| /* | |
| * E-AC-3 decoder | |
| * Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com> | |
| * Copyright (c) 2008 Justin Ruggles | |
| * | |
| * This file is part of FFmpeg. | |
| * | |
| * FFmpeg is free software; you can redistribute it and/or | |
| * modify it under the terms of the GNU Lesser General Public | |
| * License as published by the Free Software Foundation; either | |
| * version 2.1 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 | |
| * Lesser General Public License for more details. | |
| * | |
| * You should have received a copy of the GNU Lesser 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 | |
| */ | |
| /* | |
| * There are several features of E-AC-3 that this decoder does not yet support. | |
| * | |
| * Enhanced Coupling | |
| * No known samples exist. If any ever surface, this feature should not be | |
| * too difficult to implement. | |
| * | |
| * Reduced Sample Rates | |
| * No known samples exist. The spec also does not give clear information | |
| * on how this is to be implemented. | |
| * | |
| * Transient Pre-noise Processing | |
| * This is side information which a decoder should use to reduce artifacts | |
| * caused by transients. There are samples which are known to have this | |
| * information, but this decoder currently ignores it. | |
| */ | |
| #include "avcodec.h" | |
| #include "aac_ac3_parser.h" | |
| #include "ac3.h" | |
| #include "ac3dec.h" | |
| #include "ac3dec_data.h" | |
| #include "eac3_data.h" | |
| /** gain adaptive quantization mode */ | |
| typedef enum { | |
| EAC3_GAQ_NO =0, | |
| EAC3_GAQ_12, | |
| EAC3_GAQ_14, | |
| EAC3_GAQ_124 | |
| } EAC3GaqMode; | |
| #define EAC3_SR_CODE_REDUCED 3 | |
| static void ff_eac3_apply_spectral_extension(AC3DecodeContext *s) | |
| { | |
| int bin, bnd, ch, i; | |
| uint8_t wrapflag[SPX_MAX_BANDS]={1,0,}, num_copy_sections, copy_sizes[SPX_MAX_BANDS]; | |
| float rms_energy[SPX_MAX_BANDS]; | |
| /* Set copy index mapping table. Set wrap flags to apply a notch filter at | |
| wrap points later on. */ | |
| bin = s->spx_dst_start_freq; | |
| num_copy_sections = 0; | |
| for (bnd = 0; bnd < s->num_spx_bands; bnd++) { | |
| int copysize; | |
| int bandsize = s->spx_band_sizes[bnd]; | |
| if (bin + bandsize > s->spx_src_start_freq) { | |
| copy_sizes[num_copy_sections++] = bin - s->spx_dst_start_freq; | |
| bin = s->spx_dst_start_freq; | |
| wrapflag[bnd] = 1; | |
| } | |
| for (i = 0; i < bandsize; i += copysize) { | |
| if (bin == s->spx_src_start_freq) { | |
| copy_sizes[num_copy_sections++] = bin - s->spx_dst_start_freq; | |
| bin = s->spx_dst_start_freq; | |
| } | |
| copysize = FFMIN(bandsize - i, s->spx_src_start_freq - bin); | |
| bin += copysize; | |
| } | |
| } | |
| copy_sizes[num_copy_sections++] = bin - s->spx_dst_start_freq; | |
| for (ch = 1; ch <= s->fbw_channels; ch++) { | |
| if (!s->channel_uses_spx[ch]) | |
| continue; | |
| /* Copy coeffs from normal bands to extension bands */ | |
| bin = s->spx_src_start_freq; | |
| for (i = 0; i < num_copy_sections; i++) { | |
| memcpy(&s->transform_coeffs[ch][bin], | |
| &s->transform_coeffs[ch][s->spx_dst_start_freq], | |
