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)
415 int i, j, ch, bnd, subbnd;
418 i = s->start_freq[CPL_CH];
419 for(bnd=0; bnd<s->num_cpl_bands; bnd++) {
422 for(j=0; j<12; j++) {
423 for(ch=1; ch<=s->fbw_channels; ch++) {
424 if(s->channel_in_cpl[ch]) {
425 s->fixed_coeffs[ch][i] = ((int64_t)s->fixed_coeffs[CPL_CH][i] * (int64_t)s->cpl_coords[ch][bnd]) >> 23;
426 if (ch == 2 && s->phase_flags[bnd])
427 s->fixed_coeffs[ch][i] = -s->fixed_coeffs[ch][i];
432 } while(s->cpl_band_struct[subbnd]);
437 * Grouped mantissas for 3-level 5-level and 11-level quantization
449 * Decode the transform coefficients for a particular channel
450 * reference: Section 7.3 Quantization and Decoding of Mantissas
452 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
454 int start_freq = s->start_freq[ch_index];
455 int end_freq = s->end_freq[ch_index];
456 uint8_t *baps = s->bap[ch_index];
457 int8_t *exps = s->dexps[ch_index];
458 int *coeffs = s->fixed_coeffs[ch_index];
459 GetBitContext *gbc = &s->gbc;
462 for(freq = start_freq; freq < end_freq; freq++){
463 int bap = baps[freq];
467 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
472 mantissa = m->b1_mant[m->b1];
475 int bits = get_bits(gbc, 5);
476 mantissa = b1_mantissas[bits][0];
477 m->b1_mant[1] = b1_mantissas[bits][1];
478 m->b1_mant[0] = b1_mantissas[bits][2];
485 mantissa = m->b2_mant[m->b2];
488 int bits = get_bits(gbc, 7);
489 mantissa = b2_mantissas[bits][0];
490 m->b2_mant[1] = b2_mantissas[bits][1];
491 m->b2_mant[0] = b2_mantissas[bits][2];
496 mantissa = b3_mantissas[get_bits(gbc, 3)];
501 mantissa = m->b4_mant;
504 int bits = get_bits(gbc, 7);
505 mantissa = b4_mantissas[bits][0];
506 m->b4_mant = b4_mantissas[bits][1];
511 mantissa = b5_mantissas[get_bits(gbc, 4)];
513 default: /* 6 to 15 */
514 mantissa = get_bits(gbc, quantization_tab[bap]);
515 /* Shift mantissa and sign-extend it. */
516 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
519 coeffs[freq] = mantissa >> exps[freq];
524 * Remove random dithering from coefficients with zero-bit mantissas
525 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
527 static void remove_dithering(AC3DecodeContext *s) {
533 for(ch=1; ch<=s->fbw_channels; ch++) {
534 if(!s->dither_flag[ch]) {
535 coeffs = s->fixed_coeffs[ch];
537 if(s->channel_in_cpl[ch])
538 end = s->start_freq[CPL_CH];
540 end = s->end_freq[ch];
541 for(i=0; i<end; i++) {
545 if(s->channel_in_cpl[ch]) {
546 bap = s->bap[CPL_CH];
547 for(; i<s->end_freq[CPL_CH]; i++) {
556 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
559 if (!s->channel_uses_aht[ch]) {
560 ac3_decode_transform_coeffs_ch(s, ch, m);
562 /* if AHT is used, mantissas for all blocks are encoded in the first
563 block of the frame. */
565 if (!blk && CONFIG_EAC3_DECODER)
566 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
567 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
568 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
574 * Decode the transform coefficients.
576 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
582 m.b1 = m.b2 = m.b4 = 0;
584 for (ch = 1; ch <= s->channels; ch++) {
585 /* transform coefficients for full-bandwidth channel */
586 decode_transform_coeffs_ch(s, blk, ch, &m);
587 /* tranform coefficients for coupling channel come right after the
588 coefficients for the first coupled channel*/
589 if (s->channel_in_cpl[ch]) {
591 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
592 calc_transform_coeffs_cpl(s);
595 end = s->end_freq[CPL_CH];
597 end = s->end_freq[ch];
600 s->fixed_coeffs[ch][end] = 0;
604 /* zero the dithered coefficients for appropriate channels */
609 * Stereo rematrixing.
