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 i = s->start_freq[CPL_CH];
418 for(bnd=0; bnd<s->num_cpl_bands; bnd++) {
419 for (j = 0; j < s->cpl_band_sizes[bnd]; j++,i++) {
420 for(ch=1; ch<=s->fbw_channels; ch++) {
421 if(s->channel_in_cpl[ch]) {
422 s->fixed_coeffs[ch][i] = ((int64_t)s->fixed_coeffs[CPL_CH][i] *
423 (int64_t)s->cpl_coords[ch][bnd]) >> 23;
424 if (ch == 2 && s->phase_flags[bnd])
425 s->fixed_coeffs[ch][i] = -s->fixed_coeffs[ch][i];
433 * Grouped mantissas for 3-level 5-level and 11-level quantization
445 * Decode the transform coefficients for a particular channel
446 * reference: Section 7.3 Quantization and Decoding of Mantissas
448 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
450 int start_freq = s->start_freq[ch_index];
451 int end_freq = s->end_freq[ch_index];
452 uint8_t *baps = s->bap[ch_index];
453 int8_t *exps = s->dexps[ch_index];
454 int *coeffs = s->fixed_coeffs[ch_index];
455 GetBitContext *gbc = &s->gbc;
458 for(freq = start_freq; freq < end_freq; freq++){
459 int bap = baps[freq];
463 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
468 mantissa = m->b1_mant[m->b1];
471 int bits = get_bits(gbc, 5);
472 mantissa = b1_mantissas[bits][0];
473 m->b1_mant[1] = b1_mantissas[bits][1];
474 m->b1_mant[0] = b1_mantissas[bits][2];
481 mantissa = m->b2_mant[m->b2];
484 int bits = get_bits(gbc, 7);
485 mantissa = b2_mantissas[bits][0];
486 m->b2_mant[1] = b2_mantissas[bits][1];
487 m->b2_mant[0] = b2_mantissas[bits][2];
492 mantissa = b3_mantissas[get_bits(gbc, 3)];
497 mantissa = m->b4_mant;
500 int bits = get_bits(gbc, 7);
501 mantissa = b4_mantissas[bits][0];
502 m->b4_mant = b4_mantissas[bits][1];
507 mantissa = b5_mantissas[get_bits(gbc, 4)];
509 default: /* 6 to 15 */
510 mantissa = get_bits(gbc, quantization_tab[bap]);
511 /* Shift mantissa and sign-extend it. */
512 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
515 coeffs[freq] = mantissa >> exps[freq];
520 * Remove random dithering from coefficients with zero-bit mantissas
521 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
523 static void remove_dithering(AC3DecodeContext *s) {
529 for(ch=1; ch<=s->fbw_channels; ch++) {
530 if(!s->dither_flag[ch]) {
531 coeffs = s->fixed_coeffs[ch];
533 if(s->channel_in_cpl[ch])
534 end = s->start_freq[CPL_CH];
536 end = s->end_freq[ch];
537 for(i=0; i<end; i++) {
541 if(s->channel_in_cpl[ch]) {
542 bap = s->bap[CPL_CH];
543 for(; i<s->end_freq[CPL_CH]; i++) {
552 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
555 if (!s->channel_uses_aht[ch]) {
556 ac3_decode_transform_coeffs_ch(s, ch, m);
558 /* if AHT is used, mantissas for all blocks are encoded in the first
559 block of the frame. */
561 if (!blk && CONFIG_EAC3_DECODER)
562 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
563 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
564 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
570 * Decode the transform coefficients.
572 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
578 m.b1 = m.b2 = m.b4 = 0;
580 for (ch = 1; ch <= s->channels; ch++) {
581 /* transform coefficients for full-bandwidth channel */
582 decode_transform_coeffs_ch(s, blk, ch, &m);
583 /* tranform coefficients for coupling channel come right after the
584 coefficients for the first coupled channel*/
585 if (s->channel_in_cpl[ch]) {
587 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
588 calc_transform_coeffs_cpl(s);
591 end = s->end_freq[CPL_CH];
593 end = s->end_freq[ch];
596 s->fixed_coeffs[ch][end] = 0;
600 /* zero the dithered coefficients for appropriate channels */
605 * Stereo rematrixing.
