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This change set fixes bug 8126 in trunk. It is implemented via compile time options, activated via the menuselect stuff, which defaults to the old way. non-zero sample data added. Translate tables expressed in microseconds instead of milliseconds, with 5-digit data now instead of 3, giving 2 more digits of precision.

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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@80113 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Steve Murphy
2007-08-20 22:53:48 +00:00
parent c9ab65a3bf
commit 337c44236d
8 changed files with 421 additions and 55 deletions
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165
main/ulaw.c
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@@ -28,15 +28,25 @@
ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
#include "asterisk/ulaw.h"
#include "asterisk/logger.h"
#if 0
/* ZEROTRAP is the military recommendation to improve the encryption
* of u-Law traffic. It is irrelevant with modern encryption systems
* like AES, and will simply degrade the signal quality.
* ZEROTRAP is not implemented in AST_LIN2MU and so the coding table
* tests will fail if you use it */
#define ZEROTRAP /*!< turn on the trap as per the MIL-STD */
#endif
#define BIAS 0x84 /*!< define the add-in bias for 16 bit samples */
#define CLIP 32635
#ifndef G711_NEW_ALGORITHM
unsigned char __ast_lin2mu[16384];
short __ast_mulaw[256];
static unsigned char linear2ulaw(short sample)
{
static int exp_lut[256] = {
@@ -58,26 +68,102 @@ static unsigned char linear2ulaw(short sample)
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 };
int sign, exponent, mantissa;
unsigned char ulawbyte;
/* Get the sample into sign-magnitude. */
sign = (sample >> 8) & 0x80; /* set aside the sign */
if (sign != 0)
if (sign != 0)
sample = -sample; /* get magnitude */
if (sample > CLIP)
sample = CLIP; /* clip the magnitude */
/* Convert from 16 bit linear to ulaw. */
sample = sample + BIAS;
exponent = exp_lut[(sample >> 7) & 0xFF];
mantissa = (sample >> (exponent + 3)) & 0x0F;
ulawbyte = ~(sign | (exponent << 4) | mantissa);
#ifdef ZEROTRAP
if (ulawbyte == 0)
ulawbyte = 0x02; /* optional CCITT trap */
#endif
return ulawbyte;
}
#else
unsigned char __ast_lin2mu[AST_ULAW_TAB_SIZE];
short __ast_mulaw[256];
static unsigned char linear2ulaw(short sample, int full_coding)
{
static const unsigned exp_lut[256] = {
0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 };
unsigned sign, exponent, mantissa, mag;
unsigned char ulawbyte;
/* Get the sample into sign-magnitude. */
ast_ulaw_get_sign_mag(sample, &sign, &mag);
if (mag > CLIP)
mag = CLIP; /* clip the magnitude */
sign = (sample >> 8) & 0x80; /* set aside the sign */
if (sign != 0)
sample = -sample; /* get magnitude */
if (sample > CLIP)
sample = CLIP; /* clip the magnitude */
/* Convert from 16 bit linear to ulaw. */
mag += BIAS;
exponent = exp_lut[(mag >> 7) & 0xFF];
mantissa = (mag >> (exponent + 3)) & 0x0F;
if (full_coding) {
/* full encoding, with sign and xform */
ulawbyte = ~(sign | (exponent << 4) | mantissa);
#ifdef ZEROTRAP
if (ulawbyte == 0)
ulawbyte = 0x02; /* optional CCITT trap */
#endif
} else {
/* half-cooked coding -- mantissa+exponent only (for lookup tab) */
ulawbyte = (exponent << 4) | mantissa;
}
return ulawbyte;
}
static inline short ulaw2linear(unsigned char ulawbyte)
{
unsigned exponent, mantissa;
short sample;
static const short etab[]={0,132,396,924,1980,4092,8316,16764};
ulawbyte = ~ulawbyte;
exponent = (ulawbyte & 0x70) >> 4;
mantissa = ulawbyte & 0x0f;
sample = mantissa << (exponent + 3);
sample += etab[exponent];
if (ulawbyte & 0x80)
sample = -sample;
return sample;
}
#endif
/*!
* \brief Set up mu-law conversion table
@@ -85,22 +171,77 @@ static unsigned char linear2ulaw(short sample)
void ast_ulaw_init(void)
{
int i;
for (i = 0; i < 256; i++) {
short mu, e, f, y;
static short etab[] = {0,132,396,924,1980,4092,8316,16764};
mu = 255 - i;
e = (mu & 0x70) / 16;
/*
* Set up mu-law conversion table
*/
#ifndef G711_NEW_ALGORITHM
for (i = 0;i < 256;i++) {
short mu,e,f,y;
static short etab[]={0,132,396,924,1980,4092,8316,16764};
mu = 255-i;
e = (mu & 0x70)/16;
f = mu & 0x0f;
y = f * (1 << (e + 3));
y += etab[e];
if (mu & 0x80)
y = -y;
if (mu & 0x80) y = -y;
__ast_mulaw[i] = y;
}
/* set up the reverse (mu-law) conversion table */
for (i = -32768; i < 32768; i++) {
__ast_lin2mu[((unsigned short)i) >> 2] = linear2ulaw(i);
}
#else
for (i = 0; i < 256; i++) {
__ast_mulaw[i] = ulaw2linear(i);
}
/* set up the reverse (mu-law) conversion table */
for (i = 0; i <= 32768; i += AST_ULAW_STEP) {
AST_LIN2MU_LOOKUP(i) = linear2ulaw(i, 0 /* half-cooked */);
}
#endif
#ifdef TEST_CODING_TABLES
for (i = -32768; i < 32768; ++i) {
#ifndef G711_NEW_ALGORITHM
unsigned char e1 = linear2ulaw(i);
#else
unsigned char e1 = linear2ulaw(i, 1);
#endif
short d1 = ulaw2linear(e1);
unsigned char e2 = AST_LIN2MU(i);
short d2 = ulaw2linear(e2);
short d3 = AST_MULAW(e1);
if (e1 != e2 || d1 != d3 || d2 != d3) {
ast_log(LOG_WARNING, "u-Law coding tables test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d\n",
i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2);
}
}
ast_log(LOG_NOTICE, "u-Law coding table test complete.\n");
#endif /* TEST_CODING_TABLES */
#ifdef TEST_TANDEM_TRANSCODING
/* tandem transcoding test */
for (i = -32768; i < 32768; ++i) {
unsigned char e1 = AST_LIN2MU(i);
short d1 = AST_MULAW(e1);
unsigned char e2 = AST_LIN2MU(d1);
short d2 = AST_MULAW(e2);
unsigned char e3 = AST_LIN2MU(d2);
short d3 = AST_MULAW(e3);
if (i < 0 && e1 == 0x7f && e2 == 0xff && e3 == 0xff)
continue; /* known and normal negative 0 case */
if (e1 != e2 || e2 != e3 || d1 != d2 || d2 != d3) {
ast_log(LOG_WARNING, "u-Law tandem transcoding test failed on %d: e1=%u, e2=%u, d1=%d, d2=%d, d3=%d\n",
i, (unsigned)e1, (unsigned)e2, (int)d1, (int)d2, (int)d3);
}
}
ast_log(LOG_NOTICE, "u-Law tandem transcoding test complete.\n");
#endif /* TEST_TANDEM_TRANSCODING */
}