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 inline void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk,
597 int ch, mant_groups *m)
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 inline 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;
938 static inline int coupling_strategy(AC3DecodeContext *s, int blk,
939 uint8_t *bit_alloc_stages)
941 GetBitContext *bc = &s->gbc;
942 int fbw_channels = s->fbw_channels;
943 int channel_mode = s->channel_mode;
946 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
948 s->cpl_in_use[blk] = get_bits1(bc);
949 if (s->cpl_in_use[blk]) {
950 /* coupling in use */
951 int cpl_start_subband, cpl_end_subband;
953 if (channel_mode < AC3_CHMODE_STEREO) {
954 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
955 return AVERROR_INVALIDDATA;
958 /* check for enhanced coupling */
959 if (s->eac3 && get_bits1(bc)) {
960 /* TODO: parse enhanced coupling strategy info */
961 avpriv_request_sample(s->avctx, "Enhanced coupling");
962 return AVERROR_PATCHWELCOME;
965 /* determine which channels are coupled */
966 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
967 s->channel_in_cpl[1] = 1;
968 s->channel_in_cpl[2] = 1;
970 for (ch = 1; ch <= fbw_channels; ch++)
971 s->channel_in_cpl[ch] = get_bits1(bc);
974 /* phase flags in use */
975 if (channel_mode == AC3_CHMODE_STEREO)
976 s->phase_flags_in_use = get_bits1(bc);
978 /* coupling frequency range */
979 cpl_start_subband = get_bits(bc, 4);
980 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
982 if (cpl_start_subband >= cpl_end_subband) {
983 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
984 cpl_start_subband, cpl_end_subband);
985 return AVERROR_INVALIDDATA;
987 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
988 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
990 decode_band_structure(bc, blk, s->eac3, 0, cpl_start_subband,
992 ff_eac3_default_cpl_band_struct,
993 &s->num_cpl_bands, s->cpl_band_sizes);
995 /* coupling not in use */
996 for (ch = 1; ch <= fbw_channels; ch++) {
997 s->channel_in_cpl[ch] = 0;
998 s->first_cpl_coords[ch] = 1;
1000 s->first_cpl_leak = s->eac3;
1001 s->phase_flags_in_use = 0;
1007 static inline int coupling_coordinates(AC3DecodeContext *s, int blk)
1009 GetBitContext *bc = &s->gbc;
1010 int fbw_channels = s->fbw_channels;
1012 int cpl_coords_exist = 0;
1014 for (ch = 1; ch <= fbw_channels; ch++) {
1015 if (s->channel_in_cpl[ch]) {
1016 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(bc)) {
1017 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
1018 s->first_cpl_coords[ch] = 0;
1019 cpl_coords_exist = 1;
1020 master_cpl_coord = 3 * get_bits(bc, 2);
1021 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1022 cpl_coord_exp = get_bits(bc, 4);
1023 cpl_coord_mant = get_bits(bc, 4);
1024 if (cpl_coord_exp == 15)
1025 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
1027 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
1028 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
1031 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
1032 "be present in block 0\n");
1033 return AVERROR_INVALIDDATA;
1036 /* channel not in coupling */
1037 s->first_cpl_coords[ch] = 1;
1041 if (s->channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1042 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1043 s->phase_flags[bnd] = s->phase_flags_in_use ? get_bits1(bc) : 0;
1051 * Decode a single audio block from the AC-3 bitstream.
1053 static int decode_audio_block(AC3DecodeContext *s, int blk)
1055 int fbw_channels = s->fbw_channels;
1056 int channel_mode = s->channel_mode;
1057 int i, bnd, seg, ch, ret;
1058 int different_transforms;
1061 GetBitContext *gbc = &s->gbc;
1062 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
1064 /* block switch flags */
1065 different_transforms = 0;
1066 if (s->block_switch_syntax) {
1067 for (ch = 1; ch <= fbw_channels; ch++) {
1068 s->block_switch[ch] = get_bits1(gbc);
1069 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
1070 different_transforms = 1;
1074 /* dithering flags */
1075 if (s->dither_flag_syntax) {
1076 for (ch = 1; ch <= fbw_channels; ch++) {
1077 s->dither_flag[ch] = get_bits1(gbc);
1082 i = !s->channel_mode;
1084 if (get_bits1(gbc)) {
1085 /* Allow asymmetric application of DRC when drc_scale > 1.
