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
67 /** dynamic range table. converts codes to scale factors. */
68 static float dynamic_range_tab[256];
69 float ff_ac3_heavy_dynamic_range_tab[256];
72 /** Adjustments in dB gain */
73 static const float gain_levels[9] = {
77 LEVEL_MINUS_1POINT5DB,
79 LEVEL_MINUS_4POINT5DB,
85 /** Adjustments in dB gain (LFE, +10 to -21 dB) */
86 static const float gain_levels_lfe[32] = {
87 3.162275, 2.818382, 2.511886, 2.238719, 1.995261, 1.778278, 1.584893,
88 1.412536, 1.258924, 1.122018, 1.000000, 0.891251, 0.794328, 0.707946,
89 0.630957, 0.562341, 0.501187, 0.446683, 0.398107, 0.354813, 0.316227,
90 0.281838, 0.251188, 0.223872, 0.199526, 0.177828, 0.158489, 0.141253,
91 0.125892, 0.112201, 0.100000, 0.089125
95 * Table for default stereo downmixing coefficients
96 * reference: Section 7.8.2 Downmixing Into Two Channels
98 static const uint8_t ac3_default_coeffs[8][5][2] = {
99 { { 2, 7 }, { 7, 2 }, },
101 { { 2, 7 }, { 7, 2 }, },
102 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
103 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
104 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
105 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
106 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
110 * Symmetrical Dequantization
111 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
112 * Tables 7.19 to 7.23
115 symmetric_dequant(int code, int levels)
117 return ((code - (levels >> 1)) * (1 << 24)) / levels;
121 * Initialize tables at runtime.
123 static av_cold void ac3_tables_init(void)
127 /* generate table for ungrouping 3 values in 7 bits
128 reference: Section 7.1.3 Exponent Decoding */
129 for (i = 0; i < 128; i++) {
130 ungroup_3_in_7_bits_tab[i][0] = i / 25;
131 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
132 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
135 /* generate grouped mantissa tables
136 reference: Section 7.3.5 Ungrouping of Mantissas */
137 for (i = 0; i < 32; i++) {
138 /* bap=1 mantissas */
139 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
140 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
141 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
143 for (i = 0; i < 128; i++) {
144 /* bap=2 mantissas */
145 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
146 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
147 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
149 /* bap=4 mantissas */
150 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
151 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
153 /* generate ungrouped mantissa tables
154 reference: Tables 7.21 and 7.23 */
155 for (i = 0; i < 7; i++) {
156 /* bap=3 mantissas */
157 b3_mantissas[i] = symmetric_dequant(i, 7);
159 for (i = 0; i < 15; i++) {
160 /* bap=5 mantissas */
161 b5_mantissas[i] = symmetric_dequant(i, 15);
165 /* generate dynamic range table
166 reference: Section 7.7.1 Dynamic Range Control */
167 for (i = 0; i < 256; i++) {
168 int v = (i >> 5) - ((i >> 7) << 3) - 5;
169 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
172 /* generate compr dynamic range table
173 reference: Section 7.7.2 Heavy Compression */
174 for (i = 0; i < 256; i++) {
175 int v = (i >> 4) - ((i >> 7) << 4) - 4;
176 ff_ac3_heavy_dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0xF) | 0x10);
182 * AVCodec initialization
184 static av_cold int ac3_decode_init(AVCodecContext *avctx)
186 AC3DecodeContext *s = avctx->priv_data;
192 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
193 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
194 AC3_RENAME(ff_kbd_window_init)(s->window, 5.0, 256);
195 ff_bswapdsp_init(&s->bdsp);
198 s->fdsp = avpriv_alloc_fixed_dsp(avctx->flags & AV_CODEC_FLAG_BITEXACT);
200 s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
201 ff_fmt_convert_init(&s->fmt_conv, avctx);
204 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & AV_CODEC_FLAG_BITEXACT);
205 av_lfg_init(&s->dith_state, 0);
208 avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
210 avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
212 /* allow downmixing to stereo or mono */
213 if (avctx->channels > 1 &&
214 avctx->request_channel_layout == AV_CH_LAYOUT_MONO)
216 else if (avctx->channels > 2 &&
217 avctx->request_channel_layout == AV_CH_LAYOUT_STEREO)
221 for (i = 0; i < AC3_MAX_CHANNELS; i++) {
222 s->xcfptr[i] = s->transform_coeffs[i];
223 s->dlyptr[i] = s->delay[i];
230 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
231 * GetBitContext within AC3DecodeContext must point to
232 * the start of the synchronized AC-3 bitstream.
