source: python/trunk/Modules/audioop.c@ 775

Last change on this file since 775 was 391, checked in by dmik, 12 years ago

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1
2/* audioopmodule - Module to detect peak values in arrays */
3
4#include "Python.h"
5
6#if SIZEOF_INT == 4
7typedef int Py_Int32;
8typedef unsigned int Py_UInt32;
9#else
10#if SIZEOF_LONG == 4
11typedef long Py_Int32;
12typedef unsigned long Py_UInt32;
13#else
14#error "No 4-byte integral type"
15#endif
16#endif
17
18typedef short PyInt16;
19
20#if defined(__CHAR_UNSIGNED__)
21#if defined(signed)
22/* This module currently does not work on systems where only unsigned
23 characters are available. Take it out of Setup. Sorry. */
24#endif
25#endif
26
27static const int maxvals[] = {0, 0x7F, 0x7FFF, 0x7FFFFF, 0x7FFFFFFF};
28static const int minvals[] = {0, -0x80, -0x8000, -0x800000, -0x80000000};
29static const unsigned int masks[] = {0, 0xFF, 0xFFFF, 0xFFFFFF, 0xFFFFFFFF};
30
31static int
32fbound(double val, double minval, double maxval)
33{
34 if (val > maxval)
35 val = maxval;
36 else if (val < minval + 1)
37 val = minval;
38 return val;
39}
40
41
42/* Code shamelessly stolen from sox, 12.17.7, g711.c
43** (c) Craig Reese, Joe Campbell and Jeff Poskanzer 1989 */
44
45/* From g711.c:
46 *
47 * December 30, 1994:
48 * Functions linear2alaw, linear2ulaw have been updated to correctly
49 * convert unquantized 16 bit values.
50 * Tables for direct u- to A-law and A- to u-law conversions have been
51 * corrected.
52 * Borge Lindberg, Center for PersonKommunikation, Aalborg University.
53 * bli@cpk.auc.dk
54 *
55 */
56#define BIAS 0x84 /* define the add-in bias for 16 bit samples */
57#define CLIP 32635
58#define SIGN_BIT (0x80) /* Sign bit for a A-law byte. */
59#define QUANT_MASK (0xf) /* Quantization field mask. */
60#define SEG_SHIFT (4) /* Left shift for segment number. */
61#define SEG_MASK (0x70) /* Segment field mask. */
62
63static PyInt16 seg_aend[8] = {0x1F, 0x3F, 0x7F, 0xFF,
64 0x1FF, 0x3FF, 0x7FF, 0xFFF};
65static PyInt16 seg_uend[8] = {0x3F, 0x7F, 0xFF, 0x1FF,
66 0x3FF, 0x7FF, 0xFFF, 0x1FFF};
67
68static PyInt16
69search(PyInt16 val, PyInt16 *table, int size)
70{
71 int i;
72
73 for (i = 0; i < size; i++) {
74 if (val <= *table++)
75 return (i);
76 }
77 return (size);
78}
79#define st_ulaw2linear16(uc) (_st_ulaw2linear16[uc])
80#define st_alaw2linear16(uc) (_st_alaw2linear16[uc])
81
82static PyInt16 _st_ulaw2linear16[256] = {
83 -32124, -31100, -30076, -29052, -28028, -27004, -25980,
84 -24956, -23932, -22908, -21884, -20860, -19836, -18812,
85 -17788, -16764, -15996, -15484, -14972, -14460, -13948,
86 -13436, -12924, -12412, -11900, -11388, -10876, -10364,
87 -9852, -9340, -8828, -8316, -7932, -7676, -7420,
88 -7164, -6908, -6652, -6396, -6140, -5884, -5628,
89 -5372, -5116, -4860, -4604, -4348, -4092, -3900,
90 -3772, -3644, -3516, -3388, -3260, -3132, -3004,
91 -2876, -2748, -2620, -2492, -2364, -2236, -2108,
92 -1980, -1884, -1820, -1756, -1692, -1628, -1564,
93 -1500, -1436, -1372, -1308, -1244, -1180, -1116,
94 -1052, -988, -924, -876, -844, -812, -780,
95 -748, -716, -684, -652, -620, -588, -556,
96 -524, -492, -460, -428, -396, -372, -356,
97 -340, -324, -308, -292, -276, -260, -244,
98 -228, -212, -196, -180, -164, -148, -132,
99 -120, -112, -104, -96, -88, -80, -72,
100 -64, -56, -48, -40, -32, -24, -16,
101 -8, 0, 32124, 31100, 30076, 29052, 28028,
102 27004, 25980, 24956, 23932, 22908, 21884, 20860,
103 19836, 18812, 17788, 16764, 15996, 15484, 14972,
104 14460, 13948, 13436, 12924, 12412, 11900, 11388,
105 10876, 10364, 9852, 9340, 8828, 8316, 7932,
106 7676, 7420, 7164, 6908, 6652, 6396, 6140,
107 5884, 5628, 5372, 5116, 4860, 4604, 4348,
108 4092, 3900, 3772, 3644, 3516, 3388, 3260,
109 3132, 3004, 2876, 2748, 2620, 2492, 2364,
110 2236, 2108, 1980, 1884, 1820, 1756, 1692,
111 1628, 1564, 1500, 1436, 1372, 1308, 1244,
112 1180, 1116, 1052, 988, 924, 876, 844,
113 812, 780, 748, 716, 684, 652, 620,
114 588, 556, 524, 492, 460, 428, 396,
115 372, 356, 340, 324, 308, 292, 276,
116 260, 244, 228, 212, 196, 180, 164,
117 148, 132, 120, 112, 104, 96, 88,
118 80, 72, 64, 56, 48, 40, 32,
119 24, 16, 8, 0
120};
121
122/*
123 * linear2ulaw() accepts a 14-bit signed integer and encodes it as u-law data
124 * stored in a unsigned char. This function should only be called with
125 * the data shifted such that it only contains information in the lower
126 * 14-bits.
127 *
128 * In order to simplify the encoding process, the original linear magnitude
129 * is biased by adding 33 which shifts the encoding range from (0 - 8158) to
130 * (33 - 8191). The result can be seen in the following encoding table:
131 *
132 * Biased Linear Input Code Compressed Code
133 * ------------------------ ---------------
134 * 00000001wxyza 000wxyz
135 * 0000001wxyzab 001wxyz
136 * 000001wxyzabc 010wxyz
137 * 00001wxyzabcd 011wxyz
138 * 0001wxyzabcde 100wxyz
139 * 001wxyzabcdef 101wxyz
140 * 01wxyzabcdefg 110wxyz
141 * 1wxyzabcdefgh 111wxyz
142 *
143 * Each biased linear code has a leading 1 which identifies the segment
144 * number. The value of the segment number is equal to 7 minus the number
145 * of leading 0's. The quantization interval is directly available as the
146 * four bits wxyz. * The trailing bits (a - h) are ignored.
147 *
148 * Ordinarily the complement of the resulting code word is used for
149 * transmission, and so the code word is complemented before it is returned.
150 *
151 * For further information see John C. Bellamy's Digital Telephony, 1982,
152 * John Wiley & Sons, pps 98-111 and 472-476.
153 */
154static unsigned char
155st_14linear2ulaw(PyInt16 pcm_val) /* 2's complement (14-bit range) */
156{
157 PyInt16 mask;
158 PyInt16 seg;
159 unsigned char uval;
160
161 /* The original sox code does this in the calling function, not here */
162 pcm_val = pcm_val >> 2;
163
164 /* u-law inverts all bits */
165 /* Get the sign and the magnitude of the value. */
166 if (pcm_val < 0) {
167 pcm_val = -pcm_val;
168 mask = 0x7F;
169 } else {
170 mask = 0xFF;
171 }
172 if ( pcm_val > CLIP ) pcm_val = CLIP; /* clip the magnitude */
173 pcm_val += (BIAS >> 2);
174
175 /* Convert the scaled magnitude to segment number. */
176 seg = search(pcm_val, seg_uend, 8);
177
178 /*
179 * Combine the sign, segment, quantization bits;
180 * and complement the code word.
