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/opt.h"
36 #include "aac_ac3_parser.h"
37 #include "ac3_parser.h"
39 #include "ac3dec_data.h"
43 * table for ungrouping 3 values in 7 bits.
44 * used for exponents and bap=2 mantissas
46 static uint8_t ungroup_3_in_7_bits_tab[128][3];
48 /** tables for ungrouping mantissas */
49 static int b1_mantissas[32][3];
50 static int b2_mantissas[128][3];
51 static int b3_mantissas[8];
52 static int b4_mantissas[128][2];
53 static int b5_mantissas[16];
56 * Quantization table: levels for symmetric. bits for asymmetric.
57 * reference: Table 7.18 Mapping of bap to Quantizer
59 static const uint8_t quantization_tab[16] = {
61 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
64 /** dynamic range table. converts codes to scale factors. */
65 static float dynamic_range_tab[256];
67 /** Adjustments in dB gain */
68 static const float gain_levels[9] = {
72 LEVEL_MINUS_1POINT5DB,
74 LEVEL_MINUS_4POINT5DB,
81 * Table for default stereo downmixing coefficients
82 * reference: Section 7.8.2 Downmixing Into Two Channels
84 static const uint8_t ac3_default_coeffs[8][5][2] = {
85 { { 2, 7 }, { 7, 2 }, },
87 { { 2, 7 }, { 7, 2 }, },
88 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
89 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
90 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
91 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
92 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
96 * Symmetrical Dequantization
97 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
101 symmetric_dequant(int code, int levels)
103 return ((code - (levels >> 1)) << 24) / levels;
107 * Initialize tables at runtime.
109 static av_cold void ac3_tables_init(void)
113 /* generate table for ungrouping 3 values in 7 bits
114 reference: Section 7.1.3 Exponent Decoding */
115 for (i = 0; i < 128; i++) {
116 ungroup_3_in_7_bits_tab[i][0] = i / 25;
117 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
118 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
121 /* generate grouped mantissa tables
122 reference: Section 7.3.5 Ungrouping of Mantissas */
123 for (i = 0; i < 32; i++) {
124 /* bap=1 mantissas */
125 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
126 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
127 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
129 for (i = 0; i < 128; i++) {
130 /* bap=2 mantissas */
131 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
132 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
133 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
135 /* bap=4 mantissas */
136 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
137 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
139 /* generate ungrouped mantissa tables
140 reference: Tables 7.21 and 7.23 */
141 for (i = 0; i < 7; i++) {
142 /* bap=3 mantissas */
143 b3_mantissas[i] = symmetric_dequant(i, 7);
145 for (i = 0; i < 15; i++) {
146 /* bap=5 mantissas */
147 b5_mantissas[i] = symmetric_dequant(i, 15);
150 /* generate dynamic range table
151 reference: Section 7.7.1 Dynamic Range Control */
152 for (i = 0; i < 256; i++) {
153 int v = (i >> 5) - ((i >> 7) << 3) - 5;
154 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
159 * AVCodec initialization
161 static av_cold int ac3_decode_init(AVCodecContext *avctx)
163 AC3DecodeContext *s = avctx->priv_data;
168 ff_ac3_common_init();
170 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
171 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
172 ff_kbd_window_init(s->window, 5.0, 256);
173 ff_dsputil_init(&s->dsp, avctx);
174 avpriv_float_dsp_init(&s->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);
175 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
176 ff_fmt_convert_init(&s->fmt_conv, avctx);
177 av_lfg_init(&s->dith_state, 0);
179 avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
181 /* allow downmixing to stereo or mono */
182 #if FF_API_REQUEST_CHANNELS
183 FF_DISABLE_DEPRECATION_WARNINGS
184 if (avctx->request_channels == 1)
185 avctx->request_channel_layout = AV_CH_LAYOUT_MONO;
186 else if (avctx->request_channels == 2)
187 avctx->request_channel_layout = AV_CH_LAYOUT_STEREO;
188 FF_ENABLE_DEPRECATION_WARNINGS
190 if (avctx->channels > 1 &&
191 avctx->request_channel_layout == AV_CH_LAYOUT_MONO)
193 else if (avctx->channels > 2 &&
194 avctx->request_channel_layout == AV_CH_LAYOUT_STEREO)
198 for (i = 0; i < AC3_MAX_CHANNELS; i++) {
199 s->xcfptr[i] = s->transform_coeffs[i];
200 s->dlyptr[i] = s->delay[i];
207 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
208 * GetBitContext within AC3DecodeContext must point to
209 * the start of the synchronized AC-3 bitstream.
