| /* |
| * 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. |
| * |
| * Spectral Extension |
| * There is a patch to get this working for the two samples we have that |
| * use it, but it needs some minor changes in order to be accepted. |
| * |
| * 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. |
| * |
| * Dependent Streams |
| * Only the independent stream is currently decoded. Any dependent |
| * streams are skipped. We have only come across two examples of this, and |
| * they are both just test streams, one for HD-DVD and the other for |
| * Blu-ray. |
| * |
| * 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 "internal.h" |
| #include "aac_ac3_parser.h" |
| #include "ac3.h" |
| #include "ac3_parser.h" |
| #include "ac3dec.h" |
| #include "ac3dec_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 |
| |
| /** 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; |
| } |
| |
| 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] << 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 (mant == -(1 << (gbits-1))) { |
| /* large mantissa */ |
| int b; |
| mant = get_sbits(gbc, bits-2+log_gain) << (26-log_gain-bits); |
| /* remap mantissa value to correct for asymmetric quantization */ |
| if (mant >= 0) |
| b = 32768 >> (log_gain+8); |
| else |
| b = ff_eac3_gaq_remap_2_4_b[hebap-8][log_gain-1]; |
| mant += (ff_eac3_gaq_remap_2_4_a[hebap-8][log_gain-1] * (mant>>8) + b) >> 7; |
| } else { |
| /* small mantissa, no GAQ, or Gk=1 */ |
| mant <<= 24 - bits; |
| if (!log_gain) { |
| /* remap mantissa value for no GAQ or Gk=1 */ |
| mant += (ff_eac3_gaq_remap_1[hebap-8] * (mant>>8)) >> 7; |
| } |
| } |
| s->pre_mantissa[ch][bin][blk] = mant; |
| } |
| } |
| idct6(s->pre_mantissa[ch][bin]); |
| } |
| } |
| |
| 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_DEPENDENT) { |
| ff_log_missing_feature(s->avctx, "Dependent substream decoding", 1); |
| return AAC_AC3_PARSE_ERROR_FRAME_TYPE; |
| } else 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. */ |
| ff_log_missing_feature(s->avctx, "Additional substreams", 1); |
| 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. */ |
| ff_log_missing_feature(s->avctx, "Reduced sampling rates", 1); |
| return -1; |
| } |
| skip_bits(gbc, 5); // skip bitstream id |
| |
| /* volume control params */ |
| for (i = 0; i < (s->channel_mode ? 1 : 2); i++) { |
| skip_bits(gbc, 5); // skip dialog normalization |
| if (get_bits1(gbc)) { |
| skip_bits(gbc, 8); // skip compression gain word |
| } |
| } |
| |
| /* dependent stream channel map */ |
| if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT) { |
| if (get_bits1(gbc)) { |
| skip_bits(gbc, 16); // skip custom channel map |
| } |
| } |
| |
| /* mixing metadata */ |
| if (get_bits1(gbc)) { |
| /* center and surround mix levels */ |
| if (s->channel_mode > AC3_CHMODE_STEREO) { |
| skip_bits(gbc, 2); // skip preferred stereo downmix mode |
| if (s->channel_mode & 1) { |
| /* if three front channels exist */ |
| skip_bits(gbc, 3); //skip Lt/Rt center mix level |
| s->center_mix_level = get_bits(gbc, 3); |
| } |
| if (s->channel_mode & 4) { |
| /* if a surround channel exists */ |
| skip_bits(gbc, 3); //skip Lt/Rt surround mix level |
| s->surround_mix_level = get_bits(gbc, 3); |
| } |
| } |
| |
| /* lfe mix level */ |
| if (s->lfe_on && get_bits1(gbc)) { |
| // TODO: use LFE mix level |
| skip_bits(gbc, 5); // skip LFE mix level code |
| } |
| |
| /* 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)) { |
| skip_bits(gbc, 3); // skip bit stream mode |
| skip_bits(gbc, 2); // skip copyright bit and original bitstream bit |
| if (s->channel_mode == AC3_CHMODE_STEREO) { |
| skip_bits(gbc, 4); // skip Dolby surround and headphone mode |
| } |
| if (s->channel_mode >= AC3_CHMODE_2F2R) { |
| skip_bits(gbc, 2); // skip Dolby surround EX mode |
| } |
| 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++) { |
| 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 occurance 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 */ |
| if (parse_spx_atten_data) { |
| ff_log_missing_feature(s->avctx, "Spectral extension attenuation", 1); |
| for (ch = 1; ch <= s->fbw_channels; ch++) { |
| if (get_bits1(gbc)) { // channel has spx attenuation |
| skip_bits(gbc, 5); // skip spx attenuation code |
| } |
| } |
| } |
| |
| /* 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); |
| ff_log_missing_feature(s->avctx, "Block start info", 1); |
| } |
| |
| /* syntax state initialization */ |
| for (ch = 1; ch <= s->fbw_channels; ch++) { |
| s->first_cpl_coords[ch] = 1; |
| } |
| s->first_cpl_leak = 1; |
| |
| return 0; |
| } |
