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2024-07-12
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Prefacio
Esta demostración utilizará proyectos de código abierto.Codificador EasyAACEinternosrc/g726.cpp(El de la demostración ha sido renombrado ag726.c)ysrc/g726.hConvierta datos pcm little-endian de 16 bits a g726.
Nota: Los archivos de prueba relevantes se han almacenado en la demostración.
audiodirectorio, actualmente se encuentra que los archivos g726 convertidos desde pcm no se reproducen correctamente usando el software Audacity (no se encontró g726, por lo que se seleccionó VOX ADPCM), pero el g726 obtenido se reprodujo normalmente después de volver a convertirlo a pcm. dijo en línea que necesita admitir la decodificación g726. El reproductor solo puede reproducirlo, y hay un error al reproducirlo con ffmpeg, por lo que el g726 cuando vi este comentario no puede reproducirlo.
$ make clean && make # 或者`make DEBUG=1`打开调试打印信息，又或者指定`CC=your-crosscompile-gcc`进行编译交叉编译
$ ./pcm_g726_convert
Usage:
./pcm_g726_convert -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 16000 -o out_8khz_16kbps.g726
./pcm_g726_convert -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 24000 -o out_8khz_24kbps.g726
./pcm_g726_convert -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 32000 -o out_8khz_32kbps.g726
./pcm_g726_convert -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 40000 -o out_8khz_40kbps.g726
./pcm_g726_convert -t g726_2_pcm -i ./audio/test_8khz_16kbps.g726 -r 16000 -o out_8khz_16bit_mono_128kbps-1.pcm
./pcm_g726_convert -t g726_2_pcm -i ./audio/test_8khz_24kbps.g726 -r 24000 -o out_8khz_16bit_mono_128kbps-2.pcm
./pcm_g726_convert -t g726_2_pcm -i ./audio/test_8khz_32kbps.g726 -r 32000 -o out_8khz_16bit_mono_128kbps-3.pcm
./pcm_g726_convert -t g726_2_pcm -i ./audio/test_8khz_40kbps.g726 -r 40000 -o out_8khz_16bit_mono_128kbps-4.pcm
Muestreo y codificación de audio: LPCM, ADPCM, G711, G726, AAC_Blog de Ye Feng-CSDN Blog_adpcm
Algunos resúmenes del algoritmo g726_Blog de That Sunny Day-Blog CSDN
$ tree
.
├── audio
│ ├── test_8khz_16bit_mono_128kbps.pcm
│ ├── test_8khz_16kbps.g726
│ ├── test_8khz_24kbps.g726
│ ├── test_8khz_32kbps.g726
│ └── test_8khz_40kbps.g726
├── docs
│ ├── g726算法的一些总结_那年晴天的博客-CSDN博客.mhtml
│ ├── g726转pcm_ybn187的专栏-CSDN博客_g726转pcm.mhtml
│ └── 音频采样及编解码——LPCM 、ADPCM、G711、G726、AAC_夜风的博客-CSDN博客_adpcm.mhtml
├── g726.c
├── g726.h
├── main.c
├── Makefile
└── README.md
/*
Copyright (c) 2013-2016 EasyDarwin.ORG. All rights reserved.
Github: https://github.com/EasyDarwin
WEChat: EasyDarwin
Website: http://www.easydarwin.org
*/
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include "g726.h"
static const int qtab_726_16[1] =
{
261
};
static const int qtab_726_24[3] =
{
8, 218, 331
};
static const int qtab_726_32[7] =
{
-124, 80, 178, 246, 300, 349, 400
};
static const int qtab_726_40[15] =
{
-122, -16, 68, 139, 198, 250, 298, 339,
378, 413, 445, 475, 502, 528, 553
};
static __inline int top_bit(unsigned int bits)
{
#if defined(__i386__) || defined(__x86_64__)
int res;
__asm__ (" xorl %[res],%[res];n"
" decl %[res];n"
" bsrl %[bits],%[res]n"
: [res] "=&r" (res)
: [bits] "rm" (bits));
return res;
#elif defined(__ppc__) || defined(__powerpc__)
int res;
__asm__ ("cntlzw %[res],%[bits];n"
: [res] "=&r" (res)
: [bits] "r" (bits));
return 31 - res;
#elif defined(_M_IX86) // Visual Studio x86
__asm
{
xor eax, eax
dec eax
bsr eax, bits
}
#else
int res;
if (bits == 0)
return -1;
res = 0;
if (bits & 0xFFFF0000)
{
bits &= 0xFFFF0000;
res += 16;
}
if (bits & 0xFF00FF00)
{
bits &= 0xFF00FF00;
res += 8;
}
if (bits & 0xF0F0F0F0)
{
bits &= 0xF0F0F0F0;
res += 4;
}
if (bits & 0xCCCCCCCC)
{
bits &= 0xCCCCCCCC;
res += 2;
}
if (bits & 0xAAAAAAAA)
{
bits &= 0xAAAAAAAA;
res += 1;
}
return res;
#endif
}
static bitstream_state_t *bitstream_init(bitstream_state_t *s)
{
if (s == NULL)
return NULL;
s->bitstream = 0;
s->residue = 0;
return s;
}
/*
* Given a raw sample, 'd', of the difference signal and a
* quantization step size scale factor, 'y', this routine returns the
* ADPCM codeword to which that sample gets quantized. The step
* size scale factor division operation is done in the log base 2 domain
* as a subtraction.
