CCITT标准G726编解码实例
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//g726.h
/*! Bitstream handler state */typedef struct bitstream_state_s{/*! The bit stream. */unsigned int bitstream;/*! The residual bits in bitstream. */int residue;}bitstream_state_t;typedef struct g726_state_s g726_state_t;typedef short (*g726_decoder_func_t)(g726_state_t *s, unsigned char code);typedef unsigned char (*g726_encoder_func_t)(g726_state_t *s, short amp);/*!* The following is the definition of the state structure* used by the G.726 encoder and decoder to preserve their internal* state between successive calls. The meanings of the majority* of the state structure fields are explained in detail in the* CCITT Recommendation G.726. The field names are essentially indentical* to variable names in the bit level description of the coding algorithm* included in this recommendation.*/struct g726_state_s{/*! The bit rate */int rate;/*! The external coding, for tandem operation *///int ext_coding;/*! The number of bits per sample */int bits_per_sample;/*! One of the G.726_PACKING_xxx options *///int packing;/*! Locked or steady state step size multiplier. */int yl;/*! Unlocked or non-steady state step size multiplier. */short yu;/*! short term energy estimate. */short dms;/*! Long term energy estimate. */short dml;/*! Linear weighting coefficient of 'yl' and 'yu'. */short ap;/*! Coefficients of pole portion of prediction filter. */short a[2];/*! Coefficients of zero portion of prediction filter. */short b[6];/*! Signs of previous two samples of a partially reconstructed signal. */short pk[2];/*! Previous 6 samples of the quantized difference signal represented inan internal floating point format. */short dq[6];/*! Previous 2 samples of the quantized difference signal represented in aninternal floating point format. */short sr[2];/*! Delayed tone detect */int td;/*! \brief The bit stream processing context. */bitstream_state_t bs;/*! \brief The current encoder function. */g726_encoder_func_t enc_func;/*! \brief The current decoder function. */g726_decoder_func_t dec_func;};/** Maps G.726_16 code word to reconstructed scale factor normalized log* magnitude values.*/static const int g726_16_dqlntab[4] ={116, 365, 365, 116};/* Maps G.726_16 code word to log of scale factor multiplier. */static const int g726_16_witab[4] ={-704, 14048, 14048, -704};/** Maps G.726_16 code words to a set of values whose long and short* term averages are computed and then compared to give an indication* how stationary (steady state) the signal is.*/static const int g726_16_fitab[4] ={0x000, 0xE00, 0xE00, 0x000};/** Maps G.726_24 code word to reconstructed scale factor normalized log* magnitude values.*/static const int g726_24_dqlntab[8] ={-2048, 135, 273, 373, 373, 273, 135, -2048};/* Maps G.726_24 code word to log of scale factor multiplier. */static const int g726_24_witab[8] ={-128, 960, 4384, 18624, 18624, 4384, 960, -128};/** Maps G.726_24 code words to a set of values whose long and short* term averages are computed and then compared to give an indication* how stationary (steady state) the signal is.*/static const int g726_24_fitab[8] ={0x000, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0x000};/** Maps G.726_32 code word to reconstructed scale factor normalized log* magnitude values.*/static const int g726_32_dqlntab[16] ={-2048, 4, 135, 213, 273, 323, 373, 425,425, 373, 323, 273, 213, 135, 4, -2048};/* Maps G.726_32 code word to log of scale factor multiplier. */static const int g726_32_witab[16] ={-384, 576, 1312, 2048, 3584, 6336, 11360, 35904,35904, 11360, 6336, 3584, 2048, 1312, 576, -384};/** Maps G.726_32 code words to a set of values whose long and short* term averages are computed and then compared to give an indication* how stationary (steady state) the signal is.*/static const int g726_32_fitab[16] ={0x000, 0x000, 0x000, 0x200, 0x200, 0x200, 0x600, 0xE00,0xE00, 0x600, 0x200, 0x200, 0x200, 0x000, 0x000, 0x000};/** Maps G.726_40 code word to ructeconstructed scale factor normalized log* magnitude values.*/static const int g726_40_dqlntab[32] ={-2048, -66, 28, 104, 169, 224, 274, 318,358, 395, 429, 459, 488, 514, 539, 566,566, 539, 514, 488, 459, 429, 395, 358,318, 274, 224, 169, 104, 28, -66, -2048};/* Maps G.726_40 code word to log of scale factor multiplier. */static const int g726_40_witab[32] ={448, 448, 768, 1248, 1280, 1312, 1856, 3200,4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272,22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512,3200, 1856, 1312, 1280, 1248, 768, 448, 448};/** Maps G.726_40 code words to a set of values whose long and short* term averages are computed and then compared to give an indication* how stationary (steady state) the signal is.*/static const int g726_40_fitab[32] ={0x000, 0x000, 0x000, 0x000, 0x000, 0x200, 0x200, 0x200,0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00,0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200,0x200, 0x200, 0x200, 0x000, 0x000, 0x000, 0x000, 0x000};g726_state_t *g726_init(g726_state_t *s, int bit_rate);int g726_decode(g726_state_t *s, short amp[], const unsigned char g726_data[], int g726_bytes);int g726_encode(g726_state_t *s, unsigned char g726_data[], const short amp[], int len);//g726.cpp
/*Copyright (c) 2013-2016 EasyDarwin.ORG. All rights reserved.Github: https://github.com/EasyDarwinWEChat: EasyDarwinWebsite: 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, eaxdec eaxbsr eax, bits}#elseint 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;elsea2p += fa1 >> 5;if (pk0 ^ s->pk[1]){/* LIMC */if (a2p <= -12160)a2p = -12288;else if (a2p >= 12416)a2p = 12288;elsea2p -= 0x80;}else if (a2p <= -12416)a2p = -12288;else if (a2p >= 12160)a2p = 12288;elsea2p += 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;elses->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;elses->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;elses->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;}//调用实例
pcm to ccitt g726
//pcm数据采样率：，位宽：bit，通道：单通道
//一般-100ms打包一帧数据，如何ms打包一帧，pcm数据大小为字节
//pcm大小=（采样率*位宽*通道数/1000毫秒* 20毫秒）/ 8
intnPcmSize = (8000*16*1/1000 * 20) / 8;
g726_state_t*pSate726 = (g726_state_t*)malloc(sizeof(g726_state_t));
intnG726Size = 0;
intnG726SizePerFrame = 20; //每帧pcm大小
intnRateZipType = 3; //码流类型，分别用、、、表示kpbs、kpbs、kbps、kbps
intnRateZipValue = 2;
switch(nRateZipType)
{
case0:
nRateZipValue= 2; //16kpbs
break;
case1:
nRateZipValue= 3; //24kpbs
break;
case2:
nRateZipValue= 4; //32kbps
break;
case3:
nRateZipValue= 5; //40kbps
break;
}
nG726Size= nRateZipValue * nG726SizePerFrame;
pSate726= g726_init(pSate726,nRateZipValue*8000);
CStringfilePath ="";
CStringnewlFilePath ="";
charszFilter[] = {"PcmFiles (*.pcm)|*.pcm||"};
CFileDialogdlg(TRUE,NULL,NULL,OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT,szFilter,NULL);
if(dlg.DoModal()==IDOK)
{
filePath= dlg.GetPathName();
newlFilePath= filePath;
newlFilePath.Replace(".pcm",".g726_ccitt");
FILE* fpSrc = fopen(filePath.GetBuffer(filePath.GetLength()),"rb");
FILE* fpDst = fopen(newlFilePath.GetBuffer(newlFilePath.GetLength()),"wb+");
charszData[320] = {0};
unsignedcharszOutData[200]= {0};
int nDataLen =nPcmSize;
int nOutDataLen= nG726Size;
int nReadedSize= 0;
int ret = 0;
if(fpSrc !=NULL)
{
while(TRUE)
{
nReadedSize = fread(szData,sizeof(char),nDataLen,fpSrc);
if(nReadedSize<nDataLen)
{
break;
}
int iRet = g726_encode(pSate726,szOutData, (short*)szData,nReadedSize/2);
nOutDataLen = iRet;
if (nOutDataLen> 0)
{
//写入数据
int iiiii = fwrite(szOutData,1,nOutDataLen, fpDst);
}
}
fclose(fpSrc);
fclose(fpDst);
}
}
if(pSate726 !=NULL)
{
free(pSate726);
pSate726= NULL;
}
//ccitt g726 to pcm
//pcm数据采样率：，位宽：bit，通道：单通道
//一般-100ms打包一帧数据，如何ms打包一帧，pcm数据大小为字节
//pcm大小=（采样率*位宽*通道数/1000毫秒* 20毫秒）/ 8
intnPcmSize = (8000*16*1/1000 * 20) / 8;
g726_state_t*pSate726 = (g726_state_t*)malloc(sizeof(g726_state_t));
intnG726Size = 0;
intnG726SizePerFrame = 20; //每帧pcm大小
intnRateZipType = 3; //码流类型，分别用、、、表示kpbs、kpbs、kbps、kbps
intnRateZipValue = 2;
switch(nRateZipType)
{
case0:
nRateZipValue= 2; //16kpbs
break;
case1:
nRateZipValue= 3; //24kpbs
break;
case2:
nRateZipValue= 4; //32kbps
break;
case3:
nRateZipValue= 5; //40kbps
break;
}
nG726Size= nRateZipValue * nG726SizePerFrame;
pSate726= g726_init(pSate726,nRateZipValue*8000);
CStringfilePath ="";
CStringnewlFilePath ="";
charszFilter[] = {"g726_ccittFiles (*.g726_ccitt)|*.g726_ccitt||"};
CFileDialogdlg(TRUE,NULL,NULL,OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT,szFilter,NULL);
if(dlg.DoModal()==IDOK)
{
filePath= dlg.GetPathName();
newlFilePath= filePath;
newlFilePath.Replace(".g726_ccitt","_g726_ccitt.pcm");
FILE* fpSrc = fopen(filePath.GetBuffer(filePath.GetLength()),"rb");
FILE* fpDst = fopen(newlFilePath.GetBuffer(newlFilePath.GetLength()),"wb+");
unsignedcharszData[200]= {0};
shortszOutData[640] = {0};
int nDataLen =nG726Size;
int nOutDataLen= nPcmSize;
int nReadedSize= 0;
int ret = 0;
if(fpSrc !=NULL)
{
while(TRUE)
{
nReadedSize = fread(szData,sizeof(unsignedchar),nDataLen,fpSrc);
if(nReadedSize<nDataLen)
{
break;
}
int iRet = g726_decode(pSate726,szOutData,szData,nReadedSize);
nOutDataLen = iRet*2;
if (nOutDataLen> 0)
{
//写入数据
int iiiii = fwrite(szOutData,sizeof(short),iRet, fpDst );
}
}
fclose(fpSrc);
fclose(fpDst);
}
}
if(pSate726 !=NULL)
{
free(pSate726);
pSate726= NULL;
}
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