211 static int ac3_parse_header(AC3DecodeContext *s)
213 GetBitContext *gbc = &s->gbc;
216 /* read the rest of the bsi. read twice for dual mono mode. */
217 i = !s->channel_mode;
219 skip_bits(gbc, 5); // skip dialog normalization
221 skip_bits(gbc, 8); //skip compression
223 skip_bits(gbc, 8); //skip language code
225 skip_bits(gbc, 7); //skip audio production information
228 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
230 /* default dolby matrix encoding modes */
231 s->dolby_surround_ex_mode = AC3_DSUREXMOD_NOTINDICATED;
232 s->dolby_headphone_mode = AC3_DHEADPHONMOD_NOTINDICATED;
234 /* skip the timecodes or parse the Alternate Bit Stream Syntax
235 TODO: read & use the xbsi1 downmix levels */
236 if (s->bitstream_id != 6) {
238 skip_bits(gbc, 14); //skip timecode1
240 skip_bits(gbc, 14); //skip timecode2
243 skip_bits(gbc, 14); //skip xbsi1
244 if (get_bits1(gbc)) {
245 s->dolby_surround_ex_mode = get_bits(gbc, 2);
246 s->dolby_headphone_mode = get_bits(gbc, 2);
247 skip_bits(gbc, 10); // skip adconvtyp (1), xbsi2 (8), encinfo (1)
251 /* skip additional bitstream info */
252 if (get_bits1(gbc)) {
253 i = get_bits(gbc, 6);
263 * Common function to parse AC-3 or E-AC-3 frame header
265 static int parse_frame_header(AC3DecodeContext *s)
270 err = avpriv_ac3_parse_header(&s->gbc, &hdr);
274 /* get decoding parameters from header info */
275 s->bit_alloc_params.sr_code = hdr.sr_code;
276 s->bitstream_id = hdr.bitstream_id;
277 s->bitstream_mode = hdr.bitstream_mode;
278 s->channel_mode = hdr.channel_mode;
279 s->lfe_on = hdr.lfe_on;
280 s->bit_alloc_params.sr_shift = hdr.sr_shift;
281 s->sample_rate = hdr.sample_rate;
282 s->bit_rate = hdr.bit_rate;
283 s->channels = hdr.channels;
284 s->fbw_channels = s->channels - s->lfe_on;
285 s->lfe_ch = s->fbw_channels + 1;
286 s->frame_size = hdr.frame_size;
287 s->center_mix_level = hdr.center_mix_level;
288 s->surround_mix_level = hdr.surround_mix_level;
289 s->num_blocks = hdr.num_blocks;
290 s->frame_type = hdr.frame_type;
291 s->substreamid = hdr.substreamid;
292 s->dolby_surround_mode = hdr.dolby_surround_mode;
295 s->start_freq[s->lfe_ch] = 0;
296 s->end_freq[s->lfe_ch] = 7;
297 s->num_exp_groups[s->lfe_ch] = 2;
298 s->channel_in_cpl[s->lfe_ch] = 0;
301 if (s->bitstream_id <= 10) {
303 s->snr_offset_strategy = 2;
304 s->block_switch_syntax = 1;
305 s->dither_flag_syntax = 1;
306 s->bit_allocation_syntax = 1;
307 s->fast_gain_syntax = 0;
308 s->first_cpl_leak = 0;
311 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
312 return ac3_parse_header(s);
313 } else if (CONFIG_EAC3_DECODER) {
315 return ff_eac3_parse_header(s);
317 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
318 return AVERROR(ENOSYS);
323 * Set stereo downmixing coefficients based on frame header info.
324 * reference: Section 7.8.2 Downmixing Into Two Channels
326 static void set_downmix_coeffs(AC3DecodeContext *s)
329 float cmix = gain_levels[s-> center_mix_level];
330 float smix = gain_levels[s->surround_mix_level];
333 for (i = 0; i < s->fbw_channels; i++) {
334 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
335 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
337 if (s->channel_mode > 1 && s->channel_mode & 1) {
338 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
340 if (s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
341 int nf = s->channel_mode - 2;
342 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
344 if (s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
345 int nf = s->channel_mode - 4;
346 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
351 for (i = 0; i < s->fbw_channels; i++) {
352 norm0 += s->downmix_coeffs[i][0];
353 norm1 += s->downmix_coeffs[i][1];
355 norm0 = 1.0f / norm0;
356 norm1 = 1.0f / norm1;
357 for (i = 0; i < s->fbw_channels; i++) {
358 s->downmix_coeffs[i][0] *= norm0;
359 s->downmix_coeffs[i][1] *= norm1;
362 if (s->output_mode == AC3_CHMODE_MONO) {
363 for (i = 0; i < s->fbw_channels; i++)
364 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] +
365 s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
370 * Decode the grouped exponents according to exponent strategy.
371 * reference: Section 7.1.3 Exponent Decoding
373 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
374 uint8_t absexp, int8_t *dexps)
376 int i, j, grp, group_size;
381 group_size = exp_strategy + (exp_strategy == EXP_D45);
382 for (grp = 0, i = 0; grp < ngrps; grp++) {
383 expacc = get_bits(gbc, 7);
384 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
385 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
386 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
389 /* convert to absolute exps and expand groups */
391 for (i = 0, j = 0; i < ngrps * 3; i++) {
392 prevexp += dexp[i] - 2;
395 switch (group_size) {
396 case 4: dexps[j++] = prevexp;
397 dexps[j++] = prevexp;
398 case 2: dexps[j++] = prevexp;
399 case 1: dexps[j++] = prevexp;
406 * Generate transform coefficients for each coupled channel in the coupling
407 * range using the coupling coefficients and coupling coordinates.