1086 Amplification of quiet sounds is enhanced */
1087 int range_bits = get_bits(gbc, 8);
1088 INTFLOAT range = AC3_RANGE(range_bits);
1089 if (range_bits <= 127 || s->drc_scale <= 1.0)
1090 s->dynamic_range[i] = AC3_DYNAMIC_RANGE(range);
1092 s->dynamic_range[i] = range;
1093 } else if (blk == 0) {
1094 s->dynamic_range[i] = AC3_DYNAMIC_RANGE1;
1098 /* spectral extension strategy */
1099 if (s->eac3 && (!blk || get_bits1(gbc))) {
1100 s->spx_in_use = get_bits1(gbc);
1101 if (s->spx_in_use) {
1102 if ((ret = spx_strategy(s, blk)) < 0)
1106 if (!s->eac3 || !s->spx_in_use) {
1108 for (ch = 1; ch <= fbw_channels; ch++) {
1109 s->channel_uses_spx[ch] = 0;
1110 s->first_spx_coords[ch] = 1;
1114 /* spectral extension coordinates */
1118 /* coupling strategy */
1119 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
1120 if ((ret = coupling_strategy(s, blk, bit_alloc_stages)) < 0)
1122 } else if (!s->eac3) {
1124 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
1125 "be present in block 0\n");
1126 return AVERROR_INVALIDDATA;
1128 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
1131 cpl_in_use = s->cpl_in_use[blk];
1133 /* coupling coordinates */
1135 if ((ret = coupling_coordinates(s, blk)) < 0)
1139 /* stereo rematrixing strategy and band structure */
1140 if (channel_mode == AC3_CHMODE_STEREO) {
1141 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1142 s->num_rematrixing_bands = 4;
1143 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1144 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1145 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1146 s->num_rematrixing_bands--;
1148 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
1149 s->rematrixing_flags[bnd] = get_bits1(gbc);
1151 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
1152 "new rematrixing strategy not present in block 0\n");
1153 s->num_rematrixing_bands = 0;
1157 /* exponent strategies for each channel */
1158 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1160 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1161 if (s->exp_strategy[blk][ch] != EXP_REUSE)
1162 bit_alloc_stages[ch] = 3;
1165 /* channel bandwidth */
1166 for (ch = 1; ch <= fbw_channels; ch++) {
1167 s->start_freq[ch] = 0;
1168 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1170 int prev = s->end_freq[ch];
1171 if (s->channel_in_cpl[ch])
1172 s->end_freq[ch] = s->start_freq[CPL_CH];
1173 else if (s->channel_uses_spx[ch])
1174 s->end_freq[ch] = s->spx_src_start_freq;
1176 int bandwidth_code = get_bits(gbc, 6);
1177 if (bandwidth_code > 60) {
1178 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1179 return AVERROR_INVALIDDATA;
1181 s->end_freq[ch] = bandwidth_code * 3 + 73;
1183 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1184 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1185 if (blk > 0 && s->end_freq[ch] != prev)
1186 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1189 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1190 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1191 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1194 /* decode exponents for each channel */
1195 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1196 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1197 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1198 if (decode_exponents(s, gbc, s->exp_strategy[blk][ch],
1199 s->num_exp_groups[ch], s->dexps[ch][0],
1200 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1201 return AVERROR_INVALIDDATA;
1203 if (ch != CPL_CH && ch != s->lfe_ch)
1204 skip_bits(gbc, 2); /* skip gainrng */
1208 /* bit allocation information */
1209 if (s->bit_allocation_syntax) {
1210 if (get_bits1(gbc)) {
1211 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1212 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1213 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1214 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1215 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1216 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1217 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1219 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1220 "be present in block 0\n");
1221 return AVERROR_INVALIDDATA;
1225 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1226 if (!s->eac3 || !blk) {
1227 if (s->snr_offset_strategy && get_bits1(gbc)) {
1230 csnr = (get_bits(gbc, 6) - 15) << 4;
1231 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1233 if (ch == i || s->snr_offset_strategy == 2)
1234 snr = (csnr + get_bits(gbc, 4)) << 2;
1235 /* run at least last bit allocation stage if snr offset changes */
1236 if (blk && s->snr_offset[ch] != snr) {
1237 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1239 s->snr_offset[ch] = snr;
1241 /* fast gain (normal AC-3 only) */
1243 int prev = s->fast_gain[ch];
1244 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1245 /* run last 2 bit allocation stages if fast gain changes */
1246 if (blk && prev != s->fast_gain[ch])
1247 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1250 } else if (!s->eac3 && !blk) {
1251 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1252 return AVERROR_INVALIDDATA;
1256 /* fast gain (E-AC-3 only) */
1257 if (s->fast_gain_syntax && get_bits1(gbc)) {
1258 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1259 int prev = s->fast_gain[ch];
1260 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1261 /* run last 2 bit allocation stages if fast gain changes */
1262 if (blk && prev != s->fast_gain[ch])
1263 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1265 } else if (s->eac3 && !blk) {
1266 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1267 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1270 /* E-AC-3 to AC-3 converter SNR offset */
1271 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1272 skip_bits(gbc, 10); // skip converter snr offset
1275 /* coupling leak information */
1277 if (s->first_cpl_leak || get_bits1(gbc)) {
1278 int fl = get_bits(gbc, 3);
1279 int sl = get_bits(gbc, 3);
1280 /* run last 2 bit allocation stages for coupling channel if
1281 coupling leak changes */
1282 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1283 sl != s->bit_alloc_params.cpl_slow_leak)) {
1284 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1286 s->bit_alloc_params.cpl_fast_leak = fl;
1287 s->bit_alloc_params.cpl_slow_leak = sl;
1288 } else if (!s->eac3 && !blk) {
1289 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1290 "be present in block 0\n");
1291 return AVERROR_INVALIDDATA;
1293 s->first_cpl_leak = 0;
1296 /* delta bit allocation information */
1297 if (s->dba_syntax && get_bits1(gbc)) {
1298 /* delta bit allocation exists (strategy) */
1299 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1300 s->dba_mode[ch] = get_bits(gbc, 2);
1301 if (s->dba_mode[ch] == DBA_RESERVED) {
1302 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1303 return AVERROR_INVALIDDATA;
1305 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1307 /* channel delta offset, len and bit allocation */
1308 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1309 if (s->dba_mode[ch] == DBA_NEW) {
1310 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1311 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1312 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1313 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1314 s->dba_values[ch][seg] = get_bits(gbc, 3);
1316 /* run last 2 bit allocation stages if new dba values */
