/* codec_g726.c - translate between signed linear and ITU G.726-32kbps * * Asterisk -- A telephony toolkit for Linux. * * Based on frompcm.c and topcm.c from the Emiliano MIPL browser/ * interpreter. See http://www.bsdtelephony.com.mx * * Copyright (c) 2004, Digium * * Mark Spencer * * This program is free software, distributed under the terms of * the GNU General Public License */ #include #include #include #include #include #include #include #include #include #include #include #define BUFFER_SIZE 8096 /* size for the translation buffers */ #define BUF_SHIFT 5 AST_MUTEX_DEFINE_STATIC(localuser_lock); static int localusecnt = 0; static char *tdesc = "ITU G.726-32kbps G726 Transcoder"; /* Sample frame data */ #include "slin_g726_ex.h" #include "g726_slin_ex.h" /* * The following is the definition of the state structure * used by the G.721/G.723 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.721. 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 { long yl; /* Locked or steady state step size multiplier. */ short yu; /* Unlocked or non-steady state step size multiplier. */ short dms; /* Short term energy estimate. */ short dml; /* Long term energy estimate. */ short ap; /* Linear weighting coefficient of 'yl' and 'yu'. */ short a[2]; /* Coefficients of pole portion of prediction filter. */ short b[6]; /* Coefficients of zero portion of prediction filter. */ short pk[2]; /* * Signs of previous two samples of a partially * reconstructed signal. */ short dq[6]; /* * Previous 6 samples of the quantized difference * signal represented in an internal floating point * format. */ short sr[2]; /* * Previous 2 samples of the quantized difference * signal represented in an internal floating point * format. */ char td; /* delayed tone detect, new in 1988 version */ }; static short qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400}; /* * Maps G.721 code word to reconstructed scale factor normalized log * magnitude values. */ static short _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425, 425, 373, 323, 273, 213, 135, 4, -2048}; /* Maps G.721 code word to log of scale factor multiplier. */ static short _witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122, 1122, 355, 198, 112, 64, 41, 18, -12}; /* * Maps G.721 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 short _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00, 0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0}; static short power2[15] = {1, 2, 4, 8, 0x10, 0x20, 0x40, 0x80, 0x100, 0x200, 0x400, 0x800, 0x1000, 0x2000, 0x4000}; /* * quan() * * quantizes the input val against the table of size short integers. * It returns i if table[i - 1] <= val < table[i]. * * Using linear search for simple coding. */ static int quan(int val, short *table, int size) { int i; for (i = 0; i < size; i++) if (val < *table++) break; return (i); } /* * fmult() * * returns the integer product of the 14-bit integer "an" and * "floating point" representation (4-bit exponent, 6-bit mantessa) "srn". */ static int fmult(int an, int srn) { short anmag, anexp, anmant; short wanexp, wanmant; short retval; anmag = (an > 0) ? an : ((-an) & 0x1FFF); anexp = quan(anmag, power2, 15) - 6; anmant = (anmag == 0) ? 