3 * This code was developed as part of Google Summer of Code 2006.
4 * E-AC-3 support was added as part of Google Summer of Code 2007.
6 * Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com)
7 * Copyright (c) 2007-2008 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
8 * Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com>
10 * This file is part of FFmpeg.
12 * FFmpeg is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Lesser General Public
14 * License as published by the Free Software Foundation; either
15 * version 2.1 of the License, or (at your option) any later version.
17 * FFmpeg is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * Lesser General Public License for more details.
22 * You should have received a copy of the GNU Lesser General Public
23 * License along with FFmpeg; if not, write to the Free Software
24 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
32 #include "libavutil/channel_layout.h"
33 #include "libavutil/crc.h"
34 #include "libavutil/downmix_info.h"
35 #include "libavutil/opt.h"
38 #include "aac_ac3_parser.h"
39 #include "ac3_parser.h"
41 #include "ac3dec_data.h"
45 * table for ungrouping 3 values in 7 bits.
46 * used for exponents and bap=2 mantissas
48 static uint8_t ungroup_3_in_7_bits_tab[128][3];
50 /** tables for ungrouping mantissas */
51 static int b1_mantissas[32][3];
52 static int b2_mantissas[128][3];
53 static int b3_mantissas[8];
54 static int b4_mantissas[128][2];
55 static int b5_mantissas[16];
58 * Quantization table: levels for symmetric. bits for asymmetric.
59 * reference: Table 7.18 Mapping of bap to Quantizer
61 static const uint8_t quantization_tab[16] = {
63 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
66 /** dynamic range table. converts codes to scale factors. */
67 static float dynamic_range_tab[256];
69 /** Adjustments in dB gain */
70 static const float gain_levels[9] = {
74 LEVEL_MINUS_1POINT5DB,
76 LEVEL_MINUS_4POINT5DB,
82 /** Adjustments in dB gain (LFE, +10 to -21 dB) */
83 static const float gain_levels_lfe[32] = {
84 3.162275, 2.818382, 2.511886, 2.238719, 1.995261, 1.778278, 1.584893,
85 1.412536, 1.258924, 1.122018, 1.000000, 0.891251, 0.794328, 0.707946,
86 0.630957, 0.562341, 0.501187, 0.446683, 0.398107, 0.354813, 0.316227,
87 0.281838, 0.251188, 0.223872, 0.199526, 0.177828, 0.158489, 0.141253,
88 0.125892, 0.112201, 0.100000, 0.089125
92 * Table for default stereo downmixing coefficients
93 * reference: Section 7.8.2 Downmixing Into Two Channels
95 static const uint8_t ac3_default_coeffs[8][5][2] = {
96 { { 2, 7 }, { 7, 2 }, },
98 { { 2, 7 }, { 7, 2 }, },
99 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
100 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
101 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
102 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
103 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
107 * Symmetrical Dequantization
108 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
109 * Tables 7.19 to 7.23
112 symmetric_dequant(int code, int levels)
114 return ((code - (levels >> 1)) << 24) / levels;
118 * Initialize tables at runtime.
120 static av_cold void ac3_tables_init(void)
124 /* generate table for ungrouping 3 values in 7 bits
125 reference: Section 7.1.3 Exponent Decoding */
126 for (i = 0; i < 128; i++) {
127 ungroup_3_in_7_bits_tab[i][0] = i / 25;
128 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
129 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
132 /* generate grouped mantissa tables
133 reference: Section 7.3.5 Ungrouping of Mantissas */
134 for (i = 0; i < 32; i++) {
135 /* bap=1 mantissas */
136 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
137 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
138 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
140 for (i = 0; i < 128; i++) {
141 /* bap=2 mantissas */
142 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
143 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
144 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
146 /* bap=4 mantissas */
147 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
148 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
150 /* generate ungrouped mantissa tables
151 reference: Tables 7.21 and 7.23 */
152 for (i = 0; i < 7; i++) {
153 /* bap=3 mantissas */
154 b3_mantissas[i] = symmetric_dequant(i, 7);
156 for (i = 0; i < 15; i++) {
157 /* bap=5 mantissas */
158 b5_mantissas[i] = symmetric_dequant(i, 15);
161 /* generate dynamic range table
162 reference: Section 7.7.1 Dynamic Range Control */
163 for (i = 0; i < 256; i++) {
164 int v = (i >> 5) - ((i >> 7) << 3) - 5;
165 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
170 * AVCodec initialization
172 static av_cold int ac3_decode_init(AVCodecContext *avctx)
174 AC3DecodeContext *s = avctx->priv_data;
179 ff_ac3_common_init();
181 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
182 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
183 AC3_RENAME(ff_kbd_window_init)(s->window, 5.0, 256);
184 ff_bswapdsp_init(&s->bdsp);
187 s->fdsp = avpriv_alloc_fixed_dsp(avctx->flags & CODEC_FLAG_BITEXACT);
189 avpriv_float_dsp_init(&s->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);
192 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
193 ff_fmt_convert_init(&s->fmt_conv, avctx);
194 av_lfg_init(&s->dith_state, 0);
197 avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
199 avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
201 /* allow downmixing to stereo or mono */
202 #if FF_API_REQUEST_CHANNELS
203 FF_DISABLE_DEPRECATION_WARNINGS
204 if (avctx->request_channels == 1)
205 avctx->request_channel_layout = AV_CH_LAYOUT_MONO;
206 else if (avctx->request_channels == 2)
207 avctx->request_channel_layout = AV_CH_LAYOUT_STEREO;
208 FF_ENABLE_DEPRECATION_WARNINGS
210 if (avctx->channels > 1 &&
211 avctx->request_channel_layout == AV_CH_LAYOUT_MONO)
213 else if (avctx->channels > 2 &&
214 avctx->request_channel_layout == AV_CH_LAYOUT_STEREO)
218 for (i = 0; i < AC3_MAX_CHANNELS; i++) {
219 s->xcfptr[i] = s->transform_coeffs[i];
220 s->dlyptr[i] = s->delay[i];
227 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
228 * GetBitContext within AC3DecodeContext must point to
229 * the start of the synchronized AC-3 bitstream.
