static int decode_audio_block(AC3DecodeContext *s, int blk) { int fbw_channels = s->fbw_channels; int channel_mode = s->channel_mode; int i, bnd, seg, ch; int different_transforms; int downmix_output; int cpl_in_use; GetBitContext *gbc = &s->gbc; uint8_t bit_alloc_stages[AC3_MAX_CHANNELS]; memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS); /* block switch flags */ different_transforms = 0; if (s->block_switch_syntax) { for (ch = 1; ch <= fbw_channels; ch++) { s->block_switch[ch] = get_bits1(gbc); if(ch > 1 && s->block_switch[ch] != s->block_switch[1]) different_transforms = 1; } } /* dithering flags */ if (s->dither_flag_syntax) { for (ch = 1; ch <= fbw_channels; ch++) { s->dither_flag[ch] = get_bits1(gbc); } } /* dynamic range */ i = !(s->channel_mode); do { if(get_bits1(gbc)) { s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) * s->avctx->drc_scale)+1.0; } else if(blk == 0) { s->dynamic_range[i] = 1.0f; } } while(i--); /* spectral extension strategy */ if (s->eac3 && (!blk || get_bits1(gbc))) { if (get_bits1(gbc)) { av_log_missing_feature(s->avctx, "Spectral extension", 1); return -1; } /* TODO: parse spectral extension strategy info */ } /* TODO: spectral extension coordinates */ /* coupling strategy */ if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) { memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS); if (!s->eac3) s->cpl_in_use[blk] = get_bits1(gbc); if (s->cpl_in_use[blk]) { /* coupling in use */ int cpl_start_subband, cpl_end_subband; if (channel_mode < AC3_CHMODE_STEREO) { av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n"); return -1; } /* check for enhanced coupling */ if (s->eac3 && get_bits1(gbc)) { /* TODO: parse enhanced coupling strategy info */ av_log_missing_feature(s->avctx, "Enhanced coupling", 1); return -1; } /* determine which channels are coupled */ if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) { s->channel_in_cpl[1] = 1; s->channel_in_cpl[2] = 1; } else { for (ch = 1; ch <= fbw_channels; ch++) s->channel_in_cpl[ch] = get_bits1(gbc); } /* phase flags in use */ if (channel_mode == AC3_CHMODE_STEREO) s->phase_flags_in_use = get_bits1(gbc); /* coupling frequency range */ /* TODO: modify coupling end freq if spectral extension is used */ cpl_start_subband = get_bits(gbc, 4); cpl_end_subband = get_bits(gbc, 4) + 3; s->num_cpl_subbands = cpl_end_subband - cpl_start_subband; if (s->num_cpl_subbands < 0) { av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d > %d)\n", cpl_start_subband, cpl_end_subband); return -1; } s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37; s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37; decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband, cpl_end_subband, ff_eac3_default_cpl_band_struct, s->cpl_band_struct, &s->num_cpl_subbands, &s->num_cpl_bands, NULL); } else { /* coupling not in use */ for (ch = 1; ch <= fbw_channels; ch++) { s->channel_in_cpl[ch] = 0; s->first_cpl_coords[ch] = 1; } s->first_cpl_leak = s->eac3; s->phase_flags_in_use = 0; } } else if (!s->eac3) { if(!blk) { av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n"); return -1; } else { s->cpl_in_use[blk] = s->cpl_in_use[blk-1]; } } cpl_in_use = s->cpl_in_use[blk]; /* coupling coordinates */ if (cpl_in_use) { int cpl_coords_exist = 0; for (ch = 1; ch <= fbw_channels; ch++) { if (s->channel_in_cpl[ch]) { if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) { int master_cpl_coord, cpl_coord_exp, cpl_coord_mant; s->first_cpl_coords[ch] = 0; cpl_coords_exist = 1; master_cpl_coord = 3 * get_bits(gbc, 2); for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { cpl_coord_exp = get_bits(gbc, 4); cpl_coord_mant = get_bits(gbc, 4); if (cpl_coord_exp == 15) s->cpl_coords[ch][bnd] = cpl_coord_mant << 22; else s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21; s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord); } } else if (!blk) { av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n"); return -1; } } else { /* channel not in coupling */ s->first_cpl_coords[ch] = 1; } } /* phase flags */ if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) { for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0; } } } /* stereo