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Add methods for lin2ulaw, ulaw2lin, lin2alaw, and alaw2lin to pyaudioop.py #825

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Add methods for lin2ulaw, ulaw2lin, lin2alaw, and alaw2lin to pyaudioop.py #825

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e16d9c1
Update pyaudioop.py
sammygrey Dec 14, 2024
117c863
fixed sizing for alaw and ulaw buffers
sammygrey Dec 15, 2024
6987406
Changed _sample_count to use int division
sammygrey Dec 20, 2024
6e37418
Changed sign helper function to be notationally protected
sammygrey Jan 4, 2025
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54 changes: 49 additions & 5 deletions pydub/pyaudioop.py
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,7 @@ def _check_params(length, size):


def _sample_count(cp, size):
return len(cp) / size
return len(cp) // size


def _get_samples(cp, size, signed=True):
Expand Down Expand Up @@ -529,20 +529,64 @@ def ratecv(cp, size, nchannels, inrate, outrate, state, weightA=1, weightB=0):
d -= inrate


def _sign(num):
return -1 if num < 0 else 0 if num == 0 else 1


def lin2ulaw(cp, size):
raise NotImplementedError()
maxval = _get_maxval(size)
result = create_string_buffer(len(cp))

for i in range(_sample_count(cp, size)):
sample = _get_sample(cp, size, i)
val = _sign(sample/maxval)*math.log(1+255*math.abs(sample/maxval))/math.log(1+255)
_put_sample(result, size, i, val)

return result


def ulaw2lin(cp, size):
raise NotImplementedError()
maxval = _get_maxval(size)
result = create_string_buffer(len(cp))

for i in range(_sample_count(cp, size)):
sample = _get_sample(cp, size, i)
val = (_sign(sample)*((1+255)**math.abs(sample)-1)/255) * maxval
_put_sample(result, size, i, val)

return result


def lin2alaw(cp, size):
raise NotImplementedError()
maxval = _get_maxval(size)
result = create_string_buffer(len(cp))

for i in range(_sample_count(cp, size)):
sample = _get_sample(cp, size, i)
val = None
if math.abs(sample/maxval) < 1/87.6:
val = _sign(sample/maxval)*87.6*math.abs(sample/maxval)/(1+math.log(87.6))
else:
val = _sign(sample/maxval)*(1+math.log(87.6*math.abs(sample/maxval)))/(1+math.log(87.6))
_put_sample(result, size, i, val)

return result


def alaw2lin(cp, size):
raise NotImplementedError()
maxval = _get_maxval(size)
result = create_string_buffer(len(cp))

for i in range(_sample_count(cp, size)):
sample = _get_sample(cp, size, i)
val = None
if math.abs(sample) < 1/(1+math.log(87.6)):
val = _sign(sample) * math.abs(sample)*(1+math.log(87.6))/87.6 * maxval
else:
val = _sign(sample) * (math.e**(-1+math.abs(sample)*(1+math.log(87.6)))) / 87.6 * maxval
_put_sample(result, size, i, val)

return result


def lin2adpcm(cp, size, state):
Expand Down