/* * AC-3 Audio Decoder * This code is developed as part of Google Summer of Code 2006 Program. * * Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com). * * For exponent decoding the code is inspired by the code in liba52 by * Michel Lespinasse and Aaron Holtzman. * http://liba52.sourceforge.net * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include #include #include #include #define ALT_BITSTREAM_READER #include "avcodec.h" #include "ac3.h" #include "ac3tab.h" #include "bitstream.h" #include "dsputil.h" #include "random.h" static uint8_t bndtab[51]; static uint8_t masktab[253]; static const int nfchans_tbl[8] = { 2, 1, 2, 3, 3, 4, 4, 5 }; /* table for exponent to scale_factor mapping * scale_factor[i] = 2 ^ -(i + 15) */ static float scale_factors[25]; static int16_t psdtab[25]; static int8_t exp_1[128]; static int8_t exp_2[128]; static int8_t exp_3[128]; static int16_t l3_quantizers_1[32]; static int16_t l3_quantizers_2[32]; static int16_t l3_quantizers_3[32]; static int16_t l5_quantizers_1[128]; static int16_t l5_quantizers_2[128]; static int16_t l5_quantizers_3[128]; static int16_t l7_quantizers[7]; static int16_t l11_quantizers_1[128]; static int16_t l11_quantizers_2[128]; static int16_t l15_quantizers[15]; static const uint8_t qntztab[16] = { 0, 5, 7, 3, 7, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16 }; /* Adjustmens in dB gain */ #define LEVEL_MINUS_3DB 0.7071067811865476 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605 #define LEVEL_MINUS_6DB 0.5000000000000000 #define LEVEL_PLUS_3DB 1.4142135623730951 #define LEVEL_PLUS_6DB 2.0000000000000000 #define LEVEL_ZERO 0.0000000000000000 static const float clevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB, LEVEL_MINUS_6DB, LEVEL_MINUS_4POINT5DB }; static const float slevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_6DB, LEVEL_ZERO, LEVEL_MINUS_6DB }; #define BLOCK_SIZE 256 /* Output and input configurations. */ #define AC3_OUTPUT_UNMODIFIED 0x01 #define AC3_OUTPUT_MONO 0x02 #define AC3_OUTPUT_STEREO 0x04 #define AC3_OUTPUT_DOLBY 0x08 #define AC3_OUTPUT_LFEON 0x10 typedef struct { uint16_t crc1; uint8_t fscod; uint8_t acmod; uint8_t cmixlev; uint8_t surmixlev; uint8_t dsurmod; uint8_t blksw; uint8_t dithflag; uint8_t cplinu; uint8_t chincpl; uint8_t phsflginu; uint8_t cplbegf; uint8_t cplendf; uint8_t cplcoe; uint32_t cplbndstrc; uint8_t rematstr; uint8_t rematflg; uint8_t cplexpstr; uint8_t lfeexpstr; uint8_t chexpstr[5]; uint8_t sdcycod; uint8_t fdcycod; uint8_t sgaincod; uint8_t dbpbcod; uint8_t floorcod; uint8_t csnroffst; uint8_t cplfsnroffst; uint8_t cplfgaincod; uint8_t fsnroffst[5]; uint8_t fgaincod[5]; uint8_t lfefsnroffst; uint8_t lfefgaincod; uint8_t cplfleak; uint8_t cplsleak; uint8_t cpldeltbae; uint8_t deltbae[5]; uint8_t cpldeltnseg; uint8_t cpldeltoffst[8]; uint8_t cpldeltlen[8]; uint8_t cpldeltba[8]; uint8_t deltnseg[5]; uint8_t deltoffst[5][8]; uint8_t deltlen[5][8]; uint8_t deltba[5][8]; /* Derived Attributes. */ int sampling_rate; int bit_rate; int frame_size; int nfchans; //number of channels int lfeon; //lfe channel in use float dynrng; //dynamic range gain float dynrng2; //dynamic range gain for 1+1 mode float chcoeffs[6]; //normalized channel coefficients float cplco[5][18]; //coupling coordinates int ncplbnd; //number of coupling bands int ncplsubnd; //number of coupling sub bands int cplstrtmant; //coupling start mantissa int cplendmant; //coupling end mantissa int endmant[5]; //channel end mantissas AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters uint8_t dcplexps[256]; //decoded coupling exponents uint8_t dexps[5][256]; //decoded fbw channel exponents uint8_t dlfeexps[256]; //decoded lfe channel exponents uint8_t cplbap[256]; //coupling bit allocation pointers uint8_t bap[5][256]; //fbw channel bit allocation pointers uint8_t lfebap[256]; //lfe channel bit allocation pointers int blkoutput; //output configuration for block DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][BLOCK_SIZE]); //transform coefficients /* For IMDCT. */ MDCTContext imdct_512; //for 512 sample imdct transform MDCTContext imdct_256; //for 256 sample imdct transform DSPContext dsp; //for optimization DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS][BLOCK_SIZE]); //output after imdct transform and windowing DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS][BLOCK_SIZE]); //delay - added to the next block DECLARE_ALIGNED_16(float, tmp_imdct[BLOCK_SIZE]); //temporary storage for imdct transform DECLARE_ALIGNED_16(float, tmp_output[BLOCK_SIZE * 2]); //temporary storage for output before windowing DECLARE_ALIGNED_16(float, window[BLOCK_SIZE]); //window coefficients /* Miscellaneous. */ GetBitContext gb; AVRandomState dith_state; //for dither generation } AC3DecodeContext; /*********** BEGIN INIT HELPER FUNCTIONS ***********/ /** * Generate a Kaiser-Bessel Derived Window. */ static void ac3_window_init(float *window) { int i, j; double sum = 0.0, bessel, tmp; double local_window[256]; double alpha2 = (5.0 * M_PI / 256.0) * (5.0 * M_PI / 256.0); for (i = 0; i < 256; i++) { tmp = i * (256 - i) * alpha2; bessel = 1.0; for (j = 100; j > 0; j--) /* defaul to 100 iterations */ bessel = bessel * tmp / (j * j) + 1; sum += bessel; local_window[i] = sum; } sum++; for (i = 0; i < 256; i++) window[i] = sqrt(local_window[i] / sum); } /* * Generate quantizer tables. */ static void