231 static int ac3_parse_header(AC3DecodeContext *s)
233 GetBitContext *gbc = &s->gbc;
236 /* read the rest of the bsi. read twice for dual mono mode. */
237 i = !s->channel_mode;
239 skip_bits(gbc, 5); // skip dialog normalization
241 skip_bits(gbc, 8); //skip compression
243 skip_bits(gbc, 8); //skip language code
245 skip_bits(gbc, 7); //skip audio production information
248 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
250 /* skip the timecodes or parse the Alternate Bit Stream Syntax */
251 if (s->bitstream_id != 6) {
253 skip_bits(gbc, 14); //skip timecode1
255 skip_bits(gbc, 14); //skip timecode2
257 if (get_bits1(gbc)) {
258 s->preferred_downmix = get_bits(gbc, 2);
259 s->center_mix_level_ltrt = get_bits(gbc, 3);
260 s->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7);
261 s->center_mix_level = get_bits(gbc, 3);
262 s->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7);
264 if (get_bits1(gbc)) {
265 s->dolby_surround_ex_mode = get_bits(gbc, 2);
266 s->dolby_headphone_mode = get_bits(gbc, 2);
267 skip_bits(gbc, 10); // skip adconvtyp (1), xbsi2 (8), encinfo (1)
271 /* skip additional bitstream info */
272 if (get_bits1(gbc)) {
273 i = get_bits(gbc, 6);
283 * Common function to parse AC-3 or E-AC-3 frame header
285 static int parse_frame_header(AC3DecodeContext *s)
287 AC3HeaderInfo hdr, *phdr=&hdr;
290 err = avpriv_ac3_parse_header2(&s->gbc, &phdr);
294 /* get decoding parameters from header info */
295 s->bit_alloc_params.sr_code = hdr.sr_code;
296 s->bitstream_id = hdr.bitstream_id;
297 s->bitstream_mode = hdr.bitstream_mode;
298 s->channel_mode = hdr.channel_mode;
299 s->lfe_on = hdr.lfe_on;
300 s->bit_alloc_params.sr_shift = hdr.sr_shift;
301 s->sample_rate = hdr.sample_rate;
302 s->bit_rate = hdr.bit_rate;
303 s->channels = hdr.channels;
304 s->fbw_channels = s->channels - s->lfe_on;
305 s->lfe_ch = s->fbw_channels + 1;
306 s->frame_size = hdr.frame_size;
307 s->preferred_downmix = AC3_DMIXMOD_NOTINDICATED;
308 s->center_mix_level = hdr.center_mix_level;
309 s->center_mix_level_ltrt = 4; // -3.0dB
310 s->surround_mix_level = hdr.surround_mix_level;
311 s->surround_mix_level_ltrt = 4; // -3.0dB
312 s->lfe_mix_level_exists = 0;
313 s->num_blocks = hdr.num_blocks;
314 s->frame_type = hdr.frame_type;
315 s->substreamid = hdr.substreamid;
316 s->dolby_surround_mode = hdr.dolby_surround_mode;
317 s->dolby_surround_ex_mode = AC3_DSUREXMOD_NOTINDICATED;
318 s->dolby_headphone_mode = AC3_DHEADPHONMOD_NOTINDICATED;
321 s->start_freq[s->lfe_ch] = 0;
322 s->end_freq[s->lfe_ch] = 7;
323 s->num_exp_groups[s->lfe_ch] = 2;
324 s->channel_in_cpl[s->lfe_ch] = 0;
327 if (s->bitstream_id <= 10) {
329 s->snr_offset_strategy = 2;
330 s->block_switch_syntax = 1;
331 s->dither_flag_syntax = 1;
332 s->bit_allocation_syntax = 1;
333 s->fast_gain_syntax = 0;
334 s->first_cpl_leak = 0;
337 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
338 return ac3_parse_header(s);
339 } else if (CONFIG_EAC3_DECODER) {
341 return ff_eac3_parse_header(s);
343 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
344 return AVERROR(ENOSYS);
349 * Set stereo downmixing coefficients based on frame header info.
350 * reference: Section 7.8.2 Downmixing Into Two Channels
352 static void set_downmix_coeffs(AC3DecodeContext *s)
355 float cmix = gain_levels[s-> center_mix_level];
356 float smix = gain_levels[s->surround_mix_level];
358 float downmix_coeffs[AC3_MAX_CHANNELS][2];
360 for (i = 0; i < s->fbw_channels; i++) {
361 downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
362 downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
364 if (s->channel_mode > 1 && s->channel_mode & 1) {
365 downmix_coeffs[1][0] = downmix_coeffs[1][1] = cmix;
367 if (s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
368 int nf = s->channel_mode - 2;
369 downmix_coeffs[nf][0] = downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
371 if (s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
372 int nf = s->channel_mode - 4;
373 downmix_coeffs[nf][0] = downmix_coeffs[nf+1][1] = smix;
378 for (i = 0; i < s->fbw_channels; i++) {
379 norm0 += downmix_coeffs[i][0];
380 norm1 += downmix_coeffs[i][1];
382 norm0 = 1.0f / norm0;
383 norm1 = 1.0f / norm1;
384 for (i = 0; i < s->fbw_channels; i++) {
385 downmix_coeffs[i][0] *= norm0;
386 downmix_coeffs[i][1] *= norm1;
389 if (s->output_mode == AC3_CHMODE_MONO) {
390 for (i = 0; i < s->fbw_channels; i++)
391 downmix_coeffs[i][0] = (downmix_coeffs[i][0] +
392 downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
394 for (i = 0; i < s->fbw_channels; i++) {
395 s->downmix_coeffs[i][0] = FIXR12(downmix_coeffs[i][0]);
396 s->downmix_coeffs[i][1] = FIXR12(downmix_coeffs[i][1]);
401 * Decode the grouped exponents according to exponent strategy.
