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;
190 ff_ac3_common_init();
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 ff_fmt_convert_init(&s->fmt_conv, avctx);
197 av_lfg_init(&s->dith_state, 0);
199 /* set scale value for float to int16 conversion */
200 s->mul_bias = 32767.0f;
202 /* allow downmixing to stereo or mono */
203 if (avctx->channels > 0 && avctx->request_channels > 0 &&
204 avctx->request_channels < avctx->channels &&
205 avctx->request_channels <= 2) {
206 avctx->channels = avctx->request_channels;
210 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
215 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
216 * GetBitContext within AC3DecodeContext must point to
217 * the start of the synchronized AC-3 bitstream.
219 static int ac3_parse_header(AC3DecodeContext *s)
221 GetBitContext *gbc = &s->gbc;
224 /* read the rest of the bsi. read twice for dual mono mode. */
225 i = !(s->channel_mode);
227 skip_bits(gbc, 5); // skip dialog normalization
229 skip_bits(gbc, 8); //skip compression
231 skip_bits(gbc, 8); //skip language code
233 skip_bits(gbc, 7); //skip audio production information
236 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
238 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
239 TODO: read & use the xbsi1 downmix levels */
241 skip_bits(gbc, 14); //skip timecode1 / xbsi1
243 skip_bits(gbc, 14); //skip timecode2 / xbsi2
245 /* skip additional bitstream info */
246 if (get_bits1(gbc)) {
247 i = get_bits(gbc, 6);
257 * Common function to parse AC-3 or E-AC-3 frame header
259 static int parse_frame_header(AC3DecodeContext *s)
264 err = ff_ac3_parse_header(&s->gbc, &hdr);
268 /* get decoding parameters from header info */
269 s->bit_alloc_params.sr_code = hdr.sr_code;
270 s->channel_mode = hdr.channel_mode;
271 s->channel_layout = hdr.channel_layout;
272 s->lfe_on = hdr.lfe_on;
273 s->bit_alloc_params.sr_shift = hdr.sr_shift;
274 s->sample_rate = hdr.sample_rate;
275 s->bit_rate = hdr.bit_rate;
276 s->channels = hdr.channels;
277 s->fbw_channels = s->channels - s->lfe_on;
278 s->lfe_ch = s->fbw_channels + 1;
279 s->frame_size = hdr.frame_size;
280 s->center_mix_level = hdr.center_mix_level;
281 s->surround_mix_level = hdr.surround_mix_level;
282 s->num_blocks = hdr.num_blocks;
283 s->frame_type = hdr.frame_type;
284 s->substreamid = hdr.substreamid;
287 s->start_freq[s->lfe_ch] = 0;
288 s->end_freq[s->lfe_ch] = 7;
289 s->num_exp_groups[s->lfe_ch] = 2;
290 s->channel_in_cpl[s->lfe_ch] = 0;
293 if (hdr.bitstream_id <= 10) {
295 s->snr_offset_strategy = 2;
296 s->block_switch_syntax = 1;
297 s->dither_flag_syntax = 1;
298 s->bit_allocation_syntax = 1;
299 s->fast_gain_syntax = 0;
300 s->first_cpl_leak = 0;
303 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
304 return ac3_parse_header(s);
305 } else if (CONFIG_EAC3_DECODER) {
307 return ff_eac3_parse_header(s);
309 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
315 * Set stereo downmixing coefficients based on frame header info.
316 * reference: Section 7.8.2 Downmixing Into Two Channels
318 static void set_downmix_coeffs(AC3DecodeContext *s)
321 float cmix = gain_levels[center_levels[s->center_mix_level]];
322 float smix = gain_levels[surround_levels[s->surround_mix_level]];
325 for(i=0; i<s->fbw_channels; i++) {
326 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
327 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
329 if(s->channel_mode > 1 && s->channel_mode & 1) {
330 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
332 if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
333 int nf = s->channel_mode - 2;
334 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
336 if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
337 int nf = s->channel_mode - 4;
338 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
343 for(i=0; i<s->fbw_channels; i++) {
344 norm0 += s->downmix_coeffs[i][0];
345 norm1 += s->downmix_coeffs[i][1];
347 norm0 = 1.0f / norm0;
348 norm1 = 1.0f / norm1;
349 for(i=0; i<s->fbw_channels; i++) {
350 s->downmix_coeffs[i][0] *= norm0;
351 s->downmix_coeffs[i][1] *= norm1;
354 if(s->output_mode == AC3_CHMODE_MONO) {
355 for(i=0; i<s->fbw_channels; i++)
356 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
361 * Decode the grouped exponents according to exponent strategy.