606 * reference: Section 7.5.4 Rematrixing : Decoding Technique
608 static void do_rematrixing(AC3DecodeContext *s)
614 end = FFMIN(s->end_freq[1], s->end_freq[2]);
616 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
617 if(s->rematrixing_flags[bnd]) {
618 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
619 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
620 tmp0 = s->fixed_coeffs[1][i];
621 tmp1 = s->fixed_coeffs[2][i];
622 s->fixed_coeffs[1][i] = tmp0 + tmp1;
623 s->fixed_coeffs[2][i] = tmp0 - tmp1;
630 * Inverse MDCT Transform.
631 * Convert frequency domain coefficients to time-domain audio samples.
632 * reference: Section 7.9.4 Transformation Equations
634 static inline void do_imdct(AC3DecodeContext *s, int channels)
637 float add_bias = s->add_bias;
638 if(s->out_channels==1 && channels>1)
639 add_bias *= LEVEL_MINUS_3DB; // compensate for the gain in downmix
641 for (ch=1; ch<=channels; ch++) {
642 if (s->block_switch[ch]) {
644 float *x = s->tmp_output+128;
646 x[i] = s->transform_coeffs[ch][2*i];
647 ff_imdct_half(&s->imdct_256, s->tmp_output, x);
648 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
650 x[i] = s->transform_coeffs[ch][2*i+1];
651 ff_imdct_half(&s->imdct_256, s->delay[ch-1], x);
653 ff_imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
654 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
655 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
661 * Downmix the output to mono or stereo.
663 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
668 for(i=0; i<len; i++) {
670 for(j=0; j<in_ch; j++) {
671 v0 += samples[j][i] * matrix[j][0];
672 v1 += samples[j][i] * matrix[j][1];
677 } else if(out_ch == 1) {
678 for(i=0; i<len; i++) {
680 for(j=0; j<in_ch; j++)
681 v0 += samples[j][i] * matrix[j][0];
688 * Upmix delay samples from stereo to original channel layout.
690 static void ac3_upmix_delay(AC3DecodeContext *s)
692 int channel_data_size = sizeof(s->delay[0]);
693 switch(s->channel_mode) {
694 case AC3_CHMODE_DUALMONO:
695 case AC3_CHMODE_STEREO:
696 /* upmix mono to stereo */
697 memcpy(s->delay[1], s->delay[0], channel_data_size);
699 case AC3_CHMODE_2F2R:
700 memset(s->delay[3], 0, channel_data_size);
701 case AC3_CHMODE_2F1R:
702 memset(s->delay[2], 0, channel_data_size);
704 case AC3_CHMODE_3F2R:
705 memset(s->delay[4], 0, channel_data_size);
706 case AC3_CHMODE_3F1R:
707 memset(s->delay[3], 0, channel_data_size);
709 memcpy(s->delay[2], s->delay[1], channel_data_size);
710 memset(s->delay[1], 0, channel_data_size);
716 * Decode band structure for coupling, spectral extension, or enhanced coupling.
717 * The band structure defines how many subbands are in each band. For each
718 * subband in the range, 1 means it is combined with the previous band, and 0
719 * means that it starts a new band.
721 * @param[in] gbc bit reader context
722 * @param[in] blk block number
723 * @param[in] eac3 flag to indicate E-AC-3
724 * @param[in] ecpl flag to indicate enhanced coupling
725 * @param[in] start_subband subband number for start of range
726 * @param[in] end_subband subband number for end of range
727 * @param[in] default_band_struct default band structure table
728 * @param[out] num_bands number of bands (optionally NULL)
729 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
731 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
732 int ecpl, int start_subband, int end_subband,
733 const uint8_t *default_band_struct,
734 int *num_bands, uint8_t *band_sizes)
736 int subbnd, bnd, n_subbands, n_bands=0;
738 uint8_t coded_band_struct[22];
739 const uint8_t *band_struct;
741 n_subbands = end_subband - start_subband;
743 /* decode band structure from bitstream or use default */
744 if (!eac3 || get_bits1(gbc)) {
745 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
746 coded_band_struct[subbnd] = get_bits1(gbc);
748 band_struct = coded_band_struct;
750 band_struct = &default_band_struct[start_subband+1];
752 /* no change in band structure */
756 /* calculate number of bands and band sizes based on band structure.
