3 * Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
4 * Copyright (c) 2008 Justin Ruggles
6 * This file is part of Libav.
8 * Libav is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * Libav is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with Libav; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * There are several features of E-AC-3 that this decoder does not yet support.
27 * No known samples exist. If any ever surface, this feature should not be
28 * too difficult to implement.
30 * Reduced Sample Rates
31 * No known samples exist. The spec also does not give clear information
32 * on how this is to be implemented.
35 * Only the independent stream is currently decoded. Any dependent
36 * streams are skipped. We have only come across two examples of this, and
37 * they are both just test streams, one for HD-DVD and the other for
40 * Transient Pre-noise Processing
41 * This is side information which a decoder should use to reduce artifacts
42 * caused by transients. There are samples which are known to have this
43 * information, but this decoder currently ignores it.
49 #include "aac_ac3_parser.h"
51 #include "ac3_parser.h"
53 #include "ac3dec_data.h"
54 #include "eac3_data.h"
56 /** gain adaptive quantization mode */
64 #define EAC3_SR_CODE_REDUCED 3
66 void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
69 uint8_t wrapflag[SPX_MAX_BANDS]={1,0,}, num_copy_sections, copy_sizes[SPX_MAX_BANDS];
70 float rms_energy[SPX_MAX_BANDS];
72 /* Set copy index mapping table. Set wrap flags to apply a notch filter at
73 wrap points later on. */
74 bin = s->spx_dst_start_freq;
75 num_copy_sections = 0;
76 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
78 int bandsize = s->spx_band_sizes[bnd];
79 if (bin + bandsize > s->spx_src_start_freq) {
80 copy_sizes[num_copy_sections++] = bin - s->spx_dst_start_freq;
81 bin = s->spx_dst_start_freq;
84 for (i = 0; i < bandsize; i += copysize) {
85 if (bin == s->spx_src_start_freq) {
86 copy_sizes[num_copy_sections++] = bin - s->spx_dst_start_freq;
87 bin = s->spx_dst_start_freq;
89 copysize = FFMIN(bandsize - i, s->spx_src_start_freq - bin);
93 copy_sizes[num_copy_sections++] = bin - s->spx_dst_start_freq;
95 for (ch = 1; ch <= s->fbw_channels; ch++) {
96 if (!s->channel_uses_spx[ch])
99 /* Copy coeffs from normal bands to extension bands */
100 bin = s->spx_src_start_freq;
101 for (i = 0; i < num_copy_sections; i++) {
102 memcpy(&s->transform_coeffs[ch][bin],
103 &s->transform_coeffs[ch][s->spx_dst_start_freq],
104 copy_sizes[i]*sizeof(float));
105 bin += copy_sizes[i];
108 /* Calculate RMS energy for each SPX band. */
109 bin = s->spx_src_start_freq;
110 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
111 int bandsize = s->spx_band_sizes[bnd];
113 for (i = 0; i < bandsize; i++) {
114 float coeff = s->transform_coeffs[ch][bin++];
115 accum += coeff * coeff;
117 rms_energy[bnd] = sqrtf(accum / bandsize);
120 /* Apply a notch filter at transitions between normal and extension
121 bands and at all wrap points. */
122 if (s->spx_atten_code[ch] >= 0) {
123 const float *atten_tab = ff_eac3_spx_atten_tab[s->spx_atten_code[ch]];
124 bin = s->spx_src_start_freq - 2;
125 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
127 float *coeffs = &s->transform_coeffs[ch][bin];
128 coeffs[0] *= atten_tab[0];
129 coeffs[1] *= atten_tab[1];
130 coeffs[2] *= atten_tab[2];
131 coeffs[3] *= atten_tab[1];
132 coeffs[4] *= atten_tab[0];
134 bin += s->spx_band_sizes[bnd];
138 /* Apply noise-blended coefficient scaling based on previously
139 calculated RMS energy, blending factors, and SPX coordinates for
141 bin = s->spx_src_start_freq;
142 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
143 float nscale = s->spx_noise_blend[ch][bnd] * rms_energy[bnd] * (1.0f / INT32_MIN);
144 float sscale = s->spx_signal_blend[ch][bnd];
145 for (i = 0; i < s->spx_band_sizes[bnd]; i++) {
146 float noise = nscale * (int32_t)av_lfg_get(&s->dith_state);
147 s->transform_coeffs[ch][bin] *= sscale;
148 s->transform_coeffs[ch][bin++] += noise;
155 /** lrint(M_SQRT2*cos(2*M_PI/12)*(1<<23)) */
156 #define COEFF_0 10273905LL
158 /** lrint(M_SQRT2*cos(0*M_PI/12)*(1<<23)) = lrint(M_SQRT2*(1<<23)) */
159 #define COEFF_1 11863283LL
161 /** lrint(M_SQRT2*cos(5*M_PI/12)*(1<<23)) */
162 #define COEFF_2 3070444LL
165 * Calculate 6-point IDCT of the pre-mantissas.