234 static int ac3_parse_header(AC3DecodeContext *s)
236 GetBitContext *gbc = &s->gbc;
239 /* read the rest of the bsi. read twice for dual mono mode. */
240 i = !s->channel_mode;
242 s->dialog_normalization[(!s->channel_mode)-i] = -get_bits(gbc, 5);
243 if (s->dialog_normalization[(!s->channel_mode)-i] == 0) {
244 s->dialog_normalization[(!s->channel_mode)-i] = -31;
246 if (s->target_level != 0) {
247 s->level_gain[(!s->channel_mode)-i] = powf(2.0f,
248 (float)(s->target_level -
249 s->dialog_normalization[(!s->channel_mode)-i])/6.0f);
251 if (s->compression_exists[(!s->channel_mode)-i] = get_bits1(gbc)) {
252 s->heavy_dynamic_range[(!s->channel_mode)-i] =
253 AC3_HEAVY_RANGE(get_bits(gbc, 8));
256 skip_bits(gbc, 8); //skip language code
258 skip_bits(gbc, 7); //skip audio production information
261 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
263 /* skip the timecodes or parse the Alternate Bit Stream Syntax */
264 if (s->bitstream_id != 6) {
266 skip_bits(gbc, 14); //skip timecode1
268 skip_bits(gbc, 14); //skip timecode2
270 if (get_bits1(gbc)) {
271 s->preferred_downmix = get_bits(gbc, 2);
272 s->center_mix_level_ltrt = get_bits(gbc, 3);
273 s->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7);
274 s->center_mix_level = get_bits(gbc, 3);
275 s->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7);
277 if (get_bits1(gbc)) {
278 s->dolby_surround_ex_mode = get_bits(gbc, 2);
279 s->dolby_headphone_mode = get_bits(gbc, 2);
280 skip_bits(gbc, 10); // skip adconvtyp (1), xbsi2 (8), encinfo (1)
284 /* skip additional bitstream info */
285 if (get_bits1(gbc)) {
286 i = get_bits(gbc, 6);
296 * Common function to parse AC-3 or E-AC-3 frame header
298 static int parse_frame_header(AC3DecodeContext *s)
300 AC3HeaderInfo hdr, *phdr=&hdr;
303 err = avpriv_ac3_parse_header(&s->gbc, &phdr);
307 /* get decoding parameters from header info */
308 s->bit_alloc_params.sr_code = hdr.sr_code;
309 s->bitstream_id = hdr.bitstream_id;
310 s->bitstream_mode = hdr.bitstream_mode;
311 s->channel_mode = hdr.channel_mode;
312 s->lfe_on = hdr.lfe_on;
313 s->bit_alloc_params.sr_shift = hdr.sr_shift;
314 s->sample_rate = hdr.sample_rate;
315 s->bit_rate = hdr.bit_rate;
316 s->channels = hdr.channels;
317 s->fbw_channels = s->channels - s->lfe_on;
318 s->lfe_ch = s->fbw_channels + 1;
319 s->frame_size = hdr.frame_size;
320 s->preferred_downmix = AC3_DMIXMOD_NOTINDICATED;
321 s->center_mix_level = hdr.center_mix_level;
322 s->center_mix_level_ltrt = 4; // -3.0dB
323 s->surround_mix_level = hdr.surround_mix_level;
324 s->surround_mix_level_ltrt = 4; // -3.0dB
325 s->lfe_mix_level_exists = 0;
326 s->num_blocks = hdr.num_blocks;
327 s->frame_type = hdr.frame_type;
328 s->substreamid = hdr.substreamid;
329 s->dolby_surround_mode = hdr.dolby_surround_mode;
330 s->dolby_surround_ex_mode = AC3_DSUREXMOD_NOTINDICATED;
331 s->dolby_headphone_mode = AC3_DHEADPHONMOD_NOTINDICATED;
334 s->start_freq[s->lfe_ch] = 0;
335 s->end_freq[s->lfe_ch] = 7;
336 s->num_exp_groups[s->lfe_ch] = 2;
337 s->channel_in_cpl[s->lfe_ch] = 0;
340 if (s->bitstream_id <= 10) {
342 s->snr_offset_strategy = 2;
343 s->block_switch_syntax = 1;
344 s->dither_flag_syntax = 1;
345 s->bit_allocation_syntax = 1;
346 s->fast_gain_syntax = 0;
347 s->first_cpl_leak = 0;
350 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
351 return ac3_parse_header(s);
352 } else if (CONFIG_EAC3_DECODER) {
354 return ff_eac3_parse_header(s);
356 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
357 return AVERROR(ENOSYS);
362 * Set stereo downmixing coefficients based on frame header info.
363 * reference: Section 7.8.2 Downmixing Into Two Channels
365 static void set_downmix_coeffs(AC3DecodeContext *s)
368 float cmix = gain_levels[s-> center_mix_level];
369 float smix = gain_levels[s->surround_mix_level];
371 float downmix_coeffs[AC3_MAX_CHANNELS][2];
373 for (i = 0; i < s->fbw_channels; i++) {
374 downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
375 downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
377 if (s->channel_mode > 1 && s->channel_mode & 1) {
378 downmix_coeffs[1][0] = downmix_coeffs[1][1] = cmix;
380 if (s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
381 int nf = s->channel_mode - 2;
382 downmix_coeffs[nf][0] = downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
384 if (s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
385 int nf = s->channel_mode - 4;
386 downmix_coeffs[nf][0] = downmix_coeffs[nf+1][1] = smix;
391 for (i = 0; i < s->fbw_channels; i++) {
392 norm0 += downmix_coeffs[i][0];
393 norm1 += downmix_coeffs[i][1];
395 norm0 = 1.0f / norm0;
396 norm1 = 1.0f / norm1;
397 for (i = 0; i < s->fbw_channels; i++) {
398 downmix_coeffs[i][0] *= norm0;
399 downmix_coeffs[i][1] *= norm1;
402 if (s->output_mode == AC3_CHMODE_MONO) {
403 for (i = 0; i < s->fbw_channels; i++)
404 downmix_coeffs[i][0] = (downmix_coeffs[i][0] +
405 downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
407 for (i = 0; i < s->fbw_channels; i++) {
408 s->downmix_coeffs[i][0] = FIXR12(downmix_coeffs[i][0]);
409 s->downmix_coeffs[i][1] = FIXR12(downmix_coeffs[i][1]);
414 * Decode the grouped exponents according to exponent strategy.
415 * reference: Section 7.1.3 Exponent Decoding
417 static int decode_exponents(AC3DecodeContext *s,
418 GetBitContext *gbc, int exp_strategy, int ngrps,
419 uint8_t absexp, int8_t *dexps)
421 int i, j, grp, group_size;
426 group_size = exp_strategy + (exp_strategy == EXP_D45);
427 for (grp = 0, i = 0; grp < ngrps; grp++) {
428 expacc = get_bits(gbc, 7);
430 av_log(s->avctx, AV_LOG_ERROR, "expacc %d is out-of-range\n", expacc);
431 return AVERROR_INVALIDDATA;
433 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
434 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
435 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
438 /* convert to absolute exps and expand groups */
440 for (i = 0, j = 0; i < ngrps * 3; i++) {
441 prevexp += dexp[i] - 2;
443 av_log(s->avctx, AV_LOG_ERROR, "exponent %d is out-of-range\n", prevexp);
446 switch (group_size) {
447 case 4: dexps[j++] = prevexp;
448 dexps[j++] = prevexp;
449 case 2: dexps[j++] = prevexp;
450 case 1: dexps[j++] = prevexp;
457 * Generate transform coefficients for each coupled channel in the coupling
458 * range using the coupling coefficients and coupling coordinates.