757 note that the first 4 subbands in enhanced coupling span only 6 bins
759 if (num_bands || band_sizes ) {
760 n_bands = n_subbands;
761 bnd_sz[0] = ecpl ? 6 : 12;
762 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
763 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
764 if (band_struct[subbnd-1]) {
766 bnd_sz[bnd] += subbnd_size;
768 bnd_sz[++bnd] = subbnd_size;
773 /* set optional output params */
775 *num_bands = n_bands;
777 memcpy(band_sizes, bnd_sz, n_bands);
781 * Decode a single audio block from the AC-3 bitstream.
783 static int decode_audio_block(AC3DecodeContext *s, int blk)
785 int fbw_channels = s->fbw_channels;
786 int channel_mode = s->channel_mode;
788 int different_transforms;
791 GetBitContext *gbc = &s->gbc;
792 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
794 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
796 /* block switch flags */
797 different_transforms = 0;
798 if (s->block_switch_syntax) {
799 for (ch = 1; ch <= fbw_channels; ch++) {
800 s->block_switch[ch] = get_bits1(gbc);
801 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
802 different_transforms = 1;
806 /* dithering flags */
807 if (s->dither_flag_syntax) {
808 for (ch = 1; ch <= fbw_channels; ch++) {
809 s->dither_flag[ch] = get_bits1(gbc);
814 i = !(s->channel_mode);
817 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
818 s->avctx->drc_scale)+1.0;
819 } else if(blk == 0) {
820 s->dynamic_range[i] = 1.0f;
824 /* spectral extension strategy */
825 if (s->eac3 && (!blk || get_bits1(gbc))) {
826 if (get_bits1(gbc)) {
827 av_log_missing_feature(s->avctx, "Spectral extension", 1);
830 /* TODO: parse spectral extension strategy info */
833 /* TODO: spectral extension coordinates */
835 /* coupling strategy */
836 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
837 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
839 s->cpl_in_use[blk] = get_bits1(gbc);
840 if (s->cpl_in_use[blk]) {
841 /* coupling in use */
842 int cpl_start_subband, cpl_end_subband;
844 if (channel_mode < AC3_CHMODE_STEREO) {
845 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
849 /* check for enhanced coupling */
850 if (s->eac3 && get_bits1(gbc)) {
851 /* TODO: parse enhanced coupling strategy info */
852 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
856 /* determine which channels are coupled */
857 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
858 s->channel_in_cpl[1] = 1;
859 s->channel_in_cpl[2] = 1;
861 for (ch = 1; ch <= fbw_channels; ch++)
862 s->channel_in_cpl[ch] = get_bits1(gbc);
865 /* phase flags in use */
866 if (channel_mode == AC3_CHMODE_STEREO)
867 s->phase_flags_in_use = get_bits1(gbc);
869 /* coupling frequency range */
870 /* TODO: modify coupling end freq if spectral extension is used */
871 cpl_start_subband = get_bits(gbc, 4);
872 cpl_end_subband = get_bits(gbc, 4) + 3;
873 if (cpl_start_subband >= cpl_end_subband) {
874 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
875 cpl_start_subband, cpl_end_subband);
878 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
879 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
881 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
883 ff_eac3_default_cpl_band_struct,
884 &s->num_cpl_bands, s->cpl_band_sizes);
886 /* coupling not in use */
887 for (ch = 1; ch <= fbw_channels; ch++) {
888 s->channel_in_cpl[ch] = 0;
889 s->first_cpl_coords[ch] = 1;
891 s->first_cpl_leak = s->eac3;
892 s->phase_flags_in_use = 0;
894 } else if (!s->eac3) {
896 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
899 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
902 cpl_in_use = s->cpl_in_use[blk];
904 /* coupling coordinates */
906 int cpl_coords_exist = 0;
908 for (ch = 1; ch <= fbw_channels; ch++) {
909 if (s->channel_in_cpl[ch]) {
910 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
911 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
912 s->first_cpl_coords[ch] = 0;
913 cpl_coords_exist = 1;
914 master_cpl_coord = 3 * get_bits(gbc, 2);
915 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
916 cpl_coord_exp = get_bits(gbc, 4);
917 cpl_coord_mant = get_bits(gbc, 4);
918 if (cpl_coord_exp == 15)
919 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
921 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
922 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
925 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
929 /* channel not in coupling */
930 s->first_cpl_coords[ch] = 1;
