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/crc.h"
34 #include "aac_ac3_parser.h"
35 #include "ac3_parser.h"
37 #include "ac3dec_data.h"
39 /** Large enough for maximum possible frame size when the specification limit is ignored */
40 #define AC3_FRAME_BUFFER_SIZE 32768
43 * table for ungrouping 3 values in 7 bits.
44 * used for exponents and bap=2 mantissas
46 static uint8_t ungroup_3_in_7_bits_tab[128][3];
49 /** tables for ungrouping mantissas */
50 static int b1_mantissas[32][3];
51 static int b2_mantissas[128][3];
52 static int b3_mantissas[8];
53 static int b4_mantissas[128][2];
54 static int b5_mantissas[16];
57 * Quantization table: levels for symmetric. bits for asymmetric.
58 * reference: Table 7.18 Mapping of bap to Quantizer
60 static const uint8_t quantization_tab[16] = {
62 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
65 /** dynamic range table. converts codes to scale factors. */
66 static float dynamic_range_tab[256];
68 /** Adjustments in dB gain */
69 #define LEVEL_PLUS_3DB 1.4142135623730950
70 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209
71 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145
72 #define LEVEL_MINUS_3DB 0.7071067811865476
73 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605
74 #define LEVEL_MINUS_6DB 0.5000000000000000
75 #define LEVEL_MINUS_9DB 0.3535533905932738
76 #define LEVEL_ZERO 0.0000000000000000
77 #define LEVEL_ONE 1.0000000000000000
79 static const float gain_levels[9] = {
83 LEVEL_MINUS_1POINT5DB,
85 LEVEL_MINUS_4POINT5DB,
92 * Table for center mix levels
93 * reference: Section 5.4.2.4 cmixlev
95 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
98 * Table for surround mix levels
99 * reference: Section 5.4.2.5 surmixlev
101 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
104 * Table for default stereo downmixing coefficients
105 * reference: Section 7.8.2 Downmixing Into Two Channels
107 static const uint8_t ac3_default_coeffs[8][5][2] = {
108 { { 2, 7 }, { 7, 2 }, },
110 { { 2, 7 }, { 7, 2 }, },
111 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
112 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
113 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
114 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
115 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
119 * Symmetrical Dequantization
120 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
121 * Tables 7.19 to 7.23
124 symmetric_dequant(int code, int levels)
126 return ((code - (levels >> 1)) << 24) / levels;
130 * Initialize tables at runtime.
132 static av_cold void ac3_tables_init(void)
136 /* generate table for ungrouping 3 values in 7 bits
137 reference: Section 7.1.3 Exponent Decoding */
138 for(i=0; i<128; i++) {
139 ungroup_3_in_7_bits_tab[i][0] = i / 25;
140 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
141 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
144 /* generate grouped mantissa tables
145 reference: Section 7.3.5 Ungrouping of Mantissas */
146 for(i=0; i<32; i++) {
147 /* bap=1 mantissas */
148 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
149 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
150 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
152 for(i=0; i<128; i++) {
153 /* bap=2 mantissas */
154 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
155 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
156 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
158 /* bap=4 mantissas */
159 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
160 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
162 /* generate ungrouped mantissa tables
163 reference: Tables 7.21 and 7.23 */
165 /* bap=3 mantissas */
166 b3_mantissas[i] = symmetric_dequant(i, 7);
168 for(i=0; i<15; i++) {
169 /* bap=5 mantissas */
170 b5_mantissas[i] = symmetric_dequant(i, 15);
173 /* generate dynamic range table
174 reference: Section 7.7.1 Dynamic Range Control */
175 for(i=0; i<256; i++) {
176 int v = (i >> 5) - ((i >> 7) << 3) - 5;
177 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
183 * AVCodec initialization
185 static av_cold int ac3_decode_init(AVCodecContext *avctx)
187 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 ff_kbd_window_init(s->window, 5.0, 256);
195 dsputil_init(&s->dsp, avctx);
196 av_lfg_init(&s->dith_state, 0);
198 /* set bias values for float to int16 conversion */
199 if(s->dsp.float_to_int16_interleave == ff_float_to_int16_interleave_c) {
200 s->add_bias = 385.0f;
204 s->mul_bias = 32767.0f;
207 /* allow downmixing to stereo or mono */
208 if (avctx->channels > 0 && avctx->request_channels > 0 &&
209 avctx->request_channels < avctx->channels &&
210 avctx->request_channels <= 2) {
211 avctx->channels = avctx->request_channels;
215 /* allocate context input buffer */
216 if (avctx->error_recognition >= FF_ER_CAREFUL) {
217 s->input_buffer = av_mallocz(AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
218 if (!s->input_buffer)
219 return AVERROR_NOMEM;
222 avctx->sample_fmt = SAMPLE_FMT_S16;
227 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
228 * GetBitContext within AC3DecodeContext must point to
229 * the start of the synchronized AC-3 bitstream.