generate_quantizers_table(int16_t quantizers[], int level, int length) { int i; for (i = 0; i < length; i++) quantizers[i] = ((2 * i - level + 1) << 15) / level; } static void generate_quantizers_table_1(int16_t quantizers[], int level, int length1, int length2, int size) { int i, j; int16_t v; for (i = 0; i < length1; i++) { v = ((2 * i - level + 1) << 15) / level; for (j = 0; j < length2; j++) quantizers[i * length2 + j] = v; } for (i = length1 * length2; i < size; i++) quantizers[i] = 0; } static void generate_quantizers_table_2(int16_t quantizers[], int level, int length1, int length2, int size) { int i, j; int16_t v; for (i = 0; i < length1; i++) { v = ((2 * (i % level) - level + 1) << 15) / level; for (j = 0; j < length2; j++) quantizers[i * length2 + j] = v; } for (i = length1 * length2; i < size; i++) quantizers[i] = 0; } static void generate_quantizers_table_3(int16_t quantizers[], int level, int length1, int length2, int size) { int i, j; for (i = 0; i < length1; i++) for (j = 0; j < length2; j++) quantizers[i * length2 + j] = ((2 * (j % level) - level + 1) << 15) / level; for (i = length1 * length2; i < size; i++) quantizers[i] = 0; } /* * Initialize tables at runtime. */ static void ac3_tables_init(void) { int i, j, k, l, v; /* compute bndtab and masktab from bandsz */ k = 0; l = 0; for(i=0;i<50;i++) { bndtab[i] = l; v = ff_ac3_bndsz[i]; for(j=0;jpriv_data; ac3_common_init(); ac3_tables_init(); ff_mdct_init(&ctx->imdct_256, 8, 1); ff_mdct_init(&ctx->imdct_512, 9, 1); ac3_window_init(ctx->window); dsputil_init(&ctx->dsp, avctx); av_init_random(0, &ctx->dith_state); return 0; } /*********** END INIT FUNCTIONS ***********/ /* Synchronize to ac3 bitstream. * This function searches for the syncword '0xb77'. * * @param buf Pointer to "probable" ac3 bitstream buffer * @param buf_size Size of buffer * @return Returns the position where syncword is found, -1 if no syncword is found */ static int ac3_synchronize(uint8_t *buf, int buf_size) { int i; for (i = 0; i < buf_size - 1; i++) if (buf[i] == 0x0b && buf[i + 1] == 0x77) return i; return -1; } /* Parse the 'sync_info' from the ac3 bitstream. * This function extracts the sync_info from ac3 bitstream. * GetBitContext within AC3DecodeContext must point to * start of the synchronized ac3 bitstream. * * @param ctx AC3DecodeContext * @return Returns framesize, returns 0 if fscod, frmsizecod or bsid is not valid */ static int ac3_parse_sync_info(AC3DecodeContext *ctx) { GetBitContext *gb = &ctx->gb; int frmsizecod, bsid; skip_bits(gb, 16); //skip the sync_word, sync_info->sync_word = get_bits(gb, 16); ctx->crc1 = get_bits(gb, 16); ctx->fscod = get_bits(gb, 2); if (ctx->fscod == 0x03) return 0; frmsizecod = get_bits(gb, 6); if (frmsizecod >= 38) return 0; ctx->sampling_rate = ff_ac3_freqs[ctx->fscod]; ctx->bit_rate = ff_ac3_bitratetab[frmsizecod >> 1]; /* we include it here in order to determine validity of ac3 frame */ bsid = get_bits(gb, 5); if (bsid > 0x08) return 0; skip_bits(gb, 3); //skip the bsmod, bsi->bsmod = get_bits(gb, 3); switch (ctx->fscod) { case 0x00: ctx->frame_size = 4 * ctx->bit_rate; return ctx->frame_size; case 0x01: ctx->frame_size = 2 * (320 * ctx->bit_rate / 147 + (frmsizecod & 1)); return ctx->frame_size; case 0x02: ctx->frame_size = 6 * ctx->bit_rate; return ctx->frame_size; } /* never reached */ return 0; } /* Parse bsi from ac3 bitstream. * This function extracts the bitstream information (bsi) from ac3 bitstream. * * @param ctx AC3DecodeContext after processed by ac3_parse_sync_info */ static void ac3_parse_bsi(AC3DecodeContext *ctx) { GetBitContext *gb = &ctx->gb; int i; ctx->cmixlev = 0; ctx->surmixlev = 0; ctx->dsurmod = 0; ctx->nfchans = 0; ctx->cpldeltbae = DBA_NONE; ctx->cpldeltnseg = 0; for (i = 0; i < 5; i++) { ctx->deltbae[i] = DBA_NONE; ctx->deltnseg[i] = 0; } ctx->dynrng = 1.0; ctx->dynrng2 = 1.0; ctx->acmod = get_bits(gb, 3); ctx->nfchans = nfchans_tbl[ctx->acmod]; if (ctx->acmod & 0x01 && ctx->acmod != 0x01) ctx->cmixlev = get_bits(gb, 2); if (ctx->acmod & 0x04) ctx->surmixlev = get_bits(gb, 2); if (ctx->acmod == 0x02) ctx->dsurmod = get_bits(gb, 2); ctx->lfeon = get_bits1(gb); i = !(ctx->acmod); do { skip_bits(gb, 5); //skip dialog normalization if (get_bits1(gb)) skip_bits(gb, 8); //skip compression if (get_bits1(gb)) skip_bits(gb, 8); //skip language code if (get_bits1(gb)) skip_bits(gb, 7); //skip audio production information } while (i--); skip_bits(gb, 2); //skip copyright bit and original bitstream bit if (get_bits1(gb)) skip_bits(gb, 14); //skip timecode1 if (get_bits1(gb)) skip_bits(gb, 14); //skip timecode2 if (get_bits1(gb)) { i = get_bits(gb, 6); //additional bsi length do { skip_bits(gb, 8); } while(i--); } } /* Decodes the grouped exponents. * This function decodes the coded exponents according to exponent strategy * and stores them in the decoded exponents buffer. * * @param gb GetBitContext which points to start of coded exponents * @param expstr Exponent coding strategy * @param ngrps Number of grouped exponetns * @param absexp Absolute exponent * @param dexps Decoded exponents are stored in dexps * @return Returns 0 if exponents are decoded successfully, -1 if error occurs */ static int decode_exponents(GetBitContext *gb, int expstr, int ngrps, uint8_t absexp, uint8_t *dexps) { int exps; while (ngrps--) { exps = get_bits(gb, 7); absexp += exp_1[exps]; if (absexp > 24) { av_log(NULL, AV_LOG_ERROR, "Absolute