934 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
935 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
936 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
941 /* stereo rematrixing strategy and band structure */
942 if (channel_mode == AC3_CHMODE_STEREO) {
943 if ((s->eac3 && !blk) || get_bits1(gbc)) {
944 s->num_rematrixing_bands = 4;
945 if(cpl_in_use && s->start_freq[CPL_CH] <= 61)
946 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
947 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
948 s->rematrixing_flags[bnd] = get_bits1(gbc);
950 av_log(s->avctx, AV_LOG_ERROR, "new rematrixing strategy must be present in block 0\n");
955 /* exponent strategies for each channel */
956 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
958 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
959 if(s->exp_strategy[blk][ch] != EXP_REUSE)
960 bit_alloc_stages[ch] = 3;
963 /* channel bandwidth */
964 for (ch = 1; ch <= fbw_channels; ch++) {
965 s->start_freq[ch] = 0;
966 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
968 int prev = s->end_freq[ch];
969 if (s->channel_in_cpl[ch])
970 s->end_freq[ch] = s->start_freq[CPL_CH];
972 int bandwidth_code = get_bits(gbc, 6);
973 if (bandwidth_code > 60) {
974 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
977 s->end_freq[ch] = bandwidth_code * 3 + 73;
979 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
980 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
981 if(blk > 0 && s->end_freq[ch] != prev)
982 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
985 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
986 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
987 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
990 /* decode exponents for each channel */
991 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
992 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
993 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
994 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
995 s->num_exp_groups[ch], s->dexps[ch][0],
996 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
997 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1000 if(ch != CPL_CH && ch != s->lfe_ch)
1001 skip_bits(gbc, 2); /* skip gainrng */
1005 /* bit allocation information */
1006 if (s->bit_allocation_syntax) {
1007 if (get_bits1(gbc)) {
1008 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1009 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1010 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1011 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1012 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1013 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1014 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1016 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1021 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1022 if(!s->eac3 || !blk){
1023 if(s->snr_offset_strategy && get_bits1(gbc)) {
1026 csnr = (get_bits(gbc, 6) - 15) << 4;
1027 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1029 if (ch == i || s->snr_offset_strategy == 2)
1030 snr = (csnr + get_bits(gbc, 4)) << 2;
1031 /* run at least last bit allocation stage if snr offset changes */
1032 if(blk && s->snr_offset[ch] != snr) {
1033 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1035 s->snr_offset[ch] = snr;
1037 /* fast gain (normal AC-3 only) */
1039 int prev = s->fast_gain[ch];
1040 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1041 /* run last 2 bit allocation stages if fast gain changes */
1042 if(blk && prev != s->fast_gain[ch])
1043 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1046 } else if (!s->eac3 && !blk) {
1047 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1052 /* fast gain (E-AC-3 only) */
1053 if (s->fast_gain_syntax && get_bits1(gbc)) {
1054 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1055 int prev = s->fast_gain[ch];
1056 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1057 /* run last 2 bit allocation stages if fast gain changes */
1058 if(blk && prev != s->fast_gain[ch])
1059 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1061 } else if (s->eac3 && !blk) {
1062 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1063 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1066 /* E-AC-3 to AC-3 converter SNR offset */
1067 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1068 skip_bits(gbc, 10); // skip converter snr offset