408 * reference: Section 7.4.3 Coupling Coordinate Format
410 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
414 bin = s->start_freq[CPL_CH];
415 for (band = 0; band < s->num_cpl_bands; band++) {
416 int band_start = bin;
417 int band_end = bin + s->cpl_band_sizes[band];
418 for (ch = 1; ch <= s->fbw_channels; ch++) {
419 if (s->channel_in_cpl[ch]) {
420 int cpl_coord = s->cpl_coords[ch][band] << 5;
421 for (bin = band_start; bin < band_end; bin++) {
422 s->fixed_coeffs[ch][bin] =
423 MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
425 if (ch == 2 && s->phase_flags[band]) {
426 for (bin = band_start; bin < band_end; bin++)
427 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
436 * Grouped mantissas for 3-level 5-level and 11-level quantization
448 * Decode the transform coefficients for a particular channel
449 * reference: Section 7.3 Quantization and Decoding of Mantissas
451 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
453 int start_freq = s->start_freq[ch_index];
454 int end_freq = s->end_freq[ch_index];
455 uint8_t *baps = s->bap[ch_index];
456 int8_t *exps = s->dexps[ch_index];
457 int32_t *coeffs = s->fixed_coeffs[ch_index];
458 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
459 GetBitContext *gbc = &s->gbc;
462 for (freq = start_freq; freq < end_freq; freq++) {
463 int bap = baps[freq];
467 /* random noise with approximate range of -0.707 to 0.707 */
469 mantissa = (((av_lfg_get(&s->dith_state)>>8)*181)>>8) - 5931008;
476 mantissa = m->b1_mant[m->b1];
478 int bits = get_bits(gbc, 5);
479 mantissa = b1_mantissas[bits][0];
480 m->b1_mant[1] = b1_mantissas[bits][1];
481 m->b1_mant[0] = b1_mantissas[bits][2];
488 mantissa = m->b2_mant[m->b2];
490 int bits = get_bits(gbc, 7);
491 mantissa = b2_mantissas[bits][0];
492 m->b2_mant[1] = b2_mantissas[bits][1];
493 m->b2_mant[0] = b2_mantissas[bits][2];
498 mantissa = b3_mantissas[get_bits(gbc, 3)];
503 mantissa = m->b4_mant;
505 int bits = get_bits(gbc, 7);
506 mantissa = b4_mantissas[bits][0];
507 m->b4_mant = b4_mantissas[bits][1];
512 mantissa = b5_mantissas[get_bits(gbc, 4)];
514 default: /* 6 to 15 */
515 /* Shift mantissa and sign-extend it. */
517 av_log(s->avctx, AV_LOG_ERROR, "bap %d is invalid in plain AC-3\n", bap);
520 mantissa = get_sbits(gbc, quantization_tab[bap]);
521 mantissa <<= 24 - quantization_tab[bap];
524 coeffs[freq] = mantissa >> exps[freq];
529 * Remove random dithering from coupling range coefficients with zero-bit
530 * mantissas for coupled channels which do not use dithering.
531 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
533 static void remove_dithering(AC3DecodeContext *s) {
536 for (ch = 1; ch <= s->fbw_channels; ch++) {
537 if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
538 for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) {
539 if (!s->bap[CPL_CH][i])
540 s->fixed_coeffs[ch][i] = 0;
546 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
549 if (!s->channel_uses_aht[ch]) {
550 ac3_decode_transform_coeffs_ch(s, ch, m);
552 /* if AHT is used, mantissas for all blocks are encoded in the first
553 block of the frame. */
555 if (!blk && CONFIG_EAC3_DECODER)
556 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
557 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
558 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
564 * Decode the transform coefficients.
566 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
572 m.b1 = m.b2 = m.b4 = 0;
574 for (ch = 1; ch <= s->channels; ch++) {
575 /* transform coefficients for full-bandwidth channel */
576 decode_transform_coeffs_ch(s, blk, ch, &m);
577 /* transform coefficients for coupling channel come right after the
578 coefficients for the first coupled channel*/
579 if (s->channel_in_cpl[ch]) {
581 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
582 calc_transform_coeffs_cpl(s);
585 end = s->end_freq[CPL_CH];
587 end = s->end_freq[ch];
590 s->fixed_coeffs[ch][end] = 0;
594 /* zero the dithered coefficients for appropriate channels */
599 * Stereo rematrixing.
600 * reference: Section 7.5.4 Rematrixing : Decoding Technique
602 static void do_rematrixing(AC3DecodeContext *s)
607 end = FFMIN(s->end_freq[1], s->end_freq[2]);
609 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
610 if (s->rematrixing_flags[bnd]) {
611 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd + 1]);
612 for (i = ff_ac3_rematrix_band_tab[bnd]; i < bndend; i++) {
613 int tmp0 = s->fixed_coeffs[1][i];
614 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
615 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
622 * Inverse MDCT Transform.
623 * Convert frequency domain coefficients to time-domain audio samples.
624 * reference: Section 7.9.4 Transformation Equations
626 static inline void do_imdct(AC3DecodeContext *s, int channels)
630 for (ch = 1; ch <= channels; ch++) {
631 if (s->block_switch[ch]) {
633 float *x = s->tmp_output + 128;
634 for (i = 0; i < 128; i++)
635 x[i] = s->transform_coeffs[ch][2 * i];
636 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
637 s->fdsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
638 s->tmp_output, s->window, 128);
639 for (i = 0; i < 128; i++)
640 x[i] = s->transform_coeffs[ch][2 * i + 1];
641 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x);
643 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
644 s->fdsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
645 s->tmp_output, s->window, 128);
646 memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(float));
652 * Upmix delay samples from stereo to original channel layout.
654 static void ac3_upmix_delay(AC3DecodeContext *s)
656 int channel_data_size = sizeof(s->delay[0]);
657 switch (s->channel_mode) {
658 case AC3_CHMODE_DUALMONO:
659 case AC3_CHMODE_STEREO:
660 /* upmix mono to stereo */
661 memcpy(s->delay[1], s->delay[0], channel_data_size);
663 case AC3_CHMODE_2F2R:
664 memset(s->delay[3], 0, channel_data_size);
665 case AC3_CHMODE_2F1R:
666 memset(s->delay[2], 0, channel_data_size);
668 case AC3_CHMODE_3F2R:
669 memset(s->delay[4], 0, channel_data_size);
670 case AC3_CHMODE_3F1R:
671 memset(s->delay[3], 0, channel_data_size);
673 memcpy(s->delay[2], s->delay[1], channel_data_size);
674 memset(s->delay[1], 0, channel_data_size);
680 * Decode band structure for coupling, spectral extension, or enhanced coupling.