*/
static short quantize(int d, /* Raw difference signal sample */
int y, /* Step size multiplier */
const int table[], /* quantization table */
int quantizer_states) /* table size of short integers */
{
short dqm; /* Magnitude of 'd' */
short exp; /* Integer part of base 2 log of 'd' */
short mant; /* Fractional part of base 2 log */
short dl; /* Log of magnitude of 'd' */
short dln; /* Step size scale factor normalized log */
int i;
int size;
/*
* LOG
*
* Compute base 2 log of 'd', and store in 'dl'.
*/
dqm = (short) abs(d);
exp = (short) (top_bit(dqm >> 1) + 1);
/* Fractional portion. */
mant = ((dqm << 7) >> exp) & 0x7F;
dl = (exp << 7) + mant;
/*
* SUBTB
*
* "Divide" by step size multiplier.
*/
dln = dl - (short) (y >> 2);
/*
* QUAN
*
* Search for codword i for 'dln'.
*/
size = (quantizer_states - 1) >> 1;
for (i = 0; i < size; i++)
{
if (dln < table[i])
break;
}
if (d < 0)
{
/* Take 1's complement of i */
return (short) ((size << 1) + 1 - i);
}
if (i == 0 && (quantizer_states & 1))
{
/* Zero is only valid if there are an even number of states, so
take the 1's complement if the code is zero. */
return (short) quantizer_states;
}
return (short) i;
}
/*- End of function --------------------------------------------------------*/
/*
* returns the integer product of the 14-bit integer "an" and
* "floating point" representation (4-bit exponent, 6-bit mantessa) "srn".
*/
static short fmult(short an, short srn)
{
short anmag;
short anexp;
short anmant;
short wanexp;
short wanmant;
short retval;
anmag = (an > 0) ? an : ((-an) & 0x1FFF);
anexp = (short) (top_bit(anmag) - 5);
anmant = (anmag == 0) ? 32 : (anexp >= 0) ? (anmag >> anexp) : (anmag << -anexp);
wanexp = anexp + ((srn >> 6) & 0xF) - 13;
wanmant = (anmant*(srn & 0x3F) + 0x30) >> 4;
retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) : (wanmant >> -wanexp);
return (((an ^ srn) < 0) ? -retval : retval);
}
/*
* Compute the estimated signal from the 6-zero predictor.
*/
static __inline short predictor_zero(g726_state_t *s)
{
int i;
int sezi;
sezi = fmult(s->b[0] >> 2, s->dq[0]);
/* ACCUM */
for (i = 1; i < 6; i++)
sezi += fmult(s->b[i] >> 2, s->dq[i]);
return (short) sezi;
}
/*- End of function --------------------------------------------------------*/
/*
* Computes the estimated signal from the 2-pole predictor.
*/
static __inline short predictor_pole(g726_state_t *s)
{
return (fmult(s->a[1] >> 2, s->sr[1]) + fmult(s->a[0] >> 2, s->sr[0]));
}
/*
* Computes the quantization step size of the adaptive quantizer.