459 * reference: Section 7.4.3 Coupling Coordinate Format
461 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
465 bin = s->start_freq[CPL_CH];
466 for (band = 0; band < s->num_cpl_bands; band++) {
467 int band_start = bin;
468 int band_end = bin + s->cpl_band_sizes[band];
469 for (ch = 1; ch <= s->fbw_channels; ch++) {
470 if (s->channel_in_cpl[ch]) {
471 int cpl_coord = s->cpl_coords[ch][band] << 5;
472 for (bin = band_start; bin < band_end; bin++) {
473 s->fixed_coeffs[ch][bin] =
474 MULH(s->fixed_coeffs[CPL_CH][bin] * (1 << 4), cpl_coord);
476 if (ch == 2 && s->phase_flags[band]) {
477 for (bin = band_start; bin < band_end; bin++)
478 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
487 * Grouped mantissas for 3-level 5-level and 11-level quantization
489 typedef struct mant_groups {
499 * Decode the transform coefficients for a particular channel
500 * reference: Section 7.3 Quantization and Decoding of Mantissas
502 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
504 int start_freq = s->start_freq[ch_index];
505 int end_freq = s->end_freq[ch_index];
506 uint8_t *baps = s->bap[ch_index];
507 int8_t *exps = s->dexps[ch_index];
508 int32_t *coeffs = s->fixed_coeffs[ch_index];
509 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
510 GetBitContext *gbc = &s->gbc;
513 for (freq = start_freq; freq < end_freq; freq++) {
514 int bap = baps[freq];
518 /* random noise with approximate range of -0.707 to 0.707 */
520 mantissa = (((av_lfg_get(&s->dith_state)>>8)*181)>>8) - 5931008;
527 mantissa = m->b1_mant[m->b1];
529 int bits = get_bits(gbc, 5);
530 mantissa = b1_mantissas[bits][0];
531 m->b1_mant[1] = b1_mantissas[bits][1];
532 m->b1_mant[0] = b1_mantissas[bits][2];
539 mantissa = m->b2_mant[m->b2];
541 int bits = get_bits(gbc, 7);
542 mantissa = b2_mantissas[bits][0];
543 m->b2_mant[1] = b2_mantissas[bits][1];
544 m->b2_mant[0] = b2_mantissas[bits][2];
549 mantissa = b3_mantissas[get_bits(gbc, 3)];
554 mantissa = m->b4_mant;
556 int bits = get_bits(gbc, 7);
557 mantissa = b4_mantissas[bits][0];
558 m->b4_mant = b4_mantissas[bits][1];
563 mantissa = b5_mantissas[get_bits(gbc, 4)];
565 default: /* 6 to 15 */
566 /* Shift mantissa and sign-extend it. */
568 av_log(s->avctx, AV_LOG_ERROR, "bap %d is invalid in plain AC-3\n", bap);
571 mantissa = (unsigned)get_sbits(gbc, quantization_tab[bap]) << (24 - quantization_tab[bap]);
574 coeffs[freq] = mantissa >> exps[freq];
579 * Remove random dithering from coupling range coefficients with zero-bit
580 * mantissas for coupled channels which do not use dithering.
581 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
583 static void remove_dithering(AC3DecodeContext *s) {
586 for (ch = 1; ch <= s->fbw_channels; ch++) {
587 if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
588 for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) {
589 if (!s->bap[CPL_CH][i])
590 s->fixed_coeffs[ch][i] = 0;
596 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
599 if (!s->channel_uses_aht[ch]) {
600 ac3_decode_transform_coeffs_ch(s, ch, m);
602 /* if AHT is used, mantissas for all blocks are encoded in the first
603 block of the frame. */
605 if (CONFIG_EAC3_DECODER && !blk)
606 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
607 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
608 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
614 * Decode the transform coefficients.
616 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
622 m.b1 = m.b2 = m.b4 = 0;
624 for (ch = 1; ch <= s->channels; ch++) {
625 /* transform coefficients for full-bandwidth channel */
626 decode_transform_coeffs_ch(s, blk, ch, &m);
627 /* transform coefficients for coupling channel come right after the
628 coefficients for the first coupled channel*/
629 if (s->channel_in_cpl[ch]) {
631 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
632 calc_transform_coeffs_cpl(s);
635 end = s->end_freq[CPL_CH];
637 end = s->end_freq[ch];
640 s->fixed_coeffs[ch][end] = 0;
644 /* zero the dithered coefficients for appropriate channels */
649 * Stereo rematrixing.
650 * reference: Section 7.5.4 Rematrixing : Decoding Technique
652 static void do_rematrixing(AC3DecodeContext *s)
657 end = FFMIN(s->end_freq[1], s->end_freq[2]);
659 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
660 if (s->rematrixing_flags[bnd]) {
661 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd + 1]);
662 for (i = ff_ac3_rematrix_band_tab[bnd]; i < bndend; i++) {
663 int tmp0 = s->fixed_coeffs[1][i];
664 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
665 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
672 * Inverse MDCT Transform.
673 * Convert frequency domain coefficients to time-domain audio samples.
674 * reference: Section 7.9.4 Transformation Equations
676 static inline void do_imdct(AC3DecodeContext *s, int channels)
680 for (ch = 1; ch <= channels; ch++) {
681 if (s->block_switch[ch]) {
683 FFTSample *x = s->tmp_output + 128;
684 for (i = 0; i < 128; i++)
685 x[i] = s->transform_coeffs[ch][2 * i];
686 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
688 s->fdsp->vector_fmul_window_scaled(s->outptr[ch - 1], s->delay[ch - 1],
689 s->tmp_output, s->window, 128, 8);
691 s->fdsp->vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
692 s->tmp_output, s->window, 128);
694 for (i = 0; i < 128; i++)
695 x[i] = s->transform_coeffs[ch][2 * i + 1];
696 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x);
698 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
700 s->fdsp->vector_fmul_window_scaled(s->outptr[ch - 1], s->delay[ch - 1],
701 s->tmp_output, s->window, 128, 8);
703 s->fdsp->vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
704 s->tmp_output, s->window, 128);
706 memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(FFTSample));
712 * Upmix delay samples from stereo to original channel layout.