402 * reference: Section 7.1.3 Exponent Decoding
404 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
405 uint8_t absexp, int8_t *dexps)
407 int i, j, grp, group_size;
412 group_size = exp_strategy + (exp_strategy == EXP_D45);
413 for (grp = 0, i = 0; grp < ngrps; grp++) {
414 expacc = get_bits(gbc, 7);
415 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
416 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
417 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
420 /* convert to absolute exps and expand groups */
422 for (i = 0, j = 0; i < ngrps * 3; i++) {
423 prevexp += dexp[i] - 2;
426 switch (group_size) {
427 case 4: dexps[j++] = prevexp;
428 dexps[j++] = prevexp;
429 case 2: dexps[j++] = prevexp;
430 case 1: dexps[j++] = prevexp;
437 * Generate transform coefficients for each coupled channel in the coupling
438 * range using the coupling coefficients and coupling coordinates.
439 * reference: Section 7.4.3 Coupling Coordinate Format
441 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
445 bin = s->start_freq[CPL_CH];
446 for (band = 0; band < s->num_cpl_bands; band++) {
447 int band_start = bin;
448 int band_end = bin + s->cpl_band_sizes[band];
449 for (ch = 1; ch <= s->fbw_channels; ch++) {
450 if (s->channel_in_cpl[ch]) {
451 int cpl_coord = s->cpl_coords[ch][band] << 5;
452 for (bin = band_start; bin < band_end; bin++) {
453 s->fixed_coeffs[ch][bin] =
454 MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
456 if (ch == 2 && s->phase_flags[band]) {
457 for (bin = band_start; bin < band_end; bin++)
458 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
467 * Grouped mantissas for 3-level 5-level and 11-level quantization
479 * Decode the transform coefficients for a particular channel
480 * reference: Section 7.3 Quantization and Decoding of Mantissas
482 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
484 int start_freq = s->start_freq[ch_index];
485 int end_freq = s->end_freq[ch_index];
486 uint8_t *baps = s->bap[ch_index];
487 int8_t *exps = s->dexps[ch_index];
488 int32_t *coeffs = s->fixed_coeffs[ch_index];
489 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
490 GetBitContext *gbc = &s->gbc;
493 for (freq = start_freq; freq < end_freq; freq++) {
494 int bap = baps[freq];
498 /* random noise with approximate range of -0.707 to 0.707 */
500 mantissa = (((av_lfg_get(&s->dith_state)>>8)*181)>>8) - 5931008;
507 mantissa = m->b1_mant[m->b1];
509 int bits = get_bits(gbc, 5);
510 mantissa = b1_mantissas[bits][0];
511 m->b1_mant[1] = b1_mantissas[bits][1];
512 m->b1_mant[0] = b1_mantissas[bits][2];
519 mantissa = m->b2_mant[m->b2];
521 int bits = get_bits(gbc, 7);
522 mantissa = b2_mantissas[bits][0];
523 m->b2_mant[1] = b2_mantissas[bits][1];
524 m->b2_mant[0] = b2_mantissas[bits][2];
529 mantissa = b3_mantissas[get_bits(gbc, 3)];
534 mantissa = m->b4_mant;
536 int bits = get_bits(gbc, 7);
537 mantissa = b4_mantissas[bits][0];
538 m->b4_mant = b4_mantissas[bits][1];
543 mantissa = b5_mantissas[get_bits(gbc, 4)];
545 default: /* 6 to 15 */
546 /* Shift mantissa and sign-extend it. */
548 av_log(s->avctx, AV_LOG_ERROR, "bap %d is invalid in plain AC-3\n", bap);
551 mantissa = get_sbits(gbc, quantization_tab[bap]);
552 mantissa <<= 24 - quantization_tab[bap];
555 coeffs[freq] = mantissa >> exps[freq];
560 * Remove random dithering from coupling range coefficients with zero-bit
561 * mantissas for coupled channels which do not use dithering.
562 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
564 static void remove_dithering(AC3DecodeContext *s) {
567 for (ch = 1; ch <= s->fbw_channels; ch++) {
568 if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
569 for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) {
570 if (!s->bap[CPL_CH][i])
571 s->fixed_coeffs[ch][i] = 0;
577 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
580 if (!s->channel_uses_aht[ch]) {
581 ac3_decode_transform_coeffs_ch(s, ch, m);
583 /* if AHT is used, mantissas for all blocks are encoded in the first
584 block of the frame. */
586 if (!blk && CONFIG_EAC3_DECODER)
587 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
588 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
589 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
595 * Decode the transform coefficients.
597 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
603 m.b1 = m.b2 = m.b4 = 0;
605 for (ch = 1; ch <= s->channels; ch++) {
606 /* transform coefficients for full-bandwidth channel */
607 decode_transform_coeffs_ch(s, blk, ch, &m);
608 /* transform coefficients for coupling channel come right after the
609 coefficients for the first coupled channel*/
610 if (s->channel_in_cpl[ch]) {
612 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
613 calc_transform_coeffs_cpl(s);
616 end = s->end_freq[CPL_CH];
618 end = s->end_freq[ch];
621 s->fixed_coeffs[ch][end] = 0;
625 /* zero the dithered coefficients for appropriate channels */
630 * Stereo rematrixing.
631 * reference: Section 7.5.4 Rematrixing : Decoding Technique
633 static void do_rematrixing(AC3DecodeContext *s)
638 end = FFMIN(s->end_freq[1], s->end_freq[2]);
640 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
641 if (s->rematrixing_flags[bnd]) {
642 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd + 1]);
643 for (i = ff_ac3_rematrix_band_tab[bnd]; i < bndend; i++) {
644 int tmp0 = s->fixed_coeffs[1][i];
645 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
646 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
653 * Inverse MDCT Transform.
654 * Convert frequency domain coefficients to time-domain audio samples.