| copy_sizes[i]*sizeof(INTFLOAT)); | |
| bin += copy_sizes[i]; | |
| } | |
| /* Calculate RMS energy for each SPX band. */ | |
| bin = s->spx_src_start_freq; | |
| for (bnd = 0; bnd < s->num_spx_bands; bnd++) { | |
| int bandsize = s->spx_band_sizes[bnd]; | |
| float accum = 0.0f; | |
| for (i = 0; i < bandsize; i++) { | |
| float coeff = s->transform_coeffs[ch][bin++]; | |
| accum += coeff * coeff; | |
| } | |
| rms_energy[bnd] = sqrtf(accum / bandsize); | |
| } | |
| /* Apply a notch filter at transitions between normal and extension | |
| bands and at all wrap points. */ | |
| if (s->spx_atten_code[ch] >= 0) { | |
| const float *atten_tab = ff_eac3_spx_atten_tab[s->spx_atten_code[ch]]; | |
| bin = s->spx_src_start_freq - 2; | |
| for (bnd = 0; bnd < s->num_spx_bands; bnd++) { | |
| if (wrapflag[bnd]) { | |
| INTFLOAT *coeffs = &s->transform_coeffs[ch][bin]; | |
| coeffs[0] *= atten_tab[0]; | |
| coeffs[1] *= atten_tab[1]; | |
| coeffs[2] *= atten_tab[2]; | |
| coeffs[3] *= atten_tab[1]; | |
| coeffs[4] *= atten_tab[0]; | |
| } | |
| bin += s->spx_band_sizes[bnd]; | |
| } | |
| } | |
| /* Apply noise-blended coefficient scaling based on previously | |
| calculated RMS energy, blending factors, and SPX coordinates for | |
| each band. */ | |
| bin = s->spx_src_start_freq; | |
| for (bnd = 0; bnd < s->num_spx_bands; bnd++) { | |
| float nscale = s->spx_noise_blend[ch][bnd] * rms_energy[bnd] * (1.0f / INT32_MIN); | |
| float sscale = s->spx_signal_blend[ch][bnd]; | |
| #if USE_FIXED | |
| // spx_noise_blend and spx_signal_blend are both FP.23 | |
| nscale *= 1.0 / (1<<23); | |
| sscale *= 1.0 / (1<<23); | |
| if (nscale < -1.0) | |
| nscale = -1.0; | |
| #endif | |
| for (i = 0; i < s->spx_band_sizes[bnd]; i++) { | |
| UINTFLOAT noise = (INTFLOAT)(nscale * (int32_t)av_lfg_get(&s->dith_state)); | |
| s->transform_coeffs[ch][bin] *= sscale; | |
| s->transform_coeffs[ch][bin++] += noise; | |
| } | |
| } | |
| } | |
| } | |
| /** lrint(M_SQRT2*cos(2*M_PI/12)*(1<<23)) */ | |
| #define COEFF_0 10273905LL | |
| /** lrint(M_SQRT2*cos(0*M_PI/12)*(1<<23)) = lrint(M_SQRT2*(1<<23)) */ | |
| #define COEFF_1 11863283LL | |
| /** lrint(M_SQRT2*cos(5*M_PI/12)*(1<<23)) */ | |
| #define COEFF_2 3070444LL | |
| /** | |
| * Calculate 6-point IDCT of the pre-mantissas. | |
| * All calculations are 24-bit fixed-point. | |
| */ | |
| static void idct6(int pre_mant[6]) | |
| { | |
| int tmp; | |
| int even0, even1, even2, odd0, odd1, odd2; | |
| odd1 = pre_mant[1] - pre_mant[3] - pre_mant[5]; | |
| even2 = ( pre_mant[2] * COEFF_0) >> 23; | |
| tmp = ( pre_mant[4] * COEFF_1) >> 23; | |
| odd0 = ((pre_mant[1] + pre_mant[5]) * COEFF_2) >> 23; | |
| even0 = pre_mant[0] + (tmp >> 1); | |
| even1 = pre_mant[0] - tmp; | |
| tmp = even0; | |
| even0 = tmp + even2; | |
| even2 = tmp - even2; | |
| tmp = odd0; | |
| odd0 = tmp + pre_mant[1] + pre_mant[3]; | |
| odd2 = tmp + pre_mant[5] - pre_mant[3]; | |
| pre_mant[0] = even0 + odd0; | |
| pre_mant[1] = even1 + odd1; | |
| pre_mant[2] = even2 + odd2; | |
| pre_mant[3] = even2 - odd2; | |
| pre_mant[4] = even1 - odd1; | |