362 * reference: Section 7.1.3 Exponent Decoding
364 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
365 uint8_t absexp, int8_t *dexps)
367 int i, j, grp, group_size;
372 group_size = exp_strategy + (exp_strategy == EXP_D45);
373 for(grp=0,i=0; grp<ngrps; grp++) {
374 expacc = get_bits(gbc, 7);
375 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
376 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
377 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
380 /* convert to absolute exps and expand groups */
382 for(i=0,j=0; i<ngrps*3; i++) {
383 prevexp += dexp[i] - 2;
386 switch (group_size) {
387 case 4: dexps[j++] = prevexp;
388 dexps[j++] = prevexp;
389 case 2: dexps[j++] = prevexp;
390 case 1: dexps[j++] = prevexp;
397 * Generate transform coefficients for each coupled channel in the coupling
398 * range using the coupling coefficients and coupling coordinates.
399 * reference: Section 7.4.3 Coupling Coordinate Format
401 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
405 bin = s->start_freq[CPL_CH];
406 for (band = 0; band < s->num_cpl_bands; band++) {
407 int band_start = bin;
408 int band_end = bin + s->cpl_band_sizes[band];
409 for (ch = 1; ch <= s->fbw_channels; ch++) {
410 if (s->channel_in_cpl[ch]) {
411 int cpl_coord = s->cpl_coords[ch][band] << 5;
412 for (bin = band_start; bin < band_end; bin++) {
413 s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
415 if (ch == 2 && s->phase_flags[band]) {
416 for (bin = band_start; bin < band_end; bin++)
417 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
426 * Grouped mantissas for 3-level 5-level and 11-level quantization
438 * Decode the transform coefficients for a particular channel
439 * reference: Section 7.3 Quantization and Decoding of Mantissas
441 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
443 int start_freq = s->start_freq[ch_index];
444 int end_freq = s->end_freq[ch_index];
445 uint8_t *baps = s->bap[ch_index];
446 int8_t *exps = s->dexps[ch_index];
447 int *coeffs = s->fixed_coeffs[ch_index];
448 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
449 GetBitContext *gbc = &s->gbc;
452 for(freq = start_freq; freq < end_freq; freq++){
453 int bap = baps[freq];
458 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
465 mantissa = m->b1_mant[m->b1];
468 int bits = get_bits(gbc, 5);
469 mantissa = b1_mantissas[bits][0];
470 m->b1_mant[1] = b1_mantissas[bits][1];
471 m->b1_mant[0] = b1_mantissas[bits][2];
478 mantissa = m->b2_mant[m->b2];
481 int bits = get_bits(gbc, 7);
482 mantissa = b2_mantissas[bits][0];
483 m->b2_mant[1] = b2_mantissas[bits][1];
484 m->b2_mant[0] = b2_mantissas[bits][2];
489 mantissa = b3_mantissas[get_bits(gbc, 3)];
494 mantissa = m->b4_mant;
497 int bits = get_bits(gbc, 7);
498 mantissa = b4_mantissas[bits][0];
499 m->b4_mant = b4_mantissas[bits][1];
504 mantissa = b5_mantissas[get_bits(gbc, 4)];
506 default: /* 6 to 15 */
507 mantissa = get_bits(gbc, quantization_tab[bap]);
508 /* Shift mantissa and sign-extend it. */
509 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
512 coeffs[freq] = mantissa >> exps[freq];
517 * Remove random dithering from coupling range coefficients with zero-bit
518 * mantissas for coupled channels which do not use dithering.