231 static int ac3_parse_header(AC3DecodeContext *s)
233 GetBitContext *gbc = &s->gbc;
236 /* read the rest of the bsi. read twice for dual mono mode. */
237 i = !(s->channel_mode);
239 skip_bits(gbc, 5); // skip dialog normalization
241 skip_bits(gbc, 8); //skip compression
243 skip_bits(gbc, 8); //skip language code
245 skip_bits(gbc, 7); //skip audio production information
248 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
250 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
251 TODO: read & use the xbsi1 downmix levels */
253 skip_bits(gbc, 14); //skip timecode1 / xbsi1
255 skip_bits(gbc, 14); //skip timecode2 / xbsi2
257 /* skip additional bitstream info */
258 if (get_bits1(gbc)) {
259 i = get_bits(gbc, 6);
269 * Common function to parse AC-3 or E-AC-3 frame header
271 static int parse_frame_header(AC3DecodeContext *s)
276 err = ff_ac3_parse_header(&s->gbc, &hdr);
280 /* get decoding parameters from header info */
281 s->bit_alloc_params.sr_code = hdr.sr_code;
282 s->channel_mode = hdr.channel_mode;
283 s->channel_layout = hdr.channel_layout;
284 s->lfe_on = hdr.lfe_on;
285 s->bit_alloc_params.sr_shift = hdr.sr_shift;
286 s->sample_rate = hdr.sample_rate;
287 s->bit_rate = hdr.bit_rate;
288 s->channels = hdr.channels;
289 s->fbw_channels = s->channels - s->lfe_on;
290 s->lfe_ch = s->fbw_channels + 1;
291 s->frame_size = hdr.frame_size;
292 s->center_mix_level = hdr.center_mix_level;
293 s->surround_mix_level = hdr.surround_mix_level;
294 s->num_blocks = hdr.num_blocks;
295 s->frame_type = hdr.frame_type;
296 s->substreamid = hdr.substreamid;
299 s->start_freq[s->lfe_ch] = 0;
300 s->end_freq[s->lfe_ch] = 7;
301 s->num_exp_groups[s->lfe_ch] = 2;
302 s->channel_in_cpl[s->lfe_ch] = 0;
305 if (hdr.bitstream_id <= 10) {
307 s->snr_offset_strategy = 2;
308 s->block_switch_syntax = 1;
309 s->dither_flag_syntax = 1;
310 s->bit_allocation_syntax = 1;
311 s->fast_gain_syntax = 0;
312 s->first_cpl_leak = 0;
315 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
316 return ac3_parse_header(s);
317 } else if (CONFIG_EAC3_DECODER) {
319 return ff_eac3_parse_header(s);
321 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
327 * Set stereo downmixing coefficients based on frame header info.
328 * reference: Section 7.8.2 Downmixing Into Two Channels
330 static void set_downmix_coeffs(AC3DecodeContext *s)
333 float cmix = gain_levels[center_levels[s->center_mix_level]];
334 float smix = gain_levels[surround_levels[s->surround_mix_level]];
337 for(i=0; i<s->fbw_channels; i++) {
338 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
339 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
341 if(s->channel_mode > 1 && s->channel_mode & 1) {
342 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
344 if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
345 int nf = s->channel_mode - 2;
346 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
348 if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
349 int nf = s->channel_mode - 4;
350 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
355 for(i=0; i<s->fbw_channels; i++) {
356 norm0 += s->downmix_coeffs[i][0];
357 norm1 += s->downmix_coeffs[i][1];
359 norm0 = 1.0f / norm0;
360 norm1 = 1.0f / norm1;
361 for(i=0; i<s->fbw_channels; i++) {
362 s->downmix_coeffs[i][0] *= norm0;
363 s->downmix_coeffs[i][1] *= norm1;
366 if(s->output_mode == AC3_CHMODE_MONO) {
367 for(i=0; i<s->fbw_channels; i++)
368 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
373 * Decode the grouped exponents according to exponent strategy.