681 * The band structure defines how many subbands are in each band. For each
682 * subband in the range, 1 means it is combined with the previous band, and 0
683 * means that it starts a new band.
685 * @param[in] gbc bit reader context
686 * @param[in] blk block number
687 * @param[in] eac3 flag to indicate E-AC-3
688 * @param[in] ecpl flag to indicate enhanced coupling
689 * @param[in] start_subband subband number for start of range
690 * @param[in] end_subband subband number for end of range
691 * @param[in] default_band_struct default band structure table
692 * @param[out] num_bands number of bands (optionally NULL)
693 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
695 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
696 int ecpl, int start_subband, int end_subband,
697 const uint8_t *default_band_struct,
698 int *num_bands, uint8_t *band_sizes)
700 int subbnd, bnd, n_subbands, n_bands=0;
702 uint8_t coded_band_struct[22];
703 const uint8_t *band_struct;
705 n_subbands = end_subband - start_subband;
707 /* decode band structure from bitstream or use default */
708 if (!eac3 || get_bits1(gbc)) {
709 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
710 coded_band_struct[subbnd] = get_bits1(gbc);
712 band_struct = coded_band_struct;
714 band_struct = &default_band_struct[start_subband+1];
716 /* no change in band structure */
720 /* calculate number of bands and band sizes based on band structure.
721 note that the first 4 subbands in enhanced coupling span only 6 bins
723 if (num_bands || band_sizes ) {
724 n_bands = n_subbands;
725 bnd_sz[0] = ecpl ? 6 : 12;
726 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
727 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
728 if (band_struct[subbnd - 1]) {
730 bnd_sz[bnd] += subbnd_size;
732 bnd_sz[++bnd] = subbnd_size;
737 /* set optional output params */
739 *num_bands = n_bands;
741 memcpy(band_sizes, bnd_sz, n_bands);
745 * Decode a single audio block from the AC-3 bitstream.
747 static int decode_audio_block(AC3DecodeContext *s, int blk)
749 int fbw_channels = s->fbw_channels;
750 int channel_mode = s->channel_mode;
752 int different_transforms;
755 GetBitContext *gbc = &s->gbc;
756 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
758 /* block switch flags */
759 different_transforms = 0;
760 if (s->block_switch_syntax) {
761 for (ch = 1; ch <= fbw_channels; ch++) {
762 s->block_switch[ch] = get_bits1(gbc);
763 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
764 different_transforms = 1;
768 /* dithering flags */
769 if (s->dither_flag_syntax) {
770 for (ch = 1; ch <= fbw_channels; ch++) {
771 s->dither_flag[ch] = get_bits1(gbc);
776 i = !s->channel_mode;
778 if (get_bits1(gbc)) {
779 s->dynamic_range[i] = powf(dynamic_range_tab[get_bits(gbc, 8)],
781 } else if (blk == 0) {
782 s->dynamic_range[i] = 1.0f;
786 /* spectral extension strategy */
787 if (s->eac3 && (!blk || get_bits1(gbc))) {
788 s->spx_in_use = get_bits1(gbc);
790 int dst_start_freq, dst_end_freq, src_start_freq,
791 start_subband, end_subband;
793 /* determine which channels use spx */
794 if (s->channel_mode == AC3_CHMODE_MONO) {
795 s->channel_uses_spx[1] = 1;
797 for (ch = 1; ch <= fbw_channels; ch++)
798 s->channel_uses_spx[ch] = get_bits1(gbc);
801 /* get the frequency bins of the spx copy region and the spx start
803 dst_start_freq = get_bits(gbc, 2);
804 start_subband = get_bits(gbc, 3) + 2;
805 if (start_subband > 7)
806 start_subband += start_subband - 7;
807 end_subband = get_bits(gbc, 3) + 5;
809 end_subband += end_subband - 7;
810 dst_start_freq = dst_start_freq * 12 + 25;
811 src_start_freq = start_subband * 12 + 25;
812 dst_end_freq = end_subband * 12 + 25;
814 /* check validity of spx ranges */
815 if (start_subband >= end_subband) {
816 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
817 "range (%d >= %d)\n", start_subband, end_subband);
818 return AVERROR_INVALIDDATA;
820 if (dst_start_freq >= src_start_freq) {
821 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
822 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
823 return AVERROR_INVALIDDATA;
826 s->spx_dst_start_freq = dst_start_freq;
827 s->spx_src_start_freq = src_start_freq;
828 s->spx_dst_end_freq = dst_end_freq;
830 decode_band_structure(gbc, blk, s->eac3, 0,
831 start_subband, end_subband,
832 ff_eac3_default_spx_band_struct,
836 for (ch = 1; ch <= fbw_channels; ch++) {
837 s->channel_uses_spx[ch] = 0;
838 s->first_spx_coords[ch] = 1;
843 /* spectral extension coordinates */
845 for (ch = 1; ch <= fbw_channels; ch++) {
846 if (s->channel_uses_spx[ch]) {
847 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
849 int bin, master_spx_coord;
851 s->first_spx_coords[ch] = 0;
852 spx_blend = get_bits(gbc, 5) * (1.0f/32);
853 master_spx_coord = get_bits(gbc, 2) * 3;
855 bin = s->spx_src_start_freq;
856 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
858 int spx_coord_exp, spx_coord_mant;
859 float nratio, sblend, nblend, spx_coord;
861 /* calculate blending factors */
862 bandsize = s->spx_band_sizes[bnd];
863 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
864 nratio = av_clipf(nratio, 0.0f, 1.0f);
865 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
866 // to give unity variance
867 sblend = sqrtf(1.0f - nratio);
870 /* decode spx coordinates */
871 spx_coord_exp = get_bits(gbc, 4);
872 spx_coord_mant = get_bits(gbc, 2);
873 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
874 else spx_coord_mant += 4;
875 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
876 spx_coord = spx_coord_mant * (1.0f / (1 << 23));
878 /* multiply noise and signal blending factors by spx coordinate */
879 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
880 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
884 s->first_spx_coords[ch] = 1;
889 /* coupling strategy */
890 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
891 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
893 s->cpl_in_use[blk] = get_bits1(gbc);
894 if (s->cpl_in_use[blk]) {
895 /* coupling in use */
896 int cpl_start_subband, cpl_end_subband;
898 if (channel_mode < AC3_CHMODE_STEREO) {
899 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