519 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
521 static void remove_dithering(AC3DecodeContext *s) {
524 for(ch=1; ch<=s->fbw_channels; ch++) {
525 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
526 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
527 if(!s->bap[CPL_CH][i])
528 s->fixed_coeffs[ch][i] = 0;
534 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
537 if (!s->channel_uses_aht[ch]) {
538 ac3_decode_transform_coeffs_ch(s, ch, m);
540 /* if AHT is used, mantissas for all blocks are encoded in the first
541 block of the frame. */
543 if (!blk && CONFIG_EAC3_DECODER)
544 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
545 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
546 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
552 * Decode the transform coefficients.
554 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
560 m.b1 = m.b2 = m.b4 = 0;
562 for (ch = 1; ch <= s->channels; ch++) {
563 /* transform coefficients for full-bandwidth channel */
564 decode_transform_coeffs_ch(s, blk, ch, &m);
565 /* tranform coefficients for coupling channel come right after the
566 coefficients for the first coupled channel*/
567 if (s->channel_in_cpl[ch]) {
569 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
570 calc_transform_coeffs_cpl(s);
573 end = s->end_freq[CPL_CH];
575 end = s->end_freq[ch];
578 s->fixed_coeffs[ch][end] = 0;
582 /* zero the dithered coefficients for appropriate channels */
587 * Stereo rematrixing.
588 * reference: Section 7.5.4 Rematrixing : Decoding Technique
590 static void do_rematrixing(AC3DecodeContext *s)
595 end = FFMIN(s->end_freq[1], s->end_freq[2]);
597 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
598 if(s->rematrixing_flags[bnd]) {
599 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
600 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
601 int tmp0 = s->fixed_coeffs[1][i];
602 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
603 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
610 * Inverse MDCT Transform.
611 * Convert frequency domain coefficients to time-domain audio samples.
612 * reference: Section 7.9.4 Transformation Equations
614 static inline void do_imdct(AC3DecodeContext *s, int channels)
618 for (ch=1; ch<=channels; ch++) {
619 if (s->block_switch[ch]) {
621 float *x = s->tmp_output+128;
623 x[i] = s->transform_coeffs[ch][2*i];
624 ff_imdct_half(&s->imdct_256, s->tmp_output, x);
625 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
627 x[i] = s->transform_coeffs[ch][2*i+1];
628 ff_imdct_half(&s->imdct_256, s->delay[ch-1], x);
630 ff_imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
631 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
632 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
638 * Downmix the output to mono or stereo.
640 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
645 for(i=0; i<len; i++) {
647 for(j=0; j<in_ch; j++) {
648 v0 += samples[j][i] * matrix[j][0];
649 v1 += samples[j][i] * matrix[j][1];
654 } else if(out_ch == 1) {
655 for(i=0; i<len; i++) {
657 for(j=0; j<in_ch; j++)
658 v0 += samples[j][i] * matrix[j][0];
665 * Upmix delay samples from stereo to original channel layout.
667 static void ac3_upmix_delay(AC3DecodeContext *s)
669 int channel_data_size = sizeof(s->delay[0]);
670 switch(s->channel_mode) {
671 case AC3_CHMODE_DUALMONO:
672 case AC3_CHMODE_STEREO:
673 /* upmix mono to stereo */
674 memcpy(s->delay[1], s->delay[0], channel_data_size);
676 case AC3_CHMODE_2F2R:
677 memset(s->delay[3], 0, channel_data_size);
678 case AC3_CHMODE_2F1R:
679 memset(s->delay[2], 0, channel_data_size);
681 case AC3_CHMODE_3F2R:
682 memset(s->delay[4], 0, channel_data_size);
683 case AC3_CHMODE_3F1R:
684 memset(s->delay[3], 0, channel_data_size);
686 memcpy(s->delay[2], s->delay[1], channel_data_size);
687 memset(s->delay[1], 0, channel_data_size);
693 * Decode band structure for coupling, spectral extension, or enhanced coupling.
694 * The band structure defines how many subbands are in each band. For each
695 * subband in the range, 1 means it is combined with the previous band, and 0
696 * means that it starts a new band.