1071 /* coupling leak information */
1073 if (s->first_cpl_leak || get_bits1(gbc)) {
1074 int fl = get_bits(gbc, 3);
1075 int sl = get_bits(gbc, 3);
1076 /* run last 2 bit allocation stages for coupling channel if
1077 coupling leak changes */
1078 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1079 sl != s->bit_alloc_params.cpl_slow_leak)) {
1080 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1082 s->bit_alloc_params.cpl_fast_leak = fl;
1083 s->bit_alloc_params.cpl_slow_leak = sl;
1084 } else if (!s->eac3 && !blk) {
1085 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1088 s->first_cpl_leak = 0;
1091 /* delta bit allocation information */
1092 if (s->dba_syntax && get_bits1(gbc)) {
1093 /* delta bit allocation exists (strategy) */
1094 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1095 s->dba_mode[ch] = get_bits(gbc, 2);
1096 if (s->dba_mode[ch] == DBA_RESERVED) {
1097 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1100 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1102 /* channel delta offset, len and bit allocation */
1103 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1104 if (s->dba_mode[ch] == DBA_NEW) {
1105 s->dba_nsegs[ch] = get_bits(gbc, 3);
1106 for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1107 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1108 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1109 s->dba_values[ch][seg] = get_bits(gbc, 3);
1111 /* run last 2 bit allocation stages if new dba values */
1112 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1115 } else if(blk == 0) {
1116 for(ch=0; ch<=s->channels; ch++) {
1117 s->dba_mode[ch] = DBA_NONE;
1121 /* Bit allocation */
1122 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1123 if(bit_alloc_stages[ch] > 2) {
1124 /* Exponent mapping into PSD and PSD integration */
1125 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1126 s->start_freq[ch], s->end_freq[ch],
1127 s->psd[ch], s->band_psd[ch]);
1129 if(bit_alloc_stages[ch] > 1) {
1130 /* Compute excitation function, Compute masking curve, and
1131 Apply delta bit allocation */
1132 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1133 s->start_freq[ch], s->end_freq[ch],
1134 s->fast_gain[ch], (ch == s->lfe_ch),
1135 s->dba_mode[ch], s->dba_nsegs[ch],
1136 s->dba_offsets[ch], s->dba_lengths[ch],
1137 s->dba_values[ch], s->mask[ch])) {
1138 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1142 if(bit_alloc_stages[ch] > 0) {
1143 /* Compute bit allocation */
1144 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1145 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1146 ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1147 s->start_freq[ch], s->end_freq[ch],
1149 s->bit_alloc_params.floor,
1150 bap_tab, s->bap[ch]);
1154 /* unused dummy data */
1155 if (s->skip_syntax && get_bits1(gbc)) {
1156 int skipl = get_bits(gbc, 9);
1161 /* unpack the transform coefficients
1162 this also uncouples channels if coupling is in use. */
1163 decode_transform_coeffs(s, blk);
1165 /* TODO: generate enhanced coupling coordinates and uncouple */
1167 /* TODO: apply spectral extension */
1169 /* recover coefficients if rematrixing is in use */
1170 if(s->channel_mode == AC3_CHMODE_STEREO)
1173 /* apply scaling to coefficients (headroom, dynrng) */
1174 for(ch=1; ch<=s->channels; ch++) {
1175 float gain = s->mul_bias / 4194304.0f;
1176 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1177 gain *= s->dynamic_range[ch-1];
1179 gain *= s->dynamic_range[0];
1181 s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1184 /* downmix and MDCT. order depends on whether block switching is used for
1185 any channel in this block. this is because coefficients for the long
1186 and short transforms cannot be mixed. */
1187 downmix_output = s->channels != s->out_channels &&
1188 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1189 s->fbw_channels == s->out_channels);
1190 if(different_transforms) {
1191 /* the delay samples have already been downmixed, so we upmix the delay
1192 samples in order to reconstruct all channels before downmixing. */
1198 do_imdct(s, s->channels);
1200 if(downmix_output) {
1201 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1204 if(downmix_output) {
1205 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1208 if(downmix_output && !s->downmixed) {
1210 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1213 do_imdct(s, s->out_channels);
1220 * Decode a single AC-3 frame.
