1、README
前言
本demo是将使用了开源项目EasyAACEncoder里的src/g726.cpp(demo中的已重命名为g726.c)和src/g726.h将16位小字节序的pcm数据和g726进行相互转换。
注：相关测试文件已存放在demo的
audio目录下，目前发现pcm转换得到的g726文件用软件Audacity播放不正常（没找到g726，所以选的VOX ADPCM），而将所得到的g726再转换回pcm却播放正常，网上说需要支持g726解码的播放器才能播放，用ffmpeg播放也出错，所以看到本注释时的g726都是播放不了的。
a. 编译
$ 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
b. 使用
$ ./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
c. 参考文章
d. demo目录架构
$ 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
2、主要代码片段
g726.c
/*
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;
}
main.c
#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.g726\n"
" %s -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 24000 -o out_8khz_24kbps.g726\n"
" %s -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 32000 -o out_8khz_32kbps.g726\n"
" %s -t pcm_2_g726 -i ./audio/test_8khz_16bit_mono_128kbps.pcm -r 40000 -o out_8khz_40kbps.g726\n"
" %s -t g726_2_pcm -i ./audio/test_8khz_16kbps.g726 -r 16000 -o out_8khz_16bit_mono_128kbps-1.pcm\n"
" %s -t g726_2_pcm -i ./audio/test_8khz_24kbps.g726 -r 24000 -o out_8khz_16bit_mono_128kbps-2.pcm\n"
" %s -t g726_2_pcm -i ./audio/test_8khz_32kbps.g726 -r 32000 -o out_8khz_16bit_mono_128kbps-3.pcm\n"
" %s -t g726_2_pcm -i ./audio/test_8khz_40kbps.g726 -r 40000 -o out_8khz_16bit_mono_128kbps-4.pcm\n",
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: %s\n"
"input file name: %s\n"
"output file name: %s\n"
"g726 bit rates: %d bps\n"
"**************************************\n\n",
!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: %d\n", readBytes, ret);
if(ret != readBytes * bitRates / 128000)
{
printf("PCM encode to G726 failed!\n");
printf("\033[31mFailed!\033[0m\n");
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: %d\n", readBytes, ret*2);
if(ret*2 * bitRates / 128000 != readBytes)
{
printf("G726 decode to PCM failed!\n");
printf("\033[31mFailed!\033[0m\n");
break;
}
fwrite(outBuf, 2, ret, fpOutput);
}
}
else
{
printf("Unknown convert type!\n");
printf("\033[31mFailed!\033[0m\n");
return -1;
}
printf("\033[32msuccess!\033[0m\n");
// step : 释放句柄的内存
free(g726Handler);
free(inBuf);
free(outBuf);
fclose(fpInput);
fclose(fpOutput);
return 0;
}