166 * All calculations are 24-bit fixed-point.
168 static void idct6(int pre_mant[6])
171 int even0, even1, even2, odd0, odd1, odd2;
173 odd1 = pre_mant[1] - pre_mant[3] - pre_mant[5];
175 even2 = ( pre_mant[2] * COEFF_0) >> 23;
176 tmp = ( pre_mant[4] * COEFF_1) >> 23;
177 odd0 = ((pre_mant[1] + pre_mant[5]) * COEFF_2) >> 23;
179 even0 = pre_mant[0] + (tmp >> 1);
180 even1 = pre_mant[0] - tmp;
187 odd0 = tmp + pre_mant[1] + pre_mant[3];
188 odd2 = tmp + pre_mant[5] - pre_mant[3];
190 pre_mant[0] = even0 + odd0;
191 pre_mant[1] = even1 + odd1;
192 pre_mant[2] = even2 + odd2;
193 pre_mant[3] = even2 - odd2;
194 pre_mant[4] = even1 - odd1;
195 pre_mant[5] = even0 - odd0;
198 void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch)
201 int end_bap, gaq_mode;
202 GetBitContext *gbc = &s->gbc;
203 int gaq_gain[AC3_MAX_COEFS];
205 gaq_mode = get_bits(gbc, 2);
206 end_bap = (gaq_mode < 2) ? 12 : 17;
208 /* if GAQ gain is used, decode gain codes for bins with hebap between
211 if (gaq_mode == EAC3_GAQ_12 || gaq_mode == EAC3_GAQ_14) {
212 /* read 1-bit GAQ gain codes */
213 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
214 if (s->bap[ch][bin] > 7 && s->bap[ch][bin] < end_bap)
215 gaq_gain[gs++] = get_bits1(gbc) << (gaq_mode-1);
217 } else if (gaq_mode == EAC3_GAQ_124) {
218 /* read 1.67-bit GAQ gain codes (3 codes in 5 bits) */
220 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
221 if (s->bap[ch][bin] > 7 && s->bap[ch][bin] < 17) {
223 int group_code = get_bits(gbc, 5);
224 if (group_code > 26) {
225 av_log(s->avctx, AV_LOG_WARNING, "GAQ gain group code out-of-range\n");
228 gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][0];
229 gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][1];
230 gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][2];
238 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
239 int hebap = s->bap[ch][bin];
240 int bits = ff_eac3_bits_vs_hebap[hebap];
242 /* zero-mantissa dithering */
243 for (blk = 0; blk < 6; blk++) {
244 s->pre_mantissa[ch][bin][blk] = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
246 } else if (hebap < 8) {
247 /* Vector Quantization */
248 int v = get_bits(gbc, bits);
249 for (blk = 0; blk < 6; blk++) {
250 s->pre_mantissa[ch][bin][blk] = ff_eac3_mantissa_vq[hebap][v][blk] << 8;
253 /* Gain Adaptive Quantization */
255 if (gaq_mode != EAC3_GAQ_NO && hebap < end_bap) {
256 log_gain = gaq_gain[gs++];
260 gbits = bits - log_gain;
262 for (blk = 0; blk < 6; blk++) {
263 int mant = get_sbits(gbc, gbits);
264 if (log_gain && mant == -(1 << (gbits-1))) {
267 int mbits = bits - (2 - log_gain);
268 mant = get_sbits(gbc, mbits);
269 mant <<= (23 - (mbits - 1));
270 /* remap mantissa value to correct for asymmetric quantization */
272 b = 1 << (23 - log_gain);
274 b = ff_eac3_gaq_remap_2_4_b[hebap-8][log_gain-1] << 8;
275 mant += ((ff_eac3_gaq_remap_2_4_a[hebap-8][log_gain-1] * (int64_t)mant) >> 15) + b;
277 /* small mantissa, no GAQ, or Gk=1 */
280 /* remap mantissa value for no GAQ or Gk=1 */
281 mant += (ff_eac3_gaq_remap_1[hebap-8] * (int64_t)mant) >> 15;
284 s->pre_mantissa[ch][bin][blk] = mant;
287 idct6(s->pre_mantissa[ch][bin]);
291 int ff_eac3_parse_header(AC3DecodeContext *s)
294 int ac3_exponent_strategy, parse_aht_info, parse_spx_atten_data;
295 int parse_transient_proc_info;
297 GetBitContext *gbc = &s->gbc;
