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"
41 * table for ungrouping 3 values in 7 bits.
42 * used for exponents and bap=2 mantissas
44 static uint8_t ungroup_3_in_7_bits_tab[128][3];
47 /** tables for ungrouping mantissas */
48 static int b1_mantissas[32][3];
49 static int b2_mantissas[128][3];
50 static int b3_mantissas[8];
51 static int b4_mantissas[128][2];
52 static int b5_mantissas[16];
55 * Quantization table: levels for symmetric. bits for asymmetric.
56 * reference: Table 7.18 Mapping of bap to Quantizer
58 static const uint8_t quantization_tab[16] = {
60 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
63 /** dynamic range table. converts codes to scale factors. */
64 static float dynamic_range_tab[256];
66 /** Adjustments in dB gain */
67 static const float gain_levels[9] = {
71 LEVEL_MINUS_1POINT5DB,
73 LEVEL_MINUS_4POINT5DB,
80 * Table for center mix levels
81 * reference: Section 5.4.2.4 cmixlev
83 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
86 * Table for surround mix levels
87 * reference: Section 5.4.2.5 surmixlev
89 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
92 * Table for default stereo downmixing coefficients
93 * reference: Section 7.8.2 Downmixing Into Two Channels
95 static const uint8_t ac3_default_coeffs[8][5][2] = {
96 { { 2, 7 }, { 7, 2 }, },
98 { { 2, 7 }, { 7, 2 }, },
99 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
100 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
101 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
102 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
103 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
107 * Symmetrical Dequantization
108 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
109 * Tables 7.19 to 7.23
112 symmetric_dequant(int code, int levels)
114 return ((code - (levels >> 1)) << 24) / levels;
118 * Initialize tables at runtime.
120 static av_cold void ac3_tables_init(void)
124 /* generate table for ungrouping 3 values in 7 bits
125 reference: Section 7.1.3 Exponent Decoding */
126 for(i=0; i<128; i++) {
127 ungroup_3_in_7_bits_tab[i][0] = i / 25;
128 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
129 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
132 /* generate grouped mantissa tables
133 reference: Section 7.3.5 Ungrouping of Mantissas */
134 for(i=0; i<32; i++) {
135 /* bap=1 mantissas */
136 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
137 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
138 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
140 for(i=0; i<128; i++) {
141 /* bap=2 mantissas */
142 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
143 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
144 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
146 /* bap=4 mantissas */
147 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
148 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
150 /* generate ungrouped mantissa tables
151 reference: Tables 7.21 and 7.23 */
153 /* bap=3 mantissas */
154 b3_mantissas[i] = symmetric_dequant(i, 7);
156 for(i=0; i<15; i++) {
157 /* bap=5 mantissas */
158 b5_mantissas[i] = symmetric_dequant(i, 15);
161 /* generate dynamic range table
162 reference: Section 7.7.1 Dynamic Range Control */
163 for(i=0; i<256; i++) {
164 int v = (i >> 5) - ((i >> 7) << 3) - 5;
165 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
171 * AVCodec initialization
173 static av_cold int ac3_decode_init(AVCodecContext *avctx)
175 AC3DecodeContext *s = avctx->priv_data;
178 ff_ac3_common_init();
180 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
181 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
182 ff_kbd_window_init(s->window, 5.0, 256);
183 dsputil_init(&s->dsp, avctx);
184 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
185 ff_fmt_convert_init(&s->fmt_conv, avctx);
186 av_lfg_init(&s->dith_state, 0);
188 /* allow downmixing to stereo or mono */
189 if (avctx->channels > 0 && avctx->request_channels > 0 &&
190 avctx->request_channels < avctx->channels &&
191 avctx->request_channels <= 2) {
192 avctx->channels = avctx->request_channels;
196 if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
197 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
200 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
201 /* set scale value for float to int16 conversion */
202 s->mul_bias = 32767.0f;
208 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
209 * GetBitContext within AC3DecodeContext must point to
210 * the start of the synchronized AC-3 bitstream.