698 * @param[in] gbc bit reader context
699 * @param[in] blk block number
700 * @param[in] eac3 flag to indicate E-AC-3
701 * @param[in] ecpl flag to indicate enhanced coupling
702 * @param[in] start_subband subband number for start of range
703 * @param[in] end_subband subband number for end of range
704 * @param[in] default_band_struct default band structure table
705 * @param[out] num_bands number of bands (optionally NULL)
706 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
708 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
709 int ecpl, int start_subband, int end_subband,
710 const uint8_t *default_band_struct,
711 int *num_bands, uint8_t *band_sizes)
713 int subbnd, bnd, n_subbands, n_bands=0;
715 uint8_t coded_band_struct[22];
716 const uint8_t *band_struct;
718 n_subbands = end_subband - start_subband;
720 /* decode band structure from bitstream or use default */
721 if (!eac3 || get_bits1(gbc)) {
722 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
723 coded_band_struct[subbnd] = get_bits1(gbc);
725 band_struct = coded_band_struct;
727 band_struct = &default_band_struct[start_subband+1];
729 /* no change in band structure */
733 /* calculate number of bands and band sizes based on band structure.
734 note that the first 4 subbands in enhanced coupling span only 6 bins
736 if (num_bands || band_sizes ) {
737 n_bands = n_subbands;
738 bnd_sz[0] = ecpl ? 6 : 12;
739 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
740 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
741 if (band_struct[subbnd-1]) {
743 bnd_sz[bnd] += subbnd_size;
745 bnd_sz[++bnd] = subbnd_size;
750 /* set optional output params */
752 *num_bands = n_bands;
754 memcpy(band_sizes, bnd_sz, n_bands);
758 * Decode a single audio block from the AC-3 bitstream.
760 static int decode_audio_block(AC3DecodeContext *s, int blk)
762 int fbw_channels = s->fbw_channels;
763 int channel_mode = s->channel_mode;
765 int different_transforms;
768 GetBitContext *gbc = &s->gbc;
769 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
771 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
773 /* block switch flags */
774 different_transforms = 0;
775 if (s->block_switch_syntax) {
776 for (ch = 1; ch <= fbw_channels; ch++) {
777 s->block_switch[ch] = get_bits1(gbc);
778 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
779 different_transforms = 1;
783 /* dithering flags */
784 if (s->dither_flag_syntax) {
785 for (ch = 1; ch <= fbw_channels; ch++) {
786 s->dither_flag[ch] = get_bits1(gbc);
791 i = !(s->channel_mode);
794 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
795 s->avctx->drc_scale)+1.0;
796 } else if(blk == 0) {
797 s->dynamic_range[i] = 1.0f;
801 /* spectral extension strategy */
802 if (s->eac3 && (!blk || get_bits1(gbc))) {
803 s->spx_in_use = get_bits1(gbc);
805 int dst_start_freq, dst_end_freq, src_start_freq,
806 start_subband, end_subband;
808 /* determine which channels use spx */
809 if (s->channel_mode == AC3_CHMODE_MONO) {
810 s->channel_uses_spx[1] = 1;
812 for (ch = 1; ch <= fbw_channels; ch++)
813 s->channel_uses_spx[ch] = get_bits1(gbc);
816 /* get the frequency bins of the spx copy region and the spx start
818 dst_start_freq = get_bits(gbc, 2);
819 start_subband = get_bits(gbc, 3) + 2;
820 if (start_subband > 7)
821 start_subband += start_subband - 7;
822 end_subband = get_bits(gbc, 3) + 5;
824 end_subband += end_subband - 7;
825 dst_start_freq = dst_start_freq * 12 + 25;
826 src_start_freq = start_subband * 12 + 25;
827 dst_end_freq = end_subband * 12 + 25;
829 /* check validity of spx ranges */
830 if (start_subband >= end_subband) {
831 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
832 "range (%d >= %d)\n", start_subband, end_subband);
835 if (dst_start_freq >= src_start_freq) {
836 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
837 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
841 s->spx_dst_start_freq = dst_start_freq;
842 s->spx_src_start_freq = src_start_freq;
843 s->spx_dst_end_freq = dst_end_freq;
845 decode_band_structure(gbc, blk, s->eac3, 0,
846 start_subband, end_subband,
847 ff_eac3_default_spx_band_struct,
851 for (ch = 1; ch <= fbw_channels; ch++) {
852 s->channel_uses_spx[ch] = 0;
853 s->first_spx_coords[ch] = 1;
858 /* spectral extension coordinates */
860 for (ch = 1; ch <= fbw_channels; ch++) {
861 if (s->channel_uses_spx[ch]) {