1317 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1320 } else if (blk == 0) {
1321 for (ch = 0; ch <= s->channels; ch++) {
1322 s->dba_mode[ch] = DBA_NONE;
1326 /* Bit allocation */
1327 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1328 if (bit_alloc_stages[ch] > 2) {
1329 /* Exponent mapping into PSD and PSD integration */
1330 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1331 s->start_freq[ch], s->end_freq[ch],
1332 s->psd[ch], s->band_psd[ch]);
1334 if (bit_alloc_stages[ch] > 1) {
1335 /* Compute excitation function, Compute masking curve, and
1336 Apply delta bit allocation */
1337 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1338 s->start_freq[ch], s->end_freq[ch],
1339 s->fast_gain[ch], (ch == s->lfe_ch),
1340 s->dba_mode[ch], s->dba_nsegs[ch],
1341 s->dba_offsets[ch], s->dba_lengths[ch],
1342 s->dba_values[ch], s->mask[ch])) {
1343 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1344 return AVERROR_INVALIDDATA;
1347 if (bit_alloc_stages[ch] > 0) {
1348 /* Compute bit allocation */
1349 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1350 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1351 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1352 s->start_freq[ch], s->end_freq[ch],
1354 s->bit_alloc_params.floor,
1355 bap_tab, s->bap[ch]);
1359 /* unused dummy data */
1360 if (s->skip_syntax && get_bits1(gbc)) {
1361 int skipl = get_bits(gbc, 9);
1362 skip_bits_long(gbc, 8 * skipl);
1365 /* unpack the transform coefficients
1366 this also uncouples channels if coupling is in use. */
1367 decode_transform_coeffs(s, blk);
1369 /* TODO: generate enhanced coupling coordinates and uncouple */
1371 /* recover coefficients if rematrixing is in use */
1372 if (s->channel_mode == AC3_CHMODE_STEREO)
1375 /* apply scaling to coefficients (headroom, dynrng) */
1376 for (ch = 1; ch <= s->channels; ch++) {
1377 int audio_channel = 0;
1379 if (s->channel_mode == AC3_CHMODE_DUALMONO)
1380 audio_channel = 2-ch;
1381 if (s->heavy_compression && s->compression_exists[audio_channel])
1382 gain = s->heavy_dynamic_range[audio_channel];
1384 gain = s->dynamic_range[audio_channel];
1387 scale_coefs(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1389 if (s->target_level != 0)
1390 gain = gain * s->level_gain[audio_channel];
1391 gain *= 1.0 / 4194304.0f;
1392 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1393 s->fixed_coeffs[ch], gain, 256);
1397 /* apply spectral extension to high frequency bins */
1398 if (CONFIG_EAC3_DECODER && s->spx_in_use) {
1399 ff_eac3_apply_spectral_extension(s);
1402 /* downmix and MDCT. order depends on whether block switching is used for
1403 any channel in this block. this is because coefficients for the long
1404 and short transforms cannot be mixed. */
1405 downmix_output = s->channels != s->out_channels &&
1406 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1407 s->fbw_channels == s->out_channels);
1408 if (different_transforms) {
1409 /* the delay samples have already been downmixed, so we upmix the delay
1410 samples in order to reconstruct all channels before downmixing. */
1416 do_imdct(s, s->channels);
1418 if (downmix_output) {
1420 ac3_downmix_c_fixed16(s->outptr, s->downmix_coeffs,
1421 s->out_channels, s->fbw_channels, 256);
1423 s->ac3dsp.downmix(s->outptr, s->downmix_coeffs,
1424 s->out_channels, s->fbw_channels, 256);
1428 if (downmix_output) {
1429 s->ac3dsp.AC3_RENAME(downmix)(s->xcfptr + 1, s->downmix_coeffs,
1430 s->out_channels, s->fbw_channels, 256);
1433 if (downmix_output && !s->downmixed) {
1435 s->ac3dsp.AC3_RENAME(downmix)(s->dlyptr, s->downmix_coeffs,
1436 s->out_channels, s->fbw_channels, 128);
1439 do_imdct(s, s->out_channels);
1446 * Decode a single AC-3 frame.