900 return AVERROR_INVALIDDATA;
903 /* check for enhanced coupling */
904 if (s->eac3 && get_bits1(gbc)) {
905 /* TODO: parse enhanced coupling strategy info */
906 avpriv_request_sample(s->avctx, "Enhanced coupling");
907 return AVERROR_PATCHWELCOME;
910 /* determine which channels are coupled */
911 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
912 s->channel_in_cpl[1] = 1;
913 s->channel_in_cpl[2] = 1;
915 for (ch = 1; ch <= fbw_channels; ch++)
916 s->channel_in_cpl[ch] = get_bits1(gbc);
919 /* phase flags in use */
920 if (channel_mode == AC3_CHMODE_STEREO)
921 s->phase_flags_in_use = get_bits1(gbc);
923 /* coupling frequency range */
924 cpl_start_subband = get_bits(gbc, 4);
925 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
926 get_bits(gbc, 4) + 3;
927 if (cpl_start_subband >= cpl_end_subband) {
928 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
929 cpl_start_subband, cpl_end_subband);
930 return AVERROR_INVALIDDATA;
932 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
933 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
935 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
937 ff_eac3_default_cpl_band_struct,
938 &s->num_cpl_bands, s->cpl_band_sizes);
940 /* coupling not in use */
941 for (ch = 1; ch <= fbw_channels; ch++) {
942 s->channel_in_cpl[ch] = 0;
943 s->first_cpl_coords[ch] = 1;
945 s->first_cpl_leak = s->eac3;
946 s->phase_flags_in_use = 0;
948 } else if (!s->eac3) {
950 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
951 "be present in block 0\n");
952 return AVERROR_INVALIDDATA;
954 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
957 cpl_in_use = s->cpl_in_use[blk];
959 /* coupling coordinates */
961 int cpl_coords_exist = 0;
963 for (ch = 1; ch <= fbw_channels; ch++) {
964 if (s->channel_in_cpl[ch]) {
965 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
966 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
967 s->first_cpl_coords[ch] = 0;
968 cpl_coords_exist = 1;
969 master_cpl_coord = 3 * get_bits(gbc, 2);
970 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
971 cpl_coord_exp = get_bits(gbc, 4);
972 cpl_coord_mant = get_bits(gbc, 4);
973 if (cpl_coord_exp == 15)
974 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
976 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
977 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
980 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
981 "be present in block 0\n");
982 return AVERROR_INVALIDDATA;
985 /* channel not in coupling */
986 s->first_cpl_coords[ch] = 1;
990 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
991 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
992 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
997 /* stereo rematrixing strategy and band structure */
998 if (channel_mode == AC3_CHMODE_STEREO) {
999 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1000 s->num_rematrixing_bands = 4;
1001 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1002 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1003 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1004 s->num_rematrixing_bands--;
1006 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
1007 s->rematrixing_flags[bnd] = get_bits1(gbc);
1009 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
1010 "new rematrixing strategy not present in block 0\n");
1011 s->num_rematrixing_bands = 0;
1015 /* exponent strategies for each channel */
1016 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1018 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1019 if (s->exp_strategy[blk][ch] != EXP_REUSE)
1020 bit_alloc_stages[ch] = 3;
1023 /* channel bandwidth */
1024 for (ch = 1; ch <= fbw_channels; ch++) {
1025 s->start_freq[ch] = 0;
1026 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1028 int prev = s->end_freq[ch];
1029 if (s->channel_in_cpl[ch])
1030 s->end_freq[ch] = s->start_freq[CPL_CH];
1031 else if (s->channel_uses_spx[ch])
1032 s->end_freq[ch] = s->spx_src_start_freq;
1034 int bandwidth_code = get_bits(gbc, 6);
1035 if (bandwidth_code > 60) {
1036 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1037 return AVERROR_INVALIDDATA;
1039 s->end_freq[ch] = bandwidth_code * 3 + 73;
1041 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1042 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1043 if (blk > 0 && s->end_freq[ch] != prev)
1044 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1047 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1048 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1049 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1052 /* decode exponents for each channel */
1053 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1054 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1055 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1056 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1057 s->num_exp_groups[ch], s->dexps[ch][0],
1058 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1059 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1060 return AVERROR_INVALIDDATA;
1062 if (ch != CPL_CH && ch != s->lfe_ch)
1063 skip_bits(gbc, 2); /* skip gainrng */
1067 /* bit allocation information */
1068 if (s->bit_allocation_syntax) {
1069 if (get_bits1(gbc)) {
1070 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1071 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1072 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1073 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1074 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1075 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1076 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1078 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1079 "be present in block 0\n");
1080 return AVERROR_INVALIDDATA;
1084 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1085 if (!s->eac3 || !blk) {
1086 if (s->snr_offset_strategy && get_bits1(gbc)) {
1089 csnr = (get_bits(gbc, 6) - 15) << 4;
1090 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1092 if (ch == i || s->snr_offset_strategy == 2)
1093 snr = (csnr + get_bits(gbc, 4)) << 2;
1094 /* run at least last bit allocation stage if snr offset changes */