714 static void ac3_upmix_delay(AC3DecodeContext *s)
716 int channel_data_size = sizeof(s->delay[0]);
717 switch (s->channel_mode) {
718 case AC3_CHMODE_DUALMONO:
719 case AC3_CHMODE_STEREO:
720 /* upmix mono to stereo */
721 memcpy(s->delay[1], s->delay[0], channel_data_size);
723 case AC3_CHMODE_2F2R:
724 memset(s->delay[3], 0, channel_data_size);
725 case AC3_CHMODE_2F1R:
726 memset(s->delay[2], 0, channel_data_size);
728 case AC3_CHMODE_3F2R:
729 memset(s->delay[4], 0, channel_data_size);
730 case AC3_CHMODE_3F1R:
731 memset(s->delay[3], 0, channel_data_size);
733 memcpy(s->delay[2], s->delay[1], channel_data_size);
734 memset(s->delay[1], 0, channel_data_size);
740 * Decode band structure for coupling, spectral extension, or enhanced coupling.
741 * The band structure defines how many subbands are in each band. For each
742 * subband in the range, 1 means it is combined with the previous band, and 0
743 * means that it starts a new band.
745 * @param[in] gbc bit reader context
746 * @param[in] blk block number
747 * @param[in] eac3 flag to indicate E-AC-3
748 * @param[in] ecpl flag to indicate enhanced coupling
749 * @param[in] start_subband subband number for start of range
750 * @param[in] end_subband subband number for end of range
751 * @param[in] default_band_struct default band structure table
752 * @param[out] num_bands number of bands (optionally NULL)
753 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
755 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
756 int ecpl, int start_subband, int end_subband,
757 const uint8_t *default_band_struct,
758 int *num_bands, uint8_t *band_sizes)
760 int subbnd, bnd, n_subbands, n_bands=0;
762 uint8_t coded_band_struct[22];
763 const uint8_t *band_struct;
765 n_subbands = end_subband - start_subband;
767 /* decode band structure from bitstream or use default */
768 if (!eac3 || get_bits1(gbc)) {
769 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
770 coded_band_struct[subbnd] = get_bits1(gbc);
772 band_struct = coded_band_struct;
774 band_struct = &default_band_struct[start_subband+1];
776 /* no change in band structure */
780 /* calculate number of bands and band sizes based on band structure.
781 note that the first 4 subbands in enhanced coupling span only 6 bins
783 if (num_bands || band_sizes ) {
784 n_bands = n_subbands;
785 bnd_sz[0] = ecpl ? 6 : 12;
786 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
787 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
788 if (band_struct[subbnd - 1]) {
790 bnd_sz[bnd] += subbnd_size;
792 bnd_sz[++bnd] = subbnd_size;
797 /* set optional output params */
799 *num_bands = n_bands;
801 memcpy(band_sizes, bnd_sz, n_bands);
804 static inline int spx_strategy(AC3DecodeContext *s, int blk)
806 GetBitContext *bc = &s->gbc;
807 int fbw_channels = s->fbw_channels;
808 int dst_start_freq, dst_end_freq, src_start_freq,
809 start_subband, end_subband, ch;
811 /* determine which channels use spx */
812 if (s->channel_mode == AC3_CHMODE_MONO) {
813 s->channel_uses_spx[1] = 1;
815 for (ch = 1; ch <= fbw_channels; ch++)
816 s->channel_uses_spx[ch] = get_bits1(bc);
819 /* get the frequency bins of the spx copy region and the spx start
821 dst_start_freq = get_bits(bc, 2);
822 start_subband = get_bits(bc, 3) + 2;
823 if (start_subband > 7)
824 start_subband += start_subband - 7;
825 end_subband = get_bits(bc, 3) + 5;
827 s->spx_dst_end_freq = end_freq_inv_tab[end_subband-5];
830 end_subband += end_subband - 7;
831 dst_start_freq = dst_start_freq * 12 + 25;
832 src_start_freq = start_subband * 12 + 25;
833 dst_end_freq = end_subband * 12 + 25;
835 /* check validity of spx ranges */
836 if (start_subband >= end_subband) {
837 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
838 "range (%d >= %d)\n", start_subband, end_subband);
839 return AVERROR_INVALIDDATA;
841 if (dst_start_freq >= src_start_freq) {
842 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
843 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
844 return AVERROR_INVALIDDATA;
847 s->spx_dst_start_freq = dst_start_freq;
848 s->spx_src_start_freq = src_start_freq;
850 s->spx_dst_end_freq = dst_end_freq;
852 decode_band_structure(bc, blk, s->eac3, 0,
853 start_subband, end_subband,
854 ff_eac3_default_spx_band_struct,
860 static inline void spx_coordinates(AC3DecodeContext *s)
862 GetBitContext *bc = &s->gbc;
863 int fbw_channels = s->fbw_channels;
866 for (ch = 1; ch <= fbw_channels; ch++) {
867 if (s->channel_uses_spx[ch]) {
868 if (s->first_spx_coords[ch] || get_bits1(bc)) {
870 int bin, master_spx_coord;
872 s->first_spx_coords[ch] = 0;
873 spx_blend = AC3_SPX_BLEND(get_bits(bc, 5));
874 master_spx_coord = get_bits(bc, 2) * 3;
876 bin = s->spx_src_start_freq;
877 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
878 int bandsize = s->spx_band_sizes[bnd];
879 int spx_coord_exp, spx_coord_mant;
880 INTFLOAT nratio, sblend, nblend;
882 /* calculate blending factors */
883 int64_t accu = ((bin << 23) + (bandsize << 22))
884 * (int64_t)s->spx_dst_end_freq;
885 nratio = (int)(accu >> 32);
886 nratio -= spx_blend << 18;
891 } else if (nratio > 0x7fffff) {
892 nblend = 14529495; // sqrt(3) in FP.23
895 nblend = fixed_sqrt(nratio, 23);
896 accu = (int64_t)nblend * 1859775393;
897 nblend = (int)((accu + (1<<29)) >> 30);
898 sblend = fixed_sqrt(0x800000 - nratio, 23);
903 /* calculate blending factors */
904 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
905 nratio = av_clipf(nratio, 0.0f, 1.0f);
906 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
907 // to give unity variance
908 sblend = sqrtf(1.0f - nratio);
912 /* decode spx coordinates */
913 spx_coord_exp = get_bits(bc, 4);
914 spx_coord_mant = get_bits(bc, 2);
915 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
916 else spx_coord_mant += 4;
917 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
919 /* multiply noise and signal blending factors by spx coordinate */
921 accu = (int64_t)nblend * spx_coord_mant;
922 s->spx_noise_blend[ch][bnd] = (int)((accu + (1<<22)) >> 23);
923 accu = (int64_t)sblend * spx_coord_mant;
924 s->spx_signal_blend[ch][bnd] = (int)((accu + (1<<22)) >> 23);
926 spx_coord = spx_coord_mant * (1.0f / (1 << 23));
927 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
928 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
933 s->first_spx_coords[ch] = 1;
939 * Decode a single audio block from the AC-3 bitstream.