655 * reference: Section 7.9.4 Transformation Equations
657 static inline void do_imdct(AC3DecodeContext *s, int channels)
661 for (ch = 1; ch <= channels; ch++) {
662 if (s->block_switch[ch]) {
664 FFTSample *x = s->tmp_output + 128;
665 for (i = 0; i < 128; i++)
666 x[i] = s->transform_coeffs[ch][2 * i];
667 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
669 s->fdsp->vector_fmul_window_scaled(s->outptr[ch - 1], s->delay[ch - 1],
670 s->tmp_output, s->window, 128, 8);
672 s->fdsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
673 s->tmp_output, s->window, 128);
675 for (i = 0; i < 128; i++)
676 x[i] = s->transform_coeffs[ch][2 * i + 1];
677 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x);
679 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
681 s->fdsp->vector_fmul_window_scaled(s->outptr[ch - 1], s->delay[ch - 1],
682 s->tmp_output, s->window, 128, 8);
684 s->fdsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
685 s->tmp_output, s->window, 128);
687 memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(FFTSample));
693 * Upmix delay samples from stereo to original channel layout.
695 static void ac3_upmix_delay(AC3DecodeContext *s)
697 int channel_data_size = sizeof(s->delay[0]);
698 switch (s->channel_mode) {
699 case AC3_CHMODE_DUALMONO:
700 case AC3_CHMODE_STEREO:
701 /* upmix mono to stereo */
702 memcpy(s->delay[1], s->delay[0], channel_data_size);
704 case AC3_CHMODE_2F2R:
705 memset(s->delay[3], 0, channel_data_size);
706 case AC3_CHMODE_2F1R:
707 memset(s->delay[2], 0, channel_data_size);
709 case AC3_CHMODE_3F2R:
710 memset(s->delay[4], 0, channel_data_size);
711 case AC3_CHMODE_3F1R:
712 memset(s->delay[3], 0, channel_data_size);
714 memcpy(s->delay[2], s->delay[1], channel_data_size);
715 memset(s->delay[1], 0, channel_data_size);
721 * Decode band structure for coupling, spectral extension, or enhanced coupling.
722 * The band structure defines how many subbands are in each band. For each
723 * subband in the range, 1 means it is combined with the previous band, and 0
724 * means that it starts a new band.
726 * @param[in] gbc bit reader context
727 * @param[in] blk block number
728 * @param[in] eac3 flag to indicate E-AC-3
729 * @param[in] ecpl flag to indicate enhanced coupling
730 * @param[in] start_subband subband number for start of range
731 * @param[in] end_subband subband number for end of range
732 * @param[in] default_band_struct default band structure table
733 * @param[out] num_bands number of bands (optionally NULL)
734 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
736 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
737 int ecpl, int start_subband, int end_subband,
738 const uint8_t *default_band_struct,
739 int *num_bands, uint8_t *band_sizes)
741 int subbnd, bnd, n_subbands, n_bands=0;
743 uint8_t coded_band_struct[22];
744 const uint8_t *band_struct;
746 n_subbands = end_subband - start_subband;
748 /* decode band structure from bitstream or use default */
749 if (!eac3 || get_bits1(gbc)) {
750 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
751 coded_band_struct[subbnd] = get_bits1(gbc);
753 band_struct = coded_band_struct;
755 band_struct = &default_band_struct[start_subband+1];
757 /* no change in band structure */
761 /* calculate number of bands and band sizes based on band structure.
762 note that the first 4 subbands in enhanced coupling span only 6 bins
764 if (num_bands || band_sizes ) {
765 n_bands = n_subbands;
766 bnd_sz[0] = ecpl ? 6 : 12;
767 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
768 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
769 if (band_struct[subbnd - 1]) {
771 bnd_sz[bnd] += subbnd_size;
773 bnd_sz[++bnd] = subbnd_size;
778 /* set optional output params */
780 *num_bands = n_bands;
782 memcpy(band_sizes, bnd_sz, n_bands);
786 * Decode a single audio block from the AC-3 bitstream.
788 static int decode_audio_block(AC3DecodeContext *s, int blk)
790 int fbw_channels = s->fbw_channels;
791 int channel_mode = s->channel_mode;
793 int different_transforms;
796 GetBitContext *gbc = &s->gbc;
797 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
799 /* block switch flags */
800 different_transforms = 0;
801 if (s->block_switch_syntax) {
802 for (ch = 1; ch <= fbw_channels; ch++) {
803 s->block_switch[ch] = get_bits1(gbc);
804 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
805 different_transforms = 1;
809 /* dithering flags */
810 if (s->dither_flag_syntax) {
811 for (ch = 1; ch <= fbw_channels; ch++) {
812 s->dither_flag[ch] = get_bits1(gbc);
817 i = !s->channel_mode;
819 if (get_bits1(gbc)) {
820 /* Allow asymmetric application of DRC when drc_scale > 1.