374 * reference: Section 7.1.3 Exponent Decoding
376 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
377 uint8_t absexp, int8_t *dexps)
379 int i, j, grp, group_size;
384 group_size = exp_strategy + (exp_strategy == EXP_D45);
385 for(grp=0,i=0; grp<ngrps; grp++) {
386 expacc = get_bits(gbc, 7);
387 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
388 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
389 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
392 /* convert to absolute exps and expand groups */
394 for(i=0,j=0; i<ngrps*3; i++) {
395 prevexp += dexp[i] - 2;
398 switch (group_size) {
399 case 4: dexps[j++] = prevexp;
400 dexps[j++] = prevexp;
401 case 2: dexps[j++] = prevexp;
402 case 1: dexps[j++] = prevexp;
409 * Generate transform coefficients for each coupled channel in the coupling
410 * range using the coupling coefficients and coupling coordinates.
411 * reference: Section 7.4.3 Coupling Coordinate Format
413 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
417 bin = s->start_freq[CPL_CH];
418 for (band = 0; band < s->num_cpl_bands; band++) {
419 int band_start = bin;
420 int band_end = bin + s->cpl_band_sizes[band];
421 for (ch = 1; ch <= s->fbw_channels; ch++) {
422 if (s->channel_in_cpl[ch]) {
423 int cpl_coord = s->cpl_coords[ch][band] << 5;
424 for (bin = band_start; bin < band_end; bin++) {
425 s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
427 if (ch == 2 && s->phase_flags[band]) {
428 for (bin = band_start; bin < band_end; bin++)
429 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
438 * Grouped mantissas for 3-level 5-level and 11-level quantization
450 * Decode the transform coefficients for a particular channel
451 * reference: Section 7.3 Quantization and Decoding of Mantissas
453 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
455 int start_freq = s->start_freq[ch_index];
456 int end_freq = s->end_freq[ch_index];
457 uint8_t *baps = s->bap[ch_index];
458 int8_t *exps = s->dexps[ch_index];
459 int *coeffs = s->fixed_coeffs[ch_index];
460 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
461 GetBitContext *gbc = &s->gbc;
464 for(freq = start_freq; freq < end_freq; freq++){
465 int bap = baps[freq];
470 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
477 mantissa = m->b1_mant[m->b1];
480 int bits = get_bits(gbc, 5);
481 mantissa = b1_mantissas[bits][0];
482 m->b1_mant[1] = b1_mantissas[bits][1];
483 m->b1_mant[0] = b1_mantissas[bits][2];
490 mantissa = m->b2_mant[m->b2];
493 int bits = get_bits(gbc, 7);
494 mantissa = b2_mantissas[bits][0];
495 m->b2_mant[1] = b2_mantissas[bits][1];
496 m->b2_mant[0] = b2_mantissas[bits][2];
501 mantissa = b3_mantissas[get_bits(gbc, 3)];
506 mantissa = m->b4_mant;
509 int bits = get_bits(gbc, 7);
510 mantissa = b4_mantissas[bits][0];
511 m->b4_mant = b4_mantissas[bits][1];
516 mantissa = b5_mantissas[get_bits(gbc, 4)];
518 default: /* 6 to 15 */
519 mantissa = get_bits(gbc, quantization_tab[bap]);
520 /* Shift mantissa and sign-extend it. */
521 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
524 coeffs[freq] = mantissa >> exps[freq];
529 * Remove random dithering from coupling range coefficients with zero-bit
530 * mantissas for coupled channels which do not use dithering.