1095 if (blk && s->snr_offset[ch] != snr) {
1096 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1098 s->snr_offset[ch] = snr;
1100 /* fast gain (normal AC-3 only) */
1102 int prev = s->fast_gain[ch];
1103 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1104 /* run last 2 bit allocation stages if fast gain changes */
1105 if (blk && prev != s->fast_gain[ch])
1106 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1109 } else if (!s->eac3 && !blk) {
1110 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1111 return AVERROR_INVALIDDATA;
1115 /* fast gain (E-AC-3 only) */
1116 if (s->fast_gain_syntax && get_bits1(gbc)) {
1117 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1118 int prev = s->fast_gain[ch];
1119 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1120 /* run last 2 bit allocation stages if fast gain changes */
1121 if (blk && prev != s->fast_gain[ch])
1122 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1124 } else if (s->eac3 && !blk) {
1125 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1126 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1129 /* E-AC-3 to AC-3 converter SNR offset */
1130 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1131 skip_bits(gbc, 10); // skip converter snr offset
1134 /* coupling leak information */
1136 if (s->first_cpl_leak || get_bits1(gbc)) {
1137 int fl = get_bits(gbc, 3);
1138 int sl = get_bits(gbc, 3);
1139 /* run last 2 bit allocation stages for coupling channel if
1140 coupling leak changes */
1141 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1142 sl != s->bit_alloc_params.cpl_slow_leak)) {
1143 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1145 s->bit_alloc_params.cpl_fast_leak = fl;
1146 s->bit_alloc_params.cpl_slow_leak = sl;
1147 } else if (!s->eac3 && !blk) {
1148 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1149 "be present in block 0\n");
1150 return AVERROR_INVALIDDATA;
1152 s->first_cpl_leak = 0;
1155 /* delta bit allocation information */
1156 if (s->dba_syntax && get_bits1(gbc)) {
1157 /* delta bit allocation exists (strategy) */
1158 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1159 s->dba_mode[ch] = get_bits(gbc, 2);
1160 if (s->dba_mode[ch] == DBA_RESERVED) {
1161 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1162 return AVERROR_INVALIDDATA;
1164 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1166 /* channel delta offset, len and bit allocation */
1167 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1168 if (s->dba_mode[ch] == DBA_NEW) {
1169 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1170 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1171 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1172 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1173 s->dba_values[ch][seg] = get_bits(gbc, 3);
1175 /* run last 2 bit allocation stages if new dba values */
1176 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1179 } else if (blk == 0) {
1180 for (ch = 0; ch <= s->channels; ch++) {
1181 s->dba_mode[ch] = DBA_NONE;
1185 /* Bit allocation */
1186 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1187 if (bit_alloc_stages[ch] > 2) {
1188 /* Exponent mapping into PSD and PSD integration */
1189 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1190 s->start_freq[ch], s->end_freq[ch],
1191 s->psd[ch], s->band_psd[ch]);
1193 if (bit_alloc_stages[ch] > 1) {
1194 /* Compute excitation function, Compute masking curve, and
1195 Apply delta bit allocation */
1196 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1197 s->start_freq[ch], s->end_freq[ch],
1198 s->fast_gain[ch], (ch == s->lfe_ch),
1199 s->dba_mode[ch], s->dba_nsegs[ch],
1200 s->dba_offsets[ch], s->dba_lengths[ch],
1201 s->dba_values[ch], s->mask[ch])) {
1202 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1203 return AVERROR_INVALIDDATA;
1206 if (bit_alloc_stages[ch] > 0) {
1207 /* Compute bit allocation */
1208 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1209 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1210 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1211 s->start_freq[ch], s->end_freq[ch],
1213 s->bit_alloc_params.floor,
1214 bap_tab, s->bap[ch]);
1218 /* unused dummy data */
1219 if (s->skip_syntax && get_bits1(gbc)) {
1220 int skipl = get_bits(gbc, 9);
1225 /* unpack the transform coefficients
1226 this also uncouples channels if coupling is in use. */
1227 decode_transform_coeffs(s, blk);
1229 /* TODO: generate enhanced coupling coordinates and uncouple */
1231 /* recover coefficients if rematrixing is in use */
1232 if (s->channel_mode == AC3_CHMODE_STEREO)
1235 /* apply scaling to coefficients (headroom, dynrng) */
1236 for (ch = 1; ch <= s->channels; ch++) {
1237 float gain = 1.0 / 4194304.0f;
1238 if (s->channel_mode == AC3_CHMODE_DUALMONO) {
1239 gain *= s->dynamic_range[2 - ch];
1241 gain *= s->dynamic_range[0];
1243 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1244 s->fixed_coeffs[ch], gain, 256);
1247 /* apply spectral extension to high frequency bins */
1248 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1249 ff_eac3_apply_spectral_extension(s);
1252 /* downmix and MDCT. order depends on whether block switching is used for
1253 any channel in this block. this is because coefficients for the long
1254 and short transforms cannot be mixed. */
1255 downmix_output = s->channels != s->out_channels &&
1256 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1257 s->fbw_channels == s->out_channels);
1258 if (different_transforms) {
1259 /* the delay samples have already been downmixed, so we upmix the delay
1260 samples in order to reconstruct all channels before downmixing. */
1266 do_imdct(s, s->channels);
1268 if (downmix_output) {
1269 s->ac3dsp.downmix(s->outptr, s->downmix_coeffs,
1270 s->out_channels, s->fbw_channels, 256);
1273 if (downmix_output) {
1274 s->ac3dsp.downmix(s->xcfptr + 1, s->downmix_coeffs,
1275 s->out_channels, s->fbw_channels, 256);
1278 if (downmix_output && !s->downmixed) {
1280 s->ac3dsp.downmix(s->dlyptr, s->downmix_coeffs, s->out_channels,
1281 s->fbw_channels, 128);
1284 do_imdct(s, s->out_channels);
1291 * Decode a single AC-3 frame.