821 Amplification of quiet sounds is enhanced */
822 INTFLOAT range = AC3_RANGE(get_bits(gbc, 8));
823 if (range > 1.0 || s->drc_scale <= 1.0)
824 s->dynamic_range[i] = AC3_DYNAMIC_RANGE(range);
826 s->dynamic_range[i] = range;
827 } else if (blk == 0) {
828 s->dynamic_range[i] = AC3_DYNAMIC_RANGE1;
832 /* spectral extension strategy */
833 if (s->eac3 && (!blk || get_bits1(gbc))) {
834 s->spx_in_use = get_bits1(gbc);
836 int dst_start_freq, dst_end_freq, src_start_freq,
837 start_subband, end_subband;
839 /* determine which channels use spx */
840 if (s->channel_mode == AC3_CHMODE_MONO) {
841 s->channel_uses_spx[1] = 1;
843 for (ch = 1; ch <= fbw_channels; ch++)
844 s->channel_uses_spx[ch] = get_bits1(gbc);
847 /* get the frequency bins of the spx copy region and the spx start
849 dst_start_freq = get_bits(gbc, 2);
850 start_subband = get_bits(gbc, 3) + 2;
851 if (start_subband > 7)
852 start_subband += start_subband - 7;
853 end_subband = get_bits(gbc, 3) + 5;
855 s->spx_dst_end_freq = end_freq_inv_tab[end_subband];
858 end_subband += end_subband - 7;
859 dst_start_freq = dst_start_freq * 12 + 25;
860 src_start_freq = start_subband * 12 + 25;
861 dst_end_freq = end_subband * 12 + 25;
863 /* check validity of spx ranges */
864 if (start_subband >= end_subband) {
865 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
866 "range (%d >= %d)\n", start_subband, end_subband);
867 return AVERROR_INVALIDDATA;
869 if (dst_start_freq >= src_start_freq) {
870 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
871 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
872 return AVERROR_INVALIDDATA;
875 s->spx_dst_start_freq = dst_start_freq;
876 s->spx_src_start_freq = src_start_freq;
878 s->spx_dst_end_freq = dst_end_freq;
880 decode_band_structure(gbc, blk, s->eac3, 0,
881 start_subband, end_subband,
882 ff_eac3_default_spx_band_struct,
886 for (ch = 1; ch <= fbw_channels; ch++) {
887 s->channel_uses_spx[ch] = 0;
888 s->first_spx_coords[ch] = 1;
893 /* spectral extension coordinates */
895 for (ch = 1; ch <= fbw_channels; ch++) {
896 if (s->channel_uses_spx[ch]) {
897 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
899 int bin, master_spx_coord;
901 s->first_spx_coords[ch] = 0;
902 spx_blend = AC3_SPX_BLEND(get_bits(gbc, 5));
903 master_spx_coord = get_bits(gbc, 2) * 3;
905 bin = s->spx_src_start_freq;
906 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
908 int spx_coord_exp, spx_coord_mant;
909 INTFLOAT nratio, sblend, nblend;
912 /* calculate blending factors */
913 bandsize = s->spx_band_sizes[bnd];
914 accu = (int64_t)((bin << 23) + (bandsize << 22)) * s->spx_dst_end_freq;
915 nratio = (int)(accu >> 32);
916 nratio -= spx_blend << 18;
921 } else if (nratio > 0x7fffff) {
925 nblend = fixed_sqrt(nratio, 23);
926 accu = (int64_t)nblend * 1859775393;
927 nblend = (int)((accu + (1<<29)) >> 30);
928 sblend = fixed_sqrt(0x800000 - nratio, 23);
933 /* calculate blending factors */
934 bandsize = s->spx_band_sizes[bnd];
935 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
936 nratio = av_clipf(nratio, 0.0f, 1.0f);
937 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
938 // to give unity variance
939 sblend = sqrtf(1.0f - nratio);
943 /* decode spx coordinates */
944 spx_coord_exp = get_bits(gbc, 4);
945 spx_coord_mant = get_bits(gbc, 2);
946 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
947 else spx_coord_mant += 4;
948 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
950 /* multiply noise and signal blending factors by spx coordinate */
952 accu = (int64_t)nblend * spx_coord_mant;
953 s->spx_noise_blend[ch][bnd] = (int)((accu + (1<<22)) >> 23);
954 accu = (int64_t)sblend * spx_coord_mant;
955 s->spx_signal_blend[ch][bnd] = (int)((accu + (1<<22)) >> 23);
957 spx_coord = spx_coord_mant * (1.0f / (1 << 23));
958 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
959 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
964 s->first_spx_coords[ch] = 1;
969 /* coupling strategy */
970 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
971 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
973 s->cpl_in_use[blk] = get_bits1(gbc);
974 if (s->cpl_in_use[blk]) {
975 /* coupling in use */
976 int cpl_start_subband, cpl_end_subband;
978 if (channel_mode < AC3_CHMODE_STEREO) {
979 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
980 return AVERROR_INVALIDDATA;
983 /* check for enhanced coupling */
984 if (s->eac3 && get_bits1(gbc)) {
985 /* TODO: parse enhanced coupling strategy info */
986 avpriv_request_sample(s->avctx, "Enhanced coupling");
987 return AVERROR_PATCHWELCOME;
990 /* determine which channels are coupled */
991 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
992 s->channel_in_cpl[1] = 1;
993 s->channel_in_cpl[2] = 1;
995 for (ch = 1; ch <= fbw_channels; ch++)
996 s->channel_in_cpl[ch] = get_bits1(gbc);
999 /* phase flags in use */
1000 if (channel_mode == AC3_CHMODE_STEREO)
1001 s->phase_flags_in_use = get_bits1(gbc);
1003 /* coupling frequency range */
1004 cpl_start_subband = get_bits(gbc, 4);
1005 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
1006 get_bits(gbc, 4) + 3;
1007 if (cpl_start_subband >= cpl_end_subband) {
1008 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
1009 cpl_start_subband, cpl_end_subband);
1010 return AVERROR_INVALIDDATA;
1012 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
1013 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
1015 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
1017 ff_eac3_default_cpl_band_struct,
1018 &s->num_cpl_bands, s->cpl_band_sizes);
1020 /* coupling not in use */
1021 for (ch = 1; ch <= fbw_channels; ch++) {
1022 s->channel_in_cpl[ch] = 0;
1023 s->first_cpl_coords[ch] = 1;
1025 s->first_cpl_leak = s->eac3;
1026 s->phase_flags_in_use = 0;
1028 } else if (!s->eac3) {
1030 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
1031 "be present in block 0\n");
1032 return AVERROR_INVALIDDATA;
1034 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
1037 cpl_in_use = s->cpl_in_use[blk];
1039 /* coupling coordinates */
1041 int cpl_coords_exist = 0;
1043 for (ch = 1; ch <= fbw_channels; ch++) {
1044 if (s->channel_in_cpl[ch]) {
1045 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
1046 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
1047 s->first_cpl_coords[ch] = 0;