212 static int ac3_parse_header(AC3DecodeContext *s)
214 GetBitContext *gbc = &s->gbc;
217 /* read the rest of the bsi. read twice for dual mono mode. */
218 i = !(s->channel_mode);
220 skip_bits(gbc, 5); // skip dialog normalization
222 skip_bits(gbc, 8); //skip compression
224 skip_bits(gbc, 8); //skip language code
226 skip_bits(gbc, 7); //skip audio production information
229 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
231 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
232 TODO: read & use the xbsi1 downmix levels */
234 skip_bits(gbc, 14); //skip timecode1 / xbsi1
236 skip_bits(gbc, 14); //skip timecode2 / xbsi2
238 /* skip additional bitstream info */
239 if (get_bits1(gbc)) {
240 i = get_bits(gbc, 6);
250 * Common function to parse AC-3 or E-AC-3 frame header
252 static int parse_frame_header(AC3DecodeContext *s)
257 err = ff_ac3_parse_header(&s->gbc, &hdr);
261 /* get decoding parameters from header info */
262 s->bit_alloc_params.sr_code = hdr.sr_code;
263 s->bitstream_mode = hdr.bitstream_mode;
264 s->channel_mode = hdr.channel_mode;
265 s->channel_layout = hdr.channel_layout;
266 s->lfe_on = hdr.lfe_on;
267 s->bit_alloc_params.sr_shift = hdr.sr_shift;
268 s->sample_rate = hdr.sample_rate;
269 s->bit_rate = hdr.bit_rate;
270 s->channels = hdr.channels;
271 s->fbw_channels = s->channels - s->lfe_on;
272 s->lfe_ch = s->fbw_channels + 1;
273 s->frame_size = hdr.frame_size;
274 s->center_mix_level = hdr.center_mix_level;
275 s->surround_mix_level = hdr.surround_mix_level;
276 s->num_blocks = hdr.num_blocks;
277 s->frame_type = hdr.frame_type;
278 s->substreamid = hdr.substreamid;
281 s->start_freq[s->lfe_ch] = 0;
282 s->end_freq[s->lfe_ch] = 7;
283 s->num_exp_groups[s->lfe_ch] = 2;
284 s->channel_in_cpl[s->lfe_ch] = 0;
287 if (hdr.bitstream_id <= 10) {
289 s->snr_offset_strategy = 2;
290 s->block_switch_syntax = 1;
291 s->dither_flag_syntax = 1;
292 s->bit_allocation_syntax = 1;
293 s->fast_gain_syntax = 0;
294 s->first_cpl_leak = 0;
297 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
298 return ac3_parse_header(s);
299 } else if (CONFIG_EAC3_DECODER) {
301 return ff_eac3_parse_header(s);
303 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
309 * Set stereo downmixing coefficients based on frame header info.
310 * reference: Section 7.8.2 Downmixing Into Two Channels
312 static void set_downmix_coeffs(AC3DecodeContext *s)
315 float cmix = gain_levels[center_levels[s->center_mix_level]];
316 float smix = gain_levels[surround_levels[s->surround_mix_level]];
319 for(i=0; i<s->fbw_channels; i++) {
320 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
321 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
323 if(s->channel_mode > 1 && s->channel_mode & 1) {
324 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
326 if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
327 int nf = s->channel_mode - 2;
328 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
330 if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
331 int nf = s->channel_mode - 4;
332 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
337 for(i=0; i<s->fbw_channels; i++) {
338 norm0 += s->downmix_coeffs[i][0];
339 norm1 += s->downmix_coeffs[i][1];
341 norm0 = 1.0f / norm0;
342 norm1 = 1.0f / norm1;
343 for(i=0; i<s->fbw_channels; i++) {
344 s->downmix_coeffs[i][0] *= norm0;
345 s->downmix_coeffs[i][1] *= norm1;
348 if(s->output_mode == AC3_CHMODE_MONO) {
349 for(i=0; i<s->fbw_channels; i++)
350 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
355 * Decode the grouped exponents according to exponent strategy.
356 * reference: Section 7.1.3 Exponent Decoding
358 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
359 uint8_t absexp, int8_t *dexps)
361 int i, j, grp, group_size;
366 group_size = exp_strategy + (exp_strategy == EXP_D45);
367 for(grp=0,i=0; grp<ngrps; grp++) {
368 expacc = get_bits(gbc, 7);
369 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
370 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
371 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
374 /* convert to absolute exps and expand groups */
376 for(i=0,j=0; i<ngrps*3; i++) {
377 prevexp += dexp[i] - 2;
380 switch (group_size) {
381 case 4: dexps[j++] = prevexp;
382 dexps[j++] = prevexp;
383 case 2: dexps[j++] = prevexp;
384 case 1: dexps[j++] = prevexp;
391 * Generate transform coefficients for each coupled channel in the coupling
392 * range using the coupling coefficients and coupling coordinates.