| pre_mant[5] = even0 - odd0; | |
| } | |
| static void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch) | |
| { | |
| int bin, blk, gs; | |
| int end_bap, gaq_mode; | |
| GetBitContext *gbc = &s->gbc; | |
| int gaq_gain[AC3_MAX_COEFS]; | |
| gaq_mode = get_bits(gbc, 2); | |
| end_bap = (gaq_mode < 2) ? 12 : 17; | |
| /* if GAQ gain is used, decode gain codes for bins with hebap between | |
| 8 and end_bap */ | |
| gs = 0; | |
| if (gaq_mode == EAC3_GAQ_12 || gaq_mode == EAC3_GAQ_14) { | |
| /* read 1-bit GAQ gain codes */ | |
| for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) { | |
| if (s->bap[ch][bin] > 7 && s->bap[ch][bin] < end_bap) | |
| gaq_gain[gs++] = get_bits1(gbc) << (gaq_mode-1); | |
| } | |
| } else if (gaq_mode == EAC3_GAQ_124) { | |
| /* read 1.67-bit GAQ gain codes (3 codes in 5 bits) */ | |
| int gc = 2; | |
| for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) { | |
| if (s->bap[ch][bin] > 7 && s->bap[ch][bin] < 17) { | |
| if (gc++ == 2) { | |
| int group_code = get_bits(gbc, 5); | |
| if (group_code > 26) { | |
| av_log(s->avctx, AV_LOG_WARNING, "GAQ gain group code out-of-range\n"); | |
| group_code = 26; | |
| } | |
| gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][0]; | |
| gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][1]; | |
| gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][2]; | |
| gc = 0; | |
| } | |
| } | |
| } | |
| } | |
| gs=0; | |
| for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) { | |
| int hebap = s->bap[ch][bin]; | |
| int bits = ff_eac3_bits_vs_hebap[hebap]; | |
| if (!hebap) { | |
| /* zero-mantissa dithering */ | |
| for (blk = 0; blk < 6; blk++) { | |
| s->pre_mantissa[ch][bin][blk] = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000; | |
| } | |
| } else if (hebap < 8) { | |
| /* Vector Quantization */ | |
| int v = get_bits(gbc, bits); | |
| for (blk = 0; blk < 6; blk++) { | |
| s->pre_mantissa[ch][bin][blk] = ff_eac3_mantissa_vq[hebap][v][blk] * (1 << 8); | |
| } | |
| } else { | |
| /* Gain Adaptive Quantization */ | |
| int gbits, log_gain; | |
| if (gaq_mode != EAC3_GAQ_NO && hebap < end_bap) { | |
| log_gain = gaq_gain[gs++]; | |
| } else { | |
| log_gain = 0; | |
| } | |
| gbits = bits - log_gain; | |
| for (blk = 0; blk < 6; blk++) { | |
| int mant = get_sbits(gbc, gbits); | |
| if (log_gain && mant == -(1 << (gbits-1))) { | |
| /* large mantissa */ | |
| int b; | |
| int mbits = bits - (2 - log_gain); | |
| mant = get_sbits(gbc, mbits); | |
| mant = ((unsigned)mant) << (23 - (mbits - 1)); | |
| /* remap mantissa value to correct for asymmetric quantization */ | |
| if (mant >= 0) | |
| b = 1 << (23 - log_gain); | |
| else | |
| b = ff_eac3_gaq_remap_2_4_b[hebap-8][log_gain-1] * (1 << 8); | |
| mant += ((ff_eac3_gaq_remap_2_4_a[hebap-8][log_gain-1] * (int64_t)mant) >> 15) + b; | |
| } else { | |
| /* small mantissa, no GAQ, or Gk=1 */ | |
| mant *= (1 << 24 - bits); | |
| if (!log_gain) { | |
| /* remap mantissa value for no GAQ or Gk=1 */ | |
| mant += (ff_eac3_gaq_remap_1[hebap-8] * (int64_t)mant) >> 15; | |
| } | |
| } | |