1048 cpl_coords_exist = 1;
1049 master_cpl_coord = 3 * get_bits(gbc, 2);
1050 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1051 cpl_coord_exp = get_bits(gbc, 4);
1052 cpl_coord_mant = get_bits(gbc, 4);
1053 if (cpl_coord_exp == 15)
1054 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
1056 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
1057 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
1060 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
1061 "be present in block 0\n");
1062 return AVERROR_INVALIDDATA;
1065 /* channel not in coupling */
1066 s->first_cpl_coords[ch] = 1;
1070 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1071 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1072 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1077 /* stereo rematrixing strategy and band structure */
1078 if (channel_mode == AC3_CHMODE_STEREO) {
1079 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1080 s->num_rematrixing_bands = 4;
1081 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1082 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1083 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1084 s->num_rematrixing_bands--;
1086 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
1087 s->rematrixing_flags[bnd] = get_bits1(gbc);
1089 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
1090 "new rematrixing strategy not present in block 0\n");
1091 s->num_rematrixing_bands = 0;
1095 /* exponent strategies for each channel */
1096 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1098 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1099 if (s->exp_strategy[blk][ch] != EXP_REUSE)
1100 bit_alloc_stages[ch] = 3;
1103 /* channel bandwidth */
1104 for (ch = 1; ch <= fbw_channels; ch++) {
1105 s->start_freq[ch] = 0;
1106 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1108 int prev = s->end_freq[ch];
1109 if (s->channel_in_cpl[ch])
1110 s->end_freq[ch] = s->start_freq[CPL_CH];
1111 else if (s->channel_uses_spx[ch])
1112 s->end_freq[ch] = s->spx_src_start_freq;
1114 int bandwidth_code = get_bits(gbc, 6);
1115 if (bandwidth_code > 60) {
1116 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1117 return AVERROR_INVALIDDATA;
1119 s->end_freq[ch] = bandwidth_code * 3 + 73;
1121 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1122 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1123 if (blk > 0 && s->end_freq[ch] != prev)
1124 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1127 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1128 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1129 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1132 /* decode exponents for each channel */
1133 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1134 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1135 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1136 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1137 s->num_exp_groups[ch], s->dexps[ch][0],
1138 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1139 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1140 return AVERROR_INVALIDDATA;
1142 if (ch != CPL_CH && ch != s->lfe_ch)
1143 skip_bits(gbc, 2); /* skip gainrng */
1147 /* bit allocation information */
1148 if (s->bit_allocation_syntax) {
1149 if (get_bits1(gbc)) {
1150 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1151 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1152 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1153 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1154 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1155 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1156 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1158 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1159 "be present in block 0\n");
1160 return AVERROR_INVALIDDATA;
1164 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1165 if (!s->eac3 || !blk) {
1166 if (s->snr_offset_strategy && get_bits1(gbc)) {
1169 csnr = (get_bits(gbc, 6) - 15) << 4;
1170 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1172 if (ch == i || s->snr_offset_strategy == 2)
1173 snr = (csnr + get_bits(gbc, 4)) << 2;
1174 /* run at least last bit allocation stage if snr offset changes */
1175 if (blk && s->snr_offset[ch] != snr) {
1176 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1178 s->snr_offset[ch] = snr;
1180 /* fast gain (normal AC-3 only) */
1182 int prev = s->fast_gain[ch];
1183 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1184 /* run last 2 bit allocation stages if fast gain changes */
1185 if (blk && prev != s->fast_gain[ch])
1186 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1189 } else if (!s->eac3 && !blk) {
1190 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1191 return AVERROR_INVALIDDATA;
1195 /* fast gain (E-AC-3 only) */
1196 if (s->fast_gain_syntax && get_bits1(gbc)) {
1197 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1198 int prev = s->fast_gain[ch];
1199 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1200 /* run last 2 bit allocation stages if fast gain changes */
1201 if (blk && prev != s->fast_gain[ch])
1202 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1204 } else if (s->eac3 && !blk) {
1205 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1206 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1209 /* E-AC-3 to AC-3 converter SNR offset */
1210 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1211 skip_bits(gbc, 10); // skip converter snr offset
1214 /* coupling leak information */
1216 if (s->first_cpl_leak || get_bits1(gbc)) {
1217 int fl = get_bits(gbc, 3);
1218 int sl = get_bits(gbc, 3);
1219 /* run last 2 bit allocation stages for coupling channel if
1220 coupling leak changes */
1221 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1222 sl != s->bit_alloc_params.cpl_slow_leak)) {
1223 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1225 s->bit_alloc_params.cpl_fast_leak = fl;
1226 s->bit_alloc_params.cpl_slow_leak = sl;
1227 } else if (!s->eac3 && !blk) {
1228 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1229 "be present in block 0\n");
1230 return AVERROR_INVALIDDATA;
1232 s->first_cpl_leak = 0;
1235 /* delta bit allocation information */
1236 if (s->dba_syntax && get_bits1(gbc)) {
1237 /* delta bit allocation exists (strategy) */