Exponent > 24, ngrp = %d\n", ngrps); return -ngrps; } switch (expstr) { case EXP_D45: *(dexps++) = absexp; *(dexps++) = absexp; case EXP_D25: *(dexps++) = absexp; case EXP_D15: *(dexps++) = absexp; } absexp += exp_2[exps]; if (absexp > 24) { av_log(NULL, AV_LOG_ERROR, "Absolute Exponent > 24, ngrp = %d\n", ngrps); return -ngrps; } switch (expstr) { case EXP_D45: *(dexps++) = absexp; *(dexps++) = absexp; case EXP_D25: *(dexps++) = absexp; case EXP_D15: *(dexps++) = absexp; } absexp += exp_3[exps]; if (absexp > 24) { av_log(NULL, AV_LOG_ERROR, "Absolute Exponent > 24, ngrp = %d\n", ngrps); return -ngrps; } switch (expstr) { case EXP_D45: *(dexps++) = absexp; *(dexps++) = absexp; case EXP_D25: *(dexps++) = absexp; case EXP_D15: *(dexps++) = absexp; } } return 0; } /* Performs bit allocation. * This function performs bit allocation for the requested chanenl. */ static void do_bit_allocation(AC3DecodeContext *ctx, int chnl) { int fgain, snroffset; if (chnl == 5) { fgain = ff_fgaintab[ctx->cplfgaincod]; snroffset = (((ctx->csnroffst - 15) << 4) + ctx->cplfsnroffst) << 2; ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->cplbap, ctx->dcplexps, ctx->cplstrtmant, ctx->cplendmant, snroffset, fgain, 0, ctx->cpldeltbae, ctx->cpldeltnseg, ctx->cpldeltoffst, ctx->cpldeltlen, ctx->cpldeltba); } else if (chnl == 6) { fgain = ff_fgaintab[ctx->lfefgaincod]; snroffset = (((ctx->csnroffst - 15) << 4) + ctx->lfefsnroffst) << 2; ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->lfebap, ctx->dlfeexps, 0, 7, snroffset, fgain, 1, DBA_NONE, 0, NULL, NULL, NULL); } else { fgain = ff_fgaintab[ctx->fgaincod[chnl]]; snroffset = (((ctx->csnroffst - 15) << 4) + ctx->fsnroffst[chnl]) << 2; ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->bap[chnl], ctx->dexps[chnl], 0, ctx->endmant[chnl], snroffset, fgain, 0, ctx->deltbae[chnl], ctx->deltnseg[chnl], ctx->deltoffst[chnl], ctx->deltlen[chnl], ctx->deltba[chnl]); } } /* Check if snroffsets are zero. */ static int is_snr_offsets_zero(AC3DecodeContext *ctx) { int i; if ((ctx->csnroffst) || (ctx->cplinu && ctx->cplfsnroffst) || (ctx->lfeon && ctx->lfefsnroffst)) return 0; for (i = 0; i < ctx->nfchans; i++) if (ctx->fsnroffst[i]) return 0; return 1; } typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantization */ int16_t l3_quantizers[3]; int16_t l5_quantizers[3]; int16_t l11_quantizers[2]; int l3ptr; int l5ptr; int l11ptr; } mant_groups; #define TRANSFORM_COEFF(tc, m, e, f) (tc) = (m) * (f)[(e)] /* Get the transform coefficients for coupling channel and uncouple channels. * The coupling transform coefficients starts at the the cplstrtmant, which is * equal to endmant[ch] for fbw channels. Hence we can uncouple channels before * getting transform coefficients for the channel. */ static int get_transform_coeffs_cpling(AC3DecodeContext *ctx, mant_groups *m) { GetBitContext *gb = &ctx->gb; int ch, start, end, cplbndstrc, bnd, gcode, tbap; float cplcos[5], cplcoeff; uint8_t *exps = ctx->dcplexps; uint8_t *bap = ctx->cplbap; cplbndstrc = ctx->cplbndstrc; start = ctx->cplstrtmant; bnd = 0; while (start < ctx->cplendmant) { end = start + 12; while (cplbndstrc & 1) { end += 12; cplbndstrc >>= 1; } cplbndstrc >>= 1; for (ch = 0; ch < ctx->nfchans; ch++) cplcos[ch] = ctx->chcoeffs[ch] * ctx->cplco[ch][bnd]; bnd++; while (start < end) { tbap = bap[start]; switch(tbap) { case 0: for (ch = 0; ch < ctx->nfchans; ch++) if (((ctx->chincpl) >> ch) & 1) { if ((ctx->dithflag >> ch) & 1) { TRANSFORM_COEFF(cplcoeff, av_random(&ctx->dith_state) & 0xFFFF, exps[start], scale_factors); ctx->transform_coeffs[ch + 1][start] = cplcoeff * cplcos[ch] * LEVEL_MINUS_3DB; } else ctx->transform_coeffs[ch + 1][start] = 0; } start++; continue; case 1: if (m->l3ptr > 2) { gcode = get_bits(gb, 5); m->l3_quantizers[0] = l3_quantizers_1[gcode]; m->l3_quantizers[1] = l3_quantizers_2[gcode]; m->l3_quantizers[2] = l3_quantizers_3[gcode]; m->l3ptr = 0; } TRANSFORM_COEFF(cplcoeff, m->l3_quantizers[m->l3ptr++], exps[start], scale_factors); break; case 2: if (m->l5ptr > 2) { gcode = get_bits(gb, 7); m->l5_quantizers[0] = l5_quantizers_1[gcode]; m->l5_quantizers[1] = l5_quantizers_2[gcode]; m->l5_quantizers[2] = l5_quantizers_3[gcode]; m->l5ptr = 0; } TRANSFORM_COEFF(cplcoeff, m->l5_quantizers[m->l5ptr++], exps[start], scale_factors); break; case 3: TRANSFORM_COEFF(cplcoeff, l7_quantizers[get_bits(gb, 3)], exps[start], scale_factors); break; case 4: if (m->l11ptr > 1) { gcode = get_bits(gb, 7); m->l11_quantizers[0] = l11_quantizers_1[gcode]; m->l11_quantizers[1] = l11_quantizers_2[gcode]; m->l11ptr = 0; } TRANSFORM_COEFF(cplcoeff, m->l11_quantizers[m->l11ptr++], exps[start], scale_factors); break; case 5: TRANSFORM_COEFF(cplcoeff, l15_quantizers[get_bits(gb, 4)], exps[start], scale_factors); break; default: TRANSFORM_COEFF(cplcoeff, get_sbits(gb, qntztab[tbap]) << (16 - qntztab[tbap]), exps[start], scale_factors); } for (ch = 0; ch < ctx->nfchans; ch++) if ((ctx->chincpl >> ch) & 1) ctx->transform_coeffs[ch + 1][start] = cplcoeff * cplcos[ch]; start++; } } return 0; } /* Get the transform coefficients for particular channel */ static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_groups *m) { GetBitContext *gb = &ctx->gb; int i, gcode, tbap, dithflag, end; uint8_t *exps; uint8_t *bap; float *coeffs; float factors[25]; for (i = 0; i < 25; i++) factors[i] = scale_factors[i] * ctx->chcoeffs[ch_index]; if (ch_index != -1) { /* fbw channels */ dithflag = (ctx->dithflag >> ch_index) & 1; exps = ctx->dexps[ch_index]; bap = ctx->bap[ch_index]; coeffs = ctx->transform_coeffs[ch_index + 1]; end = ctx->endmant[ch_index]; } else if (ch_index == -1) { dithflag = 0; exps = ctx->dlfeexps; bap = ctx->lfebap; coeffs = ctx->transform_coeffs[0]; end = 7; } for (i = 0; i < end; i++) { tbap = bap[i]; switch (tbap) { case 0: if (!dithflag) { coeffs[i] = 0; continue; } else { TRANSFORM_COEFF(coeffs[i], av_random(&ctx->dith_state) & 0xFFFF, exps[i], factors); coeffs[i] *= LEVEL_MINUS_3DB; continue; } case 1: if (m->l3ptr > 2) { gcode = get_bits(gb, 5); m->l3_quantizers[0] = l3_quantizers_1[gcode]; m->l3_quantizers[1] = l3_quantizers_2[gcode]; m->l3_quantizers[2] = l3_quantizers_3[gcode]; m->l3ptr = 0; } TRANSFORM_COEFF(coeffs[i], m->l3_quantizers[m->l3ptr++], exps[i], factors); continue; case 2: if (m->l5ptr > 2) { gcode = get_bits(gb, 7); m->l5_quantizers[0] = l5_quantizers_1[gcode]; m->l5_quantizers[1] = l5_quantizers_2[gcode]; m->l5_quantizers[2] = l5_quantizers_3[gcode]; m->l5ptr = 0; } TRANSFORM_COEFF(coeffs[i], m->l5_quantizers[m->l5ptr++], exps[i], factors); continue; case 3: TRANSFORM_COEFF(coeffs[i], l7_quantizers[get_bits(gb, 3)], exps[i], factors); continue; case 4: if (m->l11ptr > 1) { gcode = get_bits(gb, 7); m->l11_quantizers[0] = l11_quantizers_1[gcode]; m->l11_quantizers[1] = l11_quantizers_2[gcode]; m->l11ptr = 0; } TRANSFORM_COEFF(coeffs[i], m->l11_quantizers[m->l11ptr++], exps[i], factors); continue; case 5: TRANSFORM_COEFF(coeffs[i], l15_quantizers[get_bits(gb, 4)], exps[i], factors); continue; default: TRANSFORM_COEFF(coeffs[i], get_sbits(gb, qntztab[tbap]) << (16 - qntztab[tbap]), exps[i], factors); continue; } } return 0; } /* Get the transform coefficients. * This function extracts the tranform coefficients form the ac3 bitstream. * This function is called after bit allocation is performed. */ static int get_transform_coeffs(AC3DecodeContext * ctx) { int i, end; int got_cplchan = 0; mant_groups m; m.l3ptr = m.l5ptr = m.l11ptr = 3; for (i = 0; i < ctx->nfchans; i++) { /* transform coefficients for individual channel */ if (get_transform_coeffs_ch(ctx, i, &m)) return -1; /* tranform coefficients for coupling channels */ if ((ctx->chincpl >> i) & 1) { if (!got_cplchan) { if (get_transform_coeffs_cpling(ctx, &m)) { av_log(NULL, AV_LOG_ERROR, "error in decoupling channels\n"); return -1; } got_cplchan = 1; } end = ctx->cplendmant; } else end = ctx->endmant[i]; do ctx->transform_coeffs[i + 1][end] = 0; while(++end < 256); } if (ctx->lfeon) { if (get_transform_coeffs_ch(ctx, -1, &m)) return -1; for (i = 7; i < 256; i++) { ctx->transform_coeffs[0][i] = 0; } } return 0; } /* Rematrixing routines. */ static void do_rematrixing1(AC3DecodeContext *ctx, int start, int end) { float tmp0, tmp1; while (start < end) { tmp0 = ctx->transform_coeffs[1][start]; tmp1 = ctx->transform_coeffs[2][start]; ctx->transform_coeffs[1][start] = tmp0 + tmp1; ctx->transform_coeffs[2][start] = tmp0 - tmp1; start++; } } static void do_rematrixing(AC3DecodeContext *ctx) { int bnd1 = 13, bnd2 = 25, bnd3 = 37, bnd4 = 61; int end, bndend; end = FFMIN(ctx->endmant[0], ctx->endmant[1]); if (ctx->rematflg & 1) do_rematrixing1(ctx, bnd1, bnd2); if (ctx->rematflg & 2) do_rematrixing1(ctx, bnd2, bnd3); bndend = bnd4; if (bndend > end) { bndend = end; if (ctx->rematflg & 4) do_rematrixing1(ctx, bnd3, bndend); } else { if (ctx->rematflg & 4) do_rematrixing1(ctx, bnd3, bnd4); if (ctx->rematflg & 8) do_rematrixing1(ctx, bnd4, end); } } /* This function sets the normalized channel coefficients. * Transform coefficients are multipllied by the channel * coefficients to get normalized transform coefficients. */ static void get_downmix_coeffs(AC3DecodeContext *ctx) { int from = ctx->acmod; int to = ctx->blkoutput; float clev = clevs[ctx->cmixlev]; float slev = slevs[ctx->surmixlev]; float nf = 1.0; //normalization factor for downmix coeffs int i; if (!ctx->acmod) { ctx->chcoeffs[0] = 2 * ctx->dynrng; ctx->chcoeffs[1] = 2 * ctx->dynrng2; } else { for (i = 0; i < ctx->nfchans; i++) ctx->chcoeffs[i] = 2 * ctx->dynrng; } if (to == AC3_OUTPUT_UNMODIFIED) return; switch (from) { case AC3_ACMOD_DUALMONO: switch (to) { case AC3_OUTPUT_MONO: case AC3_OUTPUT_STEREO: /* We Assume that sum of both mono channels is requested */ nf = 0.5; ctx->chcoeffs[0] *= nf; ctx->chcoeffs[1] *= nf; break; } break; case AC3_ACMOD_MONO: switch (to) { case AC3_OUTPUT_STEREO: nf = LEVEL_MINUS_3DB; ctx->chcoeffs[0] *= nf; break; } break; case AC3_ACMOD_STEREO: switch (to) { case AC3_OUTPUT_MONO: nf = LEVEL_MINUS_3DB; ctx->chcoeffs[0] *= nf; ctx->chcoeffs[1] *= nf; break; } break; case AC3_ACMOD_3F: switch (to) { case AC3_OUTPUT_MONO: nf = LEVEL_MINUS_3DB / (1.0 + clev); ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[1] *= ((nf * clev * LEVEL_MINUS_3DB) / 2.0); break; case AC3_OUTPUT_STEREO: nf = 1.0 / (1.0 + clev); ctx->chcoeffs[0] *= nf; ctx->chcoeffs[2] *= nf; ctx->chcoeffs[1] *= (nf * clev); break; } break; case AC3_ACMOD_2F1R: switch (to) { case AC3_OUTPUT_MONO: nf = 2.0 * LEVEL_MINUS_3DB / (2.0 + slev); ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[1] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[2] *= (nf * slev * LEVEL_MINUS_3DB); break; case AC3_OUTPUT_STEREO: nf = 1.0 / (1.0 + (slev * LEVEL_MINUS_3DB)); ctx->chcoeffs[0] *= nf; ctx->chcoeffs[1] *= nf; ctx->chcoeffs[2] *= (nf * slev * LEVEL_MINUS_3DB); break; case AC3_OUTPUT_DOLBY: nf = 1.0 / (1.0 + LEVEL_MINUS_3DB); ctx->chcoeffs[0] *= nf; ctx->chcoeffs[1] *= nf; ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB); break; } break; case AC3_ACMOD_3F1R: switch (to) { case AC3_OUTPUT_MONO: nf = LEVEL_MINUS_3DB / (1.0 + clev + (slev / 2.0)); ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[1] *= (nf * clev * LEVEL_PLUS_3DB); ctx->chcoeffs[3] *= (nf * slev * LEVEL_MINUS_3DB); break; case AC3_OUTPUT_STEREO: nf = 1.0 / (1.0 + clev + (slev * LEVEL_MINUS_3DB)); ctx->chcoeffs[0] *= nf; ctx->chcoeffs[2] *= nf; ctx->chcoeffs[1] *= (nf * clev); ctx->chcoeffs[3] *= (nf * slev * LEVEL_MINUS_3DB); break; case AC3_OUTPUT_DOLBY: nf = 1.0 / (1.0 + (2.0 * LEVEL_MINUS_3DB)); ctx->chcoeffs[0] *= nf; ctx->chcoeffs[1] *= nf; ctx->chcoeffs[1] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[3] *= (nf * LEVEL_MINUS_3DB); break; } break; case AC3_ACMOD_2F2R: switch (to) { case AC3_OUTPUT_MONO: nf = LEVEL_MINUS_3DB / (1.0 + slev); ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[1] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[2] *= (nf * slev * LEVEL_MINUS_3DB); ctx->chcoeffs[3] *= (nf * slev * LEVEL_MINUS_3DB); break; case AC3_OUTPUT_STEREO: nf = 1.0 / (1.0 + slev); ctx->chcoeffs[0] *= nf; ctx->chcoeffs[1] *= nf; ctx->chcoeffs[2] *= (nf * slev); ctx->chcoeffs[3] *= (nf * slev); break; case AC3_OUTPUT_DOLBY: nf = 1.0 / (1.0 + (2.0 * LEVEL_MINUS_3DB)); ctx->chcoeffs[0] *= nf; ctx->chcoeffs[1] *= nf; ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[3] *= (nf * LEVEL_MINUS_3DB); break; } break; case AC3_ACMOD_3F2R: switch (to) { case AC3_OUTPUT_MONO: nf = LEVEL_MINUS_3DB / (1.0 + clev + slev); ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[1] *= (nf * clev * LEVEL_PLUS_3DB); ctx->chcoeffs[3] *= (nf * slev * LEVEL_MINUS_3DB); ctx->chcoeffs[4] *= (nf * slev * LEVEL_MINUS_3DB); break; case AC3_OUTPUT_STEREO: nf = 1.0 / (1.0 + clev + slev); ctx->chcoeffs[0] *= nf; ctx->chcoeffs[2] *= nf; ctx->chcoeffs[1] *= (nf * clev); ctx->chcoeffs[3] *= (nf * slev); ctx->chcoeffs[4] *= (nf * slev); break; case AC3_OUTPUT_DOLBY: nf = 1.0 / (1.0 + (3.0 * LEVEL_MINUS_3DB)); ctx->chcoeffs[0] *= nf; ctx->chcoeffs[1] *= nf; ctx->chcoeffs[1] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[3] *= (nf * LEVEL_MINUS_3DB); ctx->chcoeffs[4] *= (nf * LEVEL_MINUS_3DB); break; } break; } } /*********** BEGIN DOWNMIX FUNCTIONS ***********/ static inline void mix_dualmono_to_mono(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) output[1][i] += output[2][i]; memset(output[2], 0, sizeof(output[2])); } static inline void mix_dualmono_to_stereo(AC3DecodeContext *ctx) { int i; float tmp; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { tmp = output[1][i] + output[2][i]; output[1][i] = output[2][i] = tmp; } } static inline void upmix_mono_to_stereo(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) output[2][i] = output[1][i]; } static inline void mix_stereo_to_mono(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) output[1][i] += output[2][i]; memset(output[2], 0, sizeof(output[2])); } static inline void mix_3f_to_mono(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) output[1][i] += (output[2][i] + output[3][i]); memset(output[2], 0, sizeof(output[2])); memset(output[3], 0, sizeof(output[3])); } static inline void mix_3f_to_stereo(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { output[1][i] += output[2][i]; output[2][i] += output[3][i]; } memset(output[3], 0, sizeof(output[3])); } static inline void mix_2f_1r_to_mono(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) output[1][i] += (output[2][i] + output[3][i]); memset(output[2], 0, sizeof(output[2])); memset(output[3], 0, sizeof(output[3])); } static inline void mix_2f_1r_to_stereo(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { output[1][i] += output[2][i]; output[2][i] += output[3][i]; } memset(output[3], 0, sizeof(output[3])); } static inline void mix_2f_1r_to_dolby(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { output[1][i] -= output[3][i]; output[2][i] += output[3][i]; } memset(output[3], 0, sizeof(output[3])); } static inline void mix_3f_1r_to_mono(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) output[1][i] = (output[2][i] + output[3][i] + output[4][i]); memset(output[2], 0, sizeof(output[2])); memset(output[3], 0, sizeof(output[3])); memset(output[4], 0, sizeof(output[4])); } static inline void mix_3f_1r_to_stereo(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { output[1][i] += (output[2][i] + output[4][i]); output[2][i] += (output[3][i] + output[4][i]); } memset(output[3], 0, sizeof(output[3])); memset(output[4], 0, sizeof(output[4])); } static inline void mix_3f_1r_to_dolby(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { output[1][i] += (output[2][i] - output[4][i]); output[2][i] += (output[3][i] + output[4][i]); } memset(output[3], 0, sizeof(output[3])); memset(output[4], 0, sizeof(output[4])); } static inline void mix_2f_2r_to_mono(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) output[1][i] = (output[2][i] + output[3][i] + output[4][i]); memset(output[2], 0, sizeof(output[2])); memset(output[3], 0, sizeof(output[3])); memset(output[4], 0, sizeof(output[4])); } static inline void mix_2f_2r_to_stereo(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { output[1][i] += output[3][i]; output[2][i] += output[4][i]; } memset(output[3], 0, sizeof(output[3])); memset(output[4], 0, sizeof(output[4])); } static inline void mix_2f_2r_to_dolby(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { output[1][i] -= output[3][i]; output[2][i] += output[4][i]; } memset(output[3], 0, sizeof(output[3])); memset(output[4], 0, sizeof(output[4])); } static inline void mix_3f_2r_to_mono(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) output[1][i] += (output[2][i] + output[3][i] + output[4][i] + output[5][i]); memset(output[2], 0, sizeof(output[2])); memset(output[3], 0, sizeof(output[3])); memset(output[4], 0, sizeof(output[4])); memset(output[5], 0, sizeof(output[5])); } static inline void mix_3f_2r_to_stereo(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { output[1][i] += (output[2][i] + output[4][i]); output[2][i] += (output[3][i] + output[5][i]); } memset(output[3], 0, sizeof(output[3])); memset(output[4], 0, sizeof(output[4])); memset(output[5], 0, sizeof(output[5])); } static inline void mix_3f_2r_to_dolby(AC3DecodeContext *ctx) { int i; float (*output)[BLOCK_SIZE] = ctx->output; for (i = 0; i < 256; i++) { output[1][i] += (output[2][i] - output[4][i] - output[5][i]); output[2][i] += (output[3][i] + output[4][i] + output[5][i]); } memset(output[3], 0, sizeof(output[3])); memset(output[4], 0, sizeof(output[4])); memset(output[5], 0, sizeof(output[5])); } /*********** END DOWNMIX FUNCTIONS ***********/ /* Downmix the output. * This function downmixes the output when the number of input * channels is not equal to the number of output channels requested. */ static void do_downmix(AC3DecodeContext *ctx) { int from = ctx->acmod; int to = ctx->blkoutput; if (to == AC3_OUTPUT_UNMODIFIED) return; switch (from) { case AC3_ACMOD_DUALMONO: switch (to) { case AC3_OUTPUT_MONO: mix_dualmono_to_mono(ctx); break; case AC3_OUTPUT_STEREO: /* We assume that sum of both mono channels is requested */ mix_dualmono_to_stereo(ctx); break; } break; case AC3_ACMOD_MONO: switch (to) { case AC3_OUTPUT_STEREO: upmix_mono_to_stereo(ctx); break; } break; case AC3_ACMOD_STEREO: switch (to) { case AC3_OUTPUT_MONO: mix_stereo_to_mono(ctx); break; } break; case AC3_ACMOD_3F: switch (to) { case AC3_OUTPUT_MONO: mix_3f_to_mono(ctx); break; case AC3_OUTPUT_STEREO: mix_3f_to_stereo(ctx); break; } break; case AC3_ACMOD_2F1R: switch (to) { case AC3_OUTPUT_MONO: mix_2f_1r_to_mono(ctx); break; case AC3_OUTPUT_STEREO: mix_2f_1r_to_stereo(ctx); break; case AC3_OUTPUT_DOLBY: mix_2f_1r_to_dolby(ctx); break; } break; case AC3_ACMOD_3F1R: switch (to) { case AC3_OUTPUT_MONO: mix_3f_1r_to_mono(ctx); break; case AC3_OUTPUT_STEREO: mix_3f_1r_to_stereo(ctx); break; case AC3_OUTPUT_DOLBY: mix_3f_1r_to_dolby(ctx); break; } break; case AC3_ACMOD_2F2R: switch (to) { case AC3_OUTPUT_MONO: mix_2f_2r_to_mono(ctx); break; case AC3_OUTPUT_STEREO: mix_2f_2r_to_stereo(ctx); break; case AC3_OUTPUT_DOLBY: mix_2f_2r_to_dolby(ctx); break; } break; case AC3_ACMOD_3F2R: switch (to) { case AC3_OUTPUT_MONO: mix_3f_2r_to_mono(ctx); break; case AC3_OUTPUT_STEREO: mix_3f_2r_to_stereo(ctx); break; case AC3_OUTPUT_DOLBY: mix_3f_2r_to_dolby(ctx); break; } break; } } /* This function performs the imdct on 256 sample transform * coefficients. */ static void do_imdct_256(AC3DecodeContext *ctx, int chindex) { int i, k; float x[128]; FFTComplex z[2][64]; float *o_ptr = ctx->tmp_output; for(i=0; i<2; i++) { /* de-interleave coefficients */ for(k=0; k<128; k++) { x[k] = ctx->transform_coeffs[chindex][2*k+i]; } /* run standard IMDCT */ ctx->imdct_256.fft.imdct_calc(&ctx->imdct_256, o_ptr, x, ctx->tmp_imdct); /* reverse the post-rotation & reordering from standard IMDCT */ for(k=0; k<32; k++) { z[i][32+k].re = -o_ptr[128+2*k]; z[i][32+k].im = -o_ptr[2*k]; z[i][31-k].re = o_ptr[2*k+1]; z[i][31-k].im = o_ptr[128+2*k+1]; } } /* apply AC-3 post-rotation & reordering */ for(k=0; k<64; k++) { o_ptr[ 2*k ] = -z[0][ k].im; o_ptr[ 2*k+1] = z[0][63-k].re; o_ptr[128+2*k ] = -z[0][ k].re; o_ptr[128+2*k+1] = z[0][63-k].im; o_ptr[256+2*k ] = -z[1][ k].re; o_ptr[256+2*k+1] = z[1][63-k].im; o_ptr[384+2*k ] = z[1][ k].im; o_ptr[384+2*k+1] = -z[1][63-k].re; } } /* IMDCT Transform. */ static inline void do_imdct(AC3DecodeContext *ctx) { int ch; if (ctx->blkoutput & AC3_OUTPUT_LFEON) { ctx->imdct_512.fft.imdct_calc(&ctx->imdct_512, ctx->tmp_output, ctx->transform_coeffs[0], ctx->tmp_imdct); } for (ch=1; ch<=ctx->nfchans; ch++) { if ((ctx->blksw >> (ch-1)) & 1) do_imdct_256(ctx, ch); else ctx->imdct_512.fft.imdct_calc(&ctx->imdct_512, ctx->tmp_output, ctx->transform_coeffs[ch], ctx->tmp_imdct); ctx->dsp.vector_fmul_add_add(ctx->output[ch], ctx->tmp_output, ctx->window, ctx->delay[ch], 384, 256, 1); ctx->dsp.vector_fmul_reverse(ctx->delay[ch], ctx->tmp_output+256, ctx->window, 256); } } /* Parse the audio block from ac3 bitstream. * This function extract the audio block from the ac3 bitstream * and produces the output for the block. This function must * be called for each of the six audio block in the ac3 bitstream. */ static int ac3_parse_audio_block(AC3DecodeContext * ctx) { int nfchans = ctx->nfchans; int acmod = ctx->acmod; int i, bnd, rbnd, seg, grpsize; GetBitContext *gb = &ctx->gb; int bit_alloc_flags = 0; uint8_t *dexps; int mstrcplco, cplcoexp, cplcomant; int dynrng, chbwcod, ngrps, cplabsexp, skipl; ctx->blksw = 0; for (i = 0; i < nfchans; i++) /*block switch flag */ ctx->blksw |= get_bits1(gb) << i; ctx->dithflag = 0; for (i = 0; i < nfchans; i++) /* dithering flag */ ctx->dithflag |= get_bits1(gb) << i; if (get_bits1(gb)) { /* dynamic range */ dynrng = get_sbits(gb, 8); ctx->dynrng = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]); } if (acmod == 0x00 && get_bits1(gb)) { /* dynamic range 1+1 mode */ dynrng = get_sbits(gb, 8); ctx->dynrng2 = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]); } get_downmix_coeffs(ctx); if (get_bits1(gb)) { /* coupling strategy */ ctx->cplinu = get_bits1(gb); ctx->cplbndstrc = 0; ctx->chincpl = 0; if (ctx->cplinu) { /* coupling in use */ for (i = 0; i < nfchans; i++) ctx->chincpl |= get_bits1(gb) << i; if (acmod == 0x02) ctx->phsflginu = get_bits1(gb); //phase flag in use ctx->cplbegf = get_bits(gb, 4); ctx->cplendf = get_bits(gb, 4); if (3 + ctx->cplendf - ctx->cplbegf < 0) { av_log(NULL, AV_LOG_ERROR, "cplendf = %d < cplbegf = %d\n", ctx->cplendf, ctx->cplbegf); return -1; } ctx->ncplbnd = ctx->ncplsubnd = 3 + ctx->cplendf - ctx->cplbegf; ctx->cplstrtmant = ctx->cplbegf * 12 + 37; ctx->cplendmant = ctx->cplendf * 12 + 73; for (i = 0; i < ctx->ncplsubnd - 1; i++) /* coupling band structure */ if (get_bits1(gb)) { ctx->cplbndstrc |= 1 << i; ctx->ncplbnd--; } } } if (ctx->cplinu) { ctx->cplcoe = 0; for (i = 0; i < nfchans; i++) if ((ctx->chincpl) >> i & 1) if (get_bits1(gb)) { /* coupling co-ordinates */ ctx->cplcoe |= 1 << i; mstrcplco = 3 * get_bits(gb, 2); for (bnd = 0; bnd < ctx->ncplbnd; bnd++) { cplcoexp = get_bits(gb, 4); cplcomant = get_bits(gb, 4); if (cplcoexp == 15) cplcomant <<= 14; else cplcomant = (cplcomant | 0x10) << 13; ctx->cplco[i][bnd] = cplcomant * scale_factors[cplcoexp + mstrcplco]; } } if (acmod == 0x02 && ctx->phsflginu && (ctx->cplcoe & 1 || ctx->cplcoe & 2)) for (bnd = 0; bnd < ctx->ncplbnd; bnd++) if (get_bits1(gb)) ctx->cplco[1][bnd] = -ctx->cplco[1][bnd]; } if (acmod == 0x02) {/* rematrixing */ ctx->rematstr = get_bits1(gb); if (ctx->rematstr) { ctx->rematflg = 0; if (!(ctx->cplinu) || ctx->cplbegf > 2) for (rbnd = 0; rbnd < 4; rbnd++) ctx->rematflg |= get_bits1(gb) << rbnd; if (ctx->cplbegf > 0 && ctx->cplbegf <= 2 && ctx->cplinu) for (rbnd = 0; rbnd < 3; rbnd++) ctx->rematflg |= get_bits1(gb) << rbnd; if (ctx->cplbegf == 0 && ctx->cplinu) for (rbnd = 0; rbnd < 2; rbnd++) ctx->rematflg |= get_bits1(gb) << rbnd; } } ctx->cplexpstr = EXP_REUSE; ctx->lfeexpstr = EXP_REUSE; if (ctx->cplinu) /* coupling exponent strategy */ ctx->cplexpstr = get_bits(gb, 2); for (i = 0; i < nfchans; i++) /* channel exponent strategy */ ctx->chexpstr[i] = get_bits(gb, 2); if (ctx->lfeon) /* lfe exponent strategy */ ctx->lfeexpstr = get_bits1(gb); for (i = 0; i < nfchans; i++) /* channel bandwidth code */ if (ctx->chexpstr[i] != EXP_REUSE) { if ((ctx->chincpl >> i) & 1) ctx->endmant[i] = ctx->cplstrtmant; else { chbwcod = get_bits(gb, 6); if (chbwcod > 60) { av_log(NULL, AV_LOG_ERROR, "chbwcod = %d > 60", chbwcod); return -1; } ctx->endmant[i] = chbwcod * 3 + 73; } } if (ctx->cplexpstr != EXP_REUSE) {/* coupling exponents */ bit_alloc_flags = 64; cplabsexp = get_bits(gb, 4) << 1; ngrps = (ctx->cplendmant - ctx->cplstrtmant) / (3 << (ctx->cplexpstr - 1)); if (decode_exponents(gb, ctx->cplexpstr, ngrps, cplabsexp, ctx->dcplexps + ctx->cplstrtmant)) { av_log(NULL, AV_LOG_ERROR, "error decoding coupling exponents\n"); return -1; } } for (i = 0; i < nfchans; i++) /* fbw channel exponents */ if (ctx->chexpstr[i] != EXP_REUSE) { bit_alloc_flags |= 1 << i; grpsize = 3 << (ctx->chexpstr[i] - 1); ngrps = (ctx->endmant[i] + grpsize - 4) / grpsize; dexps = ctx->dexps[i]; dexps[0] = get_bits(gb, 4); if (decode_exponents(gb, ctx->chexpstr[i], ngrps, dexps[0], dexps + 1)) { av_log(NULL, AV_LOG_ERROR, "error decoding channel %d exponents\n", i); return -1; } skip_bits(gb, 2); /* skip gainrng */ } if (ctx->lfeexpstr != EXP_REUSE) { /* lfe exponents */ bit_alloc_flags |= 32; ctx->dlfeexps[0] = get_bits(gb, 4); if (decode_exponents(gb, ctx->lfeexpstr, 2, ctx->dlfeexps[0], ctx->dlfeexps + 1)) { av_log(NULL, AV_LOG_ERROR, "error decoding lfe exponents\n"); return -1; } } if (get_bits1(gb)) { /* bit allocation information */ bit_alloc_flags = 127; ctx->sdcycod = get_bits(gb, 2); ctx->fdcycod = get_bits(gb, 2); ctx->sgaincod = get_bits(gb, 2); ctx->dbpbcod = get_bits(gb, 2); ctx->floorcod = get_bits(gb, 3); } if (get_bits1(gb)) { /* snroffset */ bit_alloc_flags = 127; ctx->csnroffst = get_bits(gb, 6); if (ctx->cplinu) { /* coupling fine snr offset and fast gain code */ ctx->cplfsnroffst = get_bits(gb, 4); ctx->cplfgaincod = get_bits(gb, 3); } for (i = 0; i < nfchans; i++) { /* channel fine snr offset and fast gain code */ ctx->fsnroffst[i] = get_bits(gb, 4); ctx->fgaincod[i] = get_bits(gb, 3); } if (ctx->lfeon) { /* lfe fine snr offset and fast gain code */ ctx->lfefsnroffst = get_bits(gb, 4); ctx->lfefgaincod = get_bits(gb, 3); } } if (ctx->cplinu && get_bits1(gb)) { /* coupling leak information */ bit_alloc_flags |= 64; ctx->cplfleak = get_bits(gb, 3); ctx->cplsleak = get_bits(gb, 3); } if (get_bits1(gb)) { /* delta bit allocation information */ bit_alloc_flags = 127; if (ctx->cplinu) { ctx->cpldeltbae = get_bits(gb, 2); if (ctx->cpldeltbae == DBA_RESERVED) { av_log(NULL, AV_LOG_ERROR, "coupling delta bit allocation strategy reserved\n"); return -1; } } for (i = 0; i < nfchans; i++) { ctx->deltbae[i] = get_bits(gb, 