531 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
533 static void remove_dithering(AC3DecodeContext *s) {
536 for(ch=1; ch<=s->fbw_channels; ch++) {
537 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
538 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
539 if(!s->bap[CPL_CH][i])
540 s->fixed_coeffs[ch][i] = 0;
546 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
549 if (!s->channel_uses_aht[ch]) {
550 ac3_decode_transform_coeffs_ch(s, ch, m);
552 /* if AHT is used, mantissas for all blocks are encoded in the first
553 block of the frame. */
555 if (!blk && CONFIG_EAC3_DECODER)
556 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
557 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
558 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
564 * Decode the transform coefficients.
566 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
572 m.b1 = m.b2 = m.b4 = 0;
574 for (ch = 1; ch <= s->channels; ch++) {
575 /* transform coefficients for full-bandwidth channel */
576 decode_transform_coeffs_ch(s, blk, ch, &m);
577 /* tranform coefficients for coupling channel come right after the
578 coefficients for the first coupled channel*/
579 if (s->channel_in_cpl[ch]) {
581 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
582 calc_transform_coeffs_cpl(s);
585 end = s->end_freq[CPL_CH];
587 end = s->end_freq[ch];
590 s->fixed_coeffs[ch][end] = 0;
594 /* zero the dithered coefficients for appropriate channels */
599 * Stereo rematrixing.
600 * reference: Section 7.5.4 Rematrixing : Decoding Technique
602 static void do_rematrixing(AC3DecodeContext *s)
607 end = FFMIN(s->end_freq[1], s->end_freq[2]);
609 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
610 if(s->rematrixing_flags[bnd]) {
611 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
612 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
613 int tmp0 = s->fixed_coeffs[1][i];
614 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
615 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
622 * Inverse MDCT Transform.
623 * Convert frequency domain coefficients to time-domain audio samples.
624 * reference: Section 7.9.4 Transformation Equations
626 static inline void do_imdct(AC3DecodeContext *s, int channels)
629 float add_bias = s->add_bias;
630 if(s->out_channels==1 && channels>1)
631 add_bias *= LEVEL_MINUS_3DB; // compensate for the gain in downmix
633 for (ch=1; ch<=channels; ch++) {
634 if (s->block_switch[ch]) {
636 float *x = s->tmp_output+128;
638 x[i] = s->transform_coeffs[ch][2*i];
639 ff_imdct_half(&s->imdct_256, s->tmp_output, x);
640 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
642 x[i] = s->transform_coeffs[ch][2*i+1];
643 ff_imdct_half(&s->imdct_256, s->delay[ch-1], x);
645 ff_imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
646 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
647 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
653 * Downmix the output to mono or stereo.
655 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
660 for(i=0; i<len; i++) {
662 for(j=0; j<in_ch; j++) {
663 v0 += samples[j][i] * matrix[j][0];
664 v1 += samples[j][i] * matrix[j][1];
669 } else if(out_ch == 1) {
670 for(i=0; i<len; i++) {
672 for(j=0; j<in_ch; j++)
673 v0 += samples[j][i] * matrix[j][0];
680 * Upmix delay samples from stereo to original channel layout.
682 static void ac3_upmix_delay(AC3DecodeContext *s)
684 int channel_data_size = sizeof(s->delay[0]);
685 switch(s->channel_mode) {
686 case AC3_CHMODE_DUALMONO:
687 case AC3_CHMODE_STEREO:
688 /* upmix mono to stereo */
689 memcpy(s->delay[1], s->delay[0], channel_data_size);
691 case AC3_CHMODE_2F2R:
692 memset(s->delay[3], 0, channel_data_size);
693 case AC3_CHMODE_2F1R:
694 memset(s->delay[2], 0, channel_data_size);
696 case AC3_CHMODE_3F2R:
697 memset(s->delay[4], 0, channel_data_size);
698 case AC3_CHMODE_3F1R:
699 memset(s->delay[3], 0, channel_data_size);
701 memcpy(s->delay[2], s->delay[1], channel_data_size);
702 memset(s->delay[1], 0, channel_data_size);
708 * Decode band structure for coupling, spectral extension, or enhanced coupling.
709 * The band structure defines how many subbands are in each band. For each
710 * subband in the range, 1 means it is combined with the previous band, and 0
711 * means that it starts a new band.