| s->pre_mantissa[ch][bin][blk] = mant; | |
| } | |
| } | |
| idct6(s->pre_mantissa[ch][bin]); | |
| } | |
| } | |
| static int ff_eac3_parse_header(AC3DecodeContext *s) | |
| { | |
| int i, blk, ch; | |
| int ac3_exponent_strategy, parse_aht_info, parse_spx_atten_data; | |
| int parse_transient_proc_info; | |
| int num_cpl_blocks; | |
| GetBitContext *gbc = &s->gbc; | |
| /* An E-AC-3 stream can have multiple independent streams which the | |
| application can select from. each independent stream can also contain | |
| dependent streams which are used to add or replace channels. */ | |
| if (s->frame_type == EAC3_FRAME_TYPE_RESERVED) { | |
| av_log(s->avctx, AV_LOG_ERROR, "Reserved frame type\n"); | |
| return AAC_AC3_PARSE_ERROR_FRAME_TYPE; | |
| } | |
| /* The substream id indicates which substream this frame belongs to. each | |
| independent stream has its own substream id, and the dependent streams | |
| associated to an independent stream have matching substream id's. */ | |
| if (s->substreamid) { | |
| /* only decode substream with id=0. skip any additional substreams. */ | |
| if (!s->eac3_subsbtreamid_found) { | |
| s->eac3_subsbtreamid_found = 1; | |
| avpriv_request_sample(s->avctx, "Additional substreams"); | |
| } | |
| return AAC_AC3_PARSE_ERROR_FRAME_TYPE; | |
| } | |
| if (s->bit_alloc_params.sr_code == EAC3_SR_CODE_REDUCED) { | |
| /* The E-AC-3 specification does not tell how to handle reduced sample | |
| rates in bit allocation. The best assumption would be that it is | |
| handled like AC-3 DolbyNet, but we cannot be sure until we have a | |
| sample which utilizes this feature. */ | |
| avpriv_request_sample(s->avctx, "Reduced sampling rate"); | |
| return AVERROR_PATCHWELCOME; | |
| } | |
| skip_bits(gbc, 5); // skip bitstream id | |
| /* volume control params */ | |
| for (i = 0; i < (s->channel_mode ? 1 : 2); i++) { | |
| s->dialog_normalization[i] = -get_bits(gbc, 5); | |
| if (s->dialog_normalization[i] == 0) { | |
| s->dialog_normalization[i] = -31; | |
| } | |
| if (s->target_level != 0) { | |
| s->level_gain[i] = powf(2.0f, | |
| (float)(s->target_level - s->dialog_normalization[i])/6.0f); | |
| } | |
| s->compression_exists[i] = get_bits1(gbc); | |
| if (s->compression_exists[i]) { | |
| s->heavy_dynamic_range[i] = AC3_HEAVY_RANGE(get_bits(gbc, 8)); | |
| } | |
| } | |
| /* dependent stream channel map */ | |
| if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT) { | |
| if (get_bits1(gbc)) { | |
| int64_t channel_layout = 0; | |
| int channel_map = get_bits(gbc, 16); | |
| av_log(s->avctx, AV_LOG_DEBUG, "channel_map: %0X\n", channel_map); | |
| for (i = 0; i < 16; i++) | |
| if (channel_map & (1 << (EAC3_MAX_CHANNELS - i - 1))) | |
| channel_layout |= ff_eac3_custom_channel_map_locations[i][1]; | |
| if (av_popcount64(channel_layout) > EAC3_MAX_CHANNELS) { | |
| return AVERROR_INVALIDDATA; | |
| } | |
| s->channel_map = channel_map; | |
| } | |
| } | |
| /* mixing metadata */ | |
| if (get_bits1(gbc)) { | |
| /* center and surround mix levels */ | |
| if (s->channel_mode > AC3_CHMODE_STEREO) { | |
| s->preferred_downmix = get_bits(gbc, 2); | |
