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Chris@5
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1
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2 # To the extent possible under law, Chris Cannam and QMUL have waived
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3 # all copyright and related or neighboring rights to this file
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4 # (http://creativecommons.org/about/cc0)
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5
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6 import wave
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7 import numpy as np
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8
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9 def decode_to_mono_samples(rawdata, n_channels):
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10 """Given raw PCM16 interleaved WAV-format audio data as a binary
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11 string, decode and return as floating-point samples in range [-1,1)"""
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12 samples = np.fromstring(rawdata, 'Int16').astype(float)
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13 samples = samples / 32768
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14 totals = sum(samples[c::n_channels] for c in range(0, n_channels))
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15 return totals / n_channels
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16
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17 def read_all_mono_samples_from_file(filename):
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18 """Read the whole of the given PCM16 WAV-format given audio file,
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19 mix down to mono by taking means across channels, and return as an
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20 array of floating-point sampless in range [-1,1)"""
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21 wavfile = wave.open(filename, 'r')
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22 n_channels = wavfile.getnchannels()
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23 rawdata = wavfile.readframes(-1) # read all data
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24 decoded = decode_to_mono_samples(rawdata, n_channels)
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25 return (decoded, wavfile.getframerate())
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26
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