610 * reference: Section 7.5.4 Rematrixing : Decoding Technique
612 static void do_rematrixing(AC3DecodeContext *s)
618 end = FFMIN(s->end_freq[1], s->end_freq[2]);
620 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
621 if(s->rematrixing_flags[bnd]) {
622 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
623 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
624 tmp0 = s->fixed_coeffs[1][i];
625 tmp1 = s->fixed_coeffs[2][i];
626 s->fixed_coeffs[1][i] = tmp0 + tmp1;
627 s->fixed_coeffs[2][i] = tmp0 - tmp1;
634 * Inverse MDCT Transform.
635 * Convert frequency domain coefficients to time-domain audio samples.
636 * reference: Section 7.9.4 Transformation Equations
638 static inline void do_imdct(AC3DecodeContext *s, int channels)
641 float add_bias = s->add_bias;
642 if(s->out_channels==1 && channels>1)
643 add_bias *= LEVEL_MINUS_3DB; // compensate for the gain in downmix
645 for (ch=1; ch<=channels; ch++) {
646 if (s->block_switch[ch]) {
648 float *x = s->tmp_output+128;
650 x[i] = s->transform_coeffs[ch][2*i];
651 ff_imdct_half(&s->imdct_256, s->tmp_output, x);
652 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
654 x[i] = s->transform_coeffs[ch][2*i+1];
655 ff_imdct_half(&s->imdct_256, s->delay[ch-1], x);
657 ff_imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
658 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
659 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
665 * Downmix the output to mono or stereo.
667 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
672 for(i=0; i<len; i++) {
674 for(j=0; j<in_ch; j++) {
675 v0 += samples[j][i] * matrix[j][0];
676 v1 += samples[j][i] * matrix[j][1];
681 } else if(out_ch == 1) {
682 for(i=0; i<len; i++) {
684 for(j=0; j<in_ch; j++)
685 v0 += samples[j][i] * matrix[j][0];
692 * Upmix delay samples from stereo to original channel layout.
694 static void ac3_upmix_delay(AC3DecodeContext *s)
696 int channel_data_size = sizeof(s->delay[0]);
697 switch(s->channel_mode) {
698 case AC3_CHMODE_DUALMONO:
699 case AC3_CHMODE_STEREO:
700 /* upmix mono to stereo */
701 memcpy(s->delay[1], s->delay[0], channel_data_size);
703 case AC3_CHMODE_2F2R:
704 memset(s->delay[3], 0, channel_data_size);
705 case AC3_CHMODE_2F1R:
706 memset(s->delay[2], 0, channel_data_size);
708 case AC3_CHMODE_3F2R:
709 memset(s->delay[4], 0, channel_data_size);
710 case AC3_CHMODE_3F1R:
711 memset(s->delay[3], 0, channel_data_size);
713 memcpy(s->delay[2], s->delay[1], channel_data_size);
714 memset(s->delay[1], 0, channel_data_size);
720 * Decode band structure for coupling, spectral extension, or enhanced coupling.
721 * The band structure defines how many subbands are in each band. For each
722 * subband in the range, 1 means it is combined with the previous band, and 0
723 * means that it starts a new band.
725 * @param[in] gbc bit reader context
726 * @param[in] blk block number
727 * @param[in] eac3 flag to indicate E-AC-3
728 * @param[in] ecpl flag to indicate enhanced coupling
729 * @param[in] start_subband subband number for start of range
730 * @param[in] end_subband subband number for end of range
731 * @param[in] default_band_struct default band structure table
732 * @param[out] band_struct decoded band structure
733 * @param[out] num_bands number of bands (optionally NULL)
734 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
736 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
737 int ecpl, int start_subband, int end_subband,
738 const uint8_t *default_band_struct,
739 uint8_t *band_struct, int *num_bands,
742 int subbnd, bnd, n_subbands, n_bands=0;
745 n_subbands = end_subband - start_subband;
747 /* decode band structure from bitstream or use default */
748 if (!eac3 || get_bits1(gbc)) {
749 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
750 band_struct[subbnd] = get_bits1(gbc);
754 &default_band_struct[start_subband+1],
757 band_struct[n_subbands-1] = 0;
759 /* calculate number of bands and band sizes based on band structure.