*/
static int step_size(g726_state_t *s)
{
int y;
int dif;
int al;
if (s->ap >= 256)
return s->yu;
y = s->yl >> 6;
dif = s->yu - y;
al = s->ap >> 2;
if (dif > 0)
y += (dif*al) >> 6;
else if (dif < 0)
y += (dif*al + 0x3F) >> 6;
return y;
}
/*- End of function --------------------------------------------------------*/
/*
* Returns reconstructed difference signal 'dq' obtained from
* codeword 'i' and quantization step size scale factor 'y'.
* Multiplication is performed in log base 2 domain as addition.
*/
static short reconstruct(int sign, /* 0 for non-negative value */
int dqln, /* G.72x codeword */
int y) /* Step size multiplier */
{
short dql; /* Log of 'dq' magnitude */
short dex; /* Integer part of log */
short dqt;
short dq; /* Reconstructed difference signal sample */
dql = (short) (dqln + (y >> 2)); /* ADDA */
if (dql < 0)
return ((sign) ? -0x8000 : 0);
/* ANTILOG */
dex = (dql >> 7) & 15;
dqt = 128 + (dql & 127);
dq = (dqt << 7) >> (14 - dex);
return ((sign) ? (dq - 0x8000) : dq);
}
/*- End of function --------------------------------------------------------*/
/*
* updates the state variables for each output code
*/
static void update(g726_state_t *s,
int y, /* quantizer step size */
int wi, /* scale factor multiplier */
int fi, /* for long/short term energies */
int dq, /* quantized prediction difference */
int sr, /* reconstructed signal */
int dqsez) /* difference from 2-pole predictor */
{
short mag;
short exp;
short a2p; /* LIMC */
short a1ul; /* UPA1 */
short pks1; /* UPA2 */
short fa1;
short ylint;
short dqthr;
short ylfrac;
short thr;
short pk0;
int i;
int tr;
a2p = 0;
/* Needed in updating predictor poles */
pk0 = (dqsez < 0) ? 1 : 0;
/* prediction difference magnitude */
mag = (short) (dq & 0x7FFF);
/* TRANS */
ylint = (short) (s->yl >> 15); /* exponent part of yl */
ylfrac = (short) ((s->yl >> 10) & 0x1F); /* fractional part of yl */
/* Limit threshold to 31 << 10 */
thr = (ylint > 9) ? (31 << 10) : ((32 + ylfrac) << ylint);
dqthr = (thr + (thr >> 1)) >> 1; /* dqthr = 0.75 * thr */
if (!s->td) /* signal supposed voice */
tr = 0;
else if (mag <= dqthr) /* supposed data, but small mag */
tr = 0; /* treated as voice */
else /* signal is data (modem) */
tr = 1;
/*
* Quantizer scale factor adaptation.
*/
/* FUNCTW & FILTD & DELAY */
/* update non-steady state step size multiplier */
s->yu = (short) (y + ((wi - y) >> 5));
/* LIMB */
if (s->yu < 544)
s->yu = 544;
else if (s->yu > 5120)
s->yu = 5120;
/* FILTE & DELAY */
/* update steady state step size multiplier */
s->yl += s->yu + ((-s->yl) >> 6);
/*
* Adaptive predictor coefficients.
*/
if (tr)
{
/* Reset the a's and b's for a modem signal */
s->a[0] = 0;
s->a[1] = 0;
s->b[0] = 0;
s->b[1] = 0;
s->b[2] = 0;
s->b[3] = 0;
s->b[4] = 0;
s->b[5] = 0;
}
else
{
/* Update the a's and b's */
/* UPA2 */
pks1 = pk0 ^ s->pk[0];
/* Update predictor pole a[1] */
a2p = s->a[1] - (s->a[1] >> 7);
if (dqsez != 0)
{
fa1 = (pks1) ? s->a[0] : -s->a[0];
/* a2p = function of fa1 */
if (fa1 < -8191)
a2p -= 0x100;
else if (fa1 > 8191)
a2p += 0xFF;
else
a2p += fa1 >> 5;
if (pk0 ^ s->pk[1])
{
/* LIMC */
if (a2p <= -12160)
a2p = -12288;
else if (a2p >= 12416)
a2p = 12288;
else
a2p -= 0x80;
}
else if (a2p <= -12416)
a2p = -12288;
else if (a2p >= 12160)
a2p = 12288;
else
a2p += 0x80;
}
/* TRIGB & DELAY */
s->a[1] = a2p;