862 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
864 int bin, master_spx_coord;
866 s->first_spx_coords[ch] = 0;
867 spx_blend = get_bits(gbc, 5) * (1.0f/32);
868 master_spx_coord = get_bits(gbc, 2) * 3;
870 bin = s->spx_src_start_freq;
871 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
873 int spx_coord_exp, spx_coord_mant;
874 float nratio, sblend, nblend, spx_coord;
876 /* calculate blending factors */
877 bandsize = s->spx_band_sizes[bnd];
878 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
879 nratio = av_clipf(nratio, 0.0f, 1.0f);
880 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) to give unity variance
881 sblend = sqrtf(1.0f - nratio);
884 /* decode spx coordinates */
885 spx_coord_exp = get_bits(gbc, 4);
886 spx_coord_mant = get_bits(gbc, 2);
887 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
888 else spx_coord_mant += 4;
889 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
890 spx_coord = spx_coord_mant * (1.0f/(1<<23));
892 /* multiply noise and signal blending factors by spx coordinate */
893 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
894 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
898 s->first_spx_coords[ch] = 1;
903 /* coupling strategy */
904 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
905 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
907 s->cpl_in_use[blk] = get_bits1(gbc);
908 if (s->cpl_in_use[blk]) {
909 /* coupling in use */
910 int cpl_start_subband, cpl_end_subband;
912 if (channel_mode < AC3_CHMODE_STEREO) {
913 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
917 /* check for enhanced coupling */
918 if (s->eac3 && get_bits1(gbc)) {
919 /* TODO: parse enhanced coupling strategy info */
920 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
924 /* determine which channels are coupled */
925 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
926 s->channel_in_cpl[1] = 1;
927 s->channel_in_cpl[2] = 1;
929 for (ch = 1; ch <= fbw_channels; ch++)
930 s->channel_in_cpl[ch] = get_bits1(gbc);
933 /* phase flags in use */
934 if (channel_mode == AC3_CHMODE_STEREO)
935 s->phase_flags_in_use = get_bits1(gbc);
937 /* coupling frequency range */
938 cpl_start_subband = get_bits(gbc, 4);
939 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
940 get_bits(gbc, 4) + 3;
941 if (cpl_start_subband >= cpl_end_subband) {
942 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
943 cpl_start_subband, cpl_end_subband);
946 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
947 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
949 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
951 ff_eac3_default_cpl_band_struct,
952 &s->num_cpl_bands, s->cpl_band_sizes);
954 /* coupling not in use */
955 for (ch = 1; ch <= fbw_channels; ch++) {
956 s->channel_in_cpl[ch] = 0;
957 s->first_cpl_coords[ch] = 1;
959 s->first_cpl_leak = s->eac3;
960 s->phase_flags_in_use = 0;
962 } else if (!s->eac3) {
964 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
967 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
970 cpl_in_use = s->cpl_in_use[blk];
972 /* coupling coordinates */
974 int cpl_coords_exist = 0;
976 for (ch = 1; ch <= fbw_channels; ch++) {
977 if (s->channel_in_cpl[ch]) {
978 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
979 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
980 s->first_cpl_coords[ch] = 0;
981 cpl_coords_exist = 1;
982 master_cpl_coord = 3 * get_bits(gbc, 2);
983 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
984 cpl_coord_exp = get_bits(gbc, 4);
985 cpl_coord_mant = get_bits(gbc, 4);
986 if (cpl_coord_exp == 15)
987 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
989 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
990 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
993 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
997 /* channel not in coupling */
998 s->first_cpl_coords[ch] = 1;
1002 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1003 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1004 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1009 /* stereo rematrixing strategy and band structure */
1010 if (channel_mode == AC3_CHMODE_STEREO) {
1011 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1012 s->num_rematrixing_bands = 4;
1013 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1014 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1015 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1016 s->num_rematrixing_bands--;