| if (s->channel_mode & 1) { | |
| /* if three front channels exist */ | |
| s->center_mix_level_ltrt = get_bits(gbc, 3); | |
| s->center_mix_level = get_bits(gbc, 3); | |
| } | |
| if (s->channel_mode & 4) { | |
| /* if a surround channel exists */ | |
| s->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7); | |
| s->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7); | |
| } | |
| } | |
| /* lfe mix level */ | |
| if (s->lfe_on && (s->lfe_mix_level_exists = get_bits1(gbc))) { | |
| s->lfe_mix_level = get_bits(gbc, 5); | |
| } | |
| /* info for mixing with other streams and substreams */ | |
| if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT) { | |
| for (i = 0; i < (s->channel_mode ? 1 : 2); i++) { | |
| // TODO: apply program scale factor | |
| if (get_bits1(gbc)) { | |
| skip_bits(gbc, 6); // skip program scale factor | |
| } | |
| } | |
| if (get_bits1(gbc)) { | |
| skip_bits(gbc, 6); // skip external program scale factor | |
| } | |
| /* skip mixing parameter data */ | |
| switch(get_bits(gbc, 2)) { | |
| case 1: skip_bits(gbc, 5); break; | |
| case 2: skip_bits(gbc, 12); break; | |
| case 3: { | |
| int mix_data_size = (get_bits(gbc, 5) + 2) << 3; | |
| skip_bits_long(gbc, mix_data_size); | |
| break; | |
| } | |
| } | |
| /* skip pan information for mono or dual mono source */ | |
| if (s->channel_mode < AC3_CHMODE_STEREO) { | |
| for (i = 0; i < (s->channel_mode ? 1 : 2); i++) { | |
| if (get_bits1(gbc)) { | |
| /* note: this is not in the ATSC A/52B specification | |
| reference: ETSI TS 102 366 V1.1.1 | |
| section: E.1.3.1.25 */ | |
| skip_bits(gbc, 8); // skip pan mean direction index | |
| skip_bits(gbc, 6); // skip reserved paninfo bits | |
| } | |
| } | |
| } | |
| /* skip mixing configuration information */ | |
| if (get_bits1(gbc)) { | |
| for (blk = 0; blk < s->num_blocks; blk++) { | |
| if (s->num_blocks == 1 || get_bits1(gbc)) { | |
| skip_bits(gbc, 5); | |
| } | |
| } | |
| } | |
| } | |
| } | |
| /* informational metadata */ | |
| if (get_bits1(gbc)) { | |
| s->bitstream_mode = get_bits(gbc, 3); | |
| skip_bits(gbc, 2); // skip copyright bit and original bitstream bit | |
| if (s->channel_mode == AC3_CHMODE_STEREO) { | |
| s->dolby_surround_mode = get_bits(gbc, 2); | |
| s->dolby_headphone_mode = get_bits(gbc, 2); | |
| } | |
| if (s->channel_mode >= AC3_CHMODE_2F2R) { | |
| s->dolby_surround_ex_mode = get_bits(gbc, 2); | |
| } | |
| for (i = 0; i < (s->channel_mode ? 1 : 2); i++) { | |
| if (get_bits1(gbc)) { | |
| skip_bits(gbc, 8); // skip mix level, room type, and A/D converter type | |
| } | |
| } | |
| if (s->bit_alloc_params.sr_code != EAC3_SR_CODE_REDUCED) { | |
| skip_bits1(gbc); // skip source sample rate code | |
| } | |
| } | |
| /* converter synchronization flag | |
| If frames are less than six blocks, this bit should be turned on | |
| once every 6 blocks to indicate the start of a frame set. | |
| reference: RFC 4598, Section 2.1.3 Frame Sets */ | |
| if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && s->num_blocks != 6) { | |
| skip_bits1(gbc); // skip converter synchronization flag | |