941 static int decode_audio_block(AC3DecodeContext *s, int blk)
943 int fbw_channels = s->fbw_channels;
944 int channel_mode = s->channel_mode;
945 int i, bnd, seg, ch, ret;
946 int different_transforms;
949 GetBitContext *gbc = &s->gbc;
950 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
952 /* block switch flags */
953 different_transforms = 0;
954 if (s->block_switch_syntax) {
955 for (ch = 1; ch <= fbw_channels; ch++) {
956 s->block_switch[ch] = get_bits1(gbc);
957 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
958 different_transforms = 1;
962 /* dithering flags */
963 if (s->dither_flag_syntax) {
964 for (ch = 1; ch <= fbw_channels; ch++) {
965 s->dither_flag[ch] = get_bits1(gbc);
970 i = !s->channel_mode;
972 if (get_bits1(gbc)) {
973 /* Allow asymmetric application of DRC when drc_scale > 1.
974 Amplification of quiet sounds is enhanced */
975 int range_bits = get_bits(gbc, 8);
976 INTFLOAT range = AC3_RANGE(range_bits);
977 if (range_bits <= 127 || s->drc_scale <= 1.0)
978 s->dynamic_range[i] = AC3_DYNAMIC_RANGE(range);
980 s->dynamic_range[i] = range;
981 } else if (blk == 0) {
982 s->dynamic_range[i] = AC3_DYNAMIC_RANGE1;
986 /* spectral extension strategy */
987 if (s->eac3 && (!blk || get_bits1(gbc))) {
988 s->spx_in_use = get_bits1(gbc);
990 if ((ret = spx_strategy(s, blk)) < 0)
994 if (!s->eac3 || !s->spx_in_use) {
996 for (ch = 1; ch <= fbw_channels; ch++) {
997 s->channel_uses_spx[ch] = 0;
998 s->first_spx_coords[ch] = 1;
1002 /* spectral extension coordinates */
1006 /* coupling strategy */
1007 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
1008 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1010 s->cpl_in_use[blk] = get_bits1(gbc);
1011 if (s->cpl_in_use[blk]) {
1012 /* coupling in use */
1013 int cpl_start_subband, cpl_end_subband;
1015 if (channel_mode < AC3_CHMODE_STEREO) {
1016 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
1017 return AVERROR_INVALIDDATA;
1020 /* check for enhanced coupling */
1021 if (s->eac3 && get_bits1(gbc)) {
1022 /* TODO: parse enhanced coupling strategy info */
1023 avpriv_request_sample(s->avctx, "Enhanced coupling");
1024 return AVERROR_PATCHWELCOME;
1027 /* determine which channels are coupled */
1028 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
1029 s->channel_in_cpl[1] = 1;
1030 s->channel_in_cpl[2] = 1;
1032 for (ch = 1; ch <= fbw_channels; ch++)
1033 s->channel_in_cpl[ch] = get_bits1(gbc);
1036 /* phase flags in use */
1037 if (channel_mode == AC3_CHMODE_STEREO)
1038 s->phase_flags_in_use = get_bits1(gbc);
1040 /* coupling frequency range */
1041 cpl_start_subband = get_bits(gbc, 4);
1042 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
1043 get_bits(gbc, 4) + 3;
1044 if (cpl_start_subband >= cpl_end_subband) {
1045 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
1046 cpl_start_subband, cpl_end_subband);
1047 return AVERROR_INVALIDDATA;
1049 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
1050 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
1052 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
1054 ff_eac3_default_cpl_band_struct,
1055 &s->num_cpl_bands, s->cpl_band_sizes);
1057 /* coupling not in use */
1058 for (ch = 1; ch <= fbw_channels; ch++) {
1059 s->channel_in_cpl[ch] = 0;
1060 s->first_cpl_coords[ch] = 1;
1062 s->first_cpl_leak = s->eac3;
1063 s->phase_flags_in_use = 0;
1065 } else if (!s->eac3) {
1067 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
1068 "be present in block 0\n");
1069 return AVERROR_INVALIDDATA;
1071 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
1074 cpl_in_use = s->cpl_in_use[blk];
1076 /* coupling coordinates */
1078 int cpl_coords_exist = 0;
1080 for (ch = 1; ch <= fbw_channels; ch++) {
1081 if (s->channel_in_cpl[ch]) {
1082 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
1083 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
1084 s->first_cpl_coords[ch] = 0;
1085 cpl_coords_exist = 1;
1086 master_cpl_coord = 3 * get_bits(gbc, 2);
1087 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1088 cpl_coord_exp = get_bits(gbc, 4);
1089 cpl_coord_mant = get_bits(gbc, 4);
1090 if (cpl_coord_exp == 15)
1091 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
1093 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
1094 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
1097 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
1098 "be present in block 0\n");
1099 return AVERROR_INVALIDDATA;
1102 /* channel not in coupling */
1103 s->first_cpl_coords[ch] = 1;
1107 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1108 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1109 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1114 /* stereo rematrixing strategy and band structure */
1115 if (channel_mode == AC3_CHMODE_STEREO) {
1116 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1117 s->num_rematrixing_bands = 4;
1118 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1119 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1120 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1121 s->num_rematrixing_bands--;
1123 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
1124 s->rematrixing_flags[bnd] = get_bits1(gbc);
1126 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
1127 "new rematrixing strategy not present in block 0\n");
1128 s->num_rematrixing_bands = 0;
1132 /* exponent strategies for each channel */
1133 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1135 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1136 if (s->exp_strategy[blk][ch] != EXP_REUSE)
1137 bit_alloc_stages[ch] = 3;
1140 /* channel bandwidth */
1141 for (ch = 1; ch <= fbw_channels; ch++) {
1142 s->start_freq[ch] = 0;