713 * @param[in] gbc bit reader context
714 * @param[in] blk block number
715 * @param[in] eac3 flag to indicate E-AC-3
716 * @param[in] ecpl flag to indicate enhanced coupling
717 * @param[in] start_subband subband number for start of range
718 * @param[in] end_subband subband number for end of range
719 * @param[in] default_band_struct default band structure table
720 * @param[out] num_bands number of bands (optionally NULL)
721 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
723 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
724 int ecpl, int start_subband, int end_subband,
725 const uint8_t *default_band_struct,
726 int *num_bands, uint8_t *band_sizes)
728 int subbnd, bnd, n_subbands, n_bands=0;
730 uint8_t coded_band_struct[22];
731 const uint8_t *band_struct;
733 n_subbands = end_subband - start_subband;
735 /* decode band structure from bitstream or use default */
736 if (!eac3 || get_bits1(gbc)) {
737 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
738 coded_band_struct[subbnd] = get_bits1(gbc);
740 band_struct = coded_band_struct;
742 band_struct = &default_band_struct[start_subband+1];
744 /* no change in band structure */
748 /* calculate number of bands and band sizes based on band structure.
749 note that the first 4 subbands in enhanced coupling span only 6 bins
751 if (num_bands || band_sizes ) {
752 n_bands = n_subbands;
753 bnd_sz[0] = ecpl ? 6 : 12;
754 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
755 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
756 if (band_struct[subbnd-1]) {
758 bnd_sz[bnd] += subbnd_size;
760 bnd_sz[++bnd] = subbnd_size;
765 /* set optional output params */
767 *num_bands = n_bands;
769 memcpy(band_sizes, bnd_sz, n_bands);
773 * Decode a single audio block from the AC-3 bitstream.
775 static int decode_audio_block(AC3DecodeContext *s, int blk)
777 int fbw_channels = s->fbw_channels;
778 int channel_mode = s->channel_mode;
780 int different_transforms;
783 GetBitContext *gbc = &s->gbc;
784 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
786 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
788 /* block switch flags */
789 different_transforms = 0;
790 if (s->block_switch_syntax) {
791 for (ch = 1; ch <= fbw_channels; ch++) {
792 s->block_switch[ch] = get_bits1(gbc);
793 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
794 different_transforms = 1;
798 /* dithering flags */
799 if (s->dither_flag_syntax) {
800 for (ch = 1; ch <= fbw_channels; ch++) {
801 s->dither_flag[ch] = get_bits1(gbc);
806 i = !(s->channel_mode);
809 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
810 s->avctx->drc_scale)+1.0;
811 } else if(blk == 0) {
812 s->dynamic_range[i] = 1.0f;
816 /* spectral extension strategy */
817 if (s->eac3 && (!blk || get_bits1(gbc))) {
818 if (get_bits1(gbc)) {
819 av_log_missing_feature(s->avctx, "Spectral extension", 1);
822 /* TODO: parse spectral extension strategy info */
825 /* TODO: spectral extension coordinates */
827 /* coupling strategy */
828 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
829 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
831 s->cpl_in_use[blk] = get_bits1(gbc);
832 if (s->cpl_in_use[blk]) {
833 /* coupling in use */
834 int cpl_start_subband, cpl_end_subband;
836 if (channel_mode < AC3_CHMODE_STEREO) {
837 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
841 /* check for enhanced coupling */
842 if (s->eac3 && get_bits1(gbc)) {
843 /* TODO: parse enhanced coupling strategy info */
844 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
848 /* determine which channels are coupled */
849 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
850 s->channel_in_cpl[1] = 1;
851 s->channel_in_cpl[2] = 1;
853 for (ch = 1; ch <= fbw_channels; ch++)
854 s->channel_in_cpl[ch] = get_bits1(gbc);
857 /* phase flags in use */
858 if (channel_mode == AC3_CHMODE_STEREO)
859 s->phase_flags_in_use = get_bits1(gbc);
861 /* coupling frequency range */
862 /* TODO: modify coupling end freq if spectral extension is used */
863 cpl_start_subband = get_bits(gbc, 4);
864 cpl_end_subband = get_bits(gbc, 4) + 3;
865 if (cpl_start_subband >= cpl_end_subband) {
866 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
867 cpl_start_subband, cpl_end_subband);
870 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
871 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
873 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
875 ff_eac3_default_cpl_band_struct,
876 &s->num_cpl_bands, s->cpl_band_sizes);
878 /* coupling not in use */
879 for (ch = 1; ch <= fbw_channels; ch++) {
880 s->channel_in_cpl[ch] = 0;
881 s->first_cpl_coords[ch] = 1;
883 s->first_cpl_leak = s->eac3;
884 s->phase_flags_in_use = 0;
886 } else if (!s->eac3) {
888 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
891 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
894 cpl_in_use = s->cpl_in_use[blk];
