splitting wav file in python

Question

I'm trying to split a wav file programmatically in Python. Based on hints from stackoverflow as well as the documentation from the Python wave module I'm doing the following

import wave

origAudio = wave.open('inputFile.wav','r')
frameRate = origAudio.getframerate()
nChannels = origAudio.getnchannels()
sampWidth = origAudio.getsampwidth()

start = float(someStartVal)
end = float(someEndVal)

origAudio.setpos(start*frameRate)
chunkData = origAudio.readframes(int((end-start)*frameRate))

chunkAudio = wave.open('outputFile.wav','w')
chunkAudio.setnchannels(nChannels)
chunkAudio.setsampwidth(sampWidth)
chunkAudio.setframerate(frameRate)
chunkAudio.writeframes(chunkData)
chunkAudio.close()

I iterate through a number of different start and end values, and extract chunks of audio from the original file in this manner. What's weird is that the technique works perfectly fine for some chunks, and produces garbage white noise for others. Also there's no obvious pattern of which start and end positions produce white noise, just that it happens consistently for an input file.

Anyone experienced this sort of behaviour before? Or know what I'm doing wrong? Suggestions on better ways of splitting an audio file programmatically are welcome.

Thanks in advance.

Answer 1

This may have to do with start*frameRate being a float when calling setpos. Perhaps after readframes you should use tell to find the current location of the file pointer instead..