1143 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1145 int prev = s->end_freq[ch];
1146 if (s->channel_in_cpl[ch])
1147 s->end_freq[ch] = s->start_freq[CPL_CH];
1148 else if (s->channel_uses_spx[ch])
1149 s->end_freq[ch] = s->spx_src_start_freq;
1151 int bandwidth_code = get_bits(gbc, 6);
1152 if (bandwidth_code > 60) {
1153 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1154 return AVERROR_INVALIDDATA;
1156 s->end_freq[ch] = bandwidth_code * 3 + 73;
1158 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1159 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1160 if (blk > 0 && s->end_freq[ch] != prev)
1161 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1164 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1165 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1166 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1169 /* decode exponents for each channel */
1170 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1171 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1172 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1173 if (decode_exponents(s, gbc, s->exp_strategy[blk][ch],
1174 s->num_exp_groups[ch], s->dexps[ch][0],
1175 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1176 return AVERROR_INVALIDDATA;
1178 if (ch != CPL_CH && ch != s->lfe_ch)
1179 skip_bits(gbc, 2); /* skip gainrng */
1183 /* bit allocation information */
1184 if (s->bit_allocation_syntax) {
1185 if (get_bits1(gbc)) {
1186 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1187 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1188 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1189 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1190 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1191 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1192 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1194 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1195 "be present in block 0\n");
1196 return AVERROR_INVALIDDATA;
1200 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1201 if (!s->eac3 || !blk) {
1202 if (s->snr_offset_strategy && get_bits1(gbc)) {
1205 csnr = (get_bits(gbc, 6) - 15) << 4;
1206 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1208 if (ch == i || s->snr_offset_strategy == 2)
1209 snr = (csnr + get_bits(gbc, 4)) << 2;
1210 /* run at least last bit allocation stage if snr offset changes */
1211 if (blk && s->snr_offset[ch] != snr) {
1212 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1214 s->snr_offset[ch] = snr;
1216 /* fast gain (normal AC-3 only) */
1218 int prev = s->fast_gain[ch];
1219 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1220 /* run last 2 bit allocation stages if fast gain changes */
1221 if (blk && prev != s->fast_gain[ch])
1222 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1225 } else if (!s->eac3 && !blk) {
1226 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1227 return AVERROR_INVALIDDATA;
1231 /* fast gain (E-AC-3 only) */
1232 if (s->fast_gain_syntax && get_bits1(gbc)) {
1233 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1234 int prev = s->fast_gain[ch];
1235 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1236 /* run last 2 bit allocation stages if fast gain changes */
1237 if (blk && prev != s->fast_gain[ch])
1238 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1240 } else if (s->eac3 && !blk) {
1241 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1242 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1245 /* E-AC-3 to AC-3 converter SNR offset */
1246 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1247 skip_bits(gbc, 10); // skip converter snr offset
1250 /* coupling leak information */
1252 if (s->first_cpl_leak || get_bits1(gbc)) {
1253 int fl = get_bits(gbc, 3);
1254 int sl = get_bits(gbc, 3);
1255 /* run last 2 bit allocation stages for coupling channel if
1256 coupling leak changes */
1257 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1258 sl != s->bit_alloc_params.cpl_slow_leak)) {
1259 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1261 s->bit_alloc_params.cpl_fast_leak = fl;
1262 s->bit_alloc_params.cpl_slow_leak = sl;
1263 } else if (!s->eac3 && !blk) {
1264 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1265 "be present in block 0\n");
1266 return AVERROR_INVALIDDATA;
1268 s->first_cpl_leak = 0;
1271 /* delta bit allocation information */
1272 if (s->dba_syntax && get_bits1(gbc)) {
1273 /* delta bit allocation exists (strategy) */
1274 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1275 s->dba_mode[ch] = get_bits(gbc, 2);
1276 if (s->dba_mode[ch] == DBA_RESERVED) {
1277 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1278 return AVERROR_INVALIDDATA;
1280 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1282 /* channel delta offset, len and bit allocation */
1283 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1284 if (s->dba_mode[ch] == DBA_NEW) {
1285 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1286 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1287 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1288 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1289 s->dba_values[ch][seg] = get_bits(gbc, 3);
1291 /* run last 2 bit allocation stages if new dba values */
1292 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1295 } else if (blk == 0) {
1296 for (ch = 0; ch <= s->channels; ch++) {
1297 s->dba_mode[ch] = DBA_NONE;
1301 /* Bit allocation */
1302 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1303 if (bit_alloc_stages[ch] > 2) {
1304 /* Exponent mapping into PSD and PSD integration */
1305 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1306 s->start_freq[ch], s->end_freq[ch],
1307 s->psd[ch], s->band_psd[ch]);
