
for (int i = 0; i < length; i++)
{
if (i != 0 && i % bytesPerSample == 0)
{
sampleIdentifier += 2 * bytesPerSample;
}
int index = length - bytesPerSample - sampleIdentifier + i;
reversedArrayWithOnlyAudioData[i] = forwardsArrayWithOnlyAudioData[index];
}
return reversedArrayWithOnlyAudioData;
}