896 /* coupling coordinates */
898 int cpl_coords_exist = 0;
900 for (ch = 1; ch <= fbw_channels; ch++) {
901 if (s->channel_in_cpl[ch]) {
902 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
903 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
904 s->first_cpl_coords[ch] = 0;
905 cpl_coords_exist = 1;
906 master_cpl_coord = 3 * get_bits(gbc, 2);
907 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
908 cpl_coord_exp = get_bits(gbc, 4);
909 cpl_coord_mant = get_bits(gbc, 4);
910 if (cpl_coord_exp == 15)
911 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
913 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
914 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
917 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
921 /* channel not in coupling */
922 s->first_cpl_coords[ch] = 1;
926 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
927 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
928 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
933 /* stereo rematrixing strategy and band structure */
934 if (channel_mode == AC3_CHMODE_STEREO) {
935 if ((s->eac3 && !blk) || get_bits1(gbc)) {
936 s->num_rematrixing_bands = 4;
937 if(cpl_in_use && s->start_freq[CPL_CH] <= 61)
938 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
939 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
940 s->rematrixing_flags[bnd] = get_bits1(gbc);
942 av_log(s->avctx, AV_LOG_WARNING, "Warning: new rematrixing strategy not present in block 0\n");
943 s->num_rematrixing_bands = 0;
947 /* exponent strategies for each channel */
948 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
950 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
951 if(s->exp_strategy[blk][ch] != EXP_REUSE)
952 bit_alloc_stages[ch] = 3;
955 /* channel bandwidth */
956 for (ch = 1; ch <= fbw_channels; ch++) {
957 s->start_freq[ch] = 0;
958 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
960 int prev = s->end_freq[ch];
961 if (s->channel_in_cpl[ch])
962 s->end_freq[ch] = s->start_freq[CPL_CH];
964 int bandwidth_code = get_bits(gbc, 6);
965 if (bandwidth_code > 60) {
966 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
969 s->end_freq[ch] = bandwidth_code * 3 + 73;
971 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
972 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
973 if(blk > 0 && s->end_freq[ch] != prev)
974 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
977 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
978 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
979 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
982 /* decode exponents for each channel */
983 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
984 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
985 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
986 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
987 s->num_exp_groups[ch], s->dexps[ch][0],
988 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
989 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
992 if(ch != CPL_CH && ch != s->lfe_ch)
993 skip_bits(gbc, 2); /* skip gainrng */
997 /* bit allocation information */
998 if (s->bit_allocation_syntax) {
999 if (get_bits1(gbc)) {
1000 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1001 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1002 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1003 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1004 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1005 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1006 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1008 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1013 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1014 if(!s->eac3 || !blk){
1015 if(s->snr_offset_strategy && get_bits1(gbc)) {
1018 csnr = (get_bits(gbc, 6) - 15) << 4;
1019 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1021 if (ch == i || s->snr_offset_strategy == 2)
1022 snr = (csnr + get_bits(gbc, 4)) << 2;
1023 /* run at least last bit allocation stage if snr offset changes */
1024 if(blk && s->snr_offset[ch] != snr) {
1025 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1027 s->snr_offset[ch] = snr;
1029 /* fast gain (normal AC-3 only) */
1031 int prev = s->fast_gain[ch];
1032 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1033 /* run last 2 bit allocation stages if fast gain changes */
1034 if(blk && prev != s->fast_gain[ch])
1035 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1038 } else if (!s->eac3 && !blk) {
1039 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1044 /* fast gain (E-AC-3 only) */
1045 if (s->fast_gain_syntax && get_bits1(gbc)) {
1046 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1047 int prev = s->fast_gain[ch];
1048 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1049 /* run last 2 bit allocation stages if fast gain changes */