2); if (ctx->deltbae[i] == DBA_RESERVED) { av_log(NULL, AV_LOG_ERROR, "delta bit allocation strategy reserved\n"); return -1; } } if (ctx->cplinu) if (ctx->cpldeltbae == DBA_NEW) { /*coupling delta offset, len and bit allocation */ ctx->cpldeltnseg = get_bits(gb, 3); for (seg = 0; seg <= ctx->cpldeltnseg; seg++) { ctx->cpldeltoffst[seg] = get_bits(gb, 5); ctx->cpldeltlen[seg] = get_bits(gb, 4); ctx->cpldeltba[seg] = get_bits(gb, 3); } } for (i = 0; i < nfchans; i++) if (ctx->deltbae[i] == DBA_NEW) {/*channel delta offset, len and bit allocation */ ctx->deltnseg[i] = get_bits(gb, 3); for (seg = 0; seg <= ctx->deltnseg[i]; seg++) { ctx->deltoffst[i][seg] = get_bits(gb, 5); ctx->deltlen[i][seg] = get_bits(gb, 4); ctx->deltba[i][seg] = get_bits(gb, 3); } } } if (bit_alloc_flags) { if (is_snr_offsets_zero(ctx)) { memset(ctx->cplbap, 0, sizeof (ctx->cplbap)); memset(ctx->lfebap, 0, sizeof (ctx->lfebap)); for (i = 0; i < nfchans; i++) memset(ctx->bap[i], 0, sizeof(ctx->bap[i])); } else { /* set bit allocation parameters */ ctx->bit_alloc_params.fscod = ctx->fscod; ctx->bit_alloc_params.halfratecod = 0; ctx->bit_alloc_params.sdecay = ff_sdecaytab[ctx->sdcycod]; ctx->bit_alloc_params.fdecay = ff_fdecaytab[ctx->fdcycod]; ctx->bit_alloc_params.sgain = ff_sgaintab[ctx->sgaincod]; ctx->bit_alloc_params.dbknee = ff_dbkneetab[ctx->dbpbcod]; ctx->bit_alloc_params.floor = ff_floortab[ctx->floorcod]; ctx->bit_alloc_params.cplfleak = ctx->cplfleak; ctx->bit_alloc_params.cplsleak = ctx->cplsleak; if (ctx->chincpl && (bit_alloc_flags & 64)) do_bit_allocation(ctx, 5); for (i = 0; i < nfchans; i++) if ((bit_alloc_flags >> i) & 1) do_bit_allocation(ctx, i); if (ctx->lfeon && (bit_alloc_flags & 32)) do_bit_allocation(ctx, 6); } } if (get_bits1(gb)) { /* unused dummy data */ skipl = get_bits(gb, 9); while(skipl--) skip_bits(gb, 8); } /* unpack the transform coefficients * * this also uncouples channels if coupling is in use. */ if (get_transform_coeffs(ctx)) { av_log(NULL, AV_LOG_ERROR, "Error in routine get_transform_coeffs\n"); return -1; } /* recover coefficients if rematrixing is in use */ if (ctx->rematflg) do_rematrixing(ctx); do_downmix(ctx); do_imdct(ctx); return 0; } static inline int16_t convert(int32_t i) { if (i > 0x43c07fff) return 32767; else if (i <= 0x43bf8000) return -32768; else return (i - 0x43c00000); } /* Decode ac3 frame. * * @param avctx Pointer to AVCodecContext * @param data Pointer to pcm smaples * @param data_size Set to number of pcm samples produced by decoding * @param buf Data to be decoded * @param buf_size Size of the buffer */ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size) { AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data; int frame_start; int16_t *out_samples = (int16_t *)data; int i, j, k, start; int32_t *int_ptr[6]; for (i = 0; i < 6; i++) int_ptr[i] = (int32_t *)(&ctx->output[i]); //Synchronize the frame. frame_start = ac3_synchronize(buf, buf_size); if (frame_start == -1) { av_log(avctx, AV_LOG_ERROR, "frame is not synchronized\n"); *data_size = 0; return buf_size; } //Initialize the GetBitContext with the start of valid AC3 Frame. init_get_bits(&(ctx->gb), buf + frame_start, (buf_size - frame_start) * 8); //Parse the syncinfo. //If 'fscod' or 'bsid' is not valid the decoder shall mute as per the standard. if (!ac3_parse_sync_info(ctx)) { av_log(avctx, AV_LOG_ERROR, "\n"); *data_size = 0; return buf_size; } //Parse the BSI. //If 'bsid' is not valid decoder shall not decode the audio as per the standard. ac3_parse_bsi(ctx); avctx->sample_rate = ctx->sampling_rate; avctx->bit_rate = ctx->bit_rate; if (avctx->channels == 0) { ctx->blkoutput |= AC3_OUTPUT_UNMODIFIED; if (ctx->lfeon) ctx->blkoutput |= AC3_OUTPUT_LFEON; avctx->channels = ctx->nfchans + ctx->lfeon; } else if (avctx->channels == 1) ctx->blkoutput |= AC3_OUTPUT_MONO; else if (avctx->channels == 2) { if (ctx->dsurmod == 0x02) ctx->blkoutput |= AC3_OUTPUT_DOLBY; else ctx->blkoutput |= AC3_OUTPUT_STEREO; } else { if (avctx->channels < (ctx->nfchans + ctx->lfeon)) av_log(avctx, AV_LOG_INFO, "ac3_decoder: AC3 Source Channels Are Less Then Specified %d: Output to %d Channels\n",avctx->channels, ctx->nfchans + ctx->lfeon); ctx->blkoutput |= AC3_OUTPUT_UNMODIFIED; if (ctx->lfeon) ctx->blkoutput |= AC3_OUTPUT_LFEON; avctx->channels = ctx->nfchans + ctx->lfeon; } //av_log(avctx, AV_LOG_INFO, "channels = %d \t bit rate = %d \t sampling rate = %d \n", avctx->channels, avctx->bit_rate * 1000, avctx->sample_rate); //Parse the Audio Blocks. for (i = 0; i < NB_BLOCKS; i++) { if (ac3_parse_audio_block(ctx)) { av_log(avctx, AV_LOG_ERROR, "error parsing the audio block\n"); *data_size = 0; return ctx->frame_size; } start = (ctx->blkoutput & AC3_OUTPUT_LFEON) ? 0 : 1; for (k = 0; k < BLOCK_SIZE; k++) for (j = start; j <= avctx->channels; j++) *(out_samples++) = convert(int_ptr[j][k]); } *data_size = NB_BLOCKS * BLOCK_SIZE * avctx->channels * sizeof (int16_t); return ctx->frame_size; } /* Uninitialize ac3 decoder. */ static int ac3_decode_end(AVCodecContext *avctx) { AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data; ff_mdct_end(&ctx->imdct_512); ff_mdct_end(&ctx->imdct_256); return 0; } AVCodec ac3_decoder = { .name = "ac3", .type = CODEC_TYPE_AUDIO, .id = CODEC_ID_AC3, .priv_data_size = sizeof (AC3DecodeContext), .init = ac3_decode_init, .close = ac3_decode_end, .decode = ac3_decode_frame, };