From d82bdf684b52d6d00cc3760ba6581e897192f923 Mon Sep 17 00:00:00 2001 From: Justin Ruggles Date: Sat, 30 Aug 2008 23:13:10 +0000 Subject: [PATCH] commit more OKed parts of the E-AC-3 decoder Originally committed as revision 15067 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/eac3dec.c | 411 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 411 insertions(+) diff --git a/libavcodec/eac3dec.c b/libavcodec/eac3dec.c index 388e2fc7ea..833b166881 100644 --- a/libavcodec/eac3dec.c +++ b/libavcodec/eac3dec.c @@ -78,3 +78,414 @@ static void idct6(int pre_mant[6]) 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_vq_hebap[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) { + av_log_missing_feature(s->avctx, "Dependent substream decoding", 1); + return 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 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. */ + av_log_missing_feature(s->avctx, "Additional substreams", 1); + return 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. */ + av_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 */ + int frmchexpstr; + for (ch = !((s->channel_mode > 1) && num_cpl_blocks); ch <= s->fbw_channels; ch++) { + 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))) { + for (ch = 1; ch <= s->fbw_channels; ch++) { + skip_bits(gbc, 5); // skip converter channel exponent strategy + } + } + + /* determine which channels use AHT */ + if (parse_aht_info) { + /* AHT is only available when there are 6 blocks in the frame. + The coupling channel can only use AHT when coupling is in use for + all blocks. + reference: Section E3.3.2 Bit Stream Helper Variables */ + s->channel_uses_aht[CPL_CH]=0; + for (ch = (num_cpl_blocks != 6); ch <= s->channels; ch++) { + int nchregs = 0; + for (blk = 0; blk < 6; blk++) { + if (ch) + nchregs += (s->exp_strategy[blk][ch] != EXP_REUSE); + else + nchregs += s->cpl_strategy_exists[blk] || + (s->exp_strategy[blk][CPL_CH] != EXP_REUSE); + } + s->channel_uses_aht[ch] = (nchregs == 1) && 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) { + av_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(gbc, block_start_bits); + } + + /* syntax state initialization */ + for (ch = 1; ch <= s->fbw_channels; ch++) { + s->first_cpl_coords[ch] = 1; + } + s->first_cpl_leak = 1; + + return 0; +}