1448 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1449 int *got_frame_ptr, AVPacket *avpkt)
1451 AVFrame *frame = data;
1452 const uint8_t *buf = avpkt->data;
1453 int buf_size = avpkt->size;
1454 AC3DecodeContext *s = avctx->priv_data;
1455 int blk, ch, err, ret;
1456 const uint8_t *channel_map;
1457 const SHORTFLOAT *output[AC3_MAX_CHANNELS];
1458 enum AVMatrixEncoding matrix_encoding;
1459 AVDownmixInfo *downmix_info;
1461 /* copy input buffer to decoder context to avoid reading past the end
1462 of the buffer, which can be caused by a damaged input stream. */
1463 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1464 // seems to be byte-swapped AC-3
1465 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1466 s->bdsp.bswap16_buf((uint16_t *) s->input_buffer,
1467 (const uint16_t *) buf, cnt);
1469 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1471 /* if consistent noise generation is enabled, seed the linear feedback generator
1472 * with the contents of the AC-3 frame so that the noise is identical across
1473 * decodes given the same AC-3 frame data, for use with non-linear edititing software. */
1474 if (s->consistent_noise_generation)
1475 av_lfg_init_from_data(&s->dith_state, s->input_buffer, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1477 buf = s->input_buffer;
1478 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1479 if ((ret = init_get_bits8(&s->gbc, buf, buf_size)) < 0)
1482 /* parse the syncinfo */
1483 err = parse_frame_header(s);
1487 case AAC_AC3_PARSE_ERROR_SYNC:
1488 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1489 return AVERROR_INVALIDDATA;
1490 case AAC_AC3_PARSE_ERROR_BSID:
1491 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1493 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1494 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1496 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1497 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1499 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1500 /* skip frame if CRC is ok. otherwise use error concealment. */
1501 /* TODO: add support for substreams and dependent frames */
1502 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1503 av_log(avctx, AV_LOG_DEBUG,
1504 "unsupported frame type %d: skipping frame\n",
1509 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1512 case AAC_AC3_PARSE_ERROR_CRC:
1513 case AAC_AC3_PARSE_ERROR_CHANNEL_CFG:
1515 default: // Normal AVERROR do not try to recover.
1520 /* check that reported frame size fits in input buffer */
1521 if (s->frame_size > buf_size) {
1522 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1523 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1524 } else if (avctx->err_recognition & (AV_EF_CRCCHECK|AV_EF_CAREFUL)) {
1525 /* check for crc mismatch */
1526 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1527 s->frame_size - 2)) {
1528 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1529 if (avctx->err_recognition & AV_EF_EXPLODE)
1530 return AVERROR_INVALIDDATA;
1531 err = AAC_AC3_PARSE_ERROR_CRC;
1536 /* if frame is ok, set audio parameters */
1538 avctx->sample_rate = s->sample_rate;
1539 avctx->bit_rate = s->bit_rate;
1542 /* channel config */
1543 if (!err || (s->channels && s->out_channels != s->channels)) {
1544 s->out_channels = s->channels;
1545 s->output_mode = s->channel_mode;
1547 s->output_mode |= AC3_OUTPUT_LFEON;
1548 if (s->channels > 1 &&
1549 avctx->request_channel_layout == AV_CH_LAYOUT_MONO) {
1550 s->out_channels = 1;
1551 s->output_mode = AC3_CHMODE_MONO;
1552 } else if (s->channels > 2 &&
1553 avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) {
1554 s->out_channels = 2;
1555 s->output_mode = AC3_CHMODE_STEREO;
1558 s->loro_center_mix_level = gain_levels[s-> center_mix_level];
1559 s->loro_surround_mix_level = gain_levels[s->surround_mix_level];
1560 s->ltrt_center_mix_level = LEVEL_MINUS_3DB;
1561 s->ltrt_surround_mix_level = LEVEL_MINUS_3DB;
1562 /* set downmixing coefficients if needed */
1563 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1564 s->fbw_channels == s->out_channels)) {
1565 set_downmix_coeffs(s);
1567 } else if (!s->channels) {