181 */
182 if (seg >= 8) /* out of range, return maximum value. */
183 return (unsigned char) (0x7F ^ mask);
184 else {
185 uval = (unsigned char) (seg << 4) | ((pcm_val >> (seg + 1)) & 0xF);
186 return (uval ^ mask);
187 }
188
189}
190
191static PyInt16 _st_alaw2linear16[256] = {
192 -5504, -5248, -6016, -5760, -4480, -4224, -4992,
193 -4736, -7552, -7296, -8064, -7808, -6528, -6272,
194 -7040, -6784, -2752, -2624, -3008, -2880, -2240,
195 -2112, -2496, -2368, -3776, -3648, -4032, -3904,
196 -3264, -3136, -3520, -3392, -22016, -20992, -24064,
197 -23040, -17920, -16896, -19968, -18944, -30208, -29184,
198 -32256, -31232, -26112, -25088, -28160, -27136, -11008,
199 -10496, -12032, -11520, -8960, -8448, -9984, -9472,
200 -15104, -14592, -16128, -15616, -13056, -12544, -14080,
201 -13568, -344, -328, -376, -360, -280, -264,
202 -312, -296, -472, -456, -504, -488, -408,
203 -392, -440, -424, -88, -72, -120, -104,
204 -24, -8, -56, -40, -216, -200, -248,
205 -232, -152, -136, -184, -168, -1376, -1312,
206 -1504, -1440, -1120, -1056, -1248, -1184, -1888,
207 -1824, -2016, -1952, -1632, -1568, -1760, -1696,
208 -688, -656, -752, -720, -560, -528, -624,
209 -592, -944, -912, -1008, -976, -816, -784,
210 -880, -848, 5504, 5248, 6016, 5760, 4480,
211 4224, 4992, 4736, 7552, 7296, 8064, 7808,
212 6528, 6272, 7040, 6784, 2752, 2624, 3008,
213 2880, 2240, 2112, 2496, 2368, 3776, 3648,
214 4032, 3904, 3264, 3136, 3520, 3392, 22016,
215 20992, 24064, 23040, 17920, 16896, 19968, 18944,
216 30208, 29184, 32256, 31232, 26112, 25088, 28160,
217 27136, 11008, 10496, 12032, 11520, 8960, 8448,
218 9984, 9472, 15104, 14592, 16128, 15616, 13056,
219 12544, 14080, 13568, 344, 328, 376, 360,
220 280, 264, 312, 296, 472, 456, 504,
221 488, 408, 392, 440, 424, 88, 72,
222 120, 104, 24, 8, 56, 40, 216,
223 200, 248, 232, 152, 136, 184, 168,
224 1376, 1312, 1504, 1440, 1120, 1056, 1248,
225 1184, 1888, 1824, 2016, 1952, 1632, 1568,
226 1760, 1696, 688, 656, 752, 720, 560,
227 528, 624, 592, 944, 912, 1008, 976,
228 816, 784, 880, 848
229};
230
231/*
232 * linear2alaw() accepts an 13-bit signed integer and encodes it as A-law data
233 * stored in a unsigned char. This function should only be called with
234 * the data shifted such that it only contains information in the lower
235 * 13-bits.
236 *
237 * Linear Input Code Compressed Code
238 * ------------------------ ---------------
239 * 0000000wxyza 000wxyz
240 * 0000001wxyza 001wxyz
241 * 000001wxyzab 010wxyz
242 * 00001wxyzabc 011wxyz
243 * 0001wxyzabcd 100wxyz
244 * 001wxyzabcde 101wxyz
245 * 01wxyzabcdef 110wxyz
246 * 1wxyzabcdefg 111wxyz
247 *
248 * For further information see John C. Bellamy's Digital Telephony, 1982,
249 * John Wiley & Sons, pps 98-111 and 472-476.
250 */
251static unsigned char
252st_linear2alaw(PyInt16 pcm_val) /* 2's complement (13-bit range) */
253{
254 PyInt16 mask;
255 short seg;
256 unsigned char aval;
257
258 /* The original sox code does this in the calling function, not here */
259 pcm_val = pcm_val >> 3;
260
261 /* A-law using even bit inversion */
262 if (pcm_val >= 0) {
263 mask = 0xD5; /* sign (7th) bit = 1 */
264 } else {
265 mask = 0x55; /* sign bit = 0 */
266 pcm_val = -pcm_val - 1;
267 }
268
269 /* Convert the scaled magnitude to segment number. */
270 seg = search(pcm_val, seg_aend, 8);
271
272 /* Combine the sign, segment, and quantization bits. */
273
274 if (seg >= 8) /* out of range, return maximum value. */
275 return (unsigned char) (0x7F ^ mask);
276 else {
277 aval = (unsigned char) seg << SEG_SHIFT;
278 if (seg < 2)
279 aval |= (pcm_val >> 1) & QUANT_MASK;
280 else
281 aval |= (pcm_val >> seg) & QUANT_MASK;
282 return (aval ^ mask);
283 }
284}
285/* End of code taken from sox */
286
287/* Intel ADPCM step variation table */
288static int indexTable[16] = {
289 -1, -1, -1, -1, 2, 4, 6, 8,
290 -1, -1, -1, -1, 2, 4, 6, 8,
291};
292
293static int stepsizeTable[89] = {
294 7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
295 19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
296 50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
297 130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
298 337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
299 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
300 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
301 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
302 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
303};
304
305#define CHARP(cp, i) ((signed char *)(cp+i))
306#define SHORTP(cp, i) ((short *)(cp+i))
307#define LONGP(cp, i) ((Py_Int32 *)(cp+i))
308
309
310
311static PyObject *AudioopError;
312
313static int
314audioop_check_size(int size)
315{
316 if (size != 1 && size != 2 && size != 4) {
317 PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");
318 return 0;
319 }
320 else
321 return 1;
322}
323
324static int
325audioop_check_parameters(int len, int size)
326{
327 if (!audioop_check_size(size))
328 return 0;
329 if (len % size != 0) {
330 PyErr_SetString(AudioopError, "not a whole number of frames");
331 return 0;
332 }
333 return 1;
334}
335
336static PyObject *
337audioop_getsample(PyObject *self, PyObject *args)
338{
339 signed char *cp;
340 int len, size, val = 0;
341 int i;
342
343 if ( !PyArg_ParseTuple(args, "s#ii:getsample", &cp, &len, &size, &i) )
344 return 0;
345 if (!audioop_check_parameters(len, size))
346 return NULL;
347 if ( i < 0 || i >= len/size ) {
348 PyErr_SetString(AudioopError, "Index out of range");
349 return 0;
350 }
351 if ( size == 1 ) val = (int)*CHARP(cp, i);
352 else if ( size == 2 ) val = (int)*SHORTP(cp, i*2);
353 else if ( size == 4 ) val = (int)*LONGP(cp, i*4);
354 return PyInt_FromLong(val);
355}
356
357static PyObject *
358audioop_max(PyObject *self, PyObject *args)
359{
360 signed char *cp;
361 int len, size, val = 0;
362 int i;
363 unsigned int absval, max = 0;
364
365 if ( !PyArg_ParseTuple(args, "s#i:max", &cp, &len, &size) )
366 return 0;
367 if (!audioop_check_parameters(len, size))
368 return NULL;
369 for ( i=0; i<len; i+= size) {
370 if ( size == 1 ) val = (int)*CHARP(cp, i);
371 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
372 else if ( size == 4 ) val = (int)*LONGP(cp, i);
373 if (val < 0) absval = (-val);
374 else absval = val;
375 if (absval > max) max = absval;
376 }
377 if (max <= INT_MAX)
378 return PyInt_FromLong(max);
379 else
380 return PyLong_FromUnsignedLong(max);
381}
382
383static PyObject *
384audioop_minmax(PyObject *self, PyObject *args)
385{
386 signed char *cp;
387 int len, size, val = 0;
388 int i;
389 int min = 0x7fffffff, max = -0x80000000;
390
391 if (!PyArg_ParseTuple(args, "s#i:minmax", &cp, &len, &size))
392 return NULL;
393 if (!audioop_check_parameters(len, size))
394 return NULL;
395 for (i = 0; i < len; i += size) {
396 if (size == 1) val = (int) *CHARP(cp, i);
397 else if (size == 2) val = (int) *SHORTP(cp, i);
398 else if (size == 4) val = (int) *LONGP(cp, i);
399 if (val > max) max = val;
400 if (val < min) min = val;
401 }
402 return Py_BuildValue("(ii)", min, max);
403}
404
405static PyObject *
406audioop_avg(PyObject *self, PyObject *args)
407{
408 signed char *cp;
409 int len, size, val = 0;
410 int i;
411 double avg = 0.0;
412
413 if ( !PyArg_ParseTuple(args, "s#i:avg", &cp, &len, &size) )
414 return 0;
415 if (!audioop_check_parameters(len, size))
416 return NULL;
417 for ( i=0; i<len; i+= size) {
418 if ( size == 1 ) val = (int)*CHARP(cp, i);
419 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
420 else if ( size == 4 ) val = (int)*LONGP(cp, i);
421 avg += val;
422 }
423 if ( len == 0 )
424 val = 0;
425 else
426 val = (int)floor(avg / (double)(len/size));
427 return PyInt_FromLong(val);
428}
429
430static PyObject *
431audioop_rms(PyObject *self, PyObject *args)
432{
433 signed char *cp;
434 int len, size, val = 0;
435 int i;
436 unsigned int res;
437 double sum_squares = 0.0;
438
439 if ( !PyArg_ParseTuple(args, "s#i:rms", &cp, &len, &size) )
440 return 0;
441 if (!audioop_check_parameters(len, size))
442 return NULL;
443 for ( i=0; i<len; i+= size) {
444 if ( size == 1 ) val = (int)*CHARP(cp, i);
445 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
446 else if ( size == 4 ) val = (int)*LONGP(cp, i);
447 sum_squares += (double)val*(double)val;
448 }
449 if ( len == 0 )
450 res = 0;
451 else
452 res = (unsigned int)sqrt(sum_squares / (double)(len/size));
453 if (res <= INT_MAX)
454 return PyInt_FromLong(res);
455 else
456 return PyLong_FromUnsignedLong(res);
457}
458
459static double _sum2(short *a, short *b, int len)
460{
461 int i;
462 double sum = 0.0;
463
464 for( i=0; i<len; i++) {
465 sum = sum + (double)a[i]*(double)b[i];
466 }
467 return sum;
468}
469
470/*
471** Findfit tries to locate a sample within another sample. Its main use
472** is in echo-cancellation (to find the feedback of the output signal in
473** the input signal).
474** The method used is as follows:
475**
476** let R be the reference signal (length n) and A the input signal (length N)
477** with N > n, and let all sums be over i from 0 to n-1.
478**
479** Now, for each j in {0..N-n} we compute a factor fj so that -fj*R matches A
480** as good as possible, i.e. sum( (A[j+i]+fj*R[i])^2 ) is minimal. This
481** equation gives fj = sum( A[j+i]R[i] ) / sum(R[i]^2).
482**
483** Next, we compute the relative distance between the original signal and
484** the modified signal and minimize that over j:
485** vj = sum( (A[j+i]-fj*R[i])^2 ) / sum( A[j+i]^2 ) =>
486** vj = ( sum(A[j+i]^2)*sum(R[i]^2) - sum(A[j+i]R[i])^2 ) / sum( A[j+i]^2 )
487**
488** In the code variables correspond as follows:
489** cp1 A
490** cp2 R
491** len1 N
492** len2 n
493** aj_m1 A[j-1]
494** aj_lm1 A[j+n-1]
495** sum_ri_2 sum(R[i]^2)
496** sum_aij_2 sum(A[i+j]^2)
497** sum_aij_ri sum(A[i+j]R[i])
498**
499** sum_ri is calculated once, sum_aij_2 is updated each step and sum_aij_ri
500** is completely recalculated each step.
501*/
502static PyObject *
503audioop_findfit(PyObject *self, PyObject *args)
504{
505 short *cp1, *cp2;
506 int len1, len2;
507 int j, best_j;
508 double aj_m1, aj_lm1;
509 double sum_ri_2, sum_aij_2, sum_aij_ri, result, best_result, factor;
510
511 /* Passing a short** for an 's' argument is correct only
512 if the string contents is aligned for interpretation
513 as short[]. Due to the definition of PyStringObject,
514 this is currently (Python 2.6) the case. */
515 if ( !PyArg_ParseTuple(args, "s#s#:findfit",
516 (char**)&cp1, &len1, (char**)&cp2, &len2) )
517 return 0;
518 if ( len1 & 1 || len2 & 1 ) {
519 PyErr_SetString(AudioopError, "Strings should be even-sized");
520 return 0;
521 }
522 len1 >>= 1;
523 len2 >>= 1;
524
525 if ( len1 < len2 ) {
526 PyErr_SetString(AudioopError, "First sample should be longer");
527 return 0;
528 }
529 sum_ri_2 = _sum2(cp2, cp2, len2);
530 sum_aij_2 = _sum2(cp1, cp1, len2);
531 sum_aij_ri = _sum2(cp1, cp2, len2);
532
533 result = (sum_ri_2*sum_aij_2 - sum_aij_ri*sum_aij_ri) / sum_aij_2;
534
535 best_result = result;
536 best_j = 0;
537
538 for (j=1; j<=len1-len2; j++) {
539 aj_m1 = (double)cp1[j-1];
540 aj_lm1 = (double)cp1[j+len2-1];
541
542 sum_aij_2 = sum_aij_2 + aj_lm1*aj_lm1 - aj_m1*aj_m1;
543 sum_aij_ri = _sum2(cp1+j, cp2, len2);
544
545 result = (sum_ri_2*sum_aij_2 - sum_aij_ri*sum_aij_ri)
546 / sum_aij_2;
547
548 if ( result < best_result ) {
549 best_result = result;
550 best_j = j;
551 }
552
553 }
554
555 factor = _sum2(cp1+best_j, cp2, len2) / sum_ri_2;
556
557 return Py_BuildValue("(if)", best_j, factor);
558}
559
560/*
561** findfactor finds a factor f so that the energy in A-fB is minimal.
562** See the comment for findfit for details.
563*/
564static PyObject *
565audioop_findfactor(PyObject *self, PyObject *args)
566{
567 short *cp1, *cp2;
568 int len1, len2;
569 double sum_ri_2, sum_aij_ri, result;
570
571 if ( !PyArg_ParseTuple(args, "s#s#:findfactor",
572 (char**)&cp1, &len1, (char**)&cp2, &len2) )
573 return 0;
574 if ( len1 & 1 || len2 & 1 ) {
575 PyErr_SetString(AudioopError, "Strings should be even-sized");
576 return 0;
577 }
578 if ( len1 != len2 ) {
579 PyErr_SetString(AudioopError, "Samples should be same size");
580 return 0;
581 }
582 len2 >>= 1;
583 sum_ri_2 = _sum2(cp2, cp2, len2);
584 sum_aij_ri = _sum2(cp1, cp2, len2);
585
586 result = sum_aij_ri / sum_ri_2;
587
588 return PyFloat_FromDouble(result);
589}
590
591/*
592** findmax returns the index of the n-sized segment of the input sample
593** that contains the most energy.
594*/
595static PyObject *
596audioop_findmax(PyObject *self, PyObject *args)
597{
598 short *cp1;
599 int len1, len2;
600 int j, best_j;
601 double aj_m1, aj_lm1;
602 double result, best_result;
603
604 if ( !PyArg_ParseTuple(args, "s#i:findmax",
605 (char**)&cp1, &len1, &len2) )
606 return 0;
607 if ( len1 & 1 ) {
608 PyErr_SetString(AudioopError, "Strings should be even-sized");
609 return 0;
610 }
611 len1 >>= 1;
612
613 if ( len2 < 0 || len1 < len2 ) {
614 PyErr_SetString(AudioopError, "Input sample should be longer");
615 return 0;
616 }
617
618 result = _sum2(cp1, cp1, len2);
619
620 best_result = result;
621 best_j = 0;
622
623 for (j=1; j<=len1-len2; j++) {
624 aj_m1 = (double)cp1[j-1];
625 aj_lm1 = (double)cp1[j+len2-1];
626
627 result = result + aj_lm1*aj_lm1 - aj_m1*aj_m1;
628
629 if ( result > best_result ) {
630 best_result = result;
631 best_j = j;
632 }
633
634 }
635
636 return PyInt_FromLong(best_j);
637}
638
639static PyObject *
640audioop_avgpp(PyObject *self, PyObject *args)
641{
642 signed char *cp;
643 int len, size, val = 0, prevval = 0, prevextremevalid = 0,
644 prevextreme = 0;
645 int i;
646 double sum = 0.0;
647 unsigned int avg;
648 int diff, prevdiff, nextreme = 0;
649
650 if ( !PyArg_ParseTuple(args, "s#i:avgpp", &cp, &len, &size) )
651 return 0;
652 if (!audioop_check_parameters(len, size))
653 return NULL;
654 if (len <= size*2)
655 return PyInt_FromLong(0);
656 if ( size == 1 ) prevval = (int)*CHARP(cp, 0);
657 else if ( size == 2 ) prevval = (int)*SHORTP(cp, 0);
658 else if ( size == 4 ) prevval = (int)*LONGP(cp, 0);
659 prevdiff = 17; /* Anything != 0, 1 */
660 for ( i=size; i<len; i+= size) {
661 if ( size == 1 ) val = (int)*CHARP(cp, i);
662 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
663 else if ( size == 4 ) val = (int)*LONGP(cp, i);
664 if (val != prevval) {
665 diff = val < prevval;
666 if (prevdiff == !diff) {
667 /* Derivative changed sign. Compute difference to last
668 ** extreme value and remember.
669 */
670 if (prevextremevalid) {
671 sum += fabs((double)prevval - (double)prevextreme);
672 nextreme++;
673 }
674 prevextremevalid = 1;
675 prevextreme = prevval;
676 }
677 prevval = val;
678 prevdiff = diff;
679 }
680 }
681 if ( nextreme == 0 )
682 avg = 0;
683 else
684 avg = (unsigned int)(sum / (double)nextreme);
685 if (avg <= INT_MAX)
686 return PyInt_FromLong(avg);
687 else
688 return PyLong_FromUnsignedLong(avg);
689}
690
691static PyObject *
692audioop_maxpp(PyObject *self, PyObject *args)
693{
694 signed char *cp;
695 int len, size, val = 0, prevval = 0, prevextremevalid = 0,
696 prevextreme = 0;
697 int i;
698 unsigned int max = 0, extremediff;
699 int diff, prevdiff;
700
701 if ( !PyArg_ParseTuple(args, "s#i:maxpp", &cp, &len, &size) )
702 return 0;
703 if (!audioop_check_parameters(len, size))
704 return NULL;
705 if (len <= size)
706 return PyInt_FromLong(0);
707 if ( size == 1 ) prevval = (int)*CHARP(cp, 0);
708 else if ( size == 2 ) prevval = (int)*SHORTP(cp, 0);
709 else if ( size == 4 ) prevval = (int)*LONGP(cp, 0);
710 prevdiff = 17; /* Anything != 0, 1 */
711 for ( i=size; i<len; i+= size) {
712 if ( size == 1 ) val = (int)*CHARP(cp, i);
713 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
714 else if ( size == 4 ) val = (int)*LONGP(cp, i);
715 if (val != prevval) {
716 diff = val < prevval;
717 if (prevdiff == !diff) {
718 /* Derivative changed sign. Compute difference to
719 ** last extreme value and remember.
720 */
721 if (prevextremevalid) {
722 if (prevval < prevextreme)
723 extremediff = (unsigned int)prevextreme -
724 (unsigned int)prevval;
725 else
726 extremediff = (unsigned int)prevval -
727 (unsigned int)prevextreme;
728 if ( extremediff > max )
729 max = extremediff;
730 }
731 prevextremevalid = 1;
732 prevextreme = prevval;
733 }
734 prevval = val;
735 prevdiff = diff;
736 }
737 }
738 if (max <= INT_MAX)
739 return PyInt_FromLong(max);
740 else
741 return PyLong_FromUnsignedLong(max);
742}
743
744static PyObject *
745audioop_cross(PyObject *self, PyObject *args)
746{
747 signed char *cp;
748 int len, size, val = 0;
749 int i;
750 int prevval, ncross;
751
752 if ( !PyArg_ParseTuple(args, "s#i:cross", &cp, &len, &size) )
753 return 0;
754 if (!audioop_check_parameters(len, size))
755 return NULL;
756 ncross = -1;
757 prevval = 17; /* Anything <> 0,1 */
758 for ( i=0; i<len; i+= size) {
759 if ( size == 1 ) val = ((int)*CHARP(cp, i)) >> 7;
760 else if ( size == 2 ) val = ((int)*SHORTP(cp, i)) >> 15;
761 else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 31;
762 val = val & 1;
763 if ( val != prevval ) ncross++;
764 prevval = val;
765 }
766 return PyInt_FromLong(ncross);
767}
768
769static PyObject *
770audioop_mul(PyObject *self, PyObject *args)
771{
772 signed char *cp, *ncp;
773 int len, size, val = 0;
774 double factor, fval, maxval, minval;
775 PyObject *rv;
776 int i;
777
778 if ( !PyArg_ParseTuple(args, "s#id:mul", &cp, &len, &size, &factor ) )
779 return 0;
780 if (!audioop_check_parameters(len, size))
781 return NULL;
782
783 maxval = (double) maxvals[size];
784 minval = (double) minvals[size];
785
786 rv = PyString_FromStringAndSize(NULL, len);
787 if ( rv == 0 )
788 return 0;
789 ncp = (signed char *)PyString_AsString(rv);
790
791
792 for ( i=0; i < len; i += size ) {
793 if ( size == 1 ) val = (int)*CHARP(cp, i);
794 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
795 else if ( size == 4 ) val = (int)*LONGP(cp, i);
796 fval = (double)val*factor;
797 val = (int)floor(fbound(fval, minval, maxval));
798 if ( size == 1 ) *CHARP(ncp, i) = (signed char)val;
799 else if ( size == 2 ) *SHORTP(ncp, i) = (short)val;
800 else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)val;
801 }
802 return rv;
803}
804
805static PyObject *
806audioop_tomono(PyObject *self, PyObject *args)
807{
808 signed char *cp, *ncp;
809 int len, size, val1 = 0, val2 = 0;
810 double fac1, fac2, fval, maxval, minval;
811 PyObject *rv;
812 int i;
813
814 if ( !PyArg_ParseTuple(args, "s#idd:tomono",
815 &cp, &len, &size, &fac1, &fac2 ) )
816 return 0;
817 if (!audioop_check_parameters(len, size))
818 return NULL;
819 if (((len / size) & 1) != 0) {
820 PyErr_SetString(AudioopError, "not a whole number of frames");
821 return NULL;
822 }
823
824 maxval = (double) maxvals[size];
825 minval = (double) minvals[size];
826
827 rv = PyString_FromStringAndSize(NULL, len/2);
828 if ( rv == 0 )
829 return 0;
830 ncp = (signed char *)PyString_AsString(rv);
831
832
833 for ( i=0; i < len; i += size*2 ) {
834 if ( size == 1 ) val1 = (int)*CHARP(cp, i);
835 else if ( size == 2 ) val1 = (int)*SHORTP(cp, i);
836 else if ( size == 4 ) val1 = (int)*LONGP(cp, i);
837 if ( size == 1 ) val2 = (int)*CHARP(cp, i+1);
838 else if ( size == 2 ) val2 = (int)*SHORTP(cp, i+2);
839 else if ( size == 4 ) val2 = (int)*LONGP(cp, i+4);
840 fval = (double)val1*fac1 + (double)val2*fac2;
841 val1 = (int)floor(fbound(fval, minval, maxval));
842 if ( size == 1 ) *CHARP(ncp, i/2) = (signed char)val1;
843 else if ( size == 2 ) *SHORTP(ncp, i/2) = (short)val1;
844 else if ( size == 4 ) *LONGP(ncp, i/2)= (Py_Int32)val1;
845 }
846 return rv;
847}
848
849static PyObject *
850audioop_tostereo(PyObject *self, PyObject *args)
851{
852 signed char *cp, *ncp;
853 int len, size, val1, val2, val = 0;
854 double fac1, fac2, fval, maxval, minval;
855 PyObject *rv;
856 int i;
857
858 if ( !PyArg_ParseTuple(args, "s#idd:tostereo",
859 &cp, &len, &size, &fac1, &fac2 ) )
860 return 0;
861 if (!audioop_check_parameters(len, size))
862 return NULL;
863
864 maxval = (double) maxvals[size];
865 minval = (double) minvals[size];
866
867 if (len > INT_MAX/2) {
868 PyErr_SetString(PyExc_MemoryError,
869 "not enough memory for output buffer");
870 return 0;
871 }
872
873 rv = PyString_FromStringAndSize(NULL, len*2);
874 if ( rv == 0 )
875 return 0;
876 ncp = (signed char *)PyString_AsString(rv);
877
878
879 for ( i=0; i < len; i += size ) {
880 if ( size == 1 ) val = (int)*CHARP(cp, i);
881 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
882 else if ( size == 4 ) val = (int)*LONGP(cp, i);
883
884 fval = (double)val*fac1;
885 val1 = (int)floor(fbound(fval, minval, maxval));
886
887 fval = (double)val*fac2;
888 val2 = (int)floor(fbound(fval, minval, maxval));
889
890 if ( size == 1 ) *CHARP(ncp, i*2) = (signed char)val1;
891 else if ( size == 2 ) *SHORTP(ncp, i*2) = (short)val1;
892 else if ( size == 4 ) *LONGP(ncp, i*2) = (Py_Int32)val1;
893
894 if ( size == 1 ) *CHARP(ncp, i*2+1) = (signed char)val2;
895 else if ( size == 2 ) *SHORTP(ncp, i*2+2) = (short)val2;
896 else if ( size == 4 ) *LONGP(ncp, i*2+4) = (Py_Int32)val2;
897 }
898 return rv;
899}
900
901static PyObject *
902audioop_add(PyObject *self, PyObject *args)
903{
904 signed char *cp1, *cp2, *ncp;
905 int len1, len2, size, val1 = 0, val2 = 0, minval, maxval, newval;
906 PyObject *rv;
907 int i;
908
909 if ( !PyArg_ParseTuple(args, "s#s#i:add",
910 &cp1, &len1, &cp2, &len2, &size ) )
911 return 0;
912 if (!audioop_check_parameters(len1, size))
913 return NULL;
914 if ( len1 != len2 ) {
915 PyErr_SetString(AudioopError, "Lengths should be the same");
916 return 0;
917 }
918
919 maxval = maxvals[size];
920 minval = minvals[size];
921
922 rv = PyString_FromStringAndSize(NULL, len1);
923 if ( rv == 0 )
924 return 0;
925 ncp = (signed char *)PyString_AsString(rv);
926
927 for ( i=0; i < len1; i += size ) {
928 if ( size == 1 ) val1 = (int)*CHARP(cp1, i);
929 else if ( size == 2 ) val1 = (int)*SHORTP(cp1, i);
930 else if ( size == 4 ) val1 = (int)*LONGP(cp1, i);
931
932 if ( size == 1 ) val2 = (int)*CHARP(cp2, i);
933 else if ( size == 2 ) val2 = (int)*SHORTP(cp2, i);
934 else if ( size == 4 ) val2 = (int)*LONGP(cp2, i);
935
936 if (size < 4) {
937 newval = val1 + val2;
938 /* truncate in case of overflow */
939 if (newval > maxval)
940 newval = maxval;
941 else if (newval < minval)
942 newval = minval;
943 }
944 else {
945 double fval = (double)val1 + (double)val2;
946 /* truncate in case of overflow */
947 newval = (int)floor(fbound(fval, minval, maxval));
948 }
949
950 if ( size == 1 ) *CHARP(ncp, i) = (signed char)newval;
951 else if ( size == 2 ) *SHORTP(ncp, i) = (short)newval;
952 else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)newval;
953 }
954 return rv;
955}
956
957static PyObject *
958audioop_bias(PyObject *self, PyObject *args)
959{
960 signed char *cp, *ncp;
961 int len, size;
962 unsigned int val = 0, mask;
963 PyObject *rv;
964 int i;
965 int bias;
966
967 if ( !PyArg_ParseTuple(args, "s#ii:bias",
968 &cp, &len, &size , &bias) )
969 return 0;
970
971 if (!audioop_check_parameters(len, size))
972 return NULL;
973
974 rv = PyString_FromStringAndSize(NULL, len);
975 if ( rv == 0 )
976 return 0;
977 ncp = (signed char *)PyString_AsString(rv);
978
979 mask = masks[size];
980
981 for ( i=0; i < len; i += size ) {
982 if ( size == 1 ) val = (unsigned int)(unsigned char)*CHARP(cp, i);
983 else if ( size == 2 ) val = (unsigned int)(unsigned short)*SHORTP(cp, i);
984 else if ( size == 4 ) val = (unsigned int)(Py_UInt32)*LONGP(cp, i);
985
986 val += (unsigned int)bias;
987 /* wrap around in case of overflow */
988 val &= mask;
989
990 if ( size == 1 ) *CHARP(ncp, i) = (signed char)(unsigned char)val;
991 else if ( size == 2 ) *SHORTP(ncp, i) = (short)(unsigned short)val;
992 else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(Py_UInt32)val;
993 }
994 return rv;
995}
996
997static PyObject *
998audioop_reverse(PyObject *self, PyObject *args)
999{
1000 signed char *cp;
1001 unsigned char *ncp;
1002 int len, size, val = 0;
1003 PyObject *rv;
1004 int i, j;
1005
1006 if ( !PyArg_ParseTuple(args, "s#i:reverse",
1007 &cp, &len, &size) )
1008 return 0;
1009
1010 if (!audioop_check_parameters(len, size))
1011 return NULL;
1012
1013 rv = PyString_FromStringAndSize(NULL, len);
1014 if ( rv == 0 )
1015 return 0;
1016 ncp = (unsigned char *)PyString_AsString(rv);
1017
1018 for ( i=0; i < len; i += size ) {
1019 if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 24;
1020 else if ( size == 2 ) val = ((int)*SHORTP(cp, i)) << 16;
1021 else if ( size == 4 ) val = (int)*LONGP(cp, i);
1022
1023 j = len - i - size;
1024
1025 if ( size == 1 ) *CHARP(ncp, j) = (signed char)(val >> 24);
1026 else if ( size == 2 ) *SHORTP(ncp, j) = (short)(val >> 16);
1027 else if ( size == 4 ) *LONGP(ncp, j) = (Py_Int32)val;
1028 }
1029 return rv;
1030}
1031
1032static PyObject *
1033audioop_lin2lin(PyObject *self, PyObject *args)
1034{
1035 signed char *cp;
1036 unsigned char *ncp;
1037 int len, size, size2, val = 0;
1038 PyObject *rv;
1039 int i, j;
1040
1041 if ( !PyArg_ParseTuple(args, "s#ii:lin2lin",
1042 &cp, &len, &size, &size2) )
1043 return 0;
1044
1045 if (!audioop_check_parameters(len, size))
1046 return NULL;
1047 if (!audioop_check_size(size2))
1048 return NULL;
1049
1050 if (len/size > INT_MAX/size2) {
1051 PyErr_SetString(PyExc_MemoryError,
1052 "not enough memory for output buffer");
1053 return 0;
1054 }
1055 rv = PyString_FromStringAndSize(NULL, (len/size)*size2);
1056 if ( rv == 0 )
1057 return 0;
1058 ncp = (unsigned char *)PyString_AsString(rv);
1059
1060 for ( i=0, j=0; i < len; i += size, j += size2 ) {
1061 if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 24;
1062 else if ( size == 2 ) val = ((int)*SHORTP(cp, i)) << 16;
1063 else if ( size == 4 ) val = (int)*LONGP(cp, i);
1064
1065 if ( size2 == 1 ) *CHARP(ncp, j) = (signed char)(val >> 24);
1066 else if ( size2 == 2 ) *SHORTP(ncp, j) = (short)(val >> 16);
1067 else if ( size2 == 4 ) *LONGP(ncp, j) = (Py_Int32)val;
1068 }
1069 return rv;
1070}
1071
1072static int
1073gcd(int a, int b)
1074{
1075 while (b > 0) {
1076 int tmp = a % b;
1077 a = b;
1078 b = tmp;
1079 }
1080 return a;
1081}
1082
1083static PyObject *
1084audioop_ratecv(PyObject *self, PyObject *args)
1085{
1086 char *cp, *ncp;
1087 int len, size, nchannels, inrate, outrate, weightA, weightB;
1088 int chan, d, *prev_i, *cur_i, cur_o;
1089 PyObject *state, *samps, *str, *rv = NULL;
1090 int bytes_per_frame;
1091
1092 weightA = 1;
1093 weightB = 0;
1094 if (!PyArg_ParseTuple(args, "s#iiiiO|ii:ratecv", &cp, &len, &size,
1095 &nchannels, &inrate, &outrate, &state,
1096 &weightA, &weightB))
1097 return NULL;
1098 if (!audioop_check_size(size))
1099 return NULL;
1100 if (nchannels < 1) {
1101 PyErr_SetString(AudioopError, "# of channels should be >= 1");
1102 return NULL;
1103 }
1104 bytes_per_frame = size * nchannels;
1105 if (bytes_per_frame / nchannels != size) {
1106 /* This overflow test is rigorously correct because
1107 both multiplicands are >= 1. Use the argument names
1108 from the docs for the error msg. */
1109 PyErr_SetString(PyExc_OverflowError,
1110 "width * nchannels too big for a C int");
1111 return NULL;
1112 }
1113 if (weightA < 1 || weightB < 0) {
1114 PyErr_SetString(AudioopError,
1115 "weightA should be >= 1, weightB should be >= 0");
1116 return NULL;
1117 }
1118 if (len % bytes_per_frame != 0) {
1119 PyErr_SetString(AudioopError, "not a whole number of frames");
1120 return NULL;
1121 }
1122 if (inrate <= 0 || outrate <= 0) {
1123 PyErr_SetString(AudioopError, "sampling rate not > 0");
1124 return NULL;
1125 }
1126 /* divide inrate and outrate by their greatest common divisor */
1127 d = gcd(inrate, outrate);
1128 inrate /= d;
1129 outrate /= d;
1130 /* divide weightA and weightB by their greatest common divisor */
1131 d = gcd(weightA, weightB);
1132 weightA /= d;
1133 weightA /= d;
1134
1135 if ((size_t)nchannels > PY_SIZE_MAX/sizeof(int)) {
1136 PyErr_SetString(PyExc_MemoryError,
1137 "not enough memory for output buffer");
1138 return 0;
1139 }
1140 prev_i = (int *) malloc(nchannels * sizeof(int));
1141 cur_i = (int *) malloc(nchannels * sizeof(int));
1142 if (prev_i == NULL || cur_i == NULL) {
1143 (void) PyErr_NoMemory();
1144 goto exit;
1145 }
1146
1147 len /= bytes_per_frame; /* # of frames */
1148
1149 if (state == Py_None) {
1150 d = -outrate;
1151 for (chan = 0; chan < nchannels; chan++)
1152 prev_i[chan] = cur_i[chan] = 0;
1153 }
1154 else {
1155 if (!PyArg_ParseTuple(state,
1156 "iO!;audioop.ratecv: illegal state argument",
1157 &d, &PyTuple_Type, &samps))
1158 goto exit;
1159 if (PyTuple_Size(samps) != nchannels) {
1160 PyErr_SetString(AudioopError,
1161 "illegal state argument");
1162 goto exit;
1163 }
1164 for (chan = 0; chan < nchannels; chan++) {
1165 if (!PyArg_ParseTuple(PyTuple_GetItem(samps, chan),
1166 "ii:ratecv", &prev_i[chan],
1167 &cur_i[chan]))
1168 goto exit;
1169 }
1170 }
1171
1172 /* str <- Space for the output buffer. */
1173 if (len == 0)
1174 str = PyString_FromStringAndSize(NULL, 0);
1175 else {
1176 /* There are len input frames, so we need (mathematically)
1177 ceiling(len*outrate/inrate) output frames, and each frame
1178 requires bytes_per_frame bytes. Computing this
1179 without spurious overflow is the challenge; we can
1180 settle for a reasonable upper bound, though, in this
1181 case ceiling(len/inrate) * outrate. */
1182
1183 /* compute ceiling(len/inrate) without overflow */
1184 int q = len > 0 ? 1 + (len - 1) / inrate : 0;
1185 if (outrate > INT_MAX / q / bytes_per_frame)
1186 str = NULL;
1187 else
1188 str = PyString_FromStringAndSize(NULL,
1189 q * outrate * bytes_per_frame);
1190 }
1191 if (str == NULL) {
1192 PyErr_SetString(PyExc_MemoryError,
1193 "not enough memory for output buffer");
1194 goto exit;
1195 }
1196 ncp = PyString_AsString(str);
1197
1198 for (;;) {
1199 while (d < 0) {
1200 if (len == 0) {
1201 samps = PyTuple_New(nchannels);
1202 if (samps == NULL)
1203 goto exit;
1204 for (chan = 0; chan < nchannels; chan++)
1205 PyTuple_SetItem(samps, chan,
1206 Py_BuildValue("(ii)",
1207 prev_i[chan],
1208 cur_i[chan]));
1209 if (PyErr_Occurred())
1210 goto exit;
1211 /* We have checked before that the length
1212 * of the string fits into int. */
1213 len = (int)(ncp - PyString_AsString(str));
1214 if (len == 0) {
1215 /*don't want to resize to zero length*/
1216 rv = PyString_FromStringAndSize("", 0);
1217 Py_DECREF(str);
1218 str = rv;
1219 } else if (_PyString_Resize(&str, len) < 0)
1220 goto exit;
1221 rv = Py_BuildValue("(O(iO))", str, d, samps);
1222 Py_DECREF(samps);
1223 Py_DECREF(str);
1224 goto exit; /* return rv */
1225 }
1226 for (chan = 0; chan < nchannels; chan++) {
1227 prev_i[chan] = cur_i[chan];
1228 if (size == 1)
1229 cur_i[chan] = ((int)*CHARP(cp, 0)) << 24;
1230 else if (size == 2)
1231 cur_i[chan] = ((int)*SHORTP(cp, 0)) << 16;
1232 else if (size == 4)
1233 cur_i[chan] = (int)*LONGP(cp, 0);
1234 cp += size;
1235 /* implements a simple digital filter */
1236 cur_i[chan] = (int)(
1237 ((double)weightA * (double)cur_i[chan] +
1238 (double)weightB * (double)prev_i[chan]) /
1239 ((double)weightA + (double)weightB));
1240 }
1241 len--;
1242 d += outrate;
1243 }
1244 while (d >= 0) {
1245 for (chan = 0; chan < nchannels; chan++) {
1246 cur_o = (int)(((double)prev_i[chan] * (double)d +
1247 (double)cur_i[chan] * (double)(outrate - d)) /
1248 (double)outrate);
1249 if (size == 1)
1250 *CHARP(ncp, 0) = (signed char)(cur_o >> 24);
1251 else if (size == 2)
1252 *SHORTP(ncp, 0) = (short)(cur_o >> 16);
1253 else if (size == 4)
1254 *LONGP(ncp, 0) = (Py_Int32)(cur_o);
1255 ncp += size;
1256 }
1257 d -= inrate;
1258 }
1259 }
1260 exit:
1261 if (prev_i != NULL)
1262 free(prev_i);
1263 if (cur_i != NULL)
1264 free(cur_i);
1265 return rv;
1266}
1267
1268static PyObject *
1269audioop_lin2ulaw(PyObject *self, PyObject *args)
1270{
1271 signed char *cp;
1272 unsigned char *ncp;
1273 int len, size, val = 0;
1274 PyObject *rv;
1275 int i;
1276
1277 if ( !PyArg_ParseTuple(args, "s#i:lin2ulaw",
1278 &cp, &len, &size) )
1279 return 0 ;
1280
1281 if (!audioop_check_parameters(len, size))
1282 return NULL;
1283
1284 rv = PyString_FromStringAndSize(NULL, len/size);
1285 if ( rv == 0 )
1286 return 0;
1287 ncp = (unsigned char *)PyString_AsString(rv);
1288
1289 for ( i=0; i < len; i += size ) {
1290 if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;
1291 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
1292 else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;
1293
1294 *ncp++ = st_14linear2ulaw(val);
1295 }
1296 return rv;
1297}
1298
1299static PyObject *
1300audioop_ulaw2lin(PyObject *self, PyObject *args)
1301{
1302 unsigned char *cp;
1303 unsigned char cval;
1304 signed char *ncp;
1305 int len, size, val;
1306 PyObject *rv;
1307 int i;
1308
1309 if ( !PyArg_ParseTuple(args, "s#i:ulaw2lin",
1310 &cp, &len, &size) )
1311 return 0;
1312
1313 if (!audioop_check_size(size))
1314 return NULL;
1315
1316 if (len > INT_MAX/size) {
1317 PyErr_SetString(PyExc_MemoryError,
1318 "not enough memory for output buffer");
1319 return 0;
1320 }
1321 rv = PyString_FromStringAndSize(NULL, len*size);
1322 if ( rv == 0 )
1323 return 0;
1324 ncp = (signed char *)PyString_AsString(rv);
1325
1326 for ( i=0; i < len*size; i += size ) {
1327 cval = *cp++;
1328 val = st_ulaw2linear16(cval);
1329
1330 if ( size == 1 ) *CHARP(ncp, i) = (signed char)(val >> 8);
1331 else if ( size == 2 ) *SHORTP(ncp, i) = (short)(val);
1332 else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(val<<16);
1333 }
1334 return rv;
1335}
1336
1337static PyObject *
1338audioop_lin2alaw(PyObject *self, PyObject *args)
1339{
1340 signed char *cp;
1341 unsigned char *ncp;
1342 int len, size, val = 0;
1343 PyObject *rv;
1344 int i;
1345
1346 if ( !PyArg_ParseTuple(args, "s#i:lin2alaw",
1347 &cp, &len, &size) )
1348 return 0;
1349
1350 if (!audioop_check_parameters(len, size))
1351 return NULL;
1352
1353 rv = PyString_FromStringAndSize(NULL, len/size);
1354 if ( rv == 0 )
1355 return 0;
1356 ncp = (unsigned char *)PyString_AsString(rv);
1357
1358 for ( i=0; i < len; i += size ) {
1359 if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;
1360 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
1361 else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;
1362
1363 *ncp++ = st_linear2alaw(val);
1364 }
1365 return rv;
1366}
1367
1368static PyObject *
1369audioop_alaw2lin(PyObject *self, PyObject *args)
1370{
1371 unsigned char *cp;
1372 unsigned char cval;
1373 signed char *ncp;
1374 int len, size, val;
1375 PyObject *rv;
1376 int i;
1377
1378 if ( !PyArg_ParseTuple(args, "s#i:alaw2lin",
1379 &cp, &len, &size) )
1380 return 0;
1381
1382 if (!audioop_check_size(size))
1383 return NULL;
1384
1385 if (len > INT_MAX/size) {
1386 PyErr_SetString(PyExc_MemoryError,
1387 "not enough memory for output buffer");
1388 return 0;
1389 }
1390 rv = PyString_FromStringAndSize(NULL, len*size);
1391 if ( rv == 0 )
1392 return 0;
1393 ncp = (signed char *)PyString_AsString(rv);
1394
1395 for ( i=0; i < len*size; i += size ) {
1396 cval = *cp++;
1397 val = st_alaw2linear16(cval);
1398
1399 if ( size == 1 ) *CHARP(ncp, i) = (signed char)(val >> 8);
1400 else if ( size == 2 ) *SHORTP(ncp, i) = (short)(val);
1401 else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(val<<16);
1402 }
1403 return rv;
1404}
1405
1406static PyObject *
1407audioop_lin2adpcm(PyObject *self, PyObject *args)
1408{
1409 signed char *cp;
1410 signed char *ncp;
1411 int len, size, val = 0, step, valpred, delta,
1412 index, sign, vpdiff, diff;
1413 PyObject *rv, *state, *str;
1414 int i, outputbuffer = 0, bufferstep;
1415
1416 if ( !PyArg_ParseTuple(args, "s#iO:lin2adpcm",
1417 &cp, &len, &size, &state) )
1418 return 0;
1419
1420 if (!audioop_check_parameters(len, size))
1421 return NULL;
1422
1423 str = PyString_FromStringAndSize(NULL, len/(size*2));
1424 if ( str == 0 )
1425 return 0;
1426 ncp = (signed char *)PyString_AsString(str);
1427
1428 /* Decode state, should have (value, step) */
1429 if ( state == Py_None ) {
1430 /* First time, it seems. Set defaults */
1431 valpred = 0;
1432 index = 0;
1433 } else if ( !PyArg_ParseTuple(state, "ii", &valpred, &index) )
1434 return 0;
1435
1436 step = stepsizeTable[index];
1437 bufferstep = 1;
1438
1439 for ( i=0; i < len; i += size ) {
1440 if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;
1441 else if ( size == 2 ) val = (int)*SHORTP(cp, i);
1442 else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;
1443
1444 /* Step 1 - compute difference with previous value */
1445 diff = val - valpred;
1446 sign = (diff < 0) ? 8 : 0;
1447 if ( sign ) diff = (-diff);
1448
1449 /* Step 2 - Divide and clamp */
1450 /* Note:
1451 ** This code *approximately* computes:
1452 ** delta = diff*4/step;
1453 ** vpdiff = (delta+0.5)*step/4;
1454 ** but in shift step bits are dropped. The net result of this
1455 ** is that even if you have fast mul/div hardware you cannot
1456 ** put it to good use since the fixup would be too expensive.
1457 */
1458 delta = 0;
1459 vpdiff = (step >> 3);
1460
1461 if ( diff >= step ) {
1462 delta = 4;
1463 diff -= step;
1464 vpdiff += step;
1465 }
1466 step >>= 1;
1467 if ( diff >= step ) {
1468 delta |= 2;
1469 diff -= step;
1470 vpdiff += step;
1471 }
1472 step >>= 1;
1473 if ( diff >= step ) {
1474 delta |= 1;
1475 vpdiff += step;
1476 }
1477
1478 /* Step 3 - Update previous value */
1479 if ( sign )
1480 valpred -= vpdiff;
1481 else
1482 valpred += vpdiff;
1483
1484 /* Step 4 - Clamp previous value to 16 bits */
1485 if ( valpred > 32767 )
1486 valpred = 32767;
1487 else if ( valpred < -32768 )
1488 valpred = -32768;
1489
1490 /* Step 5 - Assemble value, update index and step values */
1491 delta |= sign;
1492
1493 index += indexTable[delta];
1494 if ( index < 0 ) index = 0;
1495 if ( index > 88 ) index = 88;
1496 step = stepsizeTable[index];
1497
1498 /* Step 6 - Output value */
1499 if ( bufferstep ) {
1500 outputbuffer = (delta << 4) & 0xf0;
1501 } else {
1502 *ncp++ = (delta & 0x0f) | outputbuffer;
1503 }
1504 bufferstep = !bufferstep;
1505 }
1506 rv = Py_BuildValue("(O(ii))", str, valpred, index);
1507 Py_DECREF(str);
1508 return rv;
1509}
1510
1511static PyObject *
1512audioop_adpcm2lin(PyObject *self, PyObject *args)
1513{
1514 signed char *cp;
1515 signed char *ncp;
1516 int len, size, valpred, step, delta, index, sign, vpdiff;
1517 PyObject *rv, *str, *state;
1518 int i, inputbuffer = 0, bufferstep;
1519
1520 if ( !PyArg_ParseTuple(args, "s#iO:adpcm2lin",
1521 &cp, &len, &size, &state) )
1522 return 0;
1523
1524 if (!audioop_check_size(size))
1525 return NULL;
1526
1527 /* Decode state, should have (value, step) */
1528 if ( state == Py_None ) {
1529 /* First time, it seems. Set defaults */
1530 valpred = 0;
1531 index = 0;
1532 } else if ( !PyArg_ParseTuple(state, "ii", &valpred, &index) )
1533 return 0;
1534
1535 if (len > (INT_MAX/2)/size) {
1536 PyErr_SetString(PyExc_MemoryError,
1537 "not enough memory for output buffer");
1538 return 0;
1539 }
1540 str = PyString_FromStringAndSize(NULL, len*size*2);
1541 if ( str == 0 )
1542 return 0;
1543 ncp = (signed char *)PyString_AsString(str);
1544
1545 step = stepsizeTable[index];
1546 bufferstep = 0;
1547
1548 for ( i=0; i < len*size*2; i += size ) {
1549 /* Step 1 - get the delta value and compute next index */
1550 if ( bufferstep ) {
1551 delta = inputbuffer & 0xf;
1552 } else {
1553 inputbuffer = *cp++;
1554 delta = (inputbuffer >> 4) & 0xf;
1555 }
1556
1557 bufferstep = !bufferstep;
1558
1559 /* Step 2 - Find new index value (for later) */
1560 index += indexTable[delta];
1561 if ( index < 0 ) index = 0;
1562 if ( index > 88 ) index = 88;
1563
1564 /* Step 3 - Separate sign and magnitude */
1565 sign = delta & 8;
1566 delta = delta & 7;
1567
1568 /* Step 4 - Compute difference and new predicted value */
1569 /*
1570 ** Computes 'vpdiff = (delta+0.5)*step/4', but see comment
1571 ** in adpcm_coder.
1572 */
1573 vpdiff = step >> 3;
1574 if ( delta & 4 ) vpdiff += step;
1575 if ( delta & 2 ) vpdiff += step>>1;
1576 if ( delta & 1 ) vpdiff += step>>2;
1577
1578 if ( sign )
1579 valpred -= vpdiff;
1580 else
1581 valpred += vpdiff;
1582
1583 /* Step 5 - clamp output value */
1584 if ( valpred > 32767 )
1585 valpred = 32767;
1586 else if ( valpred < -32768 )
1587 valpred = -32768;
1588
1589 /* Step 6 - Update step value */
1590 step = stepsizeTable[index];
1591
1592 /* Step 6 - Output value */
1593 if ( size == 1 ) *CHARP(ncp, i) = (signed char)(valpred >> 8);
1594 else if ( size == 2 ) *SHORTP(ncp, i) = (short)(valpred);
1595 else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(valpred<<16);
1596 }
1597
1598 rv = Py_BuildValue("(O(ii))", str, valpred, index);
1599 Py_DECREF(str);
1600 return rv;
1601}
1602
1603static PyMethodDef audioop_methods[] = {
1604 { "max", audioop_max, METH_VARARGS },
1605 { "minmax", audioop_minmax, METH_VARARGS },
1606 { "avg", audioop_avg, METH_VARARGS },
1607 { "maxpp", audioop_maxpp, METH_VARARGS },
1608 { "avgpp", audioop_avgpp, METH_VARARGS },
1609 { "rms", audioop_rms, METH_VARARGS },
1610 { "findfit", audioop_findfit, METH_VARARGS },
1611 { "findmax", audioop_findmax, METH_VARARGS },
1612 { "findfactor", audioop_findfactor, METH_VARARGS },
1613 { "cross", audioop_cross, METH_VARARGS },
1614 { "mul", audioop_mul, METH_VARARGS },
1615 { "add", audioop_add, METH_VARARGS },
1616 { "bias", audioop_bias, METH_VARARGS },
1617 { "ulaw2lin", audioop_ulaw2lin, METH_VARARGS },
1618 { "lin2ulaw", audioop_lin2ulaw, METH_VARARGS },
1619 { "alaw2lin", audioop_alaw2lin, METH_VARARGS },
1620 { "lin2alaw", audioop_lin2alaw, METH_VARARGS },
1621 { "lin2lin", audioop_lin2lin, METH_VARARGS },
1622 { "adpcm2lin", audioop_adpcm2lin, METH_VARARGS },
1623 { "lin2adpcm", audioop_lin2adpcm, METH_VARARGS },
1624 { "tomono", audioop_tomono, METH_VARARGS },
1625 { "tostereo", audioop_tostereo, METH_VARARGS },
1626 { "getsample", audioop_getsample, METH_VARARGS },
1627 { "reverse", audioop_reverse, METH_VARARGS },
1628 { "ratecv", audioop_ratecv, METH_VARARGS },
1629 { 0, 0 }
1630};
1631
1632PyMODINIT_FUNC
1633initaudioop(void)
1634{
1635 PyObject *m, *d;
1636 m = Py_InitModule("audioop", audioop_methods);
1637 if (m == NULL)
1638 return;
1639 d = PyModule_GetDict(m);
1640 if (d == NULL)
1641 return;
1642 AudioopError = PyErr_NewException("audioop.error", NULL, NULL);
1643 if (AudioopError != NULL)
1644 PyDict_SetItemString(d,"error",AudioopError);
1645}
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