1238 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1239 s->dba_mode[ch] = get_bits(gbc, 2);
1240 if (s->dba_mode[ch] == DBA_RESERVED) {
1241 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1242 return AVERROR_INVALIDDATA;
1244 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1246 /* channel delta offset, len and bit allocation */
1247 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1248 if (s->dba_mode[ch] == DBA_NEW) {
1249 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1250 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1251 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1252 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1253 s->dba_values[ch][seg] = get_bits(gbc, 3);
1255 /* run last 2 bit allocation stages if new dba values */
1256 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1259 } else if (blk == 0) {
1260 for (ch = 0; ch <= s->channels; ch++) {
1261 s->dba_mode[ch] = DBA_NONE;
1265 /* Bit allocation */
1266 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1267 if (bit_alloc_stages[ch] > 2) {
1268 /* Exponent mapping into PSD and PSD integration */
1269 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1270 s->start_freq[ch], s->end_freq[ch],
1271 s->psd[ch], s->band_psd[ch]);
1273 if (bit_alloc_stages[ch] > 1) {
1274 /* Compute excitation function, Compute masking curve, and
1275 Apply delta bit allocation */
1276 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1277 s->start_freq[ch], s->end_freq[ch],
1278 s->fast_gain[ch], (ch == s->lfe_ch),
1279 s->dba_mode[ch], s->dba_nsegs[ch],
1280 s->dba_offsets[ch], s->dba_lengths[ch],
1281 s->dba_values[ch], s->mask[ch])) {
1282 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1283 return AVERROR_INVALIDDATA;
1286 if (bit_alloc_stages[ch] > 0) {
1287 /* Compute bit allocation */
1288 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1289 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1290 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1291 s->start_freq[ch], s->end_freq[ch],
1293 s->bit_alloc_params.floor,
1294 bap_tab, s->bap[ch]);
1298 /* unused dummy data */
1299 if (s->skip_syntax && get_bits1(gbc)) {
1300 int skipl = get_bits(gbc, 9);
1305 /* unpack the transform coefficients
1306 this also uncouples channels if coupling is in use. */
1307 decode_transform_coeffs(s, blk);
1309 /* TODO: generate enhanced coupling coordinates and uncouple */
1311 /* recover coefficients if rematrixing is in use */
1312 if (s->channel_mode == AC3_CHMODE_STEREO)
1315 /* apply scaling to coefficients (headroom, dynrng) */
1316 for (ch = 1; ch <= s->channels; ch++) {
1318 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1319 gain = s->dynamic_range[2-ch];
1321 gain = s->dynamic_range[0];
1324 scale_coefs(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1326 gain *= 1.0 / 4194304.0f;
1327 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1328 s->fixed_coeffs[ch], gain, 256);
1332 /* apply spectral extension to high frequency bins */
1333 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1334 ff_eac3_apply_spectral_extension(s);
1337 /* downmix and MDCT. order depends on whether block switching is used for
1338 any channel in this block. this is because coefficients for the long
1339 and short transforms cannot be mixed. */
1340 downmix_output = s->channels != s->out_channels &&
1341 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1342 s->fbw_channels == s->out_channels);
1343 if (different_transforms) {
1344 /* the delay samples have already been downmixed, so we upmix the delay
1345 samples in order to reconstruct all channels before downmixing. */
1351 do_imdct(s, s->channels);
1353 if (downmix_output) {
1355 ac3_downmix_c_fixed16(s->outptr, s->downmix_coeffs,
1356 s->out_channels, s->fbw_channels, 256);
1358 s->ac3dsp.downmix(s->outptr, s->downmix_coeffs,
1359 s->out_channels, s->fbw_channels, 256);
1363 if (downmix_output) {
1364 s->ac3dsp.AC3_RENAME(downmix)(s->xcfptr + 1, s->downmix_coeffs,
1365 s->out_channels, s->fbw_channels, 256);
1368 if (downmix_output && !s->downmixed) {
1370 s->ac3dsp.AC3_RENAME(downmix)(s->dlyptr, s->downmix_coeffs,
1371 s->out_channels, s->fbw_channels, 128);
1374 do_imdct(s, s->out_channels);
1381 * Decode a single AC-3 frame.
1383 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1384 int *got_frame_ptr, AVPacket *avpkt)
1386 AVFrame *frame = data;
1387 const uint8_t *buf = avpkt->data;
1388 int buf_size = avpkt->size;
1389 AC3DecodeContext *s = avctx->priv_data;
1390 int blk, ch, err, ret;
1391 const uint8_t *channel_map;
1392 const SHORTFLOAT *output[AC3_MAX_CHANNELS];
1393 enum AVMatrixEncoding matrix_encoding;
1394 AVDownmixInfo *downmix_info;
1396 /* copy input buffer to decoder context to avoid reading past the end
1397 of the buffer, which can be caused by a damaged input stream. */
1398 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1399 // seems to be byte-swapped AC-3
1400 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1401 s->bdsp.bswap16_buf((uint16_t *) s->input_buffer,
1402 (const uint16_t *) buf, cnt);
1404 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1405 buf = s->input_buffer;
1406 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1407 init_get_bits(&s->gbc, buf, buf_size * 8);
1409 /* parse the syncinfo */
1410 err = parse_frame_header(s);
1414 case AAC_AC3_PARSE_ERROR_SYNC:
1415 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1416 return AVERROR_INVALIDDATA;
1417 case AAC_AC3_PARSE_ERROR_BSID:
1418 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1420 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1421 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1423 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1424 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1426 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1427 /* skip frame if CRC is ok. otherwise use error concealment. */
1428 /* TODO: add support for substreams and dependent frames */
1429 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1430 av_log(avctx, AV_LOG_WARNING, "unsupported frame type : "
1431 "skipping frame\n");
1435 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1438 case AAC_AC3_PARSE_ERROR_CRC:
1439 case AAC_AC3_PARSE_ERROR_CHANNEL_CFG:
1441 default: // Normal AVERROR do not try to recover.