393 * reference: Section 7.4.3 Coupling Coordinate Format
395 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
399 bin = s->start_freq[CPL_CH];
400 for (band = 0; band < s->num_cpl_bands; band++) {
401 int band_start = bin;
402 int band_end = bin + s->cpl_band_sizes[band];
403 for (ch = 1; ch <= s->fbw_channels; ch++) {
404 if (s->channel_in_cpl[ch]) {
405 int cpl_coord = s->cpl_coords[ch][band] << 5;
406 for (bin = band_start; bin < band_end; bin++) {
407 s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
409 if (ch == 2 && s->phase_flags[band]) {
410 for (bin = band_start; bin < band_end; bin++)
411 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
420 * Grouped mantissas for 3-level 5-level and 11-level quantization
432 * Decode the transform coefficients for a particular channel
433 * reference: Section 7.3 Quantization and Decoding of Mantissas
435 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
437 int start_freq = s->start_freq[ch_index];
438 int end_freq = s->end_freq[ch_index];
439 uint8_t *baps = s->bap[ch_index];
440 int8_t *exps = s->dexps[ch_index];
441 int *coeffs = s->fixed_coeffs[ch_index];
442 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
443 GetBitContext *gbc = &s->gbc;
446 for(freq = start_freq; freq < end_freq; freq++){
447 int bap = baps[freq];
452 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
459 mantissa = m->b1_mant[m->b1];
462 int bits = get_bits(gbc, 5);
463 mantissa = b1_mantissas[bits][0];
464 m->b1_mant[1] = b1_mantissas[bits][1];
465 m->b1_mant[0] = b1_mantissas[bits][2];
472 mantissa = m->b2_mant[m->b2];
475 int bits = get_bits(gbc, 7);
476 mantissa = b2_mantissas[bits][0];
477 m->b2_mant[1] = b2_mantissas[bits][1];
478 m->b2_mant[0] = b2_mantissas[bits][2];
483 mantissa = b3_mantissas[get_bits(gbc, 3)];
488 mantissa = m->b4_mant;
491 int bits = get_bits(gbc, 7);
492 mantissa = b4_mantissas[bits][0];
493 m->b4_mant = b4_mantissas[bits][1];
498 mantissa = b5_mantissas[get_bits(gbc, 4)];
500 default: /* 6 to 15 */
501 mantissa = get_bits(gbc, quantization_tab[bap]);
502 /* Shift mantissa and sign-extend it. */
503 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
506 coeffs[freq] = mantissa >> exps[freq];
511 * Remove random dithering from coupling range coefficients with zero-bit
512 * mantissas for coupled channels which do not use dithering.
513 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
515 static void remove_dithering(AC3DecodeContext *s) {
518 for(ch=1; ch<=s->fbw_channels; ch++) {
519 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
520 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
521 if(!s->bap[CPL_CH][i])
522 s->fixed_coeffs[ch][i] = 0;
528 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
531 if (!s->channel_uses_aht[ch]) {
532 ac3_decode_transform_coeffs_ch(s, ch, m);
534 /* if AHT is used, mantissas for all blocks are encoded in the first
535 block of the frame. */
537 if (!blk && CONFIG_EAC3_DECODER)
538 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
539 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
540 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
546 * Decode the transform coefficients.
548 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
554 m.b1 = m.b2 = m.b4 = 0;
556 for (ch = 1; ch <= s->channels; ch++) {
557 /* transform coefficients for full-bandwidth channel */
558 decode_transform_coeffs_ch(s, blk, ch, &m);
559 /* tranform coefficients for coupling channel come right after the
560 coefficients for the first coupled channel*/
561 if (s->channel_in_cpl[ch]) {
563 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
564 calc_transform_coeffs_cpl(s);
567 end = s->end_freq[CPL_CH];
569 end = s->end_freq[ch];
572 s->fixed_coeffs[ch][end] = 0;
576 /* zero the dithered coefficients for appropriate channels */
581 * Stereo rematrixing.
582 * reference: Section 7.5.4 Rematrixing : Decoding Technique
584 static void do_rematrixing(AC3DecodeContext *s)
589 end = FFMIN(s->end_freq[1], s->end_freq[2]);
591 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
592 if(s->rematrixing_flags[bnd]) {
593 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
594 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
595 int tmp0 = s->fixed_coeffs[1][i];
596 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
597 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
604 * Inverse MDCT Transform.
605 * Convert frequency domain coefficients to time-domain audio samples.