760 note that the first 4 subbands in enhanced coupling span only 6 bins
762 if (num_bands || band_sizes ) {
763 n_bands = n_subbands;
764 bnd_sz[0] = ecpl ? 6 : 12;
765 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
766 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
767 if (band_struct[subbnd-1]) {
769 bnd_sz[bnd] += subbnd_size;
771 bnd_sz[++bnd] = subbnd_size;
776 /* set optional output params */
778 *num_bands = n_bands;
780 memcpy(band_sizes, bnd_sz, n_bands);
784 * Decode a single audio block from the AC-3 bitstream.
786 static int decode_audio_block(AC3DecodeContext *s, int blk)
788 int fbw_channels = s->fbw_channels;
789 int channel_mode = s->channel_mode;
791 int different_transforms;
794 GetBitContext *gbc = &s->gbc;
795 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
797 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
799 /* block switch flags */
800 different_transforms = 0;
801 if (s->block_switch_syntax) {
802 for (ch = 1; ch <= fbw_channels; ch++) {
803 s->block_switch[ch] = get_bits1(gbc);
804 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
805 different_transforms = 1;
809 /* dithering flags */
810 if (s->dither_flag_syntax) {
811 for (ch = 1; ch <= fbw_channels; ch++) {
812 s->dither_flag[ch] = get_bits1(gbc);
817 i = !(s->channel_mode);
820 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
821 s->avctx->drc_scale)+1.0;
822 } else if(blk == 0) {
823 s->dynamic_range[i] = 1.0f;
827 /* spectral extension strategy */
828 if (s->eac3 && (!blk || get_bits1(gbc))) {
829 if (get_bits1(gbc)) {
830 av_log_missing_feature(s->avctx, "Spectral extension", 1);
833 /* TODO: parse spectral extension strategy info */
836 /* TODO: spectral extension coordinates */
838 /* coupling strategy */
839 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
840 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
842 s->cpl_in_use[blk] = get_bits1(gbc);
843 if (s->cpl_in_use[blk]) {
844 /* coupling in use */
845 int cpl_start_subband, cpl_end_subband;
847 if (channel_mode < AC3_CHMODE_STEREO) {
848 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
852 /* check for enhanced coupling */
853 if (s->eac3 && get_bits1(gbc)) {
854 /* TODO: parse enhanced coupling strategy info */
855 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
859 /* determine which channels are coupled */
860 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
861 s->channel_in_cpl[1] = 1;
862 s->channel_in_cpl[2] = 1;
864 for (ch = 1; ch <= fbw_channels; ch++)
865 s->channel_in_cpl[ch] = get_bits1(gbc);
868 /* phase flags in use */
869 if (channel_mode == AC3_CHMODE_STEREO)
870 s->phase_flags_in_use = get_bits1(gbc);
872 /* coupling frequency range */
873 /* TODO: modify coupling end freq if spectral extension is used */
874 cpl_start_subband = get_bits(gbc, 4);
875 cpl_end_subband = get_bits(gbc, 4) + 3;
876 if (cpl_start_subband >= cpl_end_subband) {
877 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
878 cpl_start_subband, cpl_end_subband);
881 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
882 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
884 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
886 ff_eac3_default_cpl_band_struct,
887 s->cpl_band_struct, &s->num_cpl_bands, NULL);
889 /* coupling not in use */
890 for (ch = 1; ch <= fbw_channels; ch++) {
891 s->channel_in_cpl[ch] = 0;
892 s->first_cpl_coords[ch] = 1;
894 s->first_cpl_leak = s->eac3;
895 s->phase_flags_in_use = 0;
897 } else if (!s->eac3) {
899 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
902 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
905 cpl_in_use = s->cpl_in_use[blk];
907 /* coupling coordinates */
909 int cpl_coords_exist = 0;
911 for (ch = 1; ch <= fbw_channels; ch++) {
912 if (s->channel_in_cpl[ch]) {
913 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
914 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
915 s->first_cpl_coords[ch] = 0;
916 cpl_coords_exist = 1;
917 master_cpl_coord = 3 * get_bits(gbc, 2);
918 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
919 cpl_coord_exp = get_bits(gbc, 4);
920 cpl_coord_mant = get_bits(gbc, 4);
921 if (cpl_coord_exp == 15)
922 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
924 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
925 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
928 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
932 /* channel not in coupling */
933 s->first_cpl_coords[ch] = 1;