32 : (anexp >= 0) ? anmag >> anexp : anmag << -anexp; wanexp = anexp + ((srn >> 6) & 0xF) - 13; wanmant = (anmant * (srn & 077) + 0x30) >> 4; retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) : (wanmant >> -wanexp); return (((an ^ srn) < 0) ? -retval : retval); } /* * g72x_init_state() * * This routine initializes and/or resets the g726_state structure * pointed to by 'state_ptr'. * All the initial state values are specified in the CCITT G.721 document. */ static void g726_init_state(struct g726_state *state_ptr) { int cnta; state_ptr->yl = 34816; state_ptr->yu = 544; state_ptr->dms = 0; state_ptr->dml = 0; state_ptr->ap = 0; for (cnta = 0; cnta < 2; cnta++) { state_ptr->a[cnta] = 0; state_ptr->pk[cnta] = 0; state_ptr->sr[cnta] = 32; } for (cnta = 0; cnta < 6; cnta++) { state_ptr->b[cnta] = 0; state_ptr->dq[cnta] = 32; } state_ptr->td = 0; } /* * predictor_zero() * * computes the estimated signal from 6-zero predictor. * */ static int predictor_zero(struct g726_state *state_ptr) { int i; int sezi; sezi = fmult(state_ptr->b[0] >> 2, state_ptr->dq[0]); for (i = 1; i < 6; i++) /* ACCUM */ sezi += fmult(state_ptr->b[i] >> 2, state_ptr->dq[i]); return (sezi); } /* * predictor_pole() * * computes the estimated signal from 2-pole predictor. * */ static int predictor_pole(struct g726_state *state_ptr) { return (fmult(state_ptr->a[1] >> 2, state_ptr->sr[1]) + fmult(state_ptr->a[0] >> 2, state_ptr->sr[0])); } /* * step_size() * * computes the quantization step size of the adaptive quantizer. * */ static int step_size(struct g726_state *state_ptr) { int y; int dif; int al; if (state_ptr->ap >= 256) return (state_ptr->yu); else { y = state_ptr->yl >> 6; dif = state_ptr->yu - y; al = state_ptr->ap >> 2; if (dif > 0) y += (dif * al) >> 6; else if (dif < 0) y += (dif * al + 0x3F) >> 6; return (y); } } /* * quantize() * * 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 int quantize( int d, /* Raw difference signal sample */ int y, /* Step size multiplier */ short *table, /* quantization table */ int size) /* 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; /* * LOG * * Compute base 2 log of 'd', and store in 'dl'. */ dqm = abs(d); exp = quan(dqm >> 1, power2, 15); mant = ((dqm << 7) >> exp) & 0x7F; /* Fractional portion. */ dl = (exp << 7) + mant; /* * SUBTB * * "Divide" by step size multiplier. */ dln = dl - (y >> 2); /* * QUAN * * Obtain codword i for 'd'. */ i = quan(dln, table, size); if (d < 0) /* take 1's complement of i */ return ((size << 1) + 1 - i); else if (i == 0) /* take 1's complement of 0 */ return ((size << 1) + 1); /* new in 1988 */ else return (i); } /* * reconstruct() * * 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 int 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 = dqln + (y >> 2); /* ADDA */ if (dql < 0) { return ((sign) ? -0x8000 : 0); } else { /* ANTILOG */ dex = (dql >> 7) & 15; dqt = 128 + (dql & 127); dq = (dqt << 7) >> (14 - dex); return ((sign) ? (dq - 0x8000) : dq); } } /* * update() * * updates the state variables for each output code */ static void update( int code_size, /* distinguish 723_40 with others */ 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 */ struct g726_state *state_ptr) /* coder state pointer */ { int cnt; short mag, exp; /* Adaptive predictor, FLOAT A */ short a2p=0; /* LIMC */ short a1ul; /* UPA1 */ short pks1; /* UPA2 */ short fa1; char tr; /* tone/transition detector */ short ylint, thr2, dqthr; short ylfrac, thr1; short pk0; pk0 = (dqsez < 0) ? 1 : 0; /* needed in updating predictor poles */ mag = dq & 0x7FFF; /* prediction difference magnitude */ /* TRANS */ ylint = state_ptr->yl >> 15; /* exponent part of yl */ ylfrac = (state_ptr->yl >> 10) & 0x1F; /* fractional part of yl */ thr1 = (32 + ylfrac) << ylint; /* threshold */ thr2 = (ylint > 9) ? 