Convert 3-byte stereo WAV-file to numpy array

Question

I have been given a large WAV-file of continuous underwater recording which I would like to convert to a numpy array for analysis. I am struggling to do this.

So far

Answer 1

Here's a loop that handles 2, 3, and 4 byte WAV files with arbitrary numbers of channels:

def dataFromWave(fname):
""" return list with interleaved samples """
    f = wave.open(fname, 'rb')
    chans = f.getnchannels()
    samps = f.getnframes()
    sampwidth = f.getsampwidth()
    if  sampwidth == 3: #have to read this one sample at a time
        s = ''
        for k in xrange(samps):
            fr = f.readframes(1)
            for c in xrange(0,3*chans,3):                
                s += '\0'+fr[c:(c+3)] # put TRAILING 0 to make 32-bit (file is little-endian)
    else:
        s = f.readframes(samps)
    f.close()
    unpstr = '<{0}{1}'.format(samps*chans, {1:'b',2:'h',3:'i',4:'i',8:'q'}[sampwidth])
    x = list(struct.unpack(unpstr, s))
    if sampwidth == 3:
        x = [k >> 8 for k in x] #downshift to get +/- 2^24 with sign extension
    return x