606 * reference: Section 7.9.4 Transformation Equations
608 static inline void do_imdct(AC3DecodeContext *s, int channels)
612 for (ch=1; ch<=channels; ch++) {
613 if (s->block_switch[ch]) {
615 float *x = s->tmp_output+128;
617 x[i] = s->transform_coeffs[ch][2*i];
618 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
619 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
621 x[i] = s->transform_coeffs[ch][2*i+1];
622 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch-1], x);
624 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
625 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
626 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
632 * Downmix the output to mono or stereo.
634 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
639 for(i=0; i<len; i++) {
641 for(j=0; j<in_ch; j++) {
642 v0 += samples[j][i] * matrix[j][0];
643 v1 += samples[j][i] * matrix[j][1];
648 } else if(out_ch == 1) {
649 for(i=0; i<len; i++) {
651 for(j=0; j<in_ch; j++)
652 v0 += samples[j][i] * matrix[j][0];
659 * Upmix delay samples from stereo to original channel layout.
661 static void ac3_upmix_delay(AC3DecodeContext *s)
663 int channel_data_size = sizeof(s->delay[0]);
664 switch(s->channel_mode) {
665 case AC3_CHMODE_DUALMONO:
666 case AC3_CHMODE_STEREO:
667 /* upmix mono to stereo */
668 memcpy(s->delay[1], s->delay[0], channel_data_size);
670 case AC3_CHMODE_2F2R:
671 memset(s->delay[3], 0, channel_data_size);
672 case AC3_CHMODE_2F1R:
673 memset(s->delay[2], 0, channel_data_size);
675 case AC3_CHMODE_3F2R:
676 memset(s->delay[4], 0, channel_data_size);
677 case AC3_CHMODE_3F1R:
678 memset(s->delay[3], 0, channel_data_size);
680 memcpy(s->delay[2], s->delay[1], channel_data_size);
681 memset(s->delay[1], 0, channel_data_size);
687 * Decode band structure for coupling, spectral extension, or enhanced coupling.
688 * The band structure defines how many subbands are in each band. For each
689 * subband in the range, 1 means it is combined with the previous band, and 0
690 * means that it starts a new band.
692 * @param[in] gbc bit reader context
693 * @param[in] blk block number
694 * @param[in] eac3 flag to indicate E-AC-3
695 * @param[in] ecpl flag to indicate enhanced coupling
696 * @param[in] start_subband subband number for start of range
697 * @param[in] end_subband subband number for end of range
698 * @param[in] default_band_struct default band structure table
699 * @param[out] num_bands number of bands (optionally NULL)
700 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
702 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
703 int ecpl, int start_subband, int end_subband,
704 const uint8_t *default_band_struct,
705 int *num_bands, uint8_t *band_sizes)
707 int subbnd, bnd, n_subbands, n_bands=0;
709 uint8_t coded_band_struct[22];
710 const uint8_t *band_struct;
712 n_subbands = end_subband - start_subband;
714 /* decode band structure from bitstream or use default */
715 if (!eac3 || get_bits1(gbc)) {
716 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
717 coded_band_struct[subbnd] = get_bits1(gbc);
719 band_struct = coded_band_struct;
721 band_struct = &default_band_struct[start_subband+1];
723 /* no change in band structure */
727 /* calculate number of bands and band sizes based on band structure.
728 note that the first 4 subbands in enhanced coupling span only 6 bins
730 if (num_bands || band_sizes ) {
731 n_bands = n_subbands;
732 bnd_sz[0] = ecpl ? 6 : 12;
733 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
734 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
735 if (band_struct[subbnd-1]) {
737 bnd_sz[bnd] += subbnd_size;
739 bnd_sz[++bnd] = subbnd_size;
744 /* set optional output params */
746 *num_bands = n_bands;
748 memcpy(band_sizes, bnd_sz, n_bands);
752 * Decode a single audio block from the AC-3 bitstream.