| } | |
| /* original frame size code if this stream was converted from AC-3 */ | |
| if (s->frame_type == EAC3_FRAME_TYPE_AC3_CONVERT && | |
| (s->num_blocks == 6 || get_bits1(gbc))) { | |
| skip_bits(gbc, 6); // skip frame size code | |
| } | |
| /* additional bitstream info */ | |
| if (get_bits1(gbc)) { | |
| int addbsil = get_bits(gbc, 6); | |
| for (i = 0; i < addbsil + 1; i++) { | |
| if (i == 0) { | |
| /* In this 8 bit chunk, the LSB is equal to flag_ec3_extension_type_a | |
| which can be used to detect Atmos presence */ | |
| skip_bits(gbc, 7); | |
| if (get_bits1(gbc)) { | |
| s->eac3_extension_type_a = 1; | |
| } | |
| } else { | |
| skip_bits(gbc, 8); // skip additional bit stream info | |
| } | |
| } | |
| } | |
| /* audio frame syntax flags, strategy data, and per-frame data */ | |
| if (s->num_blocks == 6) { | |
| ac3_exponent_strategy = get_bits1(gbc); | |
| parse_aht_info = get_bits1(gbc); | |
| } else { | |
| /* less than 6 blocks, so use AC-3-style exponent strategy syntax, and | |
| do not use AHT */ | |
| ac3_exponent_strategy = 1; | |
| parse_aht_info = 0; | |
| } | |
| s->snr_offset_strategy = get_bits(gbc, 2); | |
| parse_transient_proc_info = get_bits1(gbc); | |
| s->block_switch_syntax = get_bits1(gbc); | |
| if (!s->block_switch_syntax) | |
| memset(s->block_switch, 0, sizeof(s->block_switch)); | |
| s->dither_flag_syntax = get_bits1(gbc); | |
| if (!s->dither_flag_syntax) { | |
| for (ch = 1; ch <= s->fbw_channels; ch++) | |
| s->dither_flag[ch] = 1; | |
| } | |
| s->dither_flag[CPL_CH] = s->dither_flag[s->lfe_ch] = 0; | |
| s->bit_allocation_syntax = get_bits1(gbc); | |
| if (!s->bit_allocation_syntax) { | |
| /* set default bit allocation parameters */ | |
| s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[2]; | |
| s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[1]; | |
| s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab [1]; | |
| s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[2]; | |
| s->bit_alloc_params.floor = ff_ac3_floor_tab [7]; | |
| } | |
| s->fast_gain_syntax = get_bits1(gbc); | |
| s->dba_syntax = get_bits1(gbc); | |
| s->skip_syntax = get_bits1(gbc); | |
| parse_spx_atten_data = get_bits1(gbc); | |
| /* coupling strategy occurrence and coupling use per block */ | |
| num_cpl_blocks = 0; | |
| if (s->channel_mode > 1) { | |
| for (blk = 0; blk < s->num_blocks; blk++) { | |
| s->cpl_strategy_exists[blk] = (!blk || get_bits1(gbc)); | |
| if (s->cpl_strategy_exists[blk]) { | |
| s->cpl_in_use[blk] = get_bits1(gbc); | |
| } else { | |
| s->cpl_in_use[blk] = s->cpl_in_use[blk-1]; | |
| } | |
| num_cpl_blocks += s->cpl_in_use[blk]; | |
| } | |
| } else { | |
| memset(s->cpl_in_use, 0, sizeof(s->cpl_in_use)); | |
| } | |
| /* exponent strategy data */ | |
| if (ac3_exponent_strategy) { | |
| /* AC-3-style exponent strategy syntax */ | |
| for (blk = 0; blk < s->num_blocks; blk++) { | |
| for (ch = !s->cpl_in_use[blk]; ch <= s->fbw_channels; ch++) { | |
| s->exp_strategy[blk][ch] = get_bits(gbc, 2); | |
| } | |
| } | |
| } else { | |
| /* LUT-based exponent strategy syntax */ | |