299 /* An E-AC-3 stream can have multiple independent streams which the
300 application can select from. each independent stream can also contain
301 dependent streams which are used to add or replace channels. */
302 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT) {
303 avpriv_request_sample(s->avctx, "Dependent substream decoding");
304 return AAC_AC3_PARSE_ERROR_FRAME_TYPE;
305 } else if (s->frame_type == EAC3_FRAME_TYPE_RESERVED) {
306 av_log(s->avctx, AV_LOG_ERROR, "Reserved frame type\n");
307 return AAC_AC3_PARSE_ERROR_FRAME_TYPE;
310 /* The substream id indicates which substream this frame belongs to. each
311 independent stream has its own substream id, and the dependent streams
312 associated to an independent stream have matching substream id's. */
313 if (s->substreamid) {
314 /* only decode substream with id=0. skip any additional substreams. */
315 avpriv_request_sample(s->avctx, "Additional substreams");
316 return AAC_AC3_PARSE_ERROR_FRAME_TYPE;
319 if (s->bit_alloc_params.sr_code == EAC3_SR_CODE_REDUCED) {
320 /* The E-AC-3 specification does not tell how to handle reduced sample
321 rates in bit allocation. The best assumption would be that it is
322 handled like AC-3 DolbyNet, but we cannot be sure until we have a
323 sample which utilizes this feature. */
324 avpriv_request_sample(s->avctx, "Reduced sampling rate");
325 return AVERROR_PATCHWELCOME;
327 skip_bits(gbc, 5); // skip bitstream id
329 /* volume control params */
330 for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
331 skip_bits(gbc, 5); // skip dialog normalization
332 if (get_bits1(gbc)) {
333 skip_bits(gbc, 8); // skip compression gain word
337 /* dependent stream channel map */
338 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT) {
339 if (get_bits1(gbc)) {
340 skip_bits(gbc, 16); // skip custom channel map
344 /* mixing metadata */
345 if (get_bits1(gbc)) {
346 /* center and surround mix levels */
347 if (s->channel_mode > AC3_CHMODE_STEREO) {
348 skip_bits(gbc, 2); // skip preferred stereo downmix mode
349 if (s->channel_mode & 1) {
350 /* if three front channels exist */
351 skip_bits(gbc, 3); //skip Lt/Rt center mix level
352 s->center_mix_level = get_bits(gbc, 3);
354 if (s->channel_mode & 4) {
355 /* if a surround channel exists */
356 skip_bits(gbc, 3); //skip Lt/Rt surround mix level
357 s->surround_mix_level = get_bits(gbc, 3);
362 if (s->lfe_on && get_bits1(gbc)) {
363 // TODO: use LFE mix level
364 skip_bits(gbc, 5); // skip LFE mix level code
367 /* info for mixing with other streams and substreams */
368 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT) {
369 for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
370 // TODO: apply program scale factor
371 if (get_bits1(gbc)) {
372 skip_bits(gbc, 6); // skip program scale factor
375 if (get_bits1(gbc)) {
376 skip_bits(gbc, 6); // skip external program scale factor
378 /* skip mixing parameter data */
379 switch(get_bits(gbc, 2)) {
380 case 1: skip_bits(gbc, 5); break;
381 case 2: skip_bits(gbc, 12); break;
383 int mix_data_size = (get_bits(gbc, 5) + 2) << 3;
384 skip_bits_long(gbc, mix_data_size);
388 /* skip pan information for mono or dual mono source */
389 if (s->channel_mode < AC3_CHMODE_STEREO) {
390 for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
391 if (get_bits1(gbc)) {