31 << 10 : thr1; /* limit thr2 to 31 << 10 */ dqthr = (thr2 + (thr2 >> 1)) >> 1; /* dqthr = 0.75 * thr2 */ if (state_ptr->td == 0) /* 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 */ state_ptr->yu = y + ((wi - y) >> 5); /* LIMB */ if (state_ptr->yu < 544) /* 544 <= yu <= 5120 */ state_ptr->yu = 544; else if (state_ptr->yu > 5120) state_ptr->yu = 5120; /* FILTE & DELAY */ /* update steady state step size multiplier */ state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6); /* * Adaptive predictor coefficients. */ if (tr == 1) { /* reset a's and b's for modem signal */ state_ptr->a[0] = 0; state_ptr->a[1] = 0; state_ptr->b[0] = 0; state_ptr->b[1] = 0; state_ptr->b[2] = 0; state_ptr->b[3] = 0; state_ptr->b[4] = 0; state_ptr->b[5] = 0; } else { /* update a's and b's */ pks1 = pk0 ^ state_ptr->pk[0]; /* UPA2 */ /* update predictor pole a[1] */ a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7); if (dqsez != 0) { fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0]; if (fa1 < -8191) /* a2p = function of fa1 */ a2p -= 0x100; else if (fa1 > 8191) a2p += 0xFF; else a2p += fa1 >> 5; if (pk0 ^ state_ptr->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 */ state_ptr->a[1] = a2p; /* UPA1 */ /* update predictor pole a[0] */ state_ptr->a[0] -= state_ptr->a[0] >> 8; if (dqsez != 0) { if (pks1 == 0) state_ptr->a[0] += 192; else state_ptr->a[0] -= 192; } /* LIMD */ a1ul = 15360 - a2p; if (state_ptr->a[0] < -a1ul) state_ptr->a[0] = -a1ul; else if (state_ptr->a[0] > a1ul) state_ptr->a[0] = a1ul; /* UPB : update predictor zeros b[6] */ for (cnt = 0; cnt < 6; cnt++) { if (code_size == 5) /* for 40Kbps G.723 */ state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9; else /* for G.721 and 24Kbps G.723 */ state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8; if (dq & 0x7FFF) { /* XOR */ if ((dq ^ state_ptr->dq[cnt]) >= 0) state_ptr->b[cnt] += 128; else state_ptr->b[cnt] -= 128; } } } for (cnt = 5; cnt > 0; cnt--) state_ptr->dq[cnt] = state_ptr->dq[cnt-1]; /* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */ if (mag == 0) { state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0xFC20; } else { exp = quan(mag, power2, 15); state_ptr->dq[0] = (dq >= 0) ? (exp << 6) + ((mag << 6) >> exp) : (exp << 6) + ((mag << 6) >> exp) - 0x400; } state_ptr->sr[1] = state_ptr->sr[0]; /* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */ if (sr == 0) { state_ptr->sr[0] = 0x20; } else if (sr > 0) { exp = quan(sr, power2, 15); state_ptr->sr[0] = (exp << 6) + ((sr << 6) >> exp); } else if (sr > -32768) { mag = -sr; exp = quan(mag, power2, 15); state_ptr->sr[0] = (exp << 6) + ((mag << 6) >> exp) - 0x400; } else state_ptr->sr[0] = 0xFC20; /* DELAY A */ state_ptr->pk[1] = state_ptr->pk[0]; state_ptr->pk[0] = pk0; /* TONE */ if (tr == 1) /* this sample has been treated as data */ state_ptr->td = 0; /* next one will be treated as voice */ else if (a2p < -11776) /* small sample-to-sample correlation */ state_ptr->td = 1; /* signal may be data */ else /* signal is voice */ state_ptr->td = 0; /* * Adaptation speed control. */ state_ptr->dms += (fi - state_ptr->dms) >> 5; /* FILTA */ state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7); /* FILTB */ if (tr == 1) state_ptr->ap = 256; else if (y < 1536) /* SUBTC */ state_ptr->ap += (0x200 - state_ptr->ap) >> 4; else if (state_ptr->td == 1) state_ptr->ap += (0x200 - state_ptr->ap) >> 4; else if (abs((state_ptr->dms << 2) - state_ptr->dml) >= (state_ptr->dml >> 3)) state_ptr->ap += (0x200 - state_ptr->ap) >> 4; else state_ptr->ap += (-state_ptr->ap) >> 4; } /* * g726_decode() * * Description: * * Decodes a 4-bit code of G.726-32 encoded data of i and * returns the resulting linear PCM, A-law or u-law value. * return -1 for unknown out_coding value. */ static int g726_decode(int i, struct g726_state *state_ptr) { short sezi, sei, sez, se; /* ACCUM */ short y; /* MIX */ short sr; /* ADDB */ short dq; short dqsez; i &= 0x0f; /* mask to get proper bits */ sezi = predictor_zero(state_ptr); sez = sezi >> 1; sei = sezi + predictor_pole(state_ptr); se = sei >> 1; /* se = estimated signal */ y = step_size(state_ptr); /* dynamic quantizer step size */ dq = reconstruct(i & 0x08, _dqlntab[i], y); /* quantized diff. */ sr = (dq < 0) ? (se - (dq & 0x3FFF)) : se + dq; /* reconst. signal */ dqsez = sr - se + sez; /* pole prediction diff. */ update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr); return (sr << 2); /* sr was 14-bit dynamic range */ } /* * g726_encode() * * Encodes the input vale of linear PCM, A-law or u-law data sl and returns * the resulting code. -1 is returned for unknown input coding value. */ static int g726_encode(int sl, struct g726_state *state_ptr) { short sezi, se, sez; /* ACCUM */ short d; /* SUBTA */ short sr; /* ADDB */ short y; /* MIX */ short dqsez; /* ADDC */ short dq, i; sl >>= 2; /* 14-bit dynamic range */ sezi = predictor_zero(state_ptr); sez = sezi >> 1; se = (sezi + predictor_pole(state_ptr)) >> 1; /* estimated signal */ d = sl - se; /* estimation difference */ /* quantize the prediction difference */ y = step_size(state_ptr); /* quantizer step size */ i = quantize(d, y, qtab_721, 7); /* i = G726 code */ dq = reconstruct(i & 8, _dqlntab[i], y); /* quantized est diff */ sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconst. signal */ dqsez = sr + sez - se; /* pole prediction diff. */ update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr); return (i); } /* * Private workspace for translating signed linear signals to G726. */ struct g726_encoder_pvt { struct ast_frame f; char offset[AST_FRIENDLY_OFFSET]; /* Space to build offset */ unsigned char outbuf[BUFFER_SIZE]; /* Encoded G726, two nibbles to a word */ unsigned char next_flag; struct g726_state g726; int tail; }; /* * Private workspace for translating G726 signals to signed linear. */ struct g726_decoder_pvt { struct ast_frame f; char offset[AST_FRIENDLY_OFFSET]; /* Space to build offset */ short outbuf[BUFFER_SIZE]; /* Decoded signed linear values */ struct g726_state g726; int tail; }; /* * G726ToLin_New * Create a new instance of g726_decoder_pvt. * * Results: * Returns a pointer to the new instance. * * Side effects: * None. */ static struct ast_translator_pvt * g726tolin_new (void) { struct g726_decoder_pvt *tmp; tmp = malloc (sizeof (struct g726_decoder_pvt)); if (tmp) { memset(tmp, 0, sizeof(*tmp)); tmp->tail = 0; localusecnt++; g726_init_state(&tmp->g726); ast_update_use_count (); } return (struct ast_translator_pvt *) tmp; } /* * LinToG726_New * Create a new instance of g726_encoder_pvt. * * Results: * Returns a pointer to the new instance. * * Side effects: * None. */ static struct ast_translator_pvt * lintog726_new (void) { struct g726_encoder_pvt *tmp; tmp = malloc (sizeof (struct g726_encoder_pvt)); if (tmp) { memset(tmp, 0, sizeof(*tmp)); localusecnt++; tmp->tail = 0; g726_init_state(&tmp->g726); ast_update_use_count (); } return (struct ast_translator_pvt *) tmp; } /* * G726ToLin_FrameIn * Fill an input buffer with packed 4-bit G726 values if there is room * left. * * Results: * Foo * * Side effects: * tmp->tail is the number of packed values in the buffer. */ static int g726tolin_framein (struct ast_translator_pvt *pvt, struct ast_frame *f) { struct g726_decoder_pvt *tmp = (struct g726_decoder_pvt *) pvt; unsigned char *b; int x; b = f->data; for (x=0;xdatalen;x++) { if (tmp->tail >= BUFFER_SIZE) { ast_log(LOG_WARNING, "Out of buffer space!\n"); return -1; } tmp->outbuf[tmp->tail++] = g726_decode((b[x] >> 4) & 0xf, &tmp->g726); if (tmp->tail >= BUFFER_SIZE) { ast_log(LOG_WARNING, "Out of buffer space!\n"); return -1; } tmp->outbuf[tmp->tail++] = g726_decode(b[x] & 0x0f, &tmp->g726); } return 0; } /* * G726ToLin_FrameOut * Convert 4-bit G726 encoded signals to 16-bit signed linear. * * Results: * Converted signals are placed in tmp->f.data, tmp->f.datalen * and tmp->f.samples are calculated. * * Side effects: * None. */ static struct ast_frame * g726tolin_frameout (struct ast_translator_pvt *pvt) { struct g726_decoder_pvt *tmp = (struct g726_decoder_pvt *) pvt; if (!tmp->tail) return NULL; tmp->f.frametype = AST_FRAME_VOICE; tmp->f.subclass = AST_FORMAT_SLINEAR; tmp->f.datalen = tmp->tail * 2; tmp->f.samples = tmp->tail; tmp->f.mallocd = 0; tmp->f.offset = AST_FRIENDLY_OFFSET; tmp->f.src = __PRETTY_FUNCTION__; tmp->f.data = tmp->outbuf; tmp->tail = 0; return &tmp->f; } /* * LinToG726_FrameIn * Fill an input buffer with 16-bit signed linear PCM values. * * Results: * None. * * Side effects: * tmp->tail is number of signal values in the input buffer. */ static int lintog726_framein (struct ast_translator_pvt *pvt, struct ast_frame *f) { struct g726_encoder_pvt *tmp = (struct g726_encoder_pvt *) pvt; short *s = f->data; int samples = f->datalen / 2; int x; for (x=0;xnext_flag & 0x80) { if (tmp->tail >= BUFFER_SIZE) { ast_log(LOG_WARNING, "Out of buffer space\n"); return -1; } tmp->outbuf[tmp->tail++] = ((tmp->next_flag & 0xf)<< 4) | g726_encode(s[x], &tmp->g726); tmp->next_flag = 0; } else { tmp->next_flag = 0x80 | g726_encode(s[x], &tmp->g726); } } return 0; } /* * LinToG726_FrameOut * Convert a buffer of raw 16-bit signed linear PCM to a buffer * of 4-bit G726 packed two to a byte (Big Endian). * * Results: * Foo * * Side effects: * Leftover inbuf data gets packed, tail gets updated. */ static struct ast_frame * lintog726_frameout (struct ast_translator_pvt *pvt) { struct g726_encoder_pvt *tmp = (struct g726_encoder_pvt *) pvt; if (!tmp->tail) return NULL; tmp->f.frametype = AST_FRAME_VOICE; tmp->f.subclass = AST_FORMAT_G726; tmp->f.samples = tmp->tail * 2; tmp->f.mallocd = 0; tmp->f.offset = AST_FRIENDLY_OFFSET; tmp->f.src = __PRETTY_FUNCTION__; tmp->f.data = tmp->outbuf; tmp->f.datalen = tmp->tail; tmp->tail = 0; return &tmp->f; } /* * G726ToLin_Sample */ static struct ast_frame * g726tolin_sample (void) { static struct ast_frame f; f.frametype = AST_FRAME_VOICE; f.subclass = AST_FORMAT_G726; f.datalen = sizeof (g726_slin_ex); f.samples = sizeof(g726_slin_ex) * 2; f.mallocd = 0; f.offset = 0; f.src = __PRETTY_FUNCTION__; f.data = g726_slin_ex; return &f; } /* * LinToG726_Sample */ static struct ast_frame * lintog726_sample (void) { static struct ast_frame f; f.frametype = AST_FRAME_VOICE; f.subclass = AST_FORMAT_SLINEAR; f.datalen = sizeof (slin_g726_ex); /* Assume 8000 Hz */ f.samples = sizeof (slin_g726_ex) / 2; f.mallocd = 0; f.offset = 0; f.src = __PRETTY_FUNCTION__; f.data = slin_g726_ex; return &f; } /* * G726_Destroy * Destroys a private workspace. * * Results: * It's gone! * * Side effects: * None. */ static void g726_destroy (struct ast_translator_pvt *pvt) { free (pvt); localusecnt--; ast_update_use_count (); } /* * The complete translator for G726ToLin. */ static struct ast_translator g726tolin = { "g726tolin", AST_FORMAT_G726, AST_FORMAT_SLINEAR, g726tolin_new, g726tolin_framein, g726tolin_frameout, g726_destroy, /* NULL */ g726tolin_sample }; /* * The complete translator for LinToG726. */ static struct ast_translator lintog726 = { "lintog726", AST_FORMAT_SLINEAR, AST_FORMAT_G726, lintog726_new, lintog726_framein, lintog726_frameout, g726_destroy, /* NULL */ lintog726_sample }; int unload_module (void) { int res; ast_mutex_lock (&localuser_lock); res = ast_unregister_translator (&lintog726); if (!res) res = ast_unregister_translator (&g726tolin); if (localusecnt) res = -1; ast_mutex_unlock (&localuser_lock); return res; } int load_module (void) { int res; res = ast_register_translator (&g726tolin); if (!res) res = ast_register_translator (&lintog726); else ast_unregister_translator (&g726tolin); return res; } /* * Return a description of this module. */ char * description (void) { return tdesc; } int usecount (void) { int res; STANDARD_USECOUNT (res); return res; } char * key () { return ASTERISK_GPL_KEY; }