| for (ch = !((s->channel_mode > 1) && num_cpl_blocks); ch <= s->fbw_channels; ch++) { | |
| int frmchexpstr = get_bits(gbc, 5); | |
| for (blk = 0; blk < 6; blk++) { | |
| s->exp_strategy[blk][ch] = ff_eac3_frm_expstr[frmchexpstr][blk]; | |
| } | |
| } | |
| } | |
| /* LFE exponent strategy */ | |
| if (s->lfe_on) { | |
| for (blk = 0; blk < s->num_blocks; blk++) { | |
| s->exp_strategy[blk][s->lfe_ch] = get_bits1(gbc); | |
| } | |
| } | |
| /* original exponent strategies if this stream was converted from AC-3 */ | |
| if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && | |
| (s->num_blocks == 6 || get_bits1(gbc))) { | |
| skip_bits(gbc, 5 * s->fbw_channels); // skip converter channel exponent strategy | |
| } | |
| /* determine which channels use AHT */ | |
| if (parse_aht_info) { | |
| /* For AHT to be used, all non-zero blocks must reuse exponents from | |
| the first block. Furthermore, for AHT to be used in the coupling | |
| channel, all blocks must use coupling and use the same coupling | |
| strategy. */ | |
| s->channel_uses_aht[CPL_CH]=0; | |
| for (ch = (num_cpl_blocks != 6); ch <= s->channels; ch++) { | |
| int use_aht = 1; | |
| for (blk = 1; blk < 6; blk++) { | |
| if ((s->exp_strategy[blk][ch] != EXP_REUSE) || | |
| (!ch && s->cpl_strategy_exists[blk])) { | |
| use_aht = 0; | |
| break; | |
| } | |
| } | |
| s->channel_uses_aht[ch] = use_aht && get_bits1(gbc); | |
| } | |
| } else { | |
| memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht)); | |
| } | |
| /* per-frame SNR offset */ | |
| if (!s->snr_offset_strategy) { | |
| int csnroffst = (get_bits(gbc, 6) - 15) << 4; | |
| int snroffst = (csnroffst + get_bits(gbc, 4)) << 2; | |
| for (ch = 0; ch <= s->channels; ch++) | |
| s->snr_offset[ch] = snroffst; | |
| } | |
| /* transient pre-noise processing data */ | |
| if (parse_transient_proc_info) { | |
| for (ch = 1; ch <= s->fbw_channels; ch++) { | |
| if (get_bits1(gbc)) { // channel in transient processing | |
| skip_bits(gbc, 10); // skip transient processing location | |
| skip_bits(gbc, 8); // skip transient processing length | |
| } | |
| } | |
| } | |
| /* spectral extension attenuation data */ | |
| for (ch = 1; ch <= s->fbw_channels; ch++) { | |
| if (parse_spx_atten_data && get_bits1(gbc)) { | |
| s->spx_atten_code[ch] = get_bits(gbc, 5); | |
| } else { | |
| s->spx_atten_code[ch] = -1; | |
| } | |
| } | |
| /* block start information */ | |
| if (s->num_blocks > 1 && get_bits1(gbc)) { | |
| /* reference: Section E2.3.2.27 | |
| nblkstrtbits = (numblks - 1) * (4 + ceiling(log2(words_per_frame))) | |
| The spec does not say what this data is or what it's used for. | |
| It is likely the offset of each block within the frame. */ | |
| int block_start_bits = (s->num_blocks-1) * (4 + av_log2(s->frame_size-2)); | |
| skip_bits_long(gbc, block_start_bits); | |
| avpriv_request_sample(s->avctx, "Block start info"); | |
| } | |
| /* syntax state initialization */ | |
| for (ch = 1; ch <= s->fbw_channels; ch++) { | |
| s->first_spx_coords[ch] = 1; | |
| s->first_cpl_coords[ch] = 1; | |
| } | |
| s->first_cpl_leak = 1; | |
| return 0; | |
| } |