1568 av_log(avctx, AV_LOG_ERROR, "unable to determine channel mode\n");
1569 return AVERROR_INVALIDDATA;
1571 avctx->channels = s->out_channels;
1572 avctx->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode & ~AC3_OUTPUT_LFEON];
1573 if (s->output_mode & AC3_OUTPUT_LFEON)
1574 avctx->channel_layout |= AV_CH_LOW_FREQUENCY;
1576 /* set audio service type based on bitstream mode for AC-3 */
1577 avctx->audio_service_type = s->bitstream_mode;
1578 if (s->bitstream_mode == 0x7 && s->channels > 1)
1579 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1581 /* get output buffer */
1582 frame->nb_samples = s->num_blocks * AC3_BLOCK_SIZE;
1583 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
1586 /* decode the audio blocks */
1587 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1588 for (ch = 0; ch < AC3_MAX_CHANNELS; ch++) {
1589 output[ch] = s->output[ch];
1590 s->outptr[ch] = s->output[ch];
1592 for (ch = 0; ch < s->channels; ch++) {
1593 if (ch < s->out_channels)
1594 s->outptr[channel_map[ch]] = (SHORTFLOAT *)frame->data[ch];
1596 for (blk = 0; blk < s->num_blocks; blk++) {
1597 if (!err && decode_audio_block(s, blk)) {
1598 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1602 for (ch = 0; ch < s->out_channels; ch++)
1603 memcpy(((SHORTFLOAT*)frame->data[ch]) + AC3_BLOCK_SIZE*blk, output[ch], AC3_BLOCK_SIZE*sizeof(SHORTFLOAT));
1604 for (ch = 0; ch < s->out_channels; ch++)
1605 output[ch] = s->outptr[channel_map[ch]];
1606 for (ch = 0; ch < s->out_channels; ch++) {
1607 if (!ch || channel_map[ch])
1608 s->outptr[channel_map[ch]] += AC3_BLOCK_SIZE;
1612 av_frame_set_decode_error_flags(frame, err ? FF_DECODE_ERROR_INVALID_BITSTREAM : 0);
1614 /* keep last block for error concealment in next frame */
1615 for (ch = 0; ch < s->out_channels; ch++)
1616 memcpy(s->output[ch], output[ch], AC3_BLOCK_SIZE*sizeof(SHORTFLOAT));
1621 * Check whether the input layout is compatible, and make sure we're not
1622 * downmixing (else the matrix encoding is no longer applicable).
1624 matrix_encoding = AV_MATRIX_ENCODING_NONE;
1625 if (s->channel_mode == AC3_CHMODE_STEREO &&
1626 s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) {
1627 if (s->dolby_surround_mode == AC3_DSURMOD_ON)
1628 matrix_encoding = AV_MATRIX_ENCODING_DOLBY;
1629 else if (s->dolby_headphone_mode == AC3_DHEADPHONMOD_ON)
1630 matrix_encoding = AV_MATRIX_ENCODING_DOLBYHEADPHONE;
1631 } else if (s->channel_mode >= AC3_CHMODE_2F2R &&
1632 s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) {
1633 switch (s->dolby_surround_ex_mode) {
1634 case AC3_DSUREXMOD_ON: // EX or PLIIx
1635 matrix_encoding = AV_MATRIX_ENCODING_DOLBYEX;
1637 case AC3_DSUREXMOD_PLIIZ:
1638 matrix_encoding = AV_MATRIX_ENCODING_DPLIIZ;
1640 default: // not indicated or off
1644 if ((ret = ff_side_data_update_matrix_encoding(frame, matrix_encoding)) < 0)
1648 if ((downmix_info = av_downmix_info_update_side_data(frame))) {
1649 switch (s->preferred_downmix) {
1650 case AC3_DMIXMOD_LTRT:
1651 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_LTRT;
1653 case AC3_DMIXMOD_LORO:
1654 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_LORO;
1656 case AC3_DMIXMOD_DPLII:
1657 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_DPLII;
1660 downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_UNKNOWN;
1663 downmix_info->center_mix_level = gain_levels[s-> center_mix_level];
1664 downmix_info->center_mix_level_ltrt = gain_levels[s-> center_mix_level_ltrt];
1665 downmix_info->surround_mix_level = gain_levels[s-> surround_mix_level];
1666 downmix_info->surround_mix_level_ltrt = gain_levels[s->surround_mix_level_ltrt];
1667 if (s->lfe_mix_level_exists)
1668 downmix_info->lfe_mix_level = gain_levels_lfe[s->lfe_mix_level];
1670 downmix_info->lfe_mix_level = 0.0; // -inf dB
1672 return AVERROR(ENOMEM);
1676 return FFMIN(buf_size, s->frame_size);
1680 * Uninitialize the AC-3 decoder.
1682 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1684 AC3DecodeContext *s = avctx->priv_data;
1685 ff_mdct_end(&s->imdct_512);
1686 ff_mdct_end(&s->imdct_256);
1692 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1693 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)