937 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
938 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
939 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
944 /* stereo rematrixing strategy and band structure */
945 if (channel_mode == AC3_CHMODE_STEREO) {
946 if ((s->eac3 && !blk) || get_bits1(gbc)) {
947 s->num_rematrixing_bands = 4;
948 if(cpl_in_use && s->start_freq[CPL_CH] <= 61)
949 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
950 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
951 s->rematrixing_flags[bnd] = get_bits1(gbc);
953 av_log(s->avctx, AV_LOG_ERROR, "new rematrixing strategy must be present in block 0\n");
958 /* exponent strategies for each channel */
959 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
961 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
962 if(s->exp_strategy[blk][ch] != EXP_REUSE)
963 bit_alloc_stages[ch] = 3;
966 /* channel bandwidth */
967 for (ch = 1; ch <= fbw_channels; ch++) {
968 s->start_freq[ch] = 0;
969 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
971 int prev = s->end_freq[ch];
972 if (s->channel_in_cpl[ch])
973 s->end_freq[ch] = s->start_freq[CPL_CH];
975 int bandwidth_code = get_bits(gbc, 6);
976 if (bandwidth_code > 60) {
977 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
980 s->end_freq[ch] = bandwidth_code * 3 + 73;
982 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
983 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
984 if(blk > 0 && s->end_freq[ch] != prev)
985 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
988 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
989 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
990 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
993 /* decode exponents for each channel */
994 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
995 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
996 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
997 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
998 s->num_exp_groups[ch], s->dexps[ch][0],
999 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1000 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1003 if(ch != CPL_CH && ch != s->lfe_ch)
1004 skip_bits(gbc, 2); /* skip gainrng */
1008 /* bit allocation information */
1009 if (s->bit_allocation_syntax) {
1010 if (get_bits1(gbc)) {
1011 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1012 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1013 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1014 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1015 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1016 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1017 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1019 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1024 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1025 if(!s->eac3 || !blk){
1026 if(s->snr_offset_strategy && get_bits1(gbc)) {
1029 csnr = (get_bits(gbc, 6) - 15) << 4;
1030 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1032 if (ch == i || s->snr_offset_strategy == 2)
1033 snr = (csnr + get_bits(gbc, 4)) << 2;
1034 /* run at least last bit allocation stage if snr offset changes */
1035 if(blk && s->snr_offset[ch] != snr) {
1036 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1038 s->snr_offset[ch] = snr;
1040 /* fast gain (normal AC-3 only) */
1042 int prev = s->fast_gain[ch];
1043 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1044 /* run last 2 bit allocation stages if fast gain changes */
1045 if(blk && prev != s->fast_gain[ch])
1046 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1049 } else if (!s->eac3 && !blk) {
1050 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1055 /* fast gain (E-AC-3 only) */
1056 if (s->fast_gain_syntax && get_bits1(gbc)) {
1057 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1058 int prev = s->fast_gain[ch];
1059 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1060 /* run last 2 bit allocation stages if fast gain changes */
1061 if(blk && prev != s->fast_gain[ch])
1062 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1064 } else if (s->eac3 && !blk) {
1065 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1066 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1069 /* E-AC-3 to AC-3 converter SNR offset */
1070 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1071 skip_bits(gbc, 10); // skip converter snr offset