392 /* note: this is not in the ATSC A/52B specification
393 reference: ETSI TS 102 366 V1.1.1
394 section: E.1.3.1.25 */
395 skip_bits(gbc, 8); // skip pan mean direction index
396 skip_bits(gbc, 6); // skip reserved paninfo bits
400 /* skip mixing configuration information */
401 if (get_bits1(gbc)) {
402 for (blk = 0; blk < s->num_blocks; blk++) {
403 if (s->num_blocks == 1 || get_bits1(gbc)) {
411 /* informational metadata */
412 if (get_bits1(gbc)) {
413 s->bitstream_mode = get_bits(gbc, 3);
414 skip_bits(gbc, 2); // skip copyright bit and original bitstream bit
415 if (s->channel_mode == AC3_CHMODE_STEREO) {
416 s->dolby_surround_mode = get_bits(gbc, 2);
417 s->dolby_headphone_mode = get_bits(gbc, 2);
419 if (s->channel_mode >= AC3_CHMODE_2F2R) {
420 s->dolby_surround_ex_mode = get_bits(gbc, 2);
422 for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
423 if (get_bits1(gbc)) {
424 skip_bits(gbc, 8); // skip mix level, room type, and A/D converter type
427 if (s->bit_alloc_params.sr_code != EAC3_SR_CODE_REDUCED) {
428 skip_bits1(gbc); // skip source sample rate code
432 /* converter synchronization flag
433 If frames are less than six blocks, this bit should be turned on
434 once every 6 blocks to indicate the start of a frame set.
435 reference: RFC 4598, Section 2.1.3 Frame Sets */
436 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && s->num_blocks != 6) {
437 skip_bits1(gbc); // skip converter synchronization flag
440 /* original frame size code if this stream was converted from AC-3 */
441 if (s->frame_type == EAC3_FRAME_TYPE_AC3_CONVERT &&
442 (s->num_blocks == 6 || get_bits1(gbc))) {
443 skip_bits(gbc, 6); // skip frame size code
446 /* additional bitstream info */
447 if (get_bits1(gbc)) {
448 int addbsil = get_bits(gbc, 6);
449 for (i = 0; i < addbsil + 1; i++) {
450 skip_bits(gbc, 8); // skip additional bit stream info
454 /* audio frame syntax flags, strategy data, and per-frame data */
456 if (s->num_blocks == 6) {
457 ac3_exponent_strategy = get_bits1(gbc);
458 parse_aht_info = get_bits1(gbc);
460 /* less than 6 blocks, so use AC-3-style exponent strategy syntax, and
462 ac3_exponent_strategy = 1;
466 s->snr_offset_strategy = get_bits(gbc, 2);
467 parse_transient_proc_info = get_bits1(gbc);
469 s->block_switch_syntax = get_bits1(gbc);
470 if (!s->block_switch_syntax)
471 memset(s->block_switch, 0, sizeof(s->block_switch));
473 s->dither_flag_syntax = get_bits1(gbc);
474 if (!s->dither_flag_syntax) {
475 for (ch = 1; ch <= s->fbw_channels; ch++)
476 s->dither_flag[ch] = 1;
478 s->dither_flag[CPL_CH] = s->dither_flag[s->lfe_ch] = 0;
480 s->bit_allocation_syntax = get_bits1(gbc);
481 if (!s->bit_allocation_syntax) {
482 /* set default bit allocation parameters */
483 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[2];
484 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[1];
485 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab [1];
486 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[2];
487 s->bit_alloc_params.floor = ff_ac3_floor_tab [7];
490 s->fast_gain_syntax = get_bits1(gbc);
491 s->dba_syntax = get_bits1(gbc);
492 s->skip_syntax = get_bits1(gbc);
493 parse_spx_atten_data = get_bits1(gbc);
495 /* coupling strategy occurrence and coupling use per block */
497 if (s->channel_mode > 1) {
498 for (blk = 0; blk < s->num_blocks; blk++) {
499 s->cpl_strategy_exists[blk] = (!blk || get_bits1(gbc));
500 if (s->cpl_strategy_exists[blk]) {
501 s->cpl_in_use[blk] = get_bits1(gbc);
503 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
505 num_cpl_blocks += s->cpl_in_use[blk];
508 memset(s->cpl_in_use, 0, sizeof(s->cpl_in_use));
511 /* exponent strategy data */
512 if (ac3_exponent_strategy) {
513 /* AC-3-style exponent strategy syntax */
514 for (blk = 0; blk < s->num_blocks; blk++) {
515 for (ch = !s->cpl_in_use[blk]; ch <= s->fbw_channels; ch++) {
516 s->exp_strategy[blk][ch] = get_bits(gbc, 2);
520 /* LUT-based exponent strategy syntax */
521 for (ch = !((s->channel_mode > 1) && num_cpl_blocks); ch <= s->fbw_channels; ch++) {
522 int frmchexpstr = get_bits(gbc, 5);
523 for (blk = 0; blk < 6; blk++) {
524 s->exp_strategy[blk][ch] = ff_eac3_frm_expstr[frmchexpstr][blk];
528 /* LFE exponent strategy */
530 for (blk = 0; blk < s->num_blocks; blk++) {
531 s->exp_strategy[blk][s->lfe_ch] = get_bits1(gbc);
534 /* original exponent strategies if this stream was converted from AC-3 */
535 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT &&
536 (s->num_blocks == 6 || get_bits1(gbc))) {
537 skip_bits(gbc, 5 * s->fbw_channels); // skip converter channel exponent strategy
540 /* determine which channels use AHT */
541 if (parse_aht_info) {
542 /* For AHT to be used, all non-zero blocks must reuse exponents from
543 the first block. Furthermore, for AHT to be used in the coupling
544 channel, all blocks must use coupling and use the same coupling
546 s->channel_uses_aht[CPL_CH]=0;
547 for (ch = (num_cpl_blocks != 6); ch <= s->channels; ch++) {
549 for (blk = 1; blk < 6; blk++) {
550 if ((s->exp_strategy[blk][ch] != EXP_REUSE) ||
551 (!ch && s->cpl_strategy_exists[blk])) {
556 s->channel_uses_aht[ch] = use_aht && get_bits1(gbc);
559 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
562 /* per-frame SNR offset */
563 if (!s->snr_offset_strategy) {
564 int csnroffst = (get_bits(gbc, 6) - 15) << 4;
565 int snroffst = (csnroffst + get_bits(gbc, 4)) << 2;
566 for (ch = 0; ch <= s->channels; ch++)
567 s->snr_offset[ch] = snroffst;
570 /* transient pre-noise processing data */
571 if (parse_transient_proc_info) {
572 for (ch = 1; ch <= s->fbw_channels; ch++) {
573 if (get_bits1(gbc)) { // channel in transient processing
574 skip_bits(gbc, 10); // skip transient processing location
575 skip_bits(gbc, 8); // skip transient processing length
580 /* spectral extension attenuation data */
581 for (ch = 1; ch <= s->fbw_channels; ch++) {
582 if (parse_spx_atten_data && get_bits1(gbc)) {
583 s->spx_atten_code[ch] = get_bits(gbc, 5);
585 s->spx_atten_code[ch] = -1;
589 /* block start information */
590 if (s->num_blocks > 1 && get_bits1(gbc)) {
591 /* reference: Section E2.3.2.27
592 nblkstrtbits = (numblks - 1) * (4 + ceiling(log2(words_per_frame)))
593 The spec does not say what this data is or what it's used for.
594 It is likely the offset of each block within the frame. */
595 int block_start_bits = (s->num_blocks-1) * (4 + av_log2(s->frame_size-2));
596 skip_bits_long(gbc, block_start_bits);
597 avpriv_request_sample(s->avctx, "Block start info");
600 /* syntax state initialization */
601 for (ch = 1; ch <= s->fbw_channels; ch++) {
602 s->first_spx_coords[ch] = 1;
603 s->first_cpl_coords[ch] = 1;
605 s->first_cpl_leak = 1;