1222 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1225 const uint8_t *buf = avpkt->data;
1226 int buf_size = avpkt->size;
1227 AC3DecodeContext *s = avctx->priv_data;
1228 int16_t *out_samples = (int16_t *)data;
1230 const uint8_t *channel_map;
1231 const float *output[AC3_MAX_CHANNELS];
1233 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1234 if (s->input_buffer) {
1235 /* copy input buffer to decoder context to avoid reading past the end
1236 of the buffer, which can be caused by a damaged input stream. */
1237 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1238 init_get_bits(&s->gbc, s->input_buffer, buf_size * 8);
1240 init_get_bits(&s->gbc, buf, buf_size * 8);
1243 /* parse the syncinfo */
1245 err = parse_frame_header(s);
1247 /* check that reported frame size fits in input buffer */
1248 if(s->frame_size > buf_size) {
1249 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1250 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1253 /* check for crc mismatch */
1254 if(err != AAC_AC3_PARSE_ERROR_FRAME_SIZE && avctx->error_recognition >= FF_ER_CAREFUL) {
1255 if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1256 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1257 err = AAC_AC3_PARSE_ERROR_CRC;
1261 if(err && err != AAC_AC3_PARSE_ERROR_CRC) {
1263 case AAC_AC3_PARSE_ERROR_SYNC:
1264 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1266 case AAC_AC3_PARSE_ERROR_BSID:
1267 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1269 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1270 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1272 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1273 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1275 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1276 /* skip frame if CRC is ok. otherwise use error concealment. */
1277 /* TODO: add support for substreams and dependent frames */
1278 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1279 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1280 return s->frame_size;
1282 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1286 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1291 /* if frame is ok, set audio parameters */
1293 avctx->sample_rate = s->sample_rate;
1294 avctx->bit_rate = s->bit_rate;
1296 /* channel config */
1297 s->out_channels = s->channels;
1298 s->output_mode = s->channel_mode;
1300 s->output_mode |= AC3_OUTPUT_LFEON;
1301 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1302 avctx->request_channels < s->channels) {
1303 s->out_channels = avctx->request_channels;
1304 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1305 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1307 avctx->channels = s->out_channels;
1308 avctx->channel_layout = s->channel_layout;
1310 /* set downmixing coefficients if needed */
1311 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1312 s->fbw_channels == s->out_channels)) {
1313 set_downmix_coeffs(s);
1315 } else if (!s->out_channels) {
1316 s->out_channels = avctx->channels;
1317 if(s->out_channels < s->channels)
1318 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1321 /* decode the audio blocks */
1322 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1323 for (ch = 0; ch < s->out_channels; ch++)
1324 output[ch] = s->output[channel_map[ch]];
1325 for (blk = 0; blk < s->num_blocks; blk++) {
1326 if (!err && decode_audio_block(s, blk)) {
1327 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1330 s->dsp.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1331 out_samples += 256 * s->out_channels;
1333 *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1334 return s->frame_size;
1338 * Uninitialize the AC-3 decoder.
1340 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1342 AC3DecodeContext *s = avctx->priv_data;
1343 ff_mdct_end(&s->imdct_512);
1344 ff_mdct_end(&s->imdct_256);
1346 av_freep(&s->input_buffer);
1351 AVCodec ac3_decoder = {
1353 .type = CODEC_TYPE_AUDIO,
1355 .priv_data_size = sizeof (AC3DecodeContext),
1356 .init = ac3_decode_init,
1357 .close = ac3_decode_end,
1358 .decode = ac3_decode_frame,
1359 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1362 #if CONFIG_EAC3_DECODER
1363 AVCodec eac3_decoder = {
1365 .type = CODEC_TYPE_AUDIO,
1366 .id = CODEC_ID_EAC3,
1367 .priv_data_size = sizeof (AC3DecodeContext),
1368 .init = ac3_decode_init,
1369 .close = ac3_decode_end,
1370 .decode = ac3_decode_frame,
1371 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),