1309 if (bit_alloc_stages[ch] > 1) {
1310 /* Compute excitation function, Compute masking curve, and
1311 Apply delta bit allocation */
1312 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1313 s->start_freq[ch], s->end_freq[ch],
1314 s->fast_gain[ch], (ch == s->lfe_ch),
1315 s->dba_mode[ch], s->dba_nsegs[ch],
1316 s->dba_offsets[ch], s->dba_lengths[ch],
1317 s->dba_values[ch], s->mask[ch])) {
1318 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1319 return AVERROR_INVALIDDATA;
1322 if (bit_alloc_stages[ch] > 0) {
1323 /* Compute bit allocation */
1324 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1325 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1326 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1327 s->start_freq[ch], s->end_freq[ch],
1329 s->bit_alloc_params.floor,
1330 bap_tab, s->bap[ch]);
1334 /* unused dummy data */
1335 if (s->skip_syntax && get_bits1(gbc)) {
1336 int skipl = get_bits(gbc, 9);
1341 /* unpack the transform coefficients
1342 this also uncouples channels if coupling is in use. */
1343 decode_transform_coeffs(s, blk);
1345 /* TODO: generate enhanced coupling coordinates and uncouple */
1347 /* recover coefficients if rematrixing is in use */
1348 if (s->channel_mode == AC3_CHMODE_STEREO)
1351 /* apply scaling to coefficients (headroom, dynrng) */
1352 for (ch = 1; ch <= s->channels; ch++) {
1353 int audio_channel = 0;
1355 if (s->channel_mode == AC3_CHMODE_DUALMONO)
1356 audio_channel = 2-ch;
1357 if (s->heavy_compression && s->compression_exists[audio_channel])
1358 gain = s->heavy_dynamic_range[audio_channel];
1360 gain = s->dynamic_range[audio_channel];
1363 scale_coefs(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1365 if (s->target_level != 0)
1366 gain = gain * s->level_gain[audio_channel];
1367 gain *= 1.0 / 4194304.0f;
1368 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1369 s->fixed_coeffs[ch], gain, 256);
1373 /* apply spectral extension to high frequency bins */
1374 if (CONFIG_EAC3_DECODER && s->spx_in_use) {
1375 ff_eac3_apply_spectral_extension(s);
1378 /* downmix and MDCT. order depends on whether block switching is used for
1379 any channel in this block. this is because coefficients for the long
1380 and short transforms cannot be mixed. */
1381 downmix_output = s->channels != s->out_channels &&
1382 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1383 s->fbw_channels == s->out_channels);
1384 if (different_transforms) {
1385 /* the delay samples have already been downmixed, so we upmix the delay
1386 samples in order to reconstruct all channels before downmixing. */
1392 do_imdct(s, s->channels);
1394 if (downmix_output) {
1396 ac3_downmix_c_fixed16(s->outptr, s->downmix_coeffs,
1397 s->out_channels, s->fbw_channels, 256);
1399 s->ac3dsp.downmix(s->outptr, s->downmix_coeffs,
1400 s->out_channels, s->fbw_channels, 256);
1404 if (downmix_output) {
1405 s->ac3dsp.AC3_RENAME(downmix)(s->xcfptr + 1, s->downmix_coeffs,
1406 s->out_channels, s->fbw_channels, 256);
1409 if (downmix_output && !s->downmixed) {
1411 s->ac3dsp.AC3_RENAME(downmix)(s->dlyptr, s->downmix_coeffs,
1412 s->out_channels, s->fbw_channels, 128);
1415 do_imdct(s, s->out_channels);
1422 * Decode a single AC-3 frame.
1424 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1425 int *got_frame_ptr, AVPacket *avpkt)
1427 AVFrame *frame = data;
1428 const uint8_t *buf = avpkt->data;
1429 int buf_size = avpkt->size;
1430 AC3DecodeContext *s = avctx->priv_data;
1431 int blk, ch, err, ret;
1432 const uint8_t *channel_map;
1433 const SHORTFLOAT *output[AC3_MAX_CHANNELS];
1434 enum AVMatrixEncoding matrix_encoding;
1435 AVDownmixInfo *downmix_info;
1437 /* copy input buffer to decoder context to avoid reading past the end
1438 of the buffer, which can be caused by a damaged input stream. */
1439 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1440 // seems to be byte-swapped AC-3
1441 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1442 s->bdsp.bswap16_buf((uint16_t *) s->input_buffer,
1443 (const uint16_t *) buf, cnt);
1445 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1447 /* if consistent noise generation is enabled, seed the linear feedback generator
1448 * with the contents of the AC-3 frame so that the noise is identical across
1449 * decodes given the same AC-3 frame data, for use with non-linear edititing software. */
1450 if (s->consistent_noise_generation)
1451 av_lfg_init_from_data(&s->dith_state, s->input_buffer, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1453 buf = s->input_buffer;
1454 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1455 if ((ret = init_get_bits8(&s->gbc, buf, buf_size)) < 0)
1458 /* parse the syncinfo */
1459 err = parse_frame_header(s);
1463 case AAC_AC3_PARSE_ERROR_SYNC:
1464 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1465 return AVERROR_INVALIDDATA;
1466 case AAC_AC3_PARSE_ERROR_BSID:
1467 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1469 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1470 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1472 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1473 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1475 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1476 /* skip frame if CRC is ok. otherwise use error concealment. */
1477 /* TODO: add support for substreams and dependent frames */
1478 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1479 av_log(avctx, AV_LOG_DEBUG,
1480 "unsupported frame type %d: skipping frame\n",
1485 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1488 case AAC_AC3_PARSE_ERROR_CRC:
1489 case AAC_AC3_PARSE_ERROR_CHANNEL_CFG:
1491 default: // Normal AVERROR do not try to recover.