1074 /* coupling leak information */
1076 if (s->first_cpl_leak || get_bits1(gbc)) {
1077 int fl = get_bits(gbc, 3);
1078 int sl = get_bits(gbc, 3);
1079 /* run last 2 bit allocation stages for coupling channel if
1080 coupling leak changes */
1081 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1082 sl != s->bit_alloc_params.cpl_slow_leak)) {
1083 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1085 s->bit_alloc_params.cpl_fast_leak = fl;
1086 s->bit_alloc_params.cpl_slow_leak = sl;
1087 } else if (!s->eac3 && !blk) {
1088 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1091 s->first_cpl_leak = 0;
1094 /* delta bit allocation information */
1095 if (s->dba_syntax && get_bits1(gbc)) {
1096 /* delta bit allocation exists (strategy) */
1097 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1098 s->dba_mode[ch] = get_bits(gbc, 2);
1099 if (s->dba_mode[ch] == DBA_RESERVED) {
1100 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1103 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1105 /* channel delta offset, len and bit allocation */
1106 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1107 if (s->dba_mode[ch] == DBA_NEW) {
1108 s->dba_nsegs[ch] = get_bits(gbc, 3);
1109 for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1110 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1111 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1112 s->dba_values[ch][seg] = get_bits(gbc, 3);
1114 /* run last 2 bit allocation stages if new dba values */
1115 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1118 } else if(blk == 0) {
1119 for(ch=0; ch<=s->channels; ch++) {
1120 s->dba_mode[ch] = DBA_NONE;
1124 /* Bit allocation */
1125 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1126 if(bit_alloc_stages[ch] > 2) {
1127 /* Exponent mapping into PSD and PSD integration */
1128 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1129 s->start_freq[ch], s->end_freq[ch],
1130 s->psd[ch], s->band_psd[ch]);
1132 if(bit_alloc_stages[ch] > 1) {
1133 /* Compute excitation function, Compute masking curve, and
1134 Apply delta bit allocation */
1135 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1136 s->start_freq[ch], s->end_freq[ch],
1137 s->fast_gain[ch], (ch == s->lfe_ch),
1138 s->dba_mode[ch], s->dba_nsegs[ch],
1139 s->dba_offsets[ch], s->dba_lengths[ch],
1140 s->dba_values[ch], s->mask[ch])) {
1141 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1145 if(bit_alloc_stages[ch] > 0) {
1146 /* Compute bit allocation */
1147 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1148 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1149 ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1150 s->start_freq[ch], s->end_freq[ch],
1152 s->bit_alloc_params.floor,
1153 bap_tab, s->bap[ch]);
1157 /* unused dummy data */
1158 if (s->skip_syntax && get_bits1(gbc)) {
1159 int skipl = get_bits(gbc, 9);
1164 /* unpack the transform coefficients
1165 this also uncouples channels if coupling is in use. */
1166 decode_transform_coeffs(s, blk);
1168 /* TODO: generate enhanced coupling coordinates and uncouple */
1170 /* TODO: apply spectral extension */
1172 /* recover coefficients if rematrixing is in use */
1173 if(s->channel_mode == AC3_CHMODE_STEREO)
1176 /* apply scaling to coefficients (headroom, dynrng) */
1177 for(ch=1; ch<=s->channels; ch++) {
1178 float gain = s->mul_bias / 4194304.0f;
1179 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1180 gain *= s->dynamic_range[ch-1];
1182 gain *= s->dynamic_range[0];
1184 s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1187 /* downmix and MDCT. order depends on whether block switching is used for
1188 any channel in this block. this is because coefficients for the long
1189 and short transforms cannot be mixed. */
1190 downmix_output = s->channels != s->out_channels &&
1191 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1192 s->fbw_channels == s->out_channels);
1193 if(different_transforms) {
1194 /* the delay samples have already been downmixed, so we upmix the delay
1195 samples in order to reconstruct all channels before downmixing. */
1201 do_imdct(s, s->channels);
1203 if(downmix_output) {
1204 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1207 if(downmix_output) {
1208 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1211 if(downmix_output && !s->downmixed) {
1213 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1216 do_imdct(s, s->out_channels);
1223 * Decode a single AC-3 frame.