1018 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
1019 s->rematrixing_flags[bnd] = get_bits1(gbc);
1021 av_log(s->avctx, AV_LOG_WARNING, "Warning: new rematrixing strategy not present in block 0\n");
1022 s->num_rematrixing_bands = 0;
1026 /* exponent strategies for each channel */
1027 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1029 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1030 if(s->exp_strategy[blk][ch] != EXP_REUSE)
1031 bit_alloc_stages[ch] = 3;
1034 /* channel bandwidth */
1035 for (ch = 1; ch <= fbw_channels; ch++) {
1036 s->start_freq[ch] = 0;
1037 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1039 int prev = s->end_freq[ch];
1040 if (s->channel_in_cpl[ch])
1041 s->end_freq[ch] = s->start_freq[CPL_CH];
1042 else if (s->channel_uses_spx[ch])
1043 s->end_freq[ch] = s->spx_src_start_freq;
1045 int bandwidth_code = get_bits(gbc, 6);
1046 if (bandwidth_code > 60) {
1047 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1050 s->end_freq[ch] = bandwidth_code * 3 + 73;
1052 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1053 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
1054 if(blk > 0 && s->end_freq[ch] != prev)
1055 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1058 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1059 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1060 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1063 /* decode exponents for each channel */
1064 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1065 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1066 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1067 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1068 s->num_exp_groups[ch], s->dexps[ch][0],
1069 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1070 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1073 if(ch != CPL_CH && ch != s->lfe_ch)
1074 skip_bits(gbc, 2); /* skip gainrng */
1078 /* bit allocation information */
1079 if (s->bit_allocation_syntax) {
1080 if (get_bits1(gbc)) {
1081 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1082 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1083 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1084 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1085 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1086 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1087 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1089 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1094 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1095 if(!s->eac3 || !blk){
1096 if(s->snr_offset_strategy && get_bits1(gbc)) {
1099 csnr = (get_bits(gbc, 6) - 15) << 4;
1100 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1102 if (ch == i || s->snr_offset_strategy == 2)
1103 snr = (csnr + get_bits(gbc, 4)) << 2;
1104 /* run at least last bit allocation stage if snr offset changes */
1105 if(blk && s->snr_offset[ch] != snr) {
1106 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1108 s->snr_offset[ch] = snr;
1110 /* fast gain (normal AC-3 only) */
1112 int prev = s->fast_gain[ch];
1113 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1114 /* run last 2 bit allocation stages if fast gain changes */
1115 if(blk && prev != s->fast_gain[ch])
1116 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1119 } else if (!s->eac3 && !blk) {
1120 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1125 /* fast gain (E-AC-3 only) */
1126 if (s->fast_gain_syntax && get_bits1(gbc)) {
1127 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1128 int prev = s->fast_gain[ch];
1129 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1130 /* run last 2 bit allocation stages if fast gain changes */
1131 if(blk && prev != s->fast_gain[ch])
1132 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1134 } else if (s->eac3 && !blk) {
1135 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1136 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1139 /* E-AC-3 to AC-3 converter SNR offset */
1140 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1141 skip_bits(gbc, 10); // skip converter snr offset
1144 /* coupling leak information */
1146 if (s->first_cpl_leak || get_bits1(gbc)) {
1147 int fl = get_bits(gbc, 3);
1148 int sl = get_bits(gbc, 3);
1149 /* run last 2 bit allocation stages for coupling channel if