1496 /* check that reported frame size fits in input buffer */
1497 if (s->frame_size > buf_size) {
1498 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1499 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1500 } else if (avctx->err_recognition & (AV_EF_CRCCHECK|AV_EF_CAREFUL)) {
1501 /* check for crc mismatch */
1502 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1503 s->frame_size - 2)) {
1504 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1505 if (avctx->err_recognition & AV_EF_EXPLODE)
1506 return AVERROR_INVALIDDATA;
1507 err = AAC_AC3_PARSE_ERROR_CRC;
1512 /* if frame is ok, set audio parameters */
1514 avctx->sample_rate = s->sample_rate;
1515 avctx->bit_rate = s->bit_rate;
1518 /* channel config */
1519 if (!err || (s->channels && s->out_channels != s->channels)) {
1520 s->out_channels = s->channels;
1521 s->output_mode = s->channel_mode;
1523 s->output_mode |= AC3_OUTPUT_LFEON;
1524 if (s->channels > 1 &&
1525 avctx->request_channel_layout == AV_CH_LAYOUT_MONO) {
1526 s->out_channels = 1;
1527 s->output_mode = AC3_CHMODE_MONO;
1528 } else if (s->channels > 2 &&
1529 avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) {
1530 s->out_channels = 2;
1531 s->output_mode = AC3_CHMODE_STEREO;
1534 s->loro_center_mix_level = gain_levels[s-> center_mix_level];
1535 s->loro_surround_mix_level = gain_levels[s->surround_mix_level];
1536 s->ltrt_center_mix_level = LEVEL_MINUS_3DB;
1537 s->ltrt_surround_mix_level = LEVEL_MINUS_3DB;
1538 /* set downmixing coefficients if needed */
1539 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1540 s->fbw_channels == s->out_channels)) {
1541 set_downmix_coeffs(s);
1543 } else if (!s->channels) {
1544 av_log(avctx, AV_LOG_ERROR, "unable to determine channel mode\n");
1545 return AVERROR_INVALIDDATA;
1547 avctx->channels = s->out_channels;
1548 avctx->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode & ~AC3_OUTPUT_LFEON];
1549 if (s->output_mode & AC3_OUTPUT_LFEON)
1550 avctx->channel_layout |= AV_CH_LOW_FREQUENCY;
1552 /* set audio service type based on bitstream mode for AC-3 */
1553 avctx->audio_service_type = s->bitstream_mode;
1554 if (s->bitstream_mode == 0x7 && s->channels > 1)
1555 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1557 /* get output buffer */
1558 frame->nb_samples = s->num_blocks * AC3_BLOCK_SIZE;
1559 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
1562 /* decode the audio blocks */
1563 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1564 for (ch = 0; ch < AC3_MAX_CHANNELS; ch++) {
1565 output[ch] = s->output[ch];
1566 s->outptr[ch] = s->output[ch];
1568 for (ch = 0; ch < s->channels; ch++) {
1569 if (ch < s->out_channels)
1570 s->outptr[channel_map[ch]] = (SHORTFLOAT *)frame->data[ch];
1572 for (blk = 0; blk < s->num_blocks; blk++) {
1573 if (!err && decode_audio_block(s, blk)) {
1574 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1578 for (ch = 0; ch < s->out_channels; ch++)
1579 memcpy(((SHORTFLOAT*)frame->data[ch]) + AC3_BLOCK_SIZE*blk, output[ch], AC3_BLOCK_SIZE*sizeof(SHORTFLOAT));
1580 for (ch = 0; ch < s->out_channels; ch++)
1581 output[ch] = s->outptr[channel_map[ch]];
1582 for (ch = 0; ch < s->out_channels; ch++) {
1583 if (!ch || channel_map[ch])
1584 s->outptr[channel_map[ch]] += AC3_BLOCK_SIZE;
1588 av_frame_set_decode_error_flags(frame, err ? FF_DECODE_ERROR_INVALID_BITSTREAM : 0);
1590 /* keep last block for error concealment in next frame */
1591 for (ch = 0; ch < s->out_channels; ch++)
1592 memcpy(s->output[ch], output[ch], AC3_BLOCK_SIZE*sizeof(SHORTFLOAT));
1597 * Check whether the input layout is compatible, and make sure we're not
1598 * downmixing (else the matrix encoding is no longer applicable).
1600 matrix_encoding = AV_MATRIX_ENCODING_NONE;
1601 if (s->channel_mode == AC3_CHMODE_STEREO &&
1602 s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) {
1603 if (s->dolby_surround_mode == AC3_DSURMOD_ON)
1604 matrix_encoding = AV_MATRIX_ENCODING_DOLBY;
1605 else if (s->dolby_headphone_mode == AC3_DHEADPHONMOD_ON)
1606 matrix_encoding = AV_MATRIX_ENCODING_DOLBYHEADPHONE;
1607 } else if (s->channel_mode >= AC3_CHMODE_2F2R &&
1608 s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) {
1609 switch (s->dolby_surround_ex_mode) {
1610 case AC3_DSUREXMOD_ON: // EX or PLIIx
1611 matrix_encoding = AV_MATRIX_ENCODING_DOLBYEX;
1613 case AC3_DSUREXMOD_PLIIZ:
1614 matrix_encoding = AV_MATRIX_ENCODING_DPLIIZ;
1616 default: // not indicated or off
1620 if ((ret = ff_side_data_update_matrix_encoding(frame, matrix_encoding)) < 0)
1624 if ((downmix_info = av_downmix_info_update_side_data(frame))) {
1625 switch (s->preferred_downmix) {
1626 case AC3_DMIXMOD_LTRT:
1627 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_LTRT;
1629 case AC3_DMIXMOD_LORO:
1630 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_LORO;
1632 case AC3_DMIXMOD_DPLII:
1633 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_DPLII;
1636 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_UNKNOWN;
1639 downmix_info->center_mix_level = gain_levels[s-> center_mix_level];
1640 downmix_info->center_mix_level_ltrt = gain_levels[s-> center_mix_level_ltrt];
1641 downmix_info->surround_mix_level = gain_levels[s-> surround_mix_level];
1642 downmix_info->surround_mix_level_ltrt = gain_levels[s->surround_mix_level_ltrt];
1643 if (s->lfe_mix_level_exists)
1644 downmix_info->lfe_mix_level = gain_levels_lfe[s->lfe_mix_level];
1646 downmix_info->lfe_mix_level = 0.0; // -inf dB
1648 return AVERROR(ENOMEM);
1652 return FFMIN(buf_size, s->frame_size);
1656 * Uninitialize the AC-3 decoder.
1658 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1660 AC3DecodeContext *s = avctx->priv_data;
1661 ff_mdct_end(&s->imdct_512);
1662 ff_mdct_end(&s->imdct_256);
1668 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1669 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)