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"
33 #include "libavutil/opt.h"
35 #include "aac_ac3_parser.h"
36 #include "ac3_parser.h"
38 #include "ac3dec_data.h"
42 * table for ungrouping 3 values in 7 bits.
43 * used for exponents and bap=2 mantissas
45 static uint8_t ungroup_3_in_7_bits_tab[128][3];
48 /** tables for ungrouping mantissas */
49 static int b1_mantissas[32][3];
50 static int b2_mantissas[128][3];
51 static int b3_mantissas[8];
52 static int b4_mantissas[128][2];
53 static int b5_mantissas[16];
56 * Quantization table: levels for symmetric. bits for asymmetric.
57 * reference: Table 7.18 Mapping of bap to Quantizer
59 static const uint8_t quantization_tab[16] = {
61 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
64 /** dynamic range table. converts codes to scale factors. */
65 static float dynamic_range_tab[256];
67 /** Adjustments in dB gain */
68 static const float gain_levels[9] = {
72 LEVEL_MINUS_1POINT5DB,
74 LEVEL_MINUS_4POINT5DB,
81 * Table for center mix levels
82 * reference: Section 5.4.2.4 cmixlev
84 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
87 * Table for surround mix levels
88 * reference: Section 5.4.2.5 surmixlev
90 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
93 * Table for default stereo downmixing coefficients
94 * reference: Section 7.8.2 Downmixing Into Two Channels
96 static const uint8_t ac3_default_coeffs[8][5][2] = {
97 { { 2, 7 }, { 7, 2 }, },
99 { { 2, 7 }, { 7, 2 }, },
100 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
101 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
102 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
103 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
104 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
108 * Symmetrical Dequantization
109 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
110 * Tables 7.19 to 7.23
113 symmetric_dequant(int code, int levels)
115 return ((code - (levels >> 1)) << 24) / levels;
119 * Initialize tables at runtime.
121 static av_cold void ac3_tables_init(void)
125 /* generate table for ungrouping 3 values in 7 bits
126 reference: Section 7.1.3 Exponent Decoding */
127 for(i=0; i<128; i++) {
128 ungroup_3_in_7_bits_tab[i][0] = i / 25;
129 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
130 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
133 /* generate grouped mantissa tables
134 reference: Section 7.3.5 Ungrouping of Mantissas */
135 for(i=0; i<32; i++) {
136 /* bap=1 mantissas */
137 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
138 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
139 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
141 for(i=0; i<128; i++) {
142 /* bap=2 mantissas */
143 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
144 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
145 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
147 /* bap=4 mantissas */
148 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
149 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
151 /* generate ungrouped mantissa tables
152 reference: Tables 7.21 and 7.23 */
154 /* bap=3 mantissas */
155 b3_mantissas[i] = symmetric_dequant(i, 7);
157 for(i=0; i<15; i++) {
158 /* bap=5 mantissas */
159 b5_mantissas[i] = symmetric_dequant(i, 15);
162 /* generate dynamic range table
163 reference: Section 7.7.1 Dynamic Range Control */
164 for(i=0; i<256; i++) {
165 int v = (i >> 5) - ((i >> 7) << 3) - 5;
166 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
172 * AVCodec initialization
174 static av_cold int ac3_decode_init(AVCodecContext *avctx)
176 AC3DecodeContext *s = avctx->priv_data;
179 ff_ac3_common_init();
181 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
182 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
183 ff_kbd_window_init(s->window, 5.0, 256);
184 dsputil_init(&s->dsp, avctx);
185 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
186 ff_fmt_convert_init(&s->fmt_conv, avctx);
187 av_lfg_init(&s->dith_state, 0);
189 /* set scale value for float to int16 conversion */
190 if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
192 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
194 s->mul_bias = 32767.0f;
195 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
198 /* allow downmixing to stereo or mono */
199 if (avctx->channels > 0 && avctx->request_channels > 0 &&
200 avctx->request_channels < avctx->channels &&
201 avctx->request_channels <= 2) {
202 avctx->channels = avctx->request_channels;
210 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
211 * GetBitContext within AC3DecodeContext must point to
212 * the start of the synchronized AC-3 bitstream.