754 static int decode_audio_block(AC3DecodeContext *s, int blk)
756 int fbw_channels = s->fbw_channels;
757 int channel_mode = s->channel_mode;
759 int different_transforms;
762 GetBitContext *gbc = &s->gbc;
763 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
765 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
767 /* block switch flags */
768 different_transforms = 0;
769 if (s->block_switch_syntax) {
770 for (ch = 1; ch <= fbw_channels; ch++) {
771 s->block_switch[ch] = get_bits1(gbc);
772 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
773 different_transforms = 1;
777 /* dithering flags */
778 if (s->dither_flag_syntax) {
779 for (ch = 1; ch <= fbw_channels; ch++) {
780 s->dither_flag[ch] = get_bits1(gbc);
785 i = !(s->channel_mode);
788 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
789 s->avctx->drc_scale)+1.0;
790 } else if(blk == 0) {
791 s->dynamic_range[i] = 1.0f;
795 /* spectral extension strategy */
796 if (s->eac3 && (!blk || get_bits1(gbc))) {
797 s->spx_in_use = get_bits1(gbc);
799 int dst_start_freq, dst_end_freq, src_start_freq,
800 start_subband, end_subband;
802 /* determine which channels use spx */
803 if (s->channel_mode == AC3_CHMODE_MONO) {
804 s->channel_uses_spx[1] = 1;
806 for (ch = 1; ch <= fbw_channels; ch++)
807 s->channel_uses_spx[ch] = get_bits1(gbc);
810 /* get the frequency bins of the spx copy region and the spx start
812 dst_start_freq = get_bits(gbc, 2);
813 start_subband = get_bits(gbc, 3) + 2;
814 if (start_subband > 7)
815 start_subband += start_subband - 7;
816 end_subband = get_bits(gbc, 3) + 5;
818 end_subband += end_subband - 7;
819 dst_start_freq = dst_start_freq * 12 + 25;
820 src_start_freq = start_subband * 12 + 25;
821 dst_end_freq = end_subband * 12 + 25;
823 /* check validity of spx ranges */
824 if (start_subband >= end_subband) {
825 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
826 "range (%d >= %d)\n", start_subband, end_subband);
829 if (dst_start_freq >= src_start_freq) {
830 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
831 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
835 s->spx_dst_start_freq = dst_start_freq;
836 s->spx_src_start_freq = src_start_freq;
837 s->spx_dst_end_freq = dst_end_freq;
839 decode_band_structure(gbc, blk, s->eac3, 0,
840 start_subband, end_subband,
841 ff_eac3_default_spx_band_struct,
845 for (ch = 1; ch <= fbw_channels; ch++) {
846 s->channel_uses_spx[ch] = 0;
847 s->first_spx_coords[ch] = 1;
852 /* spectral extension coordinates */
854 for (ch = 1; ch <= fbw_channels; ch++) {
855 if (s->channel_uses_spx[ch]) {
856 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
858 int bin, master_spx_coord;
860 s->first_spx_coords[ch] = 0;
861 spx_blend = get_bits(gbc, 5) * (1.0f/32);
862 master_spx_coord = get_bits(gbc, 2) * 3;
864 bin = s->spx_src_start_freq;
865 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
867 int spx_coord_exp, spx_coord_mant;
868 float nratio, sblend, nblend, spx_coord;
870 /* calculate blending factors */
871 bandsize = s->spx_band_sizes[bnd];
872 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
873 nratio = av_clipf(nratio, 0.0f, 1.0f);
874 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) to give unity variance
875 sblend = sqrtf(1.0f - nratio);
878 /* decode spx coordinates */
879 spx_coord_exp = get_bits(gbc, 4);
880 spx_coord_mant = get_bits(gbc, 2);
881 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
882 else spx_coord_mant += 4;
883 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
884 spx_coord = spx_coord_mant * (1.0f/(1<<23));
886 /* multiply noise and signal blending factors by spx coordinate */
887 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
888 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
892 s->first_spx_coords[ch] = 1;
897 /* coupling strategy */
898 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
899 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
901 s->cpl_in_use[blk] = get_bits1(gbc);
902 if (s->cpl_in_use[blk]) {
903 /* coupling in use */
904 int cpl_start_subband, cpl_end_subband;
906 if (channel_mode < AC3_CHMODE_STEREO) {
907 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
911 /* check for enhanced coupling */
912 if (s->eac3 && get_bits1(gbc)) {
913 /* TODO: parse enhanced coupling strategy info */
914 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
918 /* determine which channels are coupled */
919 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
920 s->channel_in_cpl[1] = 1;
921 s->channel_in_cpl[2] = 1;
923 for (ch = 1; ch <= fbw_channels; ch++)
924 s->channel_in_cpl[ch] = get_bits1(gbc);
927 /* phase flags in use */
928 if (channel_mode == AC3_CHMODE_STEREO)
929 s->phase_flags_in_use = get_bits1(gbc);
931 /* coupling frequency range */
932 cpl_start_subband = get_bits(gbc, 4);
933 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
934 get_bits(gbc, 4) + 3;
935 if (cpl_start_subband >= cpl_end_subband) {
936 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
937 cpl_start_subband, cpl_end_subband);
940 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
941 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
943 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
945 ff_eac3_default_cpl_band_struct,
946 &s->num_cpl_bands, s->cpl_band_sizes);
948 /* coupling not in use */
949 for (ch = 1; ch <= fbw_channels; ch++) {
950 s->channel_in_cpl[ch] = 0;
951 s->first_cpl_coords[ch] = 1;
953 s->first_cpl_leak = s->eac3;
954 s->phase_flags_in_use = 0;
956 } else if (!s->eac3) {
958 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
961 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
964 cpl_in_use = s->cpl_in_use[blk];
966 /* coupling coordinates */
968 int cpl_coords_exist = 0;
970 for (ch = 1; ch <= fbw_channels; ch++) {
971 if (s->channel_in_cpl[ch]) {
972 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
973 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
974 s->first_cpl_coords[ch] = 0;
975 cpl_coords_exist = 1;
976 master_cpl_coord = 3 * get_bits(gbc, 2);
977 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
978 cpl_coord_exp = get_bits(gbc, 4);
979 cpl_coord_mant = get_bits(gbc, 4);
980 if (cpl_coord_exp == 15)
981 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
983 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
984 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
987 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
991 /* channel not in coupling */
992 s->first_cpl_coords[ch] = 1;
996 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
997 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
998 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1003 /* stereo rematrixing strategy and band structure */
1004 if (channel_mode == AC3_CHMODE_STEREO) {
1005 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1006 s->num_rematrixing_bands = 4;
1007 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1008 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1009 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1010 s->num_rematrixing_bands--;
1012 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
1013 s->rematrixing_flags[bnd] = get_bits1(gbc);
1015 av_log(s->avctx, AV_LOG_WARNING, "Warning: new rematrixing strategy not present in block 0\n");
1016 s->num_rematrixing_bands = 0;
1020 /* exponent strategies for each channel */
1021 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1023 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1024 if(s->exp_strategy[blk][ch] != EXP_REUSE)
1025 bit_alloc_stages[ch] = 3;
1028 /* channel bandwidth */
1029 for (ch = 1; ch <= fbw_channels; ch++) {
1030 s->start_freq[ch] = 0;
1031 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1033 int prev = s->end_freq[ch];
1034 if (s->channel_in_cpl[ch])
1035 s->end_freq[ch] = s->start_freq[CPL_CH];
1036 else if (s->channel_uses_spx[ch])
1037 s->end_freq[ch] = s->spx_src_start_freq;
1039 int bandwidth_code = get_bits(gbc, 6);
1040 if (bandwidth_code > 60) {
1041 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1044 s->end_freq[ch] = bandwidth_code * 3 + 73;
1046 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1047 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
1048 if(blk > 0 && s->end_freq[ch] != prev)
1049 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1052 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1053 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1054 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1057 /* decode exponents for each channel */
1058 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1059 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1060 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1061 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1062 s->num_exp_groups[ch], s->dexps[ch][0],
1063 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1064 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1067 if(ch != CPL_CH && ch != s->lfe_ch)
1068 skip_bits(gbc, 2); /* skip gainrng */
1072 /* bit allocation information */
1073 if (s->bit_allocation_syntax) {
1074 if (get_bits1(gbc)) {
1075 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1076 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1077 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1078 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1079 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1080 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1081 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1083 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1088 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1089 if(!s->eac3 || !blk){
1090 if(s->snr_offset_strategy && get_bits1(gbc)) {
1093 csnr = (get_bits(gbc, 6) - 15) << 4;
1094 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1096 if (ch == i || s->snr_offset_strategy == 2)
1097 snr = (csnr + get_bits(gbc, 4)) << 2;
1098 /* run at least last bit allocation stage if snr offset changes */
1099 if(blk && s->snr_offset[ch] != snr) {
1100 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1102 s->snr_offset[ch] = snr;
1104 /* fast gain (normal AC-3 only) */
1106 int prev = s->fast_gain[ch];
1107 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1108 /* run last 2 bit allocation stages if fast gain changes */
1109 if(blk && prev != s->fast_gain[ch])
1110 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1113 } else if (!s->eac3 && !blk) {
1114 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1119 /* fast gain (E-AC-3 only) */
1120 if (s->fast_gain_syntax && get_bits1(gbc)) {
1121 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1122 int prev = s->fast_gain[ch];
1123 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1124 /* run last 2 bit allocation stages if fast gain changes */
1125 if(blk && prev != s->fast_gain[ch])
1126 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1128 } else if (s->eac3 && !blk) {
1129 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1130 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1133 /* E-AC-3 to AC-3 converter SNR offset */
1134 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1135 skip_bits(gbc, 10); // skip converter snr offset
1138 /* coupling leak information */
1140 if (s->first_cpl_leak || get_bits1(gbc)) {
1141 int fl = get_bits(gbc, 3);
1142 int sl = get_bits(gbc, 3);
1143 /* run last 2 bit allocation stages for coupling channel if
1144 coupling leak changes */
1145 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1146 sl != s->bit_alloc_params.cpl_slow_leak)) {
1147 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1149 s->bit_alloc_params.cpl_fast_leak = fl;
1150 s->bit_alloc_params.cpl_slow_leak = sl;
1151 } else if (!s->eac3 && !blk) {
1152 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1155 s->first_cpl_leak = 0;
1158 /* delta bit allocation information */
1159 if (s->dba_syntax && get_bits1(gbc)) {
1160 /* delta bit allocation exists (strategy) */
1161 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1162 s->dba_mode[ch] = get_bits(gbc, 2);
1163 if (s->dba_mode[ch] == DBA_RESERVED) {
1164 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1167 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1169 /* channel delta offset, len and bit allocation */
1170 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1171 if (s->dba_mode[ch] == DBA_NEW) {
1172 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1173 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1174 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1175 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1176 s->dba_values[ch][seg] = get_bits(gbc, 3);
1178 /* run last 2 bit allocation stages if new dba values */
1179 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1182 } else if(blk == 0) {
1183 for(ch=0; ch<=s->channels; ch++) {
1184 s->dba_mode[ch] = DBA_NONE;
1188 /* Bit allocation */
1189 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1190 if(bit_alloc_stages[ch] > 2) {
1191 /* Exponent mapping into PSD and PSD integration */
1192 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1193 s->start_freq[ch], s->end_freq[ch],
1194 s->psd[ch], s->band_psd[ch]);
1196 if(bit_alloc_stages[ch] > 1) {
1197 /* Compute excitation function, Compute masking curve, and
1198 Apply delta bit allocation */
1199 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1200 s->start_freq[ch], s->end_freq[ch],
1201 s->fast_gain[ch], (ch == s->lfe_ch),
1202 s->dba_mode[ch], s->dba_nsegs[ch],
1203 s->dba_offsets[ch], s->dba_lengths[ch],
1204 s->dba_values[ch], s->mask[ch])) {
1205 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1209 if(bit_alloc_stages[ch] > 0) {
1210 /* Compute bit allocation */
1211 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1212 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1213 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1214 s->start_freq[ch], s->end_freq[ch],
1216 s->bit_alloc_params.floor,
1217 bap_tab, s->bap[ch]);
1221 /* unused dummy data */
1222 if (s->skip_syntax && get_bits1(gbc)) {
1223 int skipl = get_bits(gbc, 9);
1228 /* unpack the transform coefficients
1229 this also uncouples channels if coupling is in use. */
1230 decode_transform_coeffs(s, blk);
1232 /* TODO: generate enhanced coupling coordinates and uncouple */
1234 /* recover coefficients if rematrixing is in use */
1235 if(s->channel_mode == AC3_CHMODE_STEREO)
1238 /* apply scaling to coefficients (headroom, dynrng) */
1239 for(ch=1; ch<=s->channels; ch++) {
1240 float gain = s->mul_bias / 4194304.0f;
1241 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1242 gain *= s->dynamic_range[2-ch];
1244 gain *= s->dynamic_range[0];
1246 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1249 /* apply spectral extension to high frequency bins */
1250 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1251 ff_eac3_apply_spectral_extension(s);
1254 /* downmix and MDCT. order depends on whether block switching is used for
1255 any channel in this block. this is because coefficients for the long
1256 and short transforms cannot be mixed. */
1257 downmix_output = s->channels != s->out_channels &&
1258 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1259 s->fbw_channels == s->out_channels);
1260 if(different_transforms) {
1261 /* the delay samples have already been downmixed, so we upmix the delay
1262 samples in order to reconstruct all channels before downmixing. */
1268 do_imdct(s, s->channels);
1270 if(downmix_output) {
1271 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1274 if(downmix_output) {
1275 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1278 if(downmix_output && !s->downmixed) {
1280 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1283 do_imdct(s, s->out_channels);
1290 * Decode a single AC-3 frame.
1292 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1295 const uint8_t *buf = avpkt->data;
1296 int buf_size = avpkt->size;
1297 AC3DecodeContext *s = avctx->priv_data;
1298 float *out_samples_flt = (float *)data;
1299 int16_t *out_samples = (int16_t *)data;
1301 const uint8_t *channel_map;
1302 const float *output[AC3_MAX_CHANNELS];
1304 /* copy input buffer to decoder context to avoid reading past the end
1305 of the buffer, which can be caused by a damaged input stream. */
1306 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1307 // seems to be byte-swapped AC-3
1308 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1309 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1311 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1312 buf = s->input_buffer;
1313 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1314 init_get_bits(&s->gbc, buf, buf_size * 8);
1316 /* parse the syncinfo */
1318 err = parse_frame_header(s);
1322 case AAC_AC3_PARSE_ERROR_SYNC:
1323 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1325 case AAC_AC3_PARSE_ERROR_BSID:
1326 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1328 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1329 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1331 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1332 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1334 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1335 /* skip frame if CRC is ok. otherwise use error concealment. */
1336 /* TODO: add support for substreams and dependent frames */
1337 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1338 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1339 return s->frame_size;
1341 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1345 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1349 /* check that reported frame size fits in input buffer */
1350 if (s->frame_size > buf_size) {
1351 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1352 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1353 } else if (avctx->error_recognition >= FF_ER_CAREFUL) {
1354 /* check for crc mismatch */
1355 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1356 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1357 err = AAC_AC3_PARSE_ERROR_CRC;
1362 /* if frame is ok, set audio parameters */
1364 avctx->sample_rate = s->sample_rate;
1365 avctx->bit_rate = s->bit_rate;
1367 /* channel config */
1368 s->out_channels = s->channels;
1369 s->output_mode = s->channel_mode;
1371 s->output_mode |= AC3_OUTPUT_LFEON;
1372 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1373 avctx->request_channels < s->channels) {
1374 s->out_channels = avctx->request_channels;
1375 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1376 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1378 avctx->channels = s->out_channels;
1379 avctx->channel_layout = s->channel_layout;
1381 /* set downmixing coefficients if needed */
1382 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1383 s->fbw_channels == s->out_channels)) {
1384 set_downmix_coeffs(s);
1386 } else if (!s->out_channels) {
1387 s->out_channels = avctx->channels;
1388 if(s->out_channels < s->channels)
1389 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1391 /* set audio service type based on bitstream mode for AC-3 */
1392 avctx->audio_service_type = s->bitstream_mode;
1393 if (s->bitstream_mode == 0x7 && s->channels > 1)
1394 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1396 /* decode the audio blocks */
1397 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1398 for (ch = 0; ch < s->out_channels; ch++)
1399 output[ch] = s->output[channel_map[ch]];
1400 for (blk = 0; blk < s->num_blocks; blk++) {
1401 if (!err && decode_audio_block(s, blk)) {
1402 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1405 if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT) {
1406 float_interleave_noscale(out_samples_flt, output, 256, s->out_channels);
1407 out_samples_flt += 256 * s->out_channels;
1409 s->fmt_conv.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1410 out_samples += 256 * s->out_channels;
1413 *data_size = s->num_blocks * 256 * avctx->channels;
1414 *data_size *= avctx->sample_fmt == AV_SAMPLE_FMT_FLT ? sizeof(*out_samples_flt) : sizeof(*out_samples);
1415 return FFMIN(buf_size, s->frame_size);
1419 * Uninitialize the AC-3 decoder.
1421 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1423 AC3DecodeContext *s = avctx->priv_data;
1424 ff_mdct_end(&s->imdct_512);
1425 ff_mdct_end(&s->imdct_256);
1430 AVCodec ff_ac3_decoder = {
1432 .type = AVMEDIA_TYPE_AUDIO,
1434 .priv_data_size = sizeof (AC3DecodeContext),
1435 .init = ac3_decode_init,
1436 .close = ac3_decode_end,
1437 .decode = ac3_decode_frame,
1438 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1441 #if CONFIG_EAC3_DECODER
1442 AVCodec ff_eac3_decoder = {
1444 .type = AVMEDIA_TYPE_AUDIO,
1445 .id = CODEC_ID_EAC3,
1446 .priv_data_size = sizeof (AC3DecodeContext),
1447 .init = ac3_decode_init,
1448 .close = ac3_decode_end,
1449 .decode = ac3_decode_frame,
1450 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),