/* UPA1 */
/* Update predictor pole a[0] */
s->a[0] -= s->a[0] >> 8;
if (dqsez != 0)
{
if (pks1 == 0)
s->a[0] += 192;
else
s->a[0] -= 192;
}
/* LIMD */
a1ul = 15360 - a2p;
if (s->a[0] < -a1ul)
s->a[0] = -a1ul;
else if (s->a[0] > a1ul)
s->a[0] = a1ul;
/* UPB : update predictor zeros b[6] */
for (i = 0; i < 6; i++)
{
/* Distinguish 40Kbps mode from the others */
s->b[i] -= s->b[i] >> ((s->bits_per_sample == 5) ? 9 : 8);
if (dq & 0x7FFF)
{
/* XOR */
if ((dq ^ s->dq[i]) >= 0)
s->b[i] += 128;
else
s->b[i] -= 128;
}
}
}
for (i = 5; i > 0; i--)
s->dq[i] = s->dq[i - 1];
/* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
if (mag == 0)
{
s->dq[0] = (dq >= 0) ? 0x20 : 0xFC20;
}
else
{
exp = (short) (top_bit(mag) + 1);
s->dq[0] = (dq >= 0)
? ((exp << 6) + ((mag << 6) >> exp))
: ((exp << 6) + ((mag << 6) >> exp) - 0x400);
}
s->sr[1] = s->sr[0];
/* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
if (sr == 0)
{
s->sr[0] = 0x20;
}
else if (sr > 0)
{
exp = (short) (top_bit(sr) + 1);
s->sr[0] = (short) ((exp << 6) + ((sr << 6) >> exp));
}
else if (sr > -32768)
{
mag = (short) -sr;
exp = (short) (top_bit(mag) + 1);
s->sr[0] = (exp << 6) + ((mag << 6) >> exp) - 0x400;
}
else
{
s->sr[0] = (short) 0xFC20;
}
/* DELAY A */
s->pk[1] = s->pk[0];
s->pk[0] = pk0;
/* TONE */
if (tr) /* this sample has been treated as data */
s->td = 0; /* next one will be treated as voice */
else if (a2p < -11776) /* small sample-to-sample correlation */
s->td = 1; /* signal may be data */
else /* signal is voice */
s->td = 0;
/* Adaptation speed control. */
/* FILTA */
s->dms += ((short) fi - s->dms) >> 5;
/* FILTB */
s->dml += (((short) (fi << 2) - s->dml) >> 7);
if (tr)
s->ap = 256;
else if (y < 1536) /* SUBTC */
s->ap += (0x200 - s->ap) >> 4;
else if (s->td)
s->ap += (0x200 - s->ap) >> 4;
else if (abs((s->dms << 2) - s->dml) >= (s->dml >> 3))
s->ap += (0x200 - s->ap) >> 4;
else
s->ap += (-s->ap) >> 4;
}
/*
* Decodes a 2-bit CCITT G.726_16 ADPCM code and returns
* the resulting 16-bit linear PCM, A-law or u-law sample value.
*/
static short g726_16_decoder(g726_state_t *s, unsigned char code)
{
short sezi;
short sei;
short se;
short sr;
short dq;
short dqsez;
int y;
/* Mask to get proper bits */
code &= 0x03;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
y = step_size(s);
dq = reconstruct(code & 2, g726_16_dqlntab[code], y);
/* Reconstruct the signal */
se = sei >> 1;
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_16_witab[code], g726_16_fitab[code], dq, sr, dqsez);
return (sr << 2);
}
/*- End of function --------------------------------------------------------*/
/*
* Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
*/
static unsigned char g726_16_encoder(g726_state_t *s, short amp)
{
int y;
short sei;
short sezi;
short se;
short d;
short sr;
short dqsez;
short dq;
short i;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
se = sei >> 1;
d = amp - se;
/* Quantize prediction difference */
y = step_size(s);
i = quantize(d, y, qtab_726_16, 4);
dq = reconstruct(i & 2, g726_16_dqlntab[i], y);
/* Reconstruct the signal */
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_16_witab[i], g726_16_fitab[i], dq, sr, dqsez);
return (unsigned char) i;
}
/*
* Decodes a 3-bit CCITT G.726_24 ADPCM code and returns
* the resulting 16-bit linear PCM, A-law or u-law sample value.
*/
static short g726_24_decoder(g726_state_t *s, unsigned char code)
{
short sezi;
short sei;
short se;
short sr;
short dq;
short dqsez;
int y;
/* Mask to get proper bits */
code &= 0x07;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
y = step_size(s);
dq = reconstruct(code & 4, g726_24_dqlntab[code], y);
/* Reconstruct the signal */
se = sei >> 1;
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_24_witab[code], g726_24_fitab[code], dq, sr, dqsez);
return (sr << 2);
}
/*- End of function --------------------------------------------------------*/
/*
* Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
*/
static unsigned char g726_24_encoder(g726_state_t *s, short amp)
{
short sei;
short sezi;
short se;
short d;
short sr;
short dqsez;
short dq;
short i;
int y;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
se = sei >> 1;
d = amp - se;
/* Quantize prediction difference */
y = step_size(s);
i = quantize(d, y, qtab_726_24, 7);
dq = reconstruct(i & 4, g726_24_dqlntab[i], y);
/* Reconstruct the signal */
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_24_witab[i], g726_24_fitab[i], dq, sr, dqsez);
return (unsigned char) i;
}
/*
* Decodes a 4-bit CCITT G.726_32 ADPCM code and returns
* the resulting 16-bit linear PCM, A-law or u-law sample value.
*/
static short g726_32_decoder(g726_state_t *s, unsigned char code)
{
short sezi;
short sei;
short se;
short sr;
short dq;
short dqsez;
int y;
/* Mask to get proper bits */
code &= 0x0F;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
y = step_size(s);
dq = reconstruct(code & 8, g726_32_dqlntab[code], y);
/* Reconstruct the signal */
se = sei >> 1;
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_32_witab[code], g726_32_fitab[code], dq, sr, dqsez);
return (sr << 2);
}
/*- End of function --------------------------------------------------------*/
/*
* Encodes a linear input sample and returns its 4-bit code.
*/
static unsigned char g726_32_encoder(g726_state_t *s, short amp)
{
short sei;
short sezi;
short se;
short d;
short sr;
short dqsez;
short dq;
short i;
int y;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
se = sei >> 1;
d = amp - se;
/* Quantize the prediction difference */
y = step_size(s);
i = quantize(d, y, qtab_726_32, 15);
dq = reconstruct(i & 8, g726_32_dqlntab[i], y);
/* Reconstruct the signal */
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_32_witab[i], g726_32_fitab[i], dq, sr, dqsez);
return (unsigned char) i;
}
/*
* Decodes a 5-bit CCITT G.726 40Kbps code and returns
* the resulting 16-bit linear PCM, A-law or u-law sample value.
*/
static short g726_40_decoder(g726_state_t *s, unsigned char code)
{
short sezi;
short sei;
short se;
short sr;
short dq;
short dqsez;
int y;
/* Mask to get proper bits */
code &= 0x1F;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
y = step_size(s);
dq = reconstruct(code & 0x10, g726_40_dqlntab[code], y);
/* Reconstruct the signal */
se = sei >> 1;
sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_40_witab[code], g726_40_fitab[code], dq, sr, dqsez);
return (sr << 2);
}
/*- End of function --------------------------------------------------------*/
/*
* Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens
* the resulting 5-bit CCITT G.726 40Kbps code.
*/
static unsigned char g726_40_encoder(g726_state_t *s, short amp)
{
short sei;
short sezi;
short se;
short d;
short sr;
short dqsez;
short dq;
short i;
int y;
sezi = predictor_zero(s);
sei = sezi + predictor_pole(s);
se = sei >> 1;
d = amp - se;
/* Quantize prediction difference */
y = step_size(s);
i = quantize(d, y, qtab_726_40, 31);
dq = reconstruct(i & 0x10, g726_40_dqlntab[i], y);
/* Reconstruct the signal */
sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq);
/* Pole prediction difference */
dqsez = sr + (sezi >> 1) - se;
update(s, y, g726_40_witab[i], g726_40_fitab[i], dq, sr, dqsez);
return (unsigned char) i;
}
g726_state_t *g726_init(g726_state_t *s, int bit_rate)
{
int i;
if (bit_rate != 16000 && bit_rate != 24000 && bit_rate != 32000 && bit_rate != 40000)
return NULL;
s->yl = 34816;
s->yu = 544;
s->dms = 0;
s->dml = 0;
s->ap = 0;
s->rate = bit_rate;
for (i = 0; i < 2; i++)
{
s->a[i] = 0;
s->pk[i] = 0;
s->sr[i] = 32;
}
for (i = 0; i < 6; i++)
{
s->b[i] = 0;
s->dq[i] = 32;
}
s->td = 0;
switch (bit_rate)
{
case 16000:
s->enc_func = g726_16_encoder;
s->dec_func = g726_16_decoder;
s->bits_per_sample = 2;
break;
case 24000:
s->enc_func = g726_24_encoder;
s->dec_func = g726_24_decoder;
s->bits_per_sample = 3;
break;
case 32000:
default:
s->enc_func = g726_32_encoder;
s->dec_func = g726_32_decoder;
s->bits_per_sample = 4;
break;
case 40000:
s->enc_func = g726_40_encoder;
s->dec_func = g726_40_decoder;
s->bits_per_sample = 5;
break;
}
bitstream_init(&s->bs);
return s;
}
int g726_decode(g726_state_t *s,
short amp[],
const unsigned char g726_data[],
int g726_bytes)
{
int i;
int samples;
unsigned char code;
int sl;
for (samples = i = 0; ; )
{
if (s->bs.residue < s->bits_per_sample)
{
if (i >= g726_bytes)
break;
s->bs.bitstream = (s->bs.bitstream << 8) | g726_data[i++];
s->bs.residue += 8;
}
code = (unsigned char) ((s->bs.bitstream >> (s->bs.residue - s->bits_per_sample)) & ((1 << s->bits_per_sample) - 1));
s->bs.residue -= s->bits_per_sample;
sl = s->dec_func(s, code);
amp[samples++] = (short) sl;
}
return samples;
}
int g726_encode(g726_state_t *s,
unsigned char g726_data[],
const short amp[],
int len)
{
int i;
int g726_bytes;
short sl;
unsigned char code;
for (g726_bytes = i = 0; i < len; i++)
{
sl = amp[i] >> 2;
code = s->enc_func(s, sl);
s->bs.bitstream = (s->bs.bitstream << s->bits_per_sample) | code;
s->bs.residue += s->bits_per_sample;
if (s->bs.residue >= 8)
{
g726_data[g726_bytes++] = (unsigned char) ((s->bs.bitstream >> (s->bs.residue - 8)) & 0xFF);
s->bs.residue -= 8;
}
}
return g726_bytes;
}
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include "g726.h"
// 编译时Makefile里控制
#ifdef ENABLE_DEBUG
#define DEBUG(fmt, args...) printf(fmt, ##args)
#else
#define DEBUG(fmt, args...)
#endif
#define BUF_SIZE 2048
void print_Usage(char *processName)
{
printf("Usage: n"
" %s -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 16000 -o out_8khz_16kbps.g726n"
" %s -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 24000 -o out_8khz_24kbps.g726n"
" %s -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 32000 -o out_8khz_32kbps.g726n"
" %s -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 40000 -o out_8khz_40kbps.g726n"
" %s -t g726_2_pcm -i ./audio/test_8khz_16kbps.g726 -r 16000 -o out_8khz_16bit_mono_128kbps-1.pcmn"
" %s -t g726_2_pcm -i ./audio/test_8khz_24kbps.g726 -r 24000 -o out_8khz_16bit_mono_128kbps-2.pcmn"
" %s -t g726_2_pcm -i ./audio/test_8khz_32kbps.g726 -r 32000 -o out_8khz_16bit_mono_128kbps-3.pcmn"
" %s -t g726_2_pcm -i ./audio/test_8khz_40kbps.g726 -r 40000 -o out_8khz_16bit_mono_128kbps-4.pcmn",
processName, processName, processName, processName, processName, processName, processName, processName);
}
int main(int argc, char *argv[])
{
unsigned int bitRates = 0;