214 static int ac3_parse_header(AC3DecodeContext *s)
216 GetBitContext *gbc = &s->gbc;
219 /* read the rest of the bsi. read twice for dual mono mode. */
220 i = !(s->channel_mode);
222 skip_bits(gbc, 5); // skip dialog normalization
224 skip_bits(gbc, 8); //skip compression
226 skip_bits(gbc, 8); //skip language code
228 skip_bits(gbc, 7); //skip audio production information
231 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
233 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
234 TODO: read & use the xbsi1 downmix levels */
236 skip_bits(gbc, 14); //skip timecode1 / xbsi1
238 skip_bits(gbc, 14); //skip timecode2 / xbsi2
240 /* skip additional bitstream info */
241 if (get_bits1(gbc)) {
242 i = get_bits(gbc, 6);
252 * Common function to parse AC-3 or E-AC-3 frame header
254 static int parse_frame_header(AC3DecodeContext *s)
259 err = ff_ac3_parse_header(&s->gbc, &hdr);
263 /* get decoding parameters from header info */
264 s->bit_alloc_params.sr_code = hdr.sr_code;
265 s->bitstream_mode = hdr.bitstream_mode;
266 s->channel_mode = hdr.channel_mode;
267 s->channel_layout = hdr.channel_layout;
268 s->lfe_on = hdr.lfe_on;
269 s->bit_alloc_params.sr_shift = hdr.sr_shift;
270 s->sample_rate = hdr.sample_rate;
271 s->bit_rate = hdr.bit_rate;
272 s->channels = hdr.channels;
273 s->fbw_channels = s->channels - s->lfe_on;
274 s->lfe_ch = s->fbw_channels + 1;
275 s->frame_size = hdr.frame_size;
276 s->center_mix_level = hdr.center_mix_level;
277 s->surround_mix_level = hdr.surround_mix_level;
278 s->num_blocks = hdr.num_blocks;
279 s->frame_type = hdr.frame_type;
280 s->substreamid = hdr.substreamid;
283 s->start_freq[s->lfe_ch] = 0;
284 s->end_freq[s->lfe_ch] = 7;
285 s->num_exp_groups[s->lfe_ch] = 2;
286 s->channel_in_cpl[s->lfe_ch] = 0;
289 if (hdr.bitstream_id <= 10) {
291 s->snr_offset_strategy = 2;
292 s->block_switch_syntax = 1;
293 s->dither_flag_syntax = 1;
294 s->bit_allocation_syntax = 1;
295 s->fast_gain_syntax = 0;
296 s->first_cpl_leak = 0;
299 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
300 return ac3_parse_header(s);
301 } else if (CONFIG_EAC3_DECODER) {
303 return ff_eac3_parse_header(s);
305 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
311 * Set stereo downmixing coefficients based on frame header info.
312 * reference: Section 7.8.2 Downmixing Into Two Channels
314 static void set_downmix_coeffs(AC3DecodeContext *s)
317 float cmix = gain_levels[center_levels[s->center_mix_level]];
318 float smix = gain_levels[surround_levels[s->surround_mix_level]];
321 for(i=0; i<s->fbw_channels; i++) {
322 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
323 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
325 if(s->channel_mode > 1 && s->channel_mode & 1) {
326 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
328 if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
329 int nf = s->channel_mode - 2;
330 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
332 if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
333 int nf = s->channel_mode - 4;
334 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
339 for(i=0; i<s->fbw_channels; i++) {
340 norm0 += s->downmix_coeffs[i][0];
341 norm1 += s->downmix_coeffs[i][1];
343 norm0 = 1.0f / norm0;
344 norm1 = 1.0f / norm1;
345 for(i=0; i<s->fbw_channels; i++) {
346 s->downmix_coeffs[i][0] *= norm0;
347 s->downmix_coeffs[i][1] *= norm1;
350 if(s->output_mode == AC3_CHMODE_MONO) {
351 for(i=0; i<s->fbw_channels; i++)
352 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
357 * Decode the grouped exponents according to exponent strategy.
358 * reference: Section 7.1.3 Exponent Decoding
360 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
361 uint8_t absexp, int8_t *dexps)
363 int i, j, grp, group_size;
368 group_size = exp_strategy + (exp_strategy == EXP_D45);
369 for(grp=0,i=0; grp<ngrps; grp++) {
370 expacc = get_bits(gbc, 7);
371 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
372 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
373 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
376 /* convert to absolute exps and expand groups */
378 for(i=0,j=0; i<ngrps*3; i++) {
379 prevexp += dexp[i] - 2;
382 switch (group_size) {
383 case 4: dexps[j++] = prevexp;
384 dexps[j++] = prevexp;
385 case 2: dexps[j++] = prevexp;
386 case 1: dexps[j++] = prevexp;
393 * Generate transform coefficients for each coupled channel in the coupling
394 * range using the coupling coefficients and coupling coordinates.