1293 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1294 int *got_frame_ptr, AVPacket *avpkt)
1296 AVFrame *frame = data;
1297 const uint8_t *buf = avpkt->data;
1298 int buf_size = avpkt->size;
1299 AC3DecodeContext *s = avctx->priv_data;
1300 int blk, ch, err, ret;
1301 const uint8_t *channel_map;
1302 const float *output[AC3_MAX_CHANNELS];
1303 enum AVMatrixEncoding matrix_encoding;
1305 /* copy input buffer to decoder context to avoid reading past the end
1306 of the buffer, which can be caused by a damaged input stream. */
1307 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1308 // seems to be byte-swapped AC-3
1309 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1310 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1312 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1313 buf = s->input_buffer;
1314 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1315 init_get_bits(&s->gbc, buf, buf_size * 8);
1317 /* parse the syncinfo */
1318 err = parse_frame_header(s);
1322 case AAC_AC3_PARSE_ERROR_SYNC:
1323 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1324 return AVERROR_INVALIDDATA;
1325 case AAC_AC3_PARSE_ERROR_BSID:
1326 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1328 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1329 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1331 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1332 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1334 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1335 /* skip frame if CRC is ok. otherwise use error concealment. */
1336 /* TODO: add support for substreams and dependent frames */
1337 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1338 av_log(avctx, AV_LOG_WARNING, "unsupported frame type : "
1339 "skipping frame\n");
1343 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1346 case AAC_AC3_PARSE_ERROR_CRC:
1347 case AAC_AC3_PARSE_ERROR_CHANNEL_CFG:
1349 default: // Normal AVERROR do not try to recover.
1354 /* check that reported frame size fits in input buffer */
1355 if (s->frame_size > buf_size) {
1356 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1357 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1358 } else if (avctx->err_recognition & (AV_EF_CRCCHECK|AV_EF_CAREFUL)) {
1359 /* check for crc mismatch */
1360 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1361 s->frame_size - 2)) {
1362 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1363 if (avctx->err_recognition & AV_EF_EXPLODE)
1364 return AVERROR_INVALIDDATA;
1365 err = AAC_AC3_PARSE_ERROR_CRC;
1370 /* if frame is ok, set audio parameters */
1372 avctx->sample_rate = s->sample_rate;
1373 avctx->bit_rate = s->bit_rate;
1376 /* channel config */
1377 if (!err || (s->channels && s->out_channels != s->channels)) {
1378 s->out_channels = s->channels;
1379 s->output_mode = s->channel_mode;
1381 s->output_mode |= AC3_OUTPUT_LFEON;
1382 if (s->channels > 1 &&
1383 avctx->request_channel_layout == AV_CH_LAYOUT_MONO) {
1384 s->out_channels = 1;
1385 s->output_mode = AC3_CHMODE_MONO;
1386 } else if (s->channels > 2 &&
1387 avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) {
1388 s->out_channels = 2;
1389 s->output_mode = AC3_CHMODE_STEREO;
1392 s->loro_center_mix_level = gain_levels[s-> center_mix_level];
1393 s->loro_surround_mix_level = gain_levels[s->surround_mix_level];
1394 s->ltrt_center_mix_level = LEVEL_MINUS_3DB;
1395 s->ltrt_surround_mix_level = LEVEL_MINUS_3DB;
1396 /* set downmixing coefficients if needed */
1397 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1398 s->fbw_channels == s->out_channels)) {
1399 set_downmix_coeffs(s);
1401 } else if (!s->channels) {
1402 av_log(avctx, AV_LOG_ERROR, "unable to determine channel mode\n");
1403 return AVERROR_INVALIDDATA;
1405 avctx->channels = s->out_channels;
1406 avctx->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode & ~AC3_OUTPUT_LFEON];
1407 if (s->output_mode & AC3_OUTPUT_LFEON)
1408 avctx->channel_layout |= AV_CH_LOW_FREQUENCY;
1410 /* set audio service type based on bitstream mode for AC-3 */
1411 avctx->audio_service_type = s->bitstream_mode;
1412 if (s->bitstream_mode == 0x7 && s->channels > 1)
1413 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1415 /* get output buffer */
1416 frame->nb_samples = s->num_blocks * AC3_BLOCK_SIZE;
1417 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
1420 /* decode the audio blocks */
1421 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1422 for (ch = 0; ch < AC3_MAX_CHANNELS; ch++) {
1423 output[ch] = s->output[ch];
1424 s->outptr[ch] = s->output[ch];
1426 for (ch = 0; ch < s->channels; ch++) {
1427 if (ch < s->out_channels)
1428 s->outptr[channel_map[ch]] = (float *)frame->data[ch];
1430 for (blk = 0; blk < s->num_blocks; blk++) {
1431 if (!err && decode_audio_block(s, blk)) {
1432 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1436 for (ch = 0; ch < s->out_channels; ch++)
1437 memcpy(((float*)frame->data[ch]) + AC3_BLOCK_SIZE*blk, output[ch], sizeof(**output) * AC3_BLOCK_SIZE);
1438 for (ch = 0; ch < s->out_channels; ch++)
1439 output[ch] = s->outptr[channel_map[ch]];
1440 for (ch = 0; ch < s->out_channels; ch++) {
1441 if (!ch || channel_map[ch])
1442 s->outptr[channel_map[ch]] += AC3_BLOCK_SIZE;
1446 av_frame_set_decode_error_flags(frame, err ? FF_DECODE_ERROR_INVALID_BITSTREAM : 0);
1448 /* keep last block for error concealment in next frame */
1449 for (ch = 0; ch < s->out_channels; ch++)
1450 memcpy(s->output[ch], output[ch], sizeof(**output) * AC3_BLOCK_SIZE);
1455 * Check whether the input layout is compatible, and make sure we're not
1456 * downmixing (else the matrix encoding is no longer applicable).
1458 matrix_encoding = AV_MATRIX_ENCODING_NONE;
1459 if (s->channel_mode == AC3_CHMODE_STEREO &&
1460 s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) {
1461 if (s->dolby_surround_mode == AC3_DSURMOD_ON)
1462 matrix_encoding = AV_MATRIX_ENCODING_DOLBY;
1463 else if (s->dolby_headphone_mode == AC3_DHEADPHONMOD_ON)
1464 matrix_encoding = AV_MATRIX_ENCODING_DOLBYHEADPHONE;
1465 } else if (s->channel_mode >= AC3_CHMODE_2F2R &&
1466 s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) {
1467 switch (s->dolby_surround_ex_mode) {
1468 case AC3_DSUREXMOD_ON: // EX or PLIIx
1469 matrix_encoding = AV_MATRIX_ENCODING_DOLBYEX;
1471 case AC3_DSUREXMOD_PLIIZ:
1472 matrix_encoding = AV_MATRIX_ENCODING_DPLIIZ;
1474 default: // not indicated or off
1478 if ((ret = ff_side_data_update_matrix_encoding(frame, matrix_encoding)) < 0)
1483 return FFMIN(buf_size, s->frame_size);
1487 * Uninitialize the AC-3 decoder.
1489 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1491 AC3DecodeContext *s = avctx->priv_data;
1492 ff_mdct_end(&s->imdct_512);
1493 ff_mdct_end(&s->imdct_256);
1498 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1499 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)
1500 static const AVOption options[] = {
1501 { "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), AV_OPT_TYPE_FLOAT, {.dbl = 1.0}, 0.0, 1.0, PAR },
1503 {"dmix_mode", "Preferred Stereo Downmix Mode", OFFSET(preferred_stereo_downmix), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, 2, 0, "dmix_mode"},
1504 {"ltrt_cmixlev", "Lt/Rt Center Mix Level", OFFSET(ltrt_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1505 {"ltrt_surmixlev", "Lt/Rt Surround Mix Level", OFFSET(ltrt_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1506 {"loro_cmixlev", "Lo/Ro Center Mix Level", OFFSET(loro_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1507 {"loro_surmixlev", "Lo/Ro Surround Mix Level", OFFSET(loro_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1512 static const AVClass ac3_decoder_class = {
1513 .class_name = "AC3 decoder",
1514 .item_name = av_default_item_name,
1516 .version = LIBAVUTIL_VERSION_INT,
1519 AVCodec ff_ac3_decoder = {
1521 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1522 .type = AVMEDIA_TYPE_AUDIO,
1523 .id = AV_CODEC_ID_AC3,
1524 .priv_data_size = sizeof (AC3DecodeContext),
1525 .init = ac3_decode_init,
1526 .close = ac3_decode_end,
1527 .decode = ac3_decode_frame,
1528 .capabilities = CODEC_CAP_DR1,
1529 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
1530 AV_SAMPLE_FMT_NONE },
1531 .priv_class = &ac3_decoder_class,
1534 #if CONFIG_EAC3_DECODER
1535 static const AVClass eac3_decoder_class = {
1536 .class_name = "E-AC3 decoder",
1537 .item_name = av_default_item_name,
1539 .version = LIBAVUTIL_VERSION_INT,
1542 AVCodec ff_eac3_decoder = {
1544 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1545 .type = AVMEDIA_TYPE_AUDIO,
1546 .id = AV_CODEC_ID_EAC3,
1547 .priv_data_size = sizeof (AC3DecodeContext),
1548 .init = ac3_decode_init,
1549 .close = ac3_decode_end,
1550 .decode = ac3_decode_frame,
1551 .capabilities = CODEC_CAP_DR1,
1552 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
1553 AV_SAMPLE_FMT_NONE },
1554 .priv_class = &eac3_decoder_class,