Implement alaw2lin and ulaw2lin

jiaaro · Nov 22, 2023 · 9bd05b0 · 9bd05b0
1 parent 996cec4
commit 9bd05b0
Showing 1 changed file with 97 additions and 2 deletions.
diff --git a/pydub/pyaudioop.py b/pydub/pyaudioop.py
@@ -529,20 +529,115 @@ def ratecv(cp, size, nchannels, inrate, outrate, state, weightA=1, weightB=0):
             d -= inrate
 
 
+_to_lin_tables = {
+    # Source: https://github.com/python/cpython/blob/3.12/Modules/audioop.c#L91
+    'ulaw': [
+        -32124,  -31100,  -30076,  -29052,  -28028,  -27004,  -25980,
+        -24956,  -23932,  -22908,  -21884,  -20860,  -19836,  -18812,
+        -17788,  -16764,  -15996,  -15484,  -14972,  -14460,  -13948,
+        -13436,  -12924,  -12412,  -11900,  -11388,  -10876,  -10364,
+        -9852,   -9340,   -8828,   -8316,   -7932,   -7676,   -7420,
+        -7164,   -6908,   -6652,   -6396,   -6140,   -5884,   -5628,
+        -5372,   -5116,   -4860,   -4604,   -4348,   -4092,   -3900,
+        -3772,   -3644,   -3516,   -3388,   -3260,   -3132,   -3004,
+        -2876,   -2748,   -2620,   -2492,   -2364,   -2236,   -2108,
+        -1980,   -1884,   -1820,   -1756,   -1692,   -1628,   -1564,
+        -1500,   -1436,   -1372,   -1308,   -1244,   -1180,   -1116,
+        -1052,    -988,    -924,    -876,    -844,    -812,    -780,
+        -748,    -716,    -684,    -652,    -620,    -588,    -556,
+        -524,    -492,    -460,    -428,    -396,    -372,    -356,
+        -340,    -324,    -308,    -292,    -276,    -260,    -244,
+        -228,    -212,    -196,    -180,    -164,    -148,    -132,
+        -120,    -112,    -104,     -96,     -88,     -80,     -72,
+        -64,     -56,     -48,     -40,     -32,     -24,     -16,
+        -8,       0,   32124,   31100,   30076,   29052,   28028,
+        27004,   25980,   24956,   23932,   22908,   21884,   20860,
+        19836,   18812,   17788,   16764,   15996,   15484,   14972,
+        14460,   13948,   13436,   12924,   12412,   11900,   11388,
+        10876,   10364,    9852,    9340,    8828,    8316,    7932,
+        7676,    7420,    7164,    6908,    6652,    6396,    6140,
+        5884,    5628,    5372,    5116,    4860,    4604,    4348,
+        4092,    3900,    3772,    3644,    3516,    3388,    3260,
+        3132,    3004,    2876,    2748,    2620,    2492,    2364,
+        2236,    2108,    1980,    1884,    1820,    1756,    1692,
+        1628,    1564,    1500,    1436,    1372,    1308,    1244,
+        1180,    1116,    1052,     988,     924,     876,     844,
+        812,     780,     748,     716,     684,     652,     620,
+        588,     556,     524,     492,     460,     428,     396,
+        372,     356,     340,     324,     308,     292,     276,
+        260,     244,     228,     212,     196,     180,     164,
+        148,     132,     120,     112,     104,      96,      88,
+        80,      72,      64,      56,      48,      40,      32,
+        24,      16,       8,       0
+    ],
+    # Source: https://github.com/python/cpython/blob/3.12/Modules/audioop.c#L198
+    'alaw': [
+        -5504,   -5248,   -6016,   -5760,   -4480,   -4224,   -4992,
+        -4736,   -7552,   -7296,   -8064,   -7808,   -6528,   -6272,
+        -7040,   -6784,   -2752,   -2624,   -3008,   -2880,   -2240,
+        -2112,   -2496,   -2368,   -3776,   -3648,   -4032,   -3904,
+        -3264,   -3136,   -3520,   -3392,  -22016,  -20992,  -24064,
+        -23040,  -17920,  -16896,  -19968,  -18944,  -30208,  -29184,
+        -32256,  -31232,  -26112,  -25088,  -28160,  -27136,  -11008,
+        -10496,  -12032,  -11520,   -8960,   -8448,   -9984,   -9472,
+        -15104,  -14592,  -16128,  -15616,  -13056,  -12544,  -14080,
+        -13568,    -344,    -328,    -376,    -360,    -280,    -264,
+        -312,    -296,    -472,    -456,    -504,    -488,    -408,
+        -392,    -440,    -424,     -88,     -72,    -120,    -104,
+        -24,      -8,     -56,     -40,    -216,    -200,    -248,
+        -232,    -152,    -136,    -184,    -168,   -1376,   -1312,
+        -1504,   -1440,   -1120,   -1056,   -1248,   -1184,   -1888,
+        -1824,   -2016,   -1952,   -1632,   -1568,   -1760,   -1696,
+        -688,    -656,    -752,    -720,    -560,    -528,    -624,
+        -592,    -944,    -912,   -1008,    -976,    -816,    -784,
+        -880,    -848,    5504,    5248,    6016,    5760,    4480,
+        4224,    4992,    4736,    7552,    7296,    8064,    7808,
+        6528,    6272,    7040,    6784,    2752,    2624,    3008,
+        2880,    2240,    2112,    2496,    2368,    3776,    3648,
+        4032,    3904,    3264,    3136,    3520,    3392,   22016,
+        20992,   24064,   23040,   17920,   16896,   19968,   18944,
+        30208,   29184,   32256,   31232,   26112,   25088,   28160,
+        27136,   11008,   10496,   12032,   11520,    8960,    8448,
+        9984,    9472,   15104,   14592,   16128,   15616,   13056,
+        12544,   14080,   13568,     344,     328,     376,     360,
+        280,     264,     312,     296,     472,     456,     504,
+        488,     408,     392,     440,     424,      88,      72,
+        120,     104,      24,       8,      56,      40,     216,
+        200,     248,     232,     152,     136,     184,     168,
+        1376,    1312,    1504,    1440,    1120,    1056,    1248,
+        1184,    1888,    1824,    2016,    1952,    1632,    1568,
+        1760,    1696,     688,     656,     752,     720,     560,
+        528,     624,     592,     944,     912,    1008,     976,
+        816,     784,     880,     848
+    ]}
+
+
+_to_lin_table_bin = {}
+
+
+def _to_lin(type, cp, size):
+    key = f'{type}:{size}'
+    if not key in _to_lin_table_bin:
+        _to_lin_table_bin[key] = [i.to_bytes(
+            size, byteorder='little', signed=True) for i in _to_lin_tables[type]]
+    table = _to_lin_table_bin[key]
+    return b''.join(table[val] for val in cp)
+
+
 def lin2ulaw(cp, size):
     raise NotImplementedError()
 
 
 def ulaw2lin(cp, size):
-    raise NotImplementedError()
+    return _to_lin('ulaw', cp, size)
 
 
 def lin2alaw(cp, size):
     raise NotImplementedError()
 
 
 def alaw2lin(cp, size):
-    raise NotImplementedError()
+    return _to_lin('alaw', cp, size)
 
 
 def lin2adpcm(cp, size, state):