395 * reference: Section 7.4.3 Coupling Coordinate Format
397 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
401 bin = s->start_freq[CPL_CH];
402 for (band = 0; band < s->num_cpl_bands; band++) {
403 int band_start = bin;
404 int band_end = bin + s->cpl_band_sizes[band];
405 for (ch = 1; ch <= s->fbw_channels; ch++) {
406 if (s->channel_in_cpl[ch]) {
407 int cpl_coord = s->cpl_coords[ch][band] << 5;
408 for (bin = band_start; bin < band_end; bin++) {
409 s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
411 if (ch == 2 && s->phase_flags[band]) {
412 for (bin = band_start; bin < band_end; bin++)
413 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
422 * Grouped mantissas for 3-level 5-level and 11-level quantization
434 * Decode the transform coefficients for a particular channel
435 * reference: Section 7.3 Quantization and Decoding of Mantissas
437 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
439 int start_freq = s->start_freq[ch_index];
440 int end_freq = s->end_freq[ch_index];
441 uint8_t *baps = s->bap[ch_index];
442 int8_t *exps = s->dexps[ch_index];
443 int *coeffs = s->fixed_coeffs[ch_index];
444 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
445 GetBitContext *gbc = &s->gbc;
448 for(freq = start_freq; freq < end_freq; freq++){
449 int bap = baps[freq];
454 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
461 mantissa = m->b1_mant[m->b1];
464 int bits = get_bits(gbc, 5);
465 mantissa = b1_mantissas[bits][0];
466 m->b1_mant[1] = b1_mantissas[bits][1];
467 m->b1_mant[0] = b1_mantissas[bits][2];
474 mantissa = m->b2_mant[m->b2];
477 int bits = get_bits(gbc, 7);
478 mantissa = b2_mantissas[bits][0];
479 m->b2_mant[1] = b2_mantissas[bits][1];
480 m->b2_mant[0] = b2_mantissas[bits][2];
485 mantissa = b3_mantissas[get_bits(gbc, 3)];
490 mantissa = m->b4_mant;
493 int bits = get_bits(gbc, 7);
494 mantissa = b4_mantissas[bits][0];
495 m->b4_mant = b4_mantissas[bits][1];
500 mantissa = b5_mantissas[get_bits(gbc, 4)];
502 default: /* 6 to 15 */
503 mantissa = get_bits(gbc, quantization_tab[bap]);
504 /* Shift mantissa and sign-extend it. */
505 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
508 coeffs[freq] = mantissa >> exps[freq];
513 * Remove random dithering from coupling range coefficients with zero-bit
514 * mantissas for coupled channels which do not use dithering.
515 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
517 static void remove_dithering(AC3DecodeContext *s) {
520 for(ch=1; ch<=s->fbw_channels; ch++) {
521 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
522 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
523 if(!s->bap[CPL_CH][i])
524 s->fixed_coeffs[ch][i] = 0;
530 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
533 if (!s->channel_uses_aht[ch]) {
534 ac3_decode_transform_coeffs_ch(s, ch, m);
536 /* if AHT is used, mantissas for all blocks are encoded in the first
537 block of the frame. */
539 if (!blk && CONFIG_EAC3_DECODER)
540 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
541 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
542 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
548 * Decode the transform coefficients.
550 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
556 m.b1 = m.b2 = m.b4 = 0;
558 for (ch = 1; ch <= s->channels; ch++) {
559 /* transform coefficients for full-bandwidth channel */
560 decode_transform_coeffs_ch(s, blk, ch, &m);
561 /* tranform coefficients for coupling channel come right after the
562 coefficients for the first coupled channel*/
563 if (s->channel_in_cpl[ch]) {
565 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
566 calc_transform_coeffs_cpl(s);
569 end = s->end_freq[CPL_CH];
571 end = s->end_freq[ch];
574 s->fixed_coeffs[ch][end] = 0;
578 /* zero the dithered coefficients for appropriate channels */
583 * Stereo rematrixing.
584 * reference: Section 7.5.4 Rematrixing : Decoding Technique
586 static void do_rematrixing(AC3DecodeContext *s)
591 end = FFMIN(s->end_freq[1], s->end_freq[2]);
593 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
594 if(s->rematrixing_flags[bnd]) {
595 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
596 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
597 int tmp0 = s->fixed_coeffs[1][i];
598 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
599 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
606 * Inverse MDCT Transform.
607 * Convert frequency domain coefficients to time-domain audio samples.
608 * reference: Section 7.9.4 Transformation Equations
610 static inline void do_imdct(AC3DecodeContext *s, int channels)
614 for (ch=1; ch<=channels; ch++) {
615 if (s->block_switch[ch]) {
617 float *x = s->tmp_output+128;
619 x[i] = s->transform_coeffs[ch][2*i];
620 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
621 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
623 x[i] = s->transform_coeffs[ch][2*i+1];
624 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch-1], x);
626 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
627 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
628 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
634 * Downmix the output to mono or stereo.
636 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
641 for(i=0; i<len; i++) {
643 for(j=0; j<in_ch; j++) {
644 v0 += samples[j][i] * matrix[j][0];
645 v1 += samples[j][i] * matrix[j][1];
650 } else if(out_ch == 1) {
651 for(i=0; i<len; i++) {
653 for(j=0; j<in_ch; j++)
654 v0 += samples[j][i] * matrix[j][0];
661 * Upmix delay samples from stereo to original channel layout.
663 static void ac3_upmix_delay(AC3DecodeContext *s)
665 int channel_data_size = sizeof(s->delay[0]);
666 switch(s->channel_mode) {
667 case AC3_CHMODE_DUALMONO:
668 case AC3_CHMODE_STEREO:
669 /* upmix mono to stereo */
670 memcpy(s->delay[1], s->delay[0], channel_data_size);
672 case AC3_CHMODE_2F2R:
673 memset(s->delay[3], 0, channel_data_size);
674 case AC3_CHMODE_2F1R:
675 memset(s->delay[2], 0, channel_data_size);
677 case AC3_CHMODE_3F2R:
678 memset(s->delay[4], 0, channel_data_size);
679 case AC3_CHMODE_3F1R:
680 memset(s->delay[3], 0, channel_data_size);
682 memcpy(s->delay[2], s->delay[1], channel_data_size);
683 memset(s->delay[1], 0, channel_data_size);
689 * Decode band structure for coupling, spectral extension, or enhanced coupling.
690 * The band structure defines how many subbands are in each band. For each
691 * subband in the range, 1 means it is combined with the previous band, and 0
692 * means that it starts a new band.
694 * @param[in] gbc bit reader context
695 * @param[in] blk block number
696 * @param[in] eac3 flag to indicate E-AC-3
697 * @param[in] ecpl flag to indicate enhanced coupling
698 * @param[in] start_subband subband number for start of range
699 * @param[in] end_subband subband number for end of range
700 * @param[in] default_band_struct default band structure table
701 * @param[out] num_bands number of bands (optionally NULL)
702 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
704 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
705 int ecpl, int start_subband, int end_subband,
706 const uint8_t *default_band_struct,
707 int *num_bands, uint8_t *band_sizes)
709 int subbnd, bnd, n_subbands, n_bands=0;
711 uint8_t coded_band_struct[22];
712 const uint8_t *band_struct;
714 n_subbands = end_subband - start_subband;
716 /* decode band structure from bitstream or use default */
717 if (!eac3 || get_bits1(gbc)) {
718 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
719 coded_band_struct[subbnd] = get_bits1(gbc);
721 band_struct = coded_band_struct;
723 band_struct = &default_band_struct[start_subband+1];
725 /* no change in band structure */
729 /* calculate number of bands and band sizes based on band structure.
730 note that the first 4 subbands in enhanced coupling span only 6 bins
732 if (num_bands || band_sizes ) {
733 n_bands = n_subbands;
734 bnd_sz[0] = ecpl ? 6 : 12;
735 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
736 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
737 if (band_struct[subbnd-1]) {
739 bnd_sz[bnd] += subbnd_size;
741 bnd_sz[++bnd] = subbnd_size;
746 /* set optional output params */
748 *num_bands = n_bands;
750 memcpy(band_sizes, bnd_sz, n_bands);
754 * Decode a single audio block from the AC-3 bitstream.
756 static int decode_audio_block(AC3DecodeContext *s, int blk)
758 int fbw_channels = s->fbw_channels;
759 int channel_mode = s->channel_mode;
761 int different_transforms;
764 GetBitContext *gbc = &s->gbc;
765 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
767 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
769 /* block switch flags */
770 different_transforms = 0;
771 if (s->block_switch_syntax) {
772 for (ch = 1; ch <= fbw_channels; ch++) {
773 s->block_switch[ch] = get_bits1(gbc);
774 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
775 different_transforms = 1;
779 /* dithering flags */
780 if (s->dither_flag_syntax) {
781 for (ch = 1; ch <= fbw_channels; ch++) {
782 s->dither_flag[ch] = get_bits1(gbc);
787 i = !(s->channel_mode);
790 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
791 s->avctx->drc_scale)+1.0;
792 } else if(blk == 0) {
793 s->dynamic_range[i] = 1.0f;
797 /* spectral extension strategy */
798 if (s->eac3 && (!blk || get_bits1(gbc))) {
799 s->spx_in_use = get_bits1(gbc);
801 int dst_start_freq, dst_end_freq, src_start_freq,
802 start_subband, end_subband;
804 /* determine which channels use spx */
805 if (s->channel_mode == AC3_CHMODE_MONO) {
806 s->channel_uses_spx[1] = 1;
808 for (ch = 1; ch <= fbw_channels; ch++)
809 s->channel_uses_spx[ch] = get_bits1(gbc);
812 /* get the frequency bins of the spx copy region and the spx start
814 dst_start_freq = get_bits(gbc, