Chris@5: 
Chris@5: # To the extent possible under law, Chris Cannam and QMUL have waived
Chris@5: # all copyright and related or neighboring rights to this file
Chris@5: # (http://creativecommons.org/about/cc0)
Chris@0: 
Chris@0: import wave
Chris@0: import numpy as np
Chris@0: 
Chris@0: def decode_to_mono_samples(rawdata, n_channels):
Chris@0:     """Given raw PCM16 interleaved WAV-format audio data as a binary
Chris@0:     string, decode and return as floating-point samples in range [-1,1)"""
Chris@0:     samples = np.fromstring(rawdata, 'Int16').astype(float)
Chris@0:     samples = samples / 32768
Chris@0:     totals = sum(samples[c::n_channels] for c in range(0, n_channels))
Chris@0:     return totals / n_channels
Chris@0: 
Chris@0: def read_all_mono_samples_from_file(filename):
Chris@0:     """Read the whole of the given PCM16 WAV-format given audio file,
Chris@0:     mix down to mono by taking means across channels, and return as an
Chris@0:     array of floating-point sampless in range [-1,1)"""
Chris@0:     wavfile = wave.open(filename, 'r')
Chris@0:     n_channels = wavfile.getnchannels()
Chris@0:     rawdata = wavfile.readframes(-1) # read all data
Chris@0:     decoded = decode_to_mono_samples(rawdata, n_channels)
Chris@0:     return (decoded, wavfile.getframerate())
Chris@0: