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cpython/Modules/audioop.c

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/* audioopmodule - Module to detect peak values in arrays */
#define PY_SSIZE_T_CLEAN
#include "Python.h"
#if SIZEOF_INT == 4
typedef int Py_Int32;
typedef unsigned int Py_UInt32;
#else
#if SIZEOF_LONG == 4
typedef long Py_Int32;
typedef unsigned long Py_UInt32;
#else
#error "No 4-byte integral type"
#endif
#endif
typedef short PyInt16;
#if defined(__CHAR_UNSIGNED__)
#if defined(signed)
/* This module currently does not work on systems where only unsigned
characters are available. Take it out of Setup. Sorry. */
#endif
#endif
/* Code shamelessly stolen from sox, 12.17.7, g711.c
** (c) Craig Reese, Joe Campbell and Jeff Poskanzer 1989 */
/* From g711.c:
*
* December 30, 1994:
* Functions linear2alaw, linear2ulaw have been updated to correctly
* convert unquantized 16 bit values.
* Tables for direct u- to A-law and A- to u-law conversions have been
* corrected.
* Borge Lindberg, Center for PersonKommunikation, Aalborg University.
* bli@cpk.auc.dk
*
*/
#define BIAS 0x84 /* define the add-in bias for 16 bit samples */
#define CLIP 32635
#define SIGN_BIT (0x80) /* Sign bit for a A-law byte. */
#define QUANT_MASK (0xf) /* Quantization field mask. */
#define SEG_SHIFT (4) /* Left shift for segment number. */
#define SEG_MASK (0x70) /* Segment field mask. */
static PyInt16 seg_aend[8] = {0x1F, 0x3F, 0x7F, 0xFF,
0x1FF, 0x3FF, 0x7FF, 0xFFF};
static PyInt16 seg_uend[8] = {0x3F, 0x7F, 0xFF, 0x1FF,
0x3FF, 0x7FF, 0xFFF, 0x1FFF};
static PyInt16
search(PyInt16 val, PyInt16 *table, int size)
{
int i;
for (i = 0; i < size; i++) {
if (val <= *table++)
return (i);
}
return (size);
}
#define st_ulaw2linear16(uc) (_st_ulaw2linear16[uc])
#define st_alaw2linear16(uc) (_st_alaw2linear16[uc])
static PyInt16 _st_ulaw2linear16[256] = {
-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
};
/*
* linear2ulaw() accepts a 14-bit signed integer and encodes it as u-law data
* stored in a unsigned char. This function should only be called with
* the data shifted such that it only contains information in the lower
* 14-bits.
*
* In order to simplify the encoding process, the original linear magnitude
* is biased by adding 33 which shifts the encoding range from (0 - 8158) to
* (33 - 8191). The result can be seen in the following encoding table:
*
* Biased Linear Input Code Compressed Code
* ------------------------ ---------------
* 00000001wxyza 000wxyz
* 0000001wxyzab 001wxyz
* 000001wxyzabc 010wxyz
* 00001wxyzabcd 011wxyz
* 0001wxyzabcde 100wxyz
* 001wxyzabcdef 101wxyz
* 01wxyzabcdefg 110wxyz
* 1wxyzabcdefgh 111wxyz
*
* Each biased linear code has a leading 1 which identifies the segment
* number. The value of the segment number is equal to 7 minus the number
* of leading 0's. The quantization interval is directly available as the
* four bits wxyz. * The trailing bits (a - h) are ignored.
*
* Ordinarily the complement of the resulting code word is used for
* transmission, and so the code word is complemented before it is returned.
*
* For further information see John C. Bellamy's Digital Telephony, 1982,
* John Wiley & Sons, pps 98-111 and 472-476.
*/
static unsigned char
st_14linear2ulaw(PyInt16 pcm_val) /* 2's complement (14-bit range) */
{
PyInt16 mask;
PyInt16 seg;
unsigned char uval;
/* The original sox code does this in the calling function, not here */
pcm_val = pcm_val >> 2;
/* u-law inverts all bits */
/* Get the sign and the magnitude of the value. */
if (pcm_val < 0) {
pcm_val = -pcm_val;
mask = 0x7F;
} else {
mask = 0xFF;
}
if ( pcm_val > CLIP ) pcm_val = CLIP; /* clip the magnitude */
pcm_val += (BIAS >> 2);
/* Convert the scaled magnitude to segment number. */
seg = search(pcm_val, seg_uend, 8);
/*
* Combine the sign, segment, quantization bits;
* and complement the code word.
*/
if (seg >= 8) /* out of range, return maximum value. */
return (unsigned char) (0x7F ^ mask);
else {
uval = (unsigned char) (seg << 4) | ((pcm_val >> (seg + 1)) & 0xF);
return (uval ^ mask);
}
}
static PyInt16 _st_alaw2linear16[256] = {
-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
};
/*
* linear2alaw() accepts an 13-bit signed integer and encodes it as A-law data
* stored in a unsigned char. This function should only be called with
* the data shifted such that it only contains information in the lower
* 13-bits.
*
* Linear Input Code Compressed Code
* ------------------------ ---------------
* 0000000wxyza 000wxyz
* 0000001wxyza 001wxyz
* 000001wxyzab 010wxyz
* 00001wxyzabc 011wxyz
* 0001wxyzabcd 100wxyz
* 001wxyzabcde 101wxyz
* 01wxyzabcdef 110wxyz
* 1wxyzabcdefg 111wxyz
*
* For further information see John C. Bellamy's Digital Telephony, 1982,
* John Wiley & Sons, pps 98-111 and 472-476.
*/
static unsigned char
st_linear2alaw(PyInt16 pcm_val) /* 2's complement (13-bit range) */
{
PyInt16 mask;
short seg;
unsigned char aval;
/* The original sox code does this in the calling function, not here */
pcm_val = pcm_val >> 3;
/* A-law using even bit inversion */
if (pcm_val >= 0) {
mask = 0xD5; /* sign (7th) bit = 1 */
} else {
mask = 0x55; /* sign bit = 0 */
pcm_val = -pcm_val - 1;
}
/* Convert the scaled magnitude to segment number. */
seg = search(pcm_val, seg_aend, 8);
/* Combine the sign, segment, and quantization bits. */
if (seg >= 8) /* out of range, return maximum value. */
return (unsigned char) (0x7F ^ mask);
else {
aval = (unsigned char) seg << SEG_SHIFT;
if (seg < 2)
aval |= (pcm_val >> 1) & QUANT_MASK;
else
aval |= (pcm_val >> seg) & QUANT_MASK;
return (aval ^ mask);
}
}
/* End of code taken from sox */
/* Intel ADPCM step variation table */
static int indexTable[16] = {
-1, -1, -1, -1, 2, 4, 6, 8,
-1, -1, -1, -1, 2, 4, 6, 8,
};
static int stepsizeTable[89] = {
7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
};
#define CHARP(cp, i) ((signed char *)(cp+i))
#define SHORTP(cp, i) ((short *)(cp+i))
#define LONGP(cp, i) ((Py_Int32 *)(cp+i))
static PyObject *AudioopError;
static int
audioop_check_size(int size)
{
if (size != 1 && size != 2 && size != 4) {
PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");
return 0;
}
else
return 1;
}
static int
audioop_check_parameters(Py_ssize_t len, int size)
{
if (!audioop_check_size(size))
return 0;
if (len % size != 0) {
PyErr_SetString(AudioopError, "not a whole number of frames");
return 0;
}
return 1;
}
static PyObject *
audioop_getsample(PyObject *self, PyObject *args)
{
signed char *cp;
Py_ssize_t len, i;
int size, val = 0;
if ( !PyArg_ParseTuple(args, "s#in:getsample", &cp, &len, &size, &i) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
if ( i < 0 || i >= len/size ) {
PyErr_SetString(AudioopError, "Index out of range");
return 0;
}
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i*2);
else if ( size == 4 ) val = (int)*LONGP(cp, i*4);
return PyLong_FromLong(val);
}
static PyObject *
audioop_max(PyObject *self, PyObject *args)
{
signed char *cp;
Py_ssize_t len, i;
int size, val = 0;
int max = 0;
if ( !PyArg_ParseTuple(args, "s#i:max", &cp, &len, &size) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
for ( i=0; i<len; i+= size) {
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
if ( val < 0 ) val = (-val);
if ( val > max ) max = val;
}
return PyLong_FromLong(max);
}
static PyObject *
audioop_minmax(PyObject *self, PyObject *args)
{
signed char *cp;
Py_ssize_t len, i;
int size, val = 0;
int min = 0x7fffffff, max = -0x7fffffff;
if (!PyArg_ParseTuple(args, "s#i:minmax", &cp, &len, &size))
return NULL;
if (!audioop_check_parameters(len, size))
return NULL;
for (i = 0; i < len; i += size) {
if (size == 1) val = (int) *CHARP(cp, i);
else if (size == 2) val = (int) *SHORTP(cp, i);
else if (size == 4) val = (int) *LONGP(cp, i);
if (val > max) max = val;
if (val < min) min = val;
}
return Py_BuildValue("(ii)", min, max);
}
static PyObject *
audioop_avg(PyObject *self, PyObject *args)
{
signed char *cp;
Py_ssize_t len, i;
int size, val = 0;
double avg = 0.0;
if ( !PyArg_ParseTuple(args, "s#i:avg", &cp, &len, &size) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
for ( i=0; i<len; i+= size) {
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
avg += val;
}
if ( len == 0 )
val = 0;
else
val = (int)(avg / (double)(len/size));
return PyLong_FromLong(val);
}
static PyObject *
audioop_rms(PyObject *self, PyObject *args)
{
signed char *cp;
Py_ssize_t len, i;
int size, val = 0;
double sum_squares = 0.0;
if ( !PyArg_ParseTuple(args, "s#i:rms", &cp, &len, &size) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
for ( i=0; i<len; i+= size) {
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
sum_squares += (double)val*(double)val;
}
if ( len == 0 )
val = 0;
else
val = (int)sqrt(sum_squares / (double)(len/size));
return PyLong_FromLong(val);
}
static double _sum2(short *a, short *b, Py_ssize_t len)
{
Py_ssize_t i;
double sum = 0.0;
for( i=0; i<len; i++) {
sum = sum + (double)a[i]*(double)b[i];
}
return sum;
}
/*
** Findfit tries to locate a sample within another sample. Its main use
** is in echo-cancellation (to find the feedback of the output signal in
** the input signal).
** The method used is as follows:
**
** let R be the reference signal (length n) and A the input signal (length N)
** with N > n, and let all sums be over i from 0 to n-1.
**
** Now, for each j in {0..N-n} we compute a factor fj so that -fj*R matches A
** as good as possible, i.e. sum( (A[j+i]+fj*R[i])^2 ) is minimal. This
** equation gives fj = sum( A[j+i]R[i] ) / sum(R[i]^2).
**
** Next, we compute the relative distance between the original signal and
** the modified signal and minimize that over j:
** vj = sum( (A[j+i]-fj*R[i])^2 ) / sum( A[j+i]^2 ) =>
** vj = ( sum(A[j+i]^2)*sum(R[i]^2) - sum(A[j+i]R[i])^2 ) / sum( A[j+i]^2 )
**
** In the code variables correspond as follows:
** cp1 A
** cp2 R
** len1 N
** len2 n
** aj_m1 A[j-1]
** aj_lm1 A[j+n-1]
** sum_ri_2 sum(R[i]^2)
** sum_aij_2 sum(A[i+j]^2)
** sum_aij_ri sum(A[i+j]R[i])
**
** sum_ri is calculated once, sum_aij_2 is updated each step and sum_aij_ri
** is completely recalculated each step.
*/
static PyObject *
audioop_findfit(PyObject *self, PyObject *args)
{
short *cp1, *cp2;
Py_ssize_t len1, len2;
Py_ssize_t j, best_j;
double aj_m1, aj_lm1;
double sum_ri_2, sum_aij_2, sum_aij_ri, result, best_result, factor;
/* Passing a short** for an 's' argument is correct only
if the string contents is aligned for interpretation
as short[]. Due to the definition of PyBytesObject,
this is currently (Python 2.6) the case. */
if ( !PyArg_ParseTuple(args, "s#s#:findfit",
(char**)&cp1, &len1, (char**)&cp2, &len2) )
return 0;
if ( len1 & 1 || len2 & 1 ) {
PyErr_SetString(AudioopError, "Strings should be even-sized");
return 0;
}
len1 >>= 1;
len2 >>= 1;
if ( len1 < len2 ) {
PyErr_SetString(AudioopError, "First sample should be longer");
return 0;
}
sum_ri_2 = _sum2(cp2, cp2, len2);
sum_aij_2 = _sum2(cp1, cp1, len2);
sum_aij_ri = _sum2(cp1, cp2, len2);
result = (sum_ri_2*sum_aij_2 - sum_aij_ri*sum_aij_ri) / sum_aij_2;
best_result = result;
best_j = 0;
j = 0;
for ( j=1; j<=len1-len2; j++) {
aj_m1 = (double)cp1[j-1];
aj_lm1 = (double)cp1[j+len2-1];
sum_aij_2 = sum_aij_2 + aj_lm1*aj_lm1 - aj_m1*aj_m1;
sum_aij_ri = _sum2(cp1+j, cp2, len2);
result = (sum_ri_2*sum_aij_2 - sum_aij_ri*sum_aij_ri)
/ sum_aij_2;
if ( result < best_result ) {
best_result = result;
best_j = j;
}
}
factor = _sum2(cp1+best_j, cp2, len2) / sum_ri_2;
return Py_BuildValue("(nf)", best_j, factor);
}
/*
** findfactor finds a factor f so that the energy in A-fB is minimal.
** See the comment for findfit for details.
*/
static PyObject *
audioop_findfactor(PyObject *self, PyObject *args)
{
short *cp1, *cp2;
Py_ssize_t len1, len2;
double sum_ri_2, sum_aij_ri, result;
if ( !PyArg_ParseTuple(args, "s#s#:findfactor",
(char**)&cp1, &len1, (char**)&cp2, &len2) )
return 0;
if ( len1 & 1 || len2 & 1 ) {
PyErr_SetString(AudioopError, "Strings should be even-sized");
return 0;
}
if ( len1 != len2 ) {
PyErr_SetString(AudioopError, "Samples should be same size");
return 0;
}
len2 >>= 1;
sum_ri_2 = _sum2(cp2, cp2, len2);
sum_aij_ri = _sum2(cp1, cp2, len2);
result = sum_aij_ri / sum_ri_2;
return PyFloat_FromDouble(result);
}
/*
** findmax returns the index of the n-sized segment of the input sample
** that contains the most energy.
*/
static PyObject *
audioop_findmax(PyObject *self, PyObject *args)
{
short *cp1;
Py_ssize_t len1, len2;
Py_ssize_t j, best_j;
double aj_m1, aj_lm1;
double result, best_result;
if ( !PyArg_ParseTuple(args, "s#n:findmax",
(char**)&cp1, &len1, &len2) )
return 0;
if ( len1 & 1 ) {
PyErr_SetString(AudioopError, "Strings should be even-sized");
return 0;
}
len1 >>= 1;
if ( len2 < 0 || len1 < len2 ) {
PyErr_SetString(AudioopError, "Input sample should be longer");
return 0;
}
result = _sum2(cp1, cp1, len2);
best_result = result;
best_j = 0;
j = 0;
for ( j=1; j<=len1-len2; j++) {
aj_m1 = (double)cp1[j-1];
aj_lm1 = (double)cp1[j+len2-1];
result = result + aj_lm1*aj_lm1 - aj_m1*aj_m1;
if ( result > best_result ) {
best_result = result;
best_j = j;
}
}
return PyLong_FromSsize_t(best_j);
}
static PyObject *
audioop_avgpp(PyObject *self, PyObject *args)
{
signed char *cp;
Py_ssize_t len, i;
int size, val = 0, prevval = 0, prevextremevalid = 0,
prevextreme = 0;
double avg = 0.0;
int diff, prevdiff, extremediff, nextreme = 0;
if ( !PyArg_ParseTuple(args, "s#i:avgpp", &cp, &len, &size) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
/* Compute first delta value ahead. Also automatically makes us
** skip the first extreme value
*/
if ( size == 1 ) prevval = (int)*CHARP(cp, 0);
else if ( size == 2 ) prevval = (int)*SHORTP(cp, 0);
else if ( size == 4 ) prevval = (int)*LONGP(cp, 0);
if ( size == 1 ) val = (int)*CHARP(cp, size);
else if ( size == 2 ) val = (int)*SHORTP(cp, size);
else if ( size == 4 ) val = (int)*LONGP(cp, size);
prevdiff = val - prevval;
for ( i=size; i<len; i+= size) {
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
diff = val - prevval;
if ( diff*prevdiff < 0 ) {
/* Derivative changed sign. Compute difference to last
** extreme value and remember.
*/
if ( prevextremevalid ) {
extremediff = prevval - prevextreme;
if ( extremediff < 0 )
extremediff = -extremediff;
avg += extremediff;
nextreme++;
}
prevextremevalid = 1;
prevextreme = prevval;
}
prevval = val;
if ( diff != 0 )
prevdiff = diff;
}
if ( nextreme == 0 )
val = 0;
else
val = (int)(avg / (double)nextreme);
return PyLong_FromLong(val);
}
static PyObject *
audioop_maxpp(PyObject *self, PyObject *args)
{
signed char *cp;
Py_ssize_t len, i;
int size, val = 0, prevval = 0, prevextremevalid = 0,
prevextreme = 0;
int max = 0;
int diff, prevdiff, extremediff;
if ( !PyArg_ParseTuple(args, "s#i:maxpp", &cp, &len, &size) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
/* Compute first delta value ahead. Also automatically makes us
** skip the first extreme value
*/
if ( size == 1 ) prevval = (int)*CHARP(cp, 0);
else if ( size == 2 ) prevval = (int)*SHORTP(cp, 0);
else if ( size == 4 ) prevval = (int)*LONGP(cp, 0);
if ( size == 1 ) val = (int)*CHARP(cp, size);
else if ( size == 2 ) val = (int)*SHORTP(cp, size);
else if ( size == 4 ) val = (int)*LONGP(cp, size);
prevdiff = val - prevval;
for ( i=size; i<len; i+= size) {
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
diff = val - prevval;
if ( diff*prevdiff < 0 ) {
/* Derivative changed sign. Compute difference to
** last extreme value and remember.
*/
if ( prevextremevalid ) {
extremediff = prevval - prevextreme;
if ( extremediff < 0 )
extremediff = -extremediff;
if ( extremediff > max )
max = extremediff;
}
prevextremevalid = 1;
prevextreme = prevval;
}
prevval = val;
if ( diff != 0 )
prevdiff = diff;
}
return PyLong_FromLong(max);
}
static PyObject *
audioop_cross(PyObject *self, PyObject *args)
{
signed char *cp;
Py_ssize_t len, i;
int size, val = 0;
int prevval;
Py_ssize_t ncross;
if ( !PyArg_ParseTuple(args, "s#i:cross", &cp, &len, &size) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
ncross = -1;
prevval = 17; /* Anything <> 0,1 */
for ( i=0; i<len; i+= size) {
if ( size == 1 ) val = ((int)*CHARP(cp, i)) >> 7;
else if ( size == 2 ) val = ((int)*SHORTP(cp, i)) >> 15;
else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 31;
val = val & 1;
if ( val != prevval ) ncross++;
prevval = val;
}
return PyLong_FromSsize_t(ncross);
}
static PyObject *
audioop_mul(PyObject *self, PyObject *args)
{
signed char *cp, *ncp;
Py_ssize_t len, i;
int size, val = 0;
double factor, fval, maxval;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s#id:mul", &cp, &len, &size, &factor ) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
if ( size == 1 ) maxval = (double) 0x7f;
else if ( size == 2 ) maxval = (double) 0x7fff;
else if ( size == 4 ) maxval = (double) 0x7fffffff;
else {
PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");
return 0;
}
rv = PyBytes_FromStringAndSize(NULL, len);
if ( rv == 0 )
return 0;
ncp = (signed char *)PyBytes_AsString(rv);
for ( i=0; i < len; i += size ) {
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
fval = (double)val*factor;
if ( fval > maxval ) fval = maxval;
else if ( fval < -maxval ) fval = -maxval;
val = (int)fval;
if ( size == 1 ) *CHARP(ncp, i) = (signed char)val;
else if ( size == 2 ) *SHORTP(ncp, i) = (short)val;
else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)val;
}
return rv;
}
static PyObject *
audioop_tomono(PyObject *self, PyObject *args)
{
Py_buffer pcp;
signed char *cp, *ncp;
Py_ssize_t len, i;
int size, val1 = 0, val2 = 0;
double fac1, fac2, fval, maxval;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s*idd:tomono",
&pcp, &size, &fac1, &fac2 ) )
return 0;
cp = pcp.buf;
len = pcp.len;
if (!audioop_check_parameters(len, size)) {
PyBuffer_Release(&pcp);
return NULL;
}
if (((len / size) & 1) != 0) {
PyErr_SetString(AudioopError, "not a whole number of frames");
PyBuffer_Release(&pcp);
return NULL;
}
if ( size == 1 ) maxval = (double) 0x7f;
else if ( size == 2 ) maxval = (double) 0x7fff;
else if ( size == 4 ) maxval = (double) 0x7fffffff;
else {
PyBuffer_Release(&pcp);
PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");
return 0;
}
rv = PyBytes_FromStringAndSize(NULL, len/2);
if ( rv == 0 ) {
PyBuffer_Release(&pcp);
return 0;
}
ncp = (signed char *)PyBytes_AsString(rv);
for ( i=0; i < len; i += size*2 ) {
if ( size == 1 ) val1 = (int)*CHARP(cp, i);
else if ( size == 2 ) val1 = (int)*SHORTP(cp, i);
else if ( size == 4 ) val1 = (int)*LONGP(cp, i);
if ( size == 1 ) val2 = (int)*CHARP(cp, i+1);
else if ( size == 2 ) val2 = (int)*SHORTP(cp, i+2);
else if ( size == 4 ) val2 = (int)*LONGP(cp, i+4);
fval = (double)val1*fac1 + (double)val2*fac2;
if ( fval > maxval ) fval = maxval;
else if ( fval < -maxval ) fval = -maxval;
val1 = (int)fval;
if ( size == 1 ) *CHARP(ncp, i/2) = (signed char)val1;
else if ( size == 2 ) *SHORTP(ncp, i/2) = (short)val1;
else if ( size == 4 ) *LONGP(ncp, i/2)= (Py_Int32)val1;
}
PyBuffer_Release(&pcp);
return rv;
}
static PyObject *
audioop_tostereo(PyObject *self, PyObject *args)
{
signed char *cp, *ncp;
Py_ssize_t len, i;
int size, val1, val2, val = 0;
double fac1, fac2, fval, maxval;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s#idd:tostereo",
&cp, &len, &size, &fac1, &fac2 ) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
if ( size == 1 ) maxval = (double) 0x7f;
else if ( size == 2 ) maxval = (double) 0x7fff;
else if ( size == 4 ) maxval = (double) 0x7fffffff;
else {
PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");
return 0;
}
if (len > PY_SSIZE_T_MAX/2) {
PyErr_SetString(PyExc_MemoryError,
"not enough memory for output buffer");
return 0;
}
rv = PyBytes_FromStringAndSize(NULL, len*2);
if ( rv == 0 )
return 0;
ncp = (signed char *)PyBytes_AsString(rv);
for ( i=0; i < len; i += size ) {
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
fval = (double)val*fac1;
if ( fval > maxval ) fval = maxval;
else if ( fval < -maxval ) fval = -maxval;
val1 = (int)fval;
fval = (double)val*fac2;
if ( fval > maxval ) fval = maxval;
else if ( fval < -maxval ) fval = -maxval;
val2 = (int)fval;
if ( size == 1 ) *CHARP(ncp, i*2) = (signed char)val1;
else if ( size == 2 ) *SHORTP(ncp, i*2) = (short)val1;
else if ( size == 4 ) *LONGP(ncp, i*2) = (Py_Int32)val1;
if ( size == 1 ) *CHARP(ncp, i*2+1) = (signed char)val2;
else if ( size == 2 ) *SHORTP(ncp, i*2+2) = (short)val2;
else if ( size == 4 ) *LONGP(ncp, i*2+4) = (Py_Int32)val2;
}
return rv;
}
static PyObject *
audioop_add(PyObject *self, PyObject *args)
{
signed char *cp1, *cp2, *ncp;
Py_ssize_t len1, len2, i;
int size, val1 = 0, val2 = 0, maxval, newval;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s#s#i:add",
&cp1, &len1, &cp2, &len2, &size ) )
return 0;
if (!audioop_check_parameters(len1, size))
return NULL;
if ( len1 != len2 ) {
PyErr_SetString(AudioopError, "Lengths should be the same");
return 0;
}
if ( size == 1 ) maxval = 0x7f;
else if ( size == 2 ) maxval = 0x7fff;
else if ( size == 4 ) maxval = 0x7fffffff;
else {
PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");
return 0;
}
rv = PyBytes_FromStringAndSize(NULL, len1);
if ( rv == 0 )
return 0;
ncp = (signed char *)PyBytes_AsString(rv);
for ( i=0; i < len1; i += size ) {
if ( size == 1 ) val1 = (int)*CHARP(cp1, i);
else if ( size == 2 ) val1 = (int)*SHORTP(cp1, i);
else if ( size == 4 ) val1 = (int)*LONGP(cp1, i);
if ( size == 1 ) val2 = (int)*CHARP(cp2, i);
else if ( size == 2 ) val2 = (int)*SHORTP(cp2, i);
else if ( size == 4 ) val2 = (int)*LONGP(cp2, i);
newval = val1 + val2;
/* truncate in case of overflow */
if (newval > maxval) newval = maxval;
else if (newval < -maxval) newval = -maxval;
else if (size == 4 && (newval^val1) < 0 && (newval^val2) < 0)
newval = val1 > 0 ? maxval : - maxval;
if ( size == 1 ) *CHARP(ncp, i) = (signed char)newval;
else if ( size == 2 ) *SHORTP(ncp, i) = (short)newval;
else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)newval;
}
return rv;
}
static PyObject *
audioop_bias(PyObject *self, PyObject *args)
{
signed char *cp, *ncp;
Py_ssize_t len, i;
int size, val = 0;
PyObject *rv;
int bias;
if ( !PyArg_ParseTuple(args, "s#ii:bias",
&cp, &len, &size , &bias) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
rv = PyBytes_FromStringAndSize(NULL, len);
if ( rv == 0 )
return 0;
ncp = (signed char *)PyBytes_AsString(rv);
for ( i=0; i < len; i += size ) {
if ( size == 1 ) val = (int)*CHARP(cp, i);
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = (int)*LONGP(cp, i);
if ( size == 1 ) *CHARP(ncp, i) = (signed char)(val+bias);
else if ( size == 2 ) *SHORTP(ncp, i) = (short)(val+bias);
else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(val+bias);
}
return rv;
}
static PyObject *
audioop_reverse(PyObject *self, PyObject *args)
{
signed char *cp;
unsigned char *ncp;
Py_ssize_t len, i, j;
int size, val = 0;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s#i:reverse",
&cp, &len, &size) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
rv = PyBytes_FromStringAndSize(NULL, len);
if ( rv == 0 )
return 0;
ncp = (unsigned char *)PyBytes_AsString(rv);
for ( i=0; i < len; i += size ) {
if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;
j = len - i - size;
if ( size == 1 ) *CHARP(ncp, j) = (signed char)(val >> 8);
else if ( size == 2 ) *SHORTP(ncp, j) = (short)(val);
else if ( size == 4 ) *LONGP(ncp, j) = (Py_Int32)(val<<16);
}
return rv;
}
static PyObject *
audioop_lin2lin(PyObject *self, PyObject *args)
{
signed char *cp;
unsigned char *ncp;
Py_ssize_t len, i, j;
int size, size2, val = 0;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s#ii:lin2lin",
&cp, &len, &size, &size2) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
if (!audioop_check_size(size2))
return NULL;
if (len/size > PY_SSIZE_T_MAX/size2) {
PyErr_SetString(PyExc_MemoryError,
"not enough memory for output buffer");
return 0;
}
rv = PyBytes_FromStringAndSize(NULL, (len/size)*size2);
if ( rv == 0 )
return 0;
ncp = (unsigned char *)PyBytes_AsString(rv);
for ( i=0, j=0; i < len; i += size, j += size2 ) {
if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;
if ( size2 == 1 ) *CHARP(ncp, j) = (signed char)(val >> 8);
else if ( size2 == 2 ) *SHORTP(ncp, j) = (short)(val);
else if ( size2 == 4 ) *LONGP(ncp, j) = (Py_Int32)(val<<16);
}
return rv;
}
static int
gcd(int a, int b)
{
while (b > 0) {
int tmp = a % b;
a = b;
b = tmp;
}
return a;
}
static PyObject *
audioop_ratecv(PyObject *self, PyObject *args)
{
char *cp, *ncp;
Py_ssize_t len;
int size, nchannels, inrate, outrate, weightA, weightB;
int chan, d, *prev_i, *cur_i, cur_o;
PyObject *state, *samps, *str, *rv = NULL;
int bytes_per_frame;
weightA = 1;
weightB = 0;
if (!PyArg_ParseTuple(args, "s#iiiiO|ii:ratecv", &cp, &len, &size,
&nchannels, &inrate, &outrate, &state,
&weightA, &weightB))
return NULL;
if (!audioop_check_size(size))
return NULL;
if (nchannels < 1) {
PyErr_SetString(AudioopError, "# of channels should be >= 1");
return NULL;
}
bytes_per_frame = size * nchannels;
if (bytes_per_frame / nchannels != size) {
/* This overflow test is rigorously correct because
both multiplicands are >= 1. Use the argument names
from the docs for the error msg. */
PyErr_SetString(PyExc_OverflowError,
"width * nchannels too big for a C int");
return NULL;
}
if (weightA < 1 || weightB < 0) {
PyErr_SetString(AudioopError,
"weightA should be >= 1, weightB should be >= 0");
return NULL;
}
if (len % bytes_per_frame != 0) {
PyErr_SetString(AudioopError, "not a whole number of frames");
return NULL;
}
if (inrate <= 0 || outrate <= 0) {
PyErr_SetString(AudioopError, "sampling rate not > 0");
return NULL;
}
/* divide inrate and outrate by their greatest common divisor */
d = gcd(inrate, outrate);
inrate /= d;
outrate /= d;
if ((size_t)nchannels > PY_SIZE_MAX/sizeof(int)) {
PyErr_SetString(PyExc_MemoryError,
"not enough memory for output buffer");
return 0;
}
prev_i = (int *) malloc(nchannels * sizeof(int));
cur_i = (int *) malloc(nchannels * sizeof(int));
if (prev_i == NULL || cur_i == NULL) {
(void) PyErr_NoMemory();
goto exit;
}
len /= bytes_per_frame; /* # of frames */
if (state == Py_None) {
d = -outrate;
for (chan = 0; chan < nchannels; chan++)
prev_i[chan] = cur_i[chan] = 0;
}
else {
if (!PyArg_ParseTuple(state,
"iO!;audioop.ratecv: illegal state argument",
&d, &PyTuple_Type, &samps))
goto exit;
if (PyTuple_Size(samps) != nchannels) {
PyErr_SetString(AudioopError,
"illegal state argument");
goto exit;
}
for (chan = 0; chan < nchannels; chan++) {
if (!PyArg_ParseTuple(PyTuple_GetItem(samps, chan),
"ii:ratecv", &prev_i[chan],
&cur_i[chan]))
goto exit;
}
}
/* str <- Space for the output buffer. */
{
/* There are len input frames, so we need (mathematically)
ceiling(len*outrate/inrate) output frames, and each frame
requires bytes_per_frame bytes. Computing this
without spurious overflow is the challenge; we can
settle for a reasonable upper bound, though, in this
case ceiling(len/inrate) * outrate. */
/* compute ceiling(len/inrate) without overflow */
Py_ssize_t q = len > 0 ? 1 + (len - 1) / inrate : 0;
if (outrate > PY_SSIZE_T_MAX / q / bytes_per_frame)
str = NULL;
else
str = PyBytes_FromStringAndSize(NULL,
q * outrate * bytes_per_frame);
if (str == NULL) {
PyErr_SetString(PyExc_MemoryError,
"not enough memory for output buffer");
goto exit;
}
}
ncp = PyBytes_AsString(str);
for (;;) {
while (d < 0) {
if (len == 0) {
samps = PyTuple_New(nchannels);
if (samps == NULL)
goto exit;
for (chan = 0; chan < nchannels; chan++)
PyTuple_SetItem(samps, chan,
Py_BuildValue("(ii)",
prev_i[chan],
cur_i[chan]));
if (PyErr_Occurred())
goto exit;
/* We have checked before that the length
* of the string fits into int. */
len = (Py_ssize_t)(ncp - PyBytes_AsString(str));
rv = PyBytes_FromStringAndSize
(PyBytes_AsString(str), len);
Py_DECREF(str);
str = rv;
if (str == NULL)
goto exit;
rv = Py_BuildValue("(O(iO))", str, d, samps);
Py_DECREF(samps);
Py_DECREF(str);
goto exit; /* return rv */
}
for (chan = 0; chan < nchannels; chan++) {
prev_i[chan] = cur_i[chan];
if (size == 1)
cur_i[chan] = ((int)*CHARP(cp, 0)) << 8;
else if (size == 2)
cur_i[chan] = (int)*SHORTP(cp, 0);
else if (size == 4)
cur_i[chan] = ((int)*LONGP(cp, 0)) >> 16;
cp += size;
/* implements a simple digital filter */
cur_i[chan] =
(weightA * cur_i[chan] +
weightB * prev_i[chan]) /
(weightA + weightB);
}
len--;
d += outrate;
}
while (d >= 0) {
for (chan = 0; chan < nchannels; chan++) {
cur_o = (prev_i[chan] * d +
cur_i[chan] * (outrate - d)) /
outrate;
if (size == 1)
*CHARP(ncp, 0) = (signed char)(cur_o >> 8);
else if (size == 2)
*SHORTP(ncp, 0) = (short)(cur_o);
else if (size == 4)
*LONGP(ncp, 0) = (Py_Int32)(cur_o<<16);
ncp += size;
}
d -= inrate;
}
}
exit:
if (prev_i != NULL)
free(prev_i);
if (cur_i != NULL)
free(cur_i);
return rv;
}
static PyObject *
audioop_lin2ulaw(PyObject *self, PyObject *args)
{
signed char *cp;
unsigned char *ncp;
Py_ssize_t len, i;
int size, val = 0;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s#i:lin2ulaw",
&cp, &len, &size) )
return 0 ;
if (!audioop_check_parameters(len, size))
return NULL;
rv = PyBytes_FromStringAndSize(NULL, len/size);
if ( rv == 0 )
return 0;
ncp = (unsigned char *)PyBytes_AsString(rv);
for ( i=0; i < len; i += size ) {
if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;
*ncp++ = st_14linear2ulaw(val);
}
return rv;
}
static PyObject *
audioop_ulaw2lin(PyObject *self, PyObject *args)
{
unsigned char *cp;
unsigned char cval;
signed char *ncp;
Py_ssize_t len, i;
int size, val;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s#i:ulaw2lin",
&cp, &len, &size) )
return 0;
if (!audioop_check_size(size))
return NULL;
if (len > PY_SSIZE_T_MAX/size) {
PyErr_SetString(PyExc_MemoryError,
"not enough memory for output buffer");
return 0;
}
rv = PyBytes_FromStringAndSize(NULL, len*size);
if ( rv == 0 )
return 0;
ncp = (signed char *)PyBytes_AsString(rv);
for ( i=0; i < len*size; i += size ) {
cval = *cp++;
val = st_ulaw2linear16(cval);
if ( size == 1 ) *CHARP(ncp, i) = (signed char)(val >> 8);
else if ( size == 2 ) *SHORTP(ncp, i) = (short)(val);
else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(val<<16);
}
return rv;
}
static PyObject *
audioop_lin2alaw(PyObject *self, PyObject *args)
{
signed char *cp;
unsigned char *ncp;
Py_ssize_t len, i;
int size, val = 0;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s#i:lin2alaw",
&cp, &len, &size) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
rv = PyBytes_FromStringAndSize(NULL, len/size);
if ( rv == 0 )
return 0;
ncp = (unsigned char *)PyBytes_AsString(rv);
for ( i=0; i < len; i += size ) {
if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;
*ncp++ = st_linear2alaw(val);
}
return rv;
}
static PyObject *
audioop_alaw2lin(PyObject *self, PyObject *args)
{
unsigned char *cp;
unsigned char cval;
signed char *ncp;
Py_ssize_t len, i;
int size, val;
PyObject *rv;
if ( !PyArg_ParseTuple(args, "s#i:alaw2lin",
&cp, &len, &size) )
return 0;
if (!audioop_check_size(size))
return NULL;
if (len > PY_SSIZE_T_MAX/size) {
PyErr_SetString(PyExc_MemoryError,
"not enough memory for output buffer");
return 0;
}
rv = PyBytes_FromStringAndSize(NULL, len*size);
if ( rv == 0 )
return 0;
ncp = (signed char *)PyBytes_AsString(rv);
for ( i=0; i < len*size; i += size ) {
cval = *cp++;
val = st_alaw2linear16(cval);
if ( size == 1 ) *CHARP(ncp, i) = (signed char)(val >> 8);
else if ( size == 2 ) *SHORTP(ncp, i) = (short)(val);
else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(val<<16);
}
return rv;
}
static PyObject *
audioop_lin2adpcm(PyObject *self, PyObject *args)
{
signed char *cp;
signed char *ncp;
Py_ssize_t len, i;
int size, val = 0, step, valpred, delta,
index, sign, vpdiff, diff;
PyObject *rv, *state, *str;
int outputbuffer = 0, bufferstep;
if ( !PyArg_ParseTuple(args, "s#iO:lin2adpcm",
&cp, &len, &size, &state) )
return 0;
if (!audioop_check_parameters(len, size))
return NULL;
str = PyBytes_FromStringAndSize(NULL, len/(size*2));
if ( str == 0 )
return 0;
ncp = (signed char *)PyBytes_AsString(str);
/* Decode state, should have (value, step) */
if ( state == Py_None ) {
/* First time, it seems. Set defaults */
valpred = 0;
step = 7;
index = 0;
} else if ( !PyArg_ParseTuple(state, "ii", &valpred, &index) )
return 0;
step = stepsizeTable[index];
bufferstep = 1;
for ( i=0; i < len; i += size ) {
if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;
else if ( size == 2 ) val = (int)*SHORTP(cp, i);
else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;
/* Step 1 - compute difference with previous value */
diff = val - valpred;
sign = (diff < 0) ? 8 : 0;
if ( sign ) diff = (-diff);
/* Step 2 - Divide and clamp */
/* Note:
** This code *approximately* computes:
** delta = diff*4/step;
** vpdiff = (delta+0.5)*step/4;
** but in shift step bits are dropped. The net result of this
** is that even if you have fast mul/div hardware you cannot
** put it to good use since the fixup would be too expensive.
*/
delta = 0;
vpdiff = (step >> 3);
if ( diff >= step ) {
delta = 4;
diff -= step;
vpdiff += step;
}
step >>= 1;
if ( diff >= step ) {
delta |= 2;
diff -= step;
vpdiff += step;
}
step >>= 1;
if ( diff >= step ) {
delta |= 1;
vpdiff += step;
}
/* Step 3 - Update previous value */
if ( sign )
valpred -= vpdiff;
else
valpred += vpdiff;
/* Step 4 - Clamp previous value to 16 bits */
if ( valpred > 32767 )
valpred = 32767;
else if ( valpred < -32768 )
valpred = -32768;
/* Step 5 - Assemble value, update index and step values */
delta |= sign;
index += indexTable[delta];
if ( index < 0 ) index = 0;
if ( index > 88 ) index = 88;
step = stepsizeTable[index];
/* Step 6 - Output value */
if ( bufferstep ) {
outputbuffer = (delta << 4) & 0xf0;
} else {
*ncp++ = (delta & 0x0f) | outputbuffer;
}
bufferstep = !bufferstep;
}
rv = Py_BuildValue("(O(ii))", str, valpred, index);
Py_DECREF(str);
return rv;
}
static PyObject *
audioop_adpcm2lin(PyObject *self, PyObject *args)
{
signed char *cp;
signed char *ncp;
Py_ssize_t len, i;
int size, valpred, step, delta, index, sign, vpdiff;
PyObject *rv, *str, *state;
int inputbuffer = 0, bufferstep;
if ( !PyArg_ParseTuple(args, "s#iO:adpcm2lin",
&cp, &len, &size, &state) )
return 0;
if (!audioop_check_size(size))
return NULL;
/* Decode state, should have (value, step) */
if ( state == Py_None ) {
/* First time, it seems. Set defaults */
valpred = 0;
step = 7;
index = 0;
} else if ( !PyArg_ParseTuple(state, "ii", &valpred, &index) )
return 0;
if (len > (PY_SSIZE_T_MAX/2)/size) {
PyErr_SetString(PyExc_MemoryError,
"not enough memory for output buffer");
return 0;
}
str = PyBytes_FromStringAndSize(NULL, len*size*2);
if ( str == 0 )
return 0;
ncp = (signed char *)PyBytes_AsString(str);
step = stepsizeTable[index];
bufferstep = 0;
for ( i=0; i < len*size*2; i += size ) {
/* Step 1 - get the delta value and compute next index */
if ( bufferstep ) {
delta = inputbuffer & 0xf;
} else {
inputbuffer = *cp++;
delta = (inputbuffer >> 4) & 0xf;
}
bufferstep = !bufferstep;
/* Step 2 - Find new index value (for later) */
index += indexTable[delta];
if ( index < 0 ) index = 0;
if ( index > 88 ) index = 88;
/* Step 3 - Separate sign and magnitude */
sign = delta & 8;
delta = delta & 7;
/* Step 4 - Compute difference and new predicted value */
/*
** Computes 'vpdiff = (delta+0.5)*step/4', but see comment
** in adpcm_coder.
*/
vpdiff = step >> 3;
if ( delta & 4 ) vpdiff += step;
if ( delta & 2 ) vpdiff += step>>1;
if ( delta & 1 ) vpdiff += step>>2;
if ( sign )
valpred -= vpdiff;
else
valpred += vpdiff;
/* Step 5 - clamp output value */
if ( valpred > 32767 )
valpred = 32767;
else if ( valpred < -32768 )
valpred = -32768;
/* Step 6 - Update step value */
step = stepsizeTable[index];
/* Step 6 - Output value */
if ( size == 1 ) *CHARP(ncp, i) = (signed char)(valpred >> 8);
else if ( size == 2 ) *SHORTP(ncp, i) = (short)(valpred);
else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(valpred<<16);
}
rv = Py_BuildValue("(O(ii))", str, valpred, index);
Py_DECREF(str);
return rv;
}
static PyMethodDef audioop_methods[] = {
{ "max", audioop_max, METH_VARARGS },
{ "minmax", audioop_minmax, METH_VARARGS },
{ "avg", audioop_avg, METH_VARARGS },
{ "maxpp", audioop_maxpp, METH_VARARGS },
{ "avgpp", audioop_avgpp, METH_VARARGS },
{ "rms", audioop_rms, METH_VARARGS },
{ "findfit", audioop_findfit, METH_VARARGS },
{ "findmax", audioop_findmax, METH_VARARGS },
{ "findfactor", audioop_findfactor, METH_VARARGS },
{ "cross", audioop_cross, METH_VARARGS },
{ "mul", audioop_mul, METH_VARARGS },
{ "add", audioop_add, METH_VARARGS },
{ "bias", audioop_bias, METH_VARARGS },
{ "ulaw2lin", audioop_ulaw2lin, METH_VARARGS },
{ "lin2ulaw", audioop_lin2ulaw, METH_VARARGS },
{ "alaw2lin", audioop_alaw2lin, METH_VARARGS },
{ "lin2alaw", audioop_lin2alaw, METH_VARARGS },
{ "lin2lin", audioop_lin2lin, METH_VARARGS },
{ "adpcm2lin", audioop_adpcm2lin, METH_VARARGS },
{ "lin2adpcm", audioop_lin2adpcm, METH_VARARGS },
{ "tomono", audioop_tomono, METH_VARARGS },
{ "tostereo", audioop_tostereo, METH_VARARGS },
{ "getsample", audioop_getsample, METH_VARARGS },
{ "reverse", audioop_reverse, METH_VARARGS },
{ "ratecv", audioop_ratecv, METH_VARARGS },
{ 0, 0 }
};
static struct PyModuleDef audioopmodule = {
PyModuleDef_HEAD_INIT,
"audioop",
NULL,
-1,
audioop_methods,
NULL,
NULL,
NULL,
NULL
};
PyMODINIT_FUNC
PyInit_audioop(void)
{
PyObject *m, *d;
m = PyModule_Create(&audioopmodule);
if (m == NULL)
return NULL;
d = PyModule_GetDict(m);
if (d == NULL)
return NULL;
AudioopError = PyErr_NewException("audioop.error", NULL, NULL);
if (AudioopError != NULL)
PyDict_SetItemString(d,"error",AudioopError);
return m;
}
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