1050 if(blk && prev != s->fast_gain[ch])
1051 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1053 } else if (s->eac3 && !blk) {
1054 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1055 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1058 /* E-AC-3 to AC-3 converter SNR offset */
1059 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1060 skip_bits(gbc, 10); // skip converter snr offset
1063 /* coupling leak information */
1065 if (s->first_cpl_leak || get_bits1(gbc)) {
1066 int fl = get_bits(gbc, 3);
1067 int sl = get_bits(gbc, 3);
1068 /* run last 2 bit allocation stages for coupling channel if
1069 coupling leak changes */
1070 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1071 sl != s->bit_alloc_params.cpl_slow_leak)) {
1072 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1074 s->bit_alloc_params.cpl_fast_leak = fl;
1075 s->bit_alloc_params.cpl_slow_leak = sl;
1076 } else if (!s->eac3 && !blk) {
1077 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1080 s->first_cpl_leak = 0;
1083 /* delta bit allocation information */
1084 if (s->dba_syntax && get_bits1(gbc)) {
1085 /* delta bit allocation exists (strategy) */
1086 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1087 s->dba_mode[ch] = get_bits(gbc, 2);
1088 if (s->dba_mode[ch] == DBA_RESERVED) {
1089 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1092 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1094 /* channel delta offset, len and bit allocation */
1095 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1096 if (s->dba_mode[ch] == DBA_NEW) {
1097 s->dba_nsegs[ch] = get_bits(gbc, 3);
1098 for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1099 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1100 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1101 s->dba_values[ch][seg] = get_bits(gbc, 3);
1103 /* run last 2 bit allocation stages if new dba values */
1104 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1107 } else if(blk == 0) {
1108 for(ch=0; ch<=s->channels; ch++) {
1109 s->dba_mode[ch] = DBA_NONE;
1113 /* Bit allocation */
1114 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1115 if(bit_alloc_stages[ch] > 2) {
1116 /* Exponent mapping into PSD and PSD integration */
1117 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1118 s->start_freq[ch], s->end_freq[ch],
1119 s->psd[ch], s->band_psd[ch]);
1121 if(bit_alloc_stages[ch] > 1) {
1122 /* Compute excitation function, Compute masking curve, and
1123 Apply delta bit allocation */
1124 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1125 s->start_freq[ch], s->end_freq[ch],
1126 s->fast_gain[ch], (ch == s->lfe_ch),
1127 s->dba_mode[ch], s->dba_nsegs[ch],
1128 s->dba_offsets[ch], s->dba_lengths[ch],
1129 s->dba_values[ch], s->mask[ch])) {
1130 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1134 if(bit_alloc_stages[ch] > 0) {
1135 /* Compute bit allocation */
1136 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1137 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1138 ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1139 s->start_freq[ch], s->end_freq[ch],
1141 s->bit_alloc_params.floor,
1142 bap_tab, s->bap[ch]);
1146 /* unused dummy data */
1147 if (s->skip_syntax && get_bits1(gbc)) {
1148 int skipl = get_bits(gbc, 9);
1153 /* unpack the transform coefficients
1154 this also uncouples channels if coupling is in use. */
1155 decode_transform_coeffs(s, blk);
1157 /* TODO: generate enhanced coupling coordinates and uncouple */
1159 /* TODO: apply spectral extension */
1161 /* recover coefficients if rematrixing is in use */
1162 if(s->channel_mode == AC3_CHMODE_STEREO)
1165 /* apply scaling to coefficients (headroom, dynrng) */
1166 for(ch=1; ch<=s->channels; ch++) {
1167 float gain = s->mul_bias / 4194304.0f;
1168 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1169 gain *= s->dynamic_range[2-ch];
1171 gain *= s->dynamic_range[0];
1173 s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1176 /* downmix and MDCT. order depends on whether block switching is used for
1177 any channel in this block. this is because coefficients for the long
1178 and short transforms cannot be mixed. */
1179 downmix_output = s->channels != s->out_channels &&
1180 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1181 s->fbw_channels == s->out_channels);
1182 if(different_transforms) {
1183 /* the delay samples have already been downmixed, so we upmix the delay
1184 samples in order to reconstruct all channels before downmixing. */
1190 do_imdct(s, s->channels);
1192 if(downmix_output) {
1193 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1196 if(downmix_output) {
1197 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1200 if(downmix_output && !s->downmixed) {
1202 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1205 do_imdct(s, s->out_channels);
1212 * Decode a single AC-3 frame.