rematrixing strategy and band structure */ if (channel_mode == AC3_CHMODE_STEREO) { if ((s->eac3 && !blk) || get_bits1(gbc)) { s->num_rematrixing_bands = 4; if(cpl_in_use && s->start_freq[CPL_CH] <= 61) s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37); for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) s->rematrixing_flags[bnd] = get_bits1(gbc); } else if (!blk) { av_log(s->avctx, AV_LOG_ERROR, "new rematrixing strategy must be present in block 0\n"); return -1; } } /* exponent strategies for each channel */ for (ch = !cpl_in_use; ch <= s->channels; ch++) { if (!s->eac3) s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch)); if(s->exp_strategy[blk][ch] != EXP_REUSE) bit_alloc_stages[ch] = 3; } /* channel bandwidth */ for (ch = 1; ch <= fbw_channels; ch++) { s->start_freq[ch] = 0; if (s->exp_strategy[blk][ch] != EXP_REUSE) { int group_size; int prev = s->end_freq[ch]; if (s->channel_in_cpl[ch]) s->end_freq[ch] = s->start_freq[CPL_CH]; else { int bandwidth_code = get_bits(gbc, 6); if (bandwidth_code > 60) { av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code); return -1; } s->end_freq[ch] = bandwidth_code * 3 + 73; } group_size = 3 << (s->exp_strategy[blk][ch] - 1); s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size; if(blk > 0 && s->end_freq[ch] != prev) memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS); } } if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) { s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) / (3 << (s->exp_strategy[blk][CPL_CH] - 1)); } /* decode exponents for each channel */ for (ch = !cpl_in_use; ch <= s->channels; ch++) { if (s->exp_strategy[blk][ch] != EXP_REUSE) { s->dexps[ch][0] = get_bits(gbc, 4) << !ch; if (decode_exponents(gbc, s->exp_strategy[blk][ch], s->num_exp_groups[ch], s->dexps[ch][0], &s->dexps[ch][s->start_freq[ch]+!!ch])) { av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n"); return -1; } if(ch != CPL_CH && ch != s->lfe_ch) skip_bits(gbc, 2); /* skip gainrng */ } } /* bit allocation information */ if (s->bit_allocation_syntax) { if (get_bits1(gbc)) { s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift; s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift; s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)]; s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)]; s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)]; for(ch=!cpl_in_use; ch<=s->channels; ch++) bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); } else if (!blk) { av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n"); return -1; } } /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */ if(!s->eac3 || !blk){ if(s->snr_offset_strategy && get_bits1(gbc)) { int snr = 0; int csnr; csnr = (get_bits(gbc, 6) - 15) << 4; for (i = ch = !cpl_in_use; ch <= s->channels; ch++) { /* snr offset */ if (ch == i || s->snr_offset_strategy == 2) snr = (csnr + get_bits(gbc, 4)) << 2; /* run at least last bit allocation stage if snr offset changes */ if(blk && s->snr_offset[ch] != snr) { bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1); } s->snr_offset[ch] = snr; /* fast gain (normal AC-3 only) */ if (!s->eac3) { int prev = s->fast_gain[ch]; s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)]; /* run last 2 bit allocation stages if fast gain changes */ if(blk && prev != s->fast_gain[ch]) bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); } } } else if (!s->eac3 && !blk) { av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n"); return -1; } } /* fast gain (E-AC-3 only) */ if (s->fast_gain_syntax && get_bits1(gbc)) { for (ch = !cpl_in_use; ch <= s->channels; ch++) { int prev = s->fast_gain[ch]; s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)]; /* run last 2 bit allocation stages if fast gain changes */ if(blk && prev != s->fast_gain[ch]) bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); } } else if (s->eac3 && !blk) { for (ch = !cpl_in_use; ch <= s->channels; ch++) s->fast_gain[ch] = ff_ac3_fast_gain_tab[4]; } /* E-AC-3 to AC-3 converter SNR offset */ if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) { skip_bits(gbc, 10); // skip