1225 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1228 const uint8_t *buf = avpkt->data;
1229 int buf_size = avpkt->size;
1230 AC3DecodeContext *s = avctx->priv_data;
1231 int16_t *out_samples = (int16_t *)data;
1233 const uint8_t *channel_map;
1234 const float *output[AC3_MAX_CHANNELS];
1236 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1237 if (s->input_buffer) {
1238 /* copy input buffer to decoder context to avoid reading past the end
1239 of the buffer, which can be caused by a damaged input stream. */
1240 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1241 init_get_bits(&s->gbc, s->input_buffer, buf_size * 8);
1243 init_get_bits(&s->gbc, buf, buf_size * 8);
1246 /* parse the syncinfo */
1248 err = parse_frame_header(s);
1250 /* check that reported frame size fits in input buffer */
1251 if(s->frame_size > buf_size) {
1252 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1253 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1256 /* check for crc mismatch */
1257 if(err != AAC_AC3_PARSE_ERROR_FRAME_SIZE && avctx->error_recognition >= FF_ER_CAREFUL) {
1258 if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1259 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1260 err = AAC_AC3_PARSE_ERROR_CRC;
1264 if(err && err != AAC_AC3_PARSE_ERROR_CRC) {
1266 case AAC_AC3_PARSE_ERROR_SYNC:
1267 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1269 case AAC_AC3_PARSE_ERROR_BSID:
1270 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1272 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1273 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1275 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1276 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1278 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1279 /* skip frame if CRC is ok. otherwise use error concealment. */
1280 /* TODO: add support for substreams and dependent frames */
1281 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1282 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1283 return s->frame_size;
1285 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1289 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1294 /* if frame is ok, set audio parameters */
1296 avctx->sample_rate = s->sample_rate;
1297 avctx->bit_rate = s->bit_rate;
1299 /* channel config */
1300 s->out_channels = s->channels;
1301 s->output_mode = s->channel_mode;
1303 s->output_mode |= AC3_OUTPUT_LFEON;
1304 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1305 avctx->request_channels < s->channels) {
1306 s->out_channels = avctx->request_channels;
1307 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1308 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1310 avctx->channels = s->out_channels;
1311 avctx->channel_layout = s->channel_layout;
1313 /* set downmixing coefficients if needed */
1314 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1315 s->fbw_channels == s->out_channels)) {
1316 set_downmix_coeffs(s);
1318 } else if (!s->out_channels) {
1319 s->out_channels = avctx->channels;
1320 if(s->out_channels < s->channels)
1321 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1324 /* decode the audio blocks */
1325 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1326 for (ch = 0; ch < s->out_channels; ch++)
1327 output[ch] = s->output[channel_map[ch]];
1328 for (blk = 0; blk < s->num_blocks; blk++) {
1329 if (!err && decode_audio_block(s, blk)) {
1330 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1333 s->dsp.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1334 out_samples += 256 * s->out_channels;
1336 *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1337 return s->frame_size;
1341 * Uninitialize the AC-3 decoder.
1343 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1345 AC3DecodeContext *s = avctx->priv_data;
1346 ff_mdct_end(&s->imdct_512);
1347 ff_mdct_end(&s->imdct_256);
1349 av_freep(&s->input_buffer);
1354 AVCodec ac3_decoder = {
1356 .type = CODEC_TYPE_AUDIO,
1358 .priv_data_size = sizeof (AC3DecodeContext),
1359 .init = ac3_decode_init,
1360 .close = ac3_decode_end,
1361 .decode = ac3_decode_frame,
1362 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1365 #if CONFIG_EAC3_DECODER
1366 AVCodec eac3_decoder = {
1368 .type = CODEC_TYPE_AUDIO,
1369 .id = CODEC_ID_EAC3,
1370 .priv_data_size = sizeof (AC3DecodeContext),
1371 .init = ac3_decode_init,
1372 .close = ac3_decode_end,
1373 .decode = ac3_decode_frame,
1374 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),