1214 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1217 const uint8_t *buf = avpkt->data;
1218 int buf_size = avpkt->size;
1219 AC3DecodeContext *s = avctx->priv_data;
1220 int16_t *out_samples = (int16_t *)data;
1222 const uint8_t *channel_map;
1223 const float *output[AC3_MAX_CHANNELS];
1225 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1226 if (s->input_buffer) {
1227 /* copy input buffer to decoder context to avoid reading past the end
1228 of the buffer, which can be caused by a damaged input stream. */
1229 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1230 init_get_bits(&s->gbc, s->input_buffer, buf_size * 8);
1232 init_get_bits(&s->gbc, buf, buf_size * 8);
1235 /* parse the syncinfo */
1237 err = parse_frame_header(s);
1241 case AAC_AC3_PARSE_ERROR_SYNC:
1242 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1244 case AAC_AC3_PARSE_ERROR_BSID:
1245 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1247 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1248 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1250 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1251 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1253 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1254 /* skip frame if CRC is ok. otherwise use error concealment. */
1255 /* TODO: add support for substreams and dependent frames */
1256 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1257 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1258 return s->frame_size;
1260 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1264 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1268 /* check that reported frame size fits in input buffer */
1269 if (s->frame_size > buf_size) {
1270 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1271 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1272 } else if (avctx->error_recognition >= FF_ER_CAREFUL) {
1273 /* check for crc mismatch */
1274 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1275 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1276 err = AAC_AC3_PARSE_ERROR_CRC;
1281 /* if frame is ok, set audio parameters */
1283 avctx->sample_rate = s->sample_rate;
1284 avctx->bit_rate = s->bit_rate;
1286 /* channel config */
1287 s->out_channels = s->channels;
1288 s->output_mode = s->channel_mode;
1290 s->output_mode |= AC3_OUTPUT_LFEON;
1291 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1292 avctx->request_channels < s->channels) {
1293 s->out_channels = avctx->request_channels;
1294 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1295 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1297 avctx->channels = s->out_channels;
1298 avctx->channel_layout = s->channel_layout;
1300 /* set downmixing coefficients if needed */
1301 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1302 s->fbw_channels == s->out_channels)) {
1303 set_downmix_coeffs(s);
1305 } else if (!s->out_channels) {
1306 s->out_channels = avctx->channels;
1307 if(s->out_channels < s->channels)
1308 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1311 /* decode the audio blocks */
1312 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1313 for (ch = 0; ch < s->out_channels; ch++)
1314 output[ch] = s->output[channel_map[ch]];
1315 for (blk = 0; blk < s->num_blocks; blk++) {
1316 if (!err && decode_audio_block(s, blk)) {
1317 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1320 s->dsp.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1321 out_samples += 256 * s->out_channels;
1323 *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1324 return s->frame_size;
1328 * Uninitialize the AC-3 decoder.
1330 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1332 AC3DecodeContext *s = avctx->priv_data;
1333 ff_mdct_end(&s->imdct_512);
1334 ff_mdct_end(&s->imdct_256);
1336 av_freep(&s->input_buffer);
1341 AVCodec ac3_decoder = {
1343 .type = CODEC_TYPE_AUDIO,
1345 .priv_data_size = sizeof (AC3DecodeContext),
1346 .init = ac3_decode_init,
1347 .close = ac3_decode_end,
1348 .decode = ac3_decode_frame,
1349 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1352 #if CONFIG_EAC3_DECODER
1353 AVCodec eac3_decoder = {
1355 .type = CODEC_TYPE_AUDIO,
1356 .id = CODEC_ID_EAC3,
1357 .priv_data_size = sizeof (AC3DecodeContext),
1358 .init = ac3_decode_init,
1359 .close = ac3_decode_end,
1360 .decode = ac3_decode_frame,
1361 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),