unsigned char *inBuf = (unsigned char *)malloc(BUF_SIZE);
unsigned char *outBuf = (unsigned char *)malloc(BUF_SIZE);
char convertType[128];
char inputFileName[128];
char outputFileName[128];
FILE *fpInput = NULL;
FILE *fpOutput = NULL;
g726_state_t *g726Handler = NULL; // g726操作句柄
if(argc == 1)
{
print_Usage(argv[0]);
return -1;
}
// 解析命令行参数 -- start --
char option = 0;
int option_index = 0;
const char *short_options = "ht:i:o:r:";
struct option long_options[] =
{
{"help", no_argument, NULL, 'h'},
{"convert_type", required_argument, NULL, 't'},
{"input_file", required_argument, NULL, 'i'},
{"output_file", required_argument, NULL, 'o'},
{"bit_rates", required_argument, NULL, 'r'},
{NULL, 0, NULL, 0 },
};
while((option = getopt_long_only(argc, argv, short_options, long_options, &option_index)) != -1)
{
switch(option)
{
case 'h':
print_Usage(argv[0]);
return 0;
case 't':
strncpy(convertType, optarg, 128);
break;
case 'i':
strncpy(inputFileName, optarg, 128);
break;
case 'o':
strncpy(outputFileName, optarg, 128);
break;
case 'r':
bitRates = atoi(optarg);
break;
defalut:
printf("Unknown argument!n");
break;
}
}
// 解析命令行参数 -- end --
printf("n**************************************n"
"convert type: %sn"
"input file name: %sn"
"output file name: %sn"
"g726 bit rates: %d bpsn"
"**************************************nn",
!strcmp(convertType, "pcm_2_g726") ? "pcm -> g726" : "g726 -> pcm",
inputFileName, outputFileName, bitRates);
fpInput = fopen(inputFileName, "rb");
fpOutput = fopen(outputFileName, "wb");
if(!fpInput || !fpOutput)
{
printf("Open Input/Output file failed!n");
return -1;
}
// step 1: 先分配内存空间给操作句柄
g726Handler = (g726_state_t *)malloc(sizeof(g726_state_t));
if(g726Handler == NULL)
{
printf("Alloc memory for g726 handler failed!n");
return -1;
}
// step 2: 根据比特率（码率）进行初始化得到句柄
g726Handler = g726_init(g726Handler, bitRates);
// 按一"帧"160个采样点进行操作
#define SAMPLES_PER_FRAME (160)
if(strcmp(convertType, "pcm_2_g726") == 0) // encode
{
int readBytes = -1;
int ret = -1;
while(1)
{
readBytes = fread(inBuf, 1, SAMPLES_PER_FRAME*(16/8), fpInput);
if(readBytes <= 0)
break;
/* 参数：句柄、g726缓存（传出）、pcm缓存（传入）、pcm的采样点个数；
* 返回值：编码得到的g726数据长度
*/
ret = g726_encode(g726Handler, (unsigned char*)outBuf, (const short*)inBuf, readBytes/2); // 记得读到的字节数要除以2
DEBUG("[g726_encode] read pcm bytes: %d -> encode g726 bytes: %dn", readBytes, ret);
if(ret != readBytes * bitRates / 128000)
{
printf("PCM encode to G726 failed!n");
printf("033[31mFailed!033[0mn");
break;
}
fwrite(outBuf, 1, ret, fpOutput);
}
}
else if(strcmp(convertType, "g726_2_pcm") == 0) // decode
{
int readBytes = -1;
int ret = -1;
while(1)
{
readBytes = fread(inBuf, 1, SAMPLES_PER_FRAME * (16/8) * bitRates / 128000, fpInput);
if(readBytes <= 0)
break;
/* 参数：句柄、pcm缓存（传出）、g726缓存（传入）、g726数据长度；
* 返回值：pcm的采样点个数，注意不是字节数！！！所以字节数是要x2
*/
ret = g726_decode(g726Handler, (short*)outBuf, inBuf, readBytes);
DEBUG("[g726_decode] read g726 bytes: %d -> decode pcm bytes: %dn", readBytes, ret*2);
if(ret*2 * bitRates / 128000 != readBytes)
{
printf("G726 decode to PCM failed!n");
printf("033[31mFailed!033[0mn");
break;
}
fwrite(outBuf, 2, ret, fpOutput);
}
}
else
{
printf("Unknown convert type!n");
printf("033[31mFailed!033[0mn");
return -1;
}
printf("033[32msuccess!033[0mn");
// step : 释放句柄的内存
free(g726Handler);
free(inBuf);
free(outBuf);
fclose(fpInput);
fclose(fpOutput);
return 0;
}
Se ha dedicado a la investigación de tecnología durante más de 30 años y domina varios lenguajes como java, linux, javascript, php, css, etc. Ha realizado muchas contribuciones en el campo del código abierto. Estación de documentación para desarrolladores para compartir algunos problemas en el desarrollo de tecnología para referencia futura.
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