1150 coupling leak changes */
1151 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1152 sl != s->bit_alloc_params.cpl_slow_leak)) {
1153 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1155 s->bit_alloc_params.cpl_fast_leak = fl;
1156 s->bit_alloc_params.cpl_slow_leak = sl;
1157 } else if (!s->eac3 && !blk) {
1158 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1161 s->first_cpl_leak = 0;
1164 /* delta bit allocation information */
1165 if (s->dba_syntax && get_bits1(gbc)) {
1166 /* delta bit allocation exists (strategy) */
1167 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1168 s->dba_mode[ch] = get_bits(gbc, 2);
1169 if (s->dba_mode[ch] == DBA_RESERVED) {
1170 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1173 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1175 /* channel delta offset, len and bit allocation */
1176 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1177 if (s->dba_mode[ch] == DBA_NEW) {
1178 s->dba_nsegs[ch] = get_bits(gbc, 3);
1179 for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1180 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1181 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1182 s->dba_values[ch][seg] = get_bits(gbc, 3);
1184 /* run last 2 bit allocation stages if new dba values */
1185 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1188 } else if(blk == 0) {
1189 for(ch=0; ch<=s->channels; ch++) {
1190 s->dba_mode[ch] = DBA_NONE;
1194 /* Bit allocation */
1195 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1196 if(bit_alloc_stages[ch] > 2) {
1197 /* Exponent mapping into PSD and PSD integration */
1198 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1199 s->start_freq[ch], s->end_freq[ch],
1200 s->psd[ch], s->band_psd[ch]);
1202 if(bit_alloc_stages[ch] > 1) {
1203 /* Compute excitation function, Compute masking curve, and
1204 Apply delta bit allocation */
1205 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1206 s->start_freq[ch], s->end_freq[ch],
1207 s->fast_gain[ch], (ch == s->lfe_ch),
1208 s->dba_mode[ch], s->dba_nsegs[ch],
1209 s->dba_offsets[ch], s->dba_lengths[ch],
1210 s->dba_values[ch], s->mask[ch])) {
1211 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1215 if(bit_alloc_stages[ch] > 0) {
1216 /* Compute bit allocation */
1217 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1218 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1219 ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1220 s->start_freq[ch], s->end_freq[ch],
1222 s->bit_alloc_params.floor,
1223 bap_tab, s->bap[ch]);
1227 /* unused dummy data */
1228 if (s->skip_syntax && get_bits1(gbc)) {
1229 int skipl = get_bits(gbc, 9);
1234 /* unpack the transform coefficients
1235 this also uncouples channels if coupling is in use. */
1236 decode_transform_coeffs(s, blk);
1238 /* TODO: generate enhanced coupling coordinates and uncouple */
1240 /* recover coefficients if rematrixing is in use */
1241 if(s->channel_mode == AC3_CHMODE_STEREO)
1244 /* apply scaling to coefficients (headroom, dynrng) */
1245 for(ch=1; ch<=s->channels; ch++) {
1246 float gain = s->mul_bias / 4194304.0f;
1247 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1248 gain *= s->dynamic_range[2-ch];
1250 gain *= s->dynamic_range[0];
1252 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1255 /* apply spectral extension to high frequency bins */
1256 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1257 ff_eac3_apply_spectral_extension(s);
1260 /* downmix and MDCT. order depends on whether block switching is used for
1261 any channel in this block. this is because coefficients for the long
1262 and short transforms cannot be mixed. */
1263 downmix_output = s->channels != s->out_channels &&
1264 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1265 s->fbw_channels == s->out_channels);
1266 if(different_transforms) {
1267 /* the delay samples have already been downmixed, so we upmix the delay
1268 samples in order to reconstruct all channels before downmixing. */
1274 do_imdct(s, s->channels);
1276 if(downmix_output) {
1277 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1280 if(downmix_output) {
1281 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1284 if(downmix_output && !s->downmixed) {
1286 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1289 do_imdct(s, s->out_channels);
1296 * Decode a single AC-3 frame.