converter snr offset } /* coupling leak information */ if (cpl_in_use) { if (s->first_cpl_leak || get_bits1(gbc)) { int fl = get_bits(gbc, 3); int sl = get_bits(gbc, 3); /* run last 2 bit allocation stages for coupling channel if coupling leak changes */ if(blk && (fl != s->bit_alloc_params.cpl_fast_leak || sl != s->bit_alloc_params.cpl_slow_leak)) { bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2); } s->bit_alloc_params.cpl_fast_leak = fl; s->bit_alloc_params.cpl_slow_leak = sl; } else if (!s->eac3 && !blk) { av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n"); return -1; } s->first_cpl_leak = 0; } /* delta bit allocation information */ if (s->dba_syntax && get_bits1(gbc)) { /* delta bit allocation exists (strategy) */ for (ch = !cpl_in_use; ch <= fbw_channels; ch++) { s->dba_mode[ch] = get_bits(gbc, 2); if (s->dba_mode[ch] == DBA_RESERVED) { av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n"); return -1; } bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); } /* channel delta offset, len and bit allocation */ for (ch = !cpl_in_use; ch <= fbw_channels; ch++) { if (s->dba_mode[ch] == DBA_NEW) { s->dba_nsegs[ch] = get_bits(gbc, 3); for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) { s->dba_offsets[ch][seg] = get_bits(gbc, 5); s->dba_lengths[ch][seg] = get_bits(gbc, 4); s->dba_values[ch][seg] = get_bits(gbc, 3); } /* run last 2 bit allocation stages if new dba values */ bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); } } } else if(blk == 0) { for(ch=0; ch<=s->channels; ch++) { s->dba_mode[ch] = DBA_NONE; } } /* Bit allocation */ for(ch=!cpl_in_use; ch<=s->channels; ch++) { if(bit_alloc_stages[ch] > 2) { /* Exponent mapping into PSD and PSD integration */ ff_ac3_bit_alloc_calc_psd(s->dexps[ch], s->start_freq[ch], s->end_freq[ch], s->psd[ch], s->band_psd[ch]); } if(bit_alloc_stages[ch] > 1) { /* Compute excitation function, Compute masking curve, and Apply delta bit allocation */ ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch], s->start_freq[ch], s->end_freq[ch], s->fast_gain[ch], (ch == s->lfe_ch), s->dba_mode[ch], s->dba_nsegs[ch], s->dba_offsets[ch], s->dba_lengths[ch], s->dba_values[ch], s->mask[ch]); } if(bit_alloc_stages[ch] > 0) { /* Compute bit allocation */ const uint8_t *bap_tab = s->channel_uses_aht[ch] ? ff_eac3_hebap_tab : ff_ac3_bap_tab; ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch], s->start_freq[ch], s->end_freq[ch], s->snr_offset[ch], s->bit_alloc_params.floor, bap_tab, s->bap[ch]); } } /* unused dummy data */ if (s->skip_syntax && get_bits1(gbc)) { int skipl = get_bits(gbc, 9); while(skipl--) skip_bits(gbc, 8); } /* unpack the transform coefficients this also uncouples channels if coupling is in use. */ decode_transform_coeffs(s, blk); /* TODO: generate enhanced coupling coordinates and uncouple */ /* TODO: apply spectral extension */ /* recover coefficients if rematrixing is in use */ if(s->channel_mode == AC3_CHMODE_STEREO) do_rematrixing(s); /* apply scaling to coefficients (headroom, dynrng) */ for(ch=1; ch<=s->channels; ch++) { float gain = s->mul_bias / 4194304.0f; if(s->channel_mode == AC3_CHMODE_DUALMONO) { gain *= s->dynamic_range[ch-1]; } else { gain *= s->dynamic_range[0]; } s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256); } /* downmix and MDCT. order depends on whether block switching is used for any channel in this block. this is because coefficients for the long and short transforms cannot be mixed. */ downmix_output = s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) && s->fbw_channels == s->out_channels); if(different_transforms) { /* the delay samples have already been downmixed, so we upmix the delay samples in order to reconstruct all channels before downmixing. */ if(s->downmixed) { s->downmixed = 0; ac3_upmix_delay(s); } do_imdct(s, s->channels); if(downmix_output) { s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256); } } else { if(downmix_output) { s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256); } if(downmix_output && !s->downmixed) { s->downmixed = 1; s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128); } do_imdct(s, s->out_channels); } return 0; }