1446 /* check that reported frame size fits in input buffer */
1447 if (s->frame_size > buf_size) {
1448 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1449 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1450 } else if (avctx->err_recognition & (AV_EF_CRCCHECK|AV_EF_CAREFUL)) {
1451 /* check for crc mismatch */
1452 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1453 s->frame_size - 2)) {
1454 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1455 if (avctx->err_recognition & AV_EF_EXPLODE)
1456 return AVERROR_INVALIDDATA;
1457 err = AAC_AC3_PARSE_ERROR_CRC;
1462 /* if frame is ok, set audio parameters */
1464 avctx->sample_rate = s->sample_rate;
1465 avctx->bit_rate = s->bit_rate;
1468 /* channel config */
1469 if (!err || (s->channels && s->out_channels != s->channels)) {
1470 s->out_channels = s->channels;
1471 s->output_mode = s->channel_mode;
1473 s->output_mode |= AC3_OUTPUT_LFEON;
1474 if (s->channels > 1 &&
1475 avctx->request_channel_layout == AV_CH_LAYOUT_MONO) {
1476 s->out_channels = 1;
1477 s->output_mode = AC3_CHMODE_MONO;
1478 } else if (s->channels > 2 &&
1479 avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) {
1480 s->out_channels = 2;
1481 s->output_mode = AC3_CHMODE_STEREO;
1484 s->loro_center_mix_level = gain_levels[s-> center_mix_level];
1485 s->loro_surround_mix_level = gain_levels[s->surround_mix_level];
1486 s->ltrt_center_mix_level = LEVEL_MINUS_3DB;
1487 s->ltrt_surround_mix_level = LEVEL_MINUS_3DB;
1488 /* set downmixing coefficients if needed */
1489 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1490 s->fbw_channels == s->out_channels)) {
1491 set_downmix_coeffs(s);
1493 } else if (!s->channels) {
1494 av_log(avctx, AV_LOG_ERROR, "unable to determine channel mode\n");
1495 return AVERROR_INVALIDDATA;
1497 avctx->channels = s->out_channels;
1498 avctx->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode & ~AC3_OUTPUT_LFEON];
1499 if (s->output_mode & AC3_OUTPUT_LFEON)
1500 avctx->channel_layout |= AV_CH_LOW_FREQUENCY;
1502 /* set audio service type based on bitstream mode for AC-3 */
1503 avctx->audio_service_type = s->bitstream_mode;
1504 if (s->bitstream_mode == 0x7 && s->channels > 1)
1505 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1507 /* get output buffer */
1508 frame->nb_samples = s->num_blocks * AC3_BLOCK_SIZE;
1509 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
1512 /* decode the audio blocks */
1513 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1514 for (ch = 0; ch < AC3_MAX_CHANNELS; ch++) {
1515 output[ch] = s->output[ch];
1516 s->outptr[ch] = s->output[ch];
1518 for (ch = 0; ch < s->channels; ch++) {
1519 if (ch < s->out_channels)
1520 s->outptr[channel_map[ch]] = (SHORTFLOAT *)frame->data[ch];
1522 for (blk = 0; blk < s->num_blocks; blk++) {
1523 if (!err && decode_audio_block(s, blk)) {
1524 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1528 for (ch = 0; ch < s->out_channels; ch++)
1529 memcpy(((SHORTFLOAT*)frame->data[ch]) + AC3_BLOCK_SIZE*blk, output[ch], AC3_BLOCK_SIZE*sizeof(SHORTFLOAT));
1530 for (ch = 0; ch < s->out_channels; ch++)
1531 output[ch] = s->outptr[channel_map[ch]];
1532 for (ch = 0; ch < s->out_channels; ch++) {
1533 if (!ch || channel_map[ch])
1534 s->outptr[channel_map[ch]] += AC3_BLOCK_SIZE;
1538 av_frame_set_decode_error_flags(frame, err ? FF_DECODE_ERROR_INVALID_BITSTREAM : 0);
1540 /* keep last block for error concealment in next frame */
1541 for (ch = 0; ch < s->out_channels; ch++)
1542 memcpy(s->output[ch], output[ch], AC3_BLOCK_SIZE*sizeof(SHORTFLOAT));
1547 * Check whether the input layout is compatible, and make sure we're not
1548 * downmixing (else the matrix encoding is no longer applicable).
1550 matrix_encoding = AV_MATRIX_ENCODING_NONE;
1551 if (s->channel_mode == AC3_CHMODE_STEREO &&
1552 s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) {
1553 if (s->dolby_surround_mode == AC3_DSURMOD_ON)
1554 matrix_encoding = AV_MATRIX_ENCODING_DOLBY;
1555 else if (s->dolby_headphone_mode == AC3_DHEADPHONMOD_ON)
1556 matrix_encoding = AV_MATRIX_ENCODING_DOLBYHEADPHONE;
1557 } else if (s->channel_mode >= AC3_CHMODE_2F2R &&
1558 s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) {
1559 switch (s->dolby_surround_ex_mode) {
1560 case AC3_DSUREXMOD_ON: // EX or PLIIx
1561 matrix_encoding = AV_MATRIX_ENCODING_DOLBYEX;
1563 case AC3_DSUREXMOD_PLIIZ:
1564 matrix_encoding = AV_MATRIX_ENCODING_DPLIIZ;
1566 default: // not indicated or off
1570 if ((ret = ff_side_data_update_matrix_encoding(frame, matrix_encoding)) < 0)
1574 if ((downmix_info = av_downmix_info_update_side_data(frame))) {
1575 switch (s->preferred_downmix) {
1576 case AC3_DMIXMOD_LTRT:
1577 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_LTRT;
1579 case AC3_DMIXMOD_LORO:
1580 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_LORO;
1582 case AC3_DMIXMOD_DPLII:
1583 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_DPLII;
1586 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_UNKNOWN;
1589 downmix_info->center_mix_level = gain_levels[s-> center_mix_level];
1590 downmix_info->center_mix_level_ltrt = gain_levels[s-> center_mix_level_ltrt];
1591 downmix_info->surround_mix_level = gain_levels[s-> surround_mix_level];
1592 downmix_info->surround_mix_level_ltrt = gain_levels[s->surround_mix_level_ltrt];
1593 if (s->lfe_mix_level_exists)
1594 downmix_info->lfe_mix_level = gain_levels_lfe[s->lfe_mix_level];
1596 downmix_info->lfe_mix_level = 0.0; // -inf dB
1598 return AVERROR(ENOMEM);
1602 return FFMIN(buf_size, s->frame_size);
1606 * Uninitialize the AC-3 decoder.
1608 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1610 AC3DecodeContext *s = avctx->priv_data;
1611 ff_mdct_end(&s->imdct_512);
1612 ff_mdct_end(&s->imdct_256);
1620 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1621 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)