1298 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1301 const uint8_t *buf = avpkt->data;
1302 int buf_size = avpkt->size;
1303 AC3DecodeContext *s = avctx->priv_data;
1304 int16_t *out_samples = (int16_t *)data;
1306 const uint8_t *channel_map;
1307 const float *output[AC3_MAX_CHANNELS];
1308 // if it seems to be byte-swapped AC-3 (aka DNET)
1309 int is_swapped = buf_size >= 2 && AV_RB16(buf) == 0x770B;
1311 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1312 if (is_swapped || avctx->error_recognition >= FF_ER_CAREFUL) {
1313 /* allocate context input buffer */
1314 if (!s->input_buffer)
1315 s->input_buffer = av_mallocz(AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
1316 if (!s->input_buffer)
1317 return AVERROR(ENOMEM);
1319 /* copy input buffer to decoder context to avoid reading past the end
1320 of the buffer, which can be caused by a damaged input stream. */
1322 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1323 s->dsp.bswap16_buf(s->input_buffer, buf, cnt);
1325 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1326 buf = s->input_buffer;
1328 init_get_bits(&s->gbc, buf, buf_size * 8);
1330 /* parse the syncinfo */
1332 err = parse_frame_header(s);
1336 case AAC_AC3_PARSE_ERROR_SYNC:
1337 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1339 case AAC_AC3_PARSE_ERROR_BSID:
1340 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1342 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1343 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1345 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1346 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1348 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1349 /* skip frame if CRC is ok. otherwise use error concealment. */
1350 /* TODO: add support for substreams and dependent frames */
1351 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1352 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1353 return s->frame_size;
1355 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1359 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1363 /* check that reported frame size fits in input buffer */
1364 if (s->frame_size > buf_size) {
1365 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1366 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1367 } else if (avctx->error_recognition >= FF_ER_CAREFUL) {
1368 /* check for crc mismatch */
1369 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1370 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1371 err = AAC_AC3_PARSE_ERROR_CRC;
1376 /* if frame is ok, set audio parameters */
1378 avctx->sample_rate = s->sample_rate;
1379 avctx->bit_rate = s->bit_rate;
1381 /* channel config */
1382 s->out_channels = s->channels;
1383 s->output_mode = s->channel_mode;
1385 s->output_mode |= AC3_OUTPUT_LFEON;
1386 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1387 avctx->request_channels < s->channels) {
1388 s->out_channels = avctx->request_channels;
1389 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1390 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1392 avctx->channels = s->out_channels;
1393 avctx->channel_layout = s->channel_layout;
1395 /* set downmixing coefficients if needed */
1396 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1397 s->fbw_channels == s->out_channels)) {
1398 set_downmix_coeffs(s);
1400 } else if (!s->out_channels) {
1401 s->out_channels = avctx->channels;
1402 if(s->out_channels < s->channels)
1403 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1406 /* decode the audio blocks */
1407 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1408 for (ch = 0; ch < s->out_channels; ch++)
1409 output[ch] = s->output[channel_map[ch]];
1410 for (blk = 0; blk < s->num_blocks; blk++) {
1411 if (!err && decode_audio_block(s, blk)) {
1412 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1415 s->fmt_conv.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1416 out_samples += 256 * s->out_channels;
1418 *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1419 return FFMIN(buf_size, s->frame_size);
1423 * Uninitialize the AC-3 decoder.
1425 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1427 AC3DecodeContext *s = avctx->priv_data;
1428 ff_mdct_end(&s->imdct_512);
1429 ff_mdct_end(&s->imdct_256);
1431 av_freep(&s->input_buffer);
1436 AVCodec ff_ac3_decoder = {
1438 .type = AVMEDIA_TYPE_AUDIO,
1440 .priv_data_size = sizeof (AC3DecodeContext),
1441 .init = ac3_decode_init,
1442 .close = ac3_decode_end,
1443 .decode = ac3_decode_frame,
1444 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1447 #if CONFIG_EAC3_DECODER
1448 AVCodec ff_eac3_decoder = {
1450 .type = AVMEDIA_TYPE_AUDIO,
1451 .id = CODEC_ID_EAC3,
1452 .priv_data_size = sizeof (AC3DecodeContext),
1453 .init = ac3_decode_init,
1454 .close = ac3_decode_end,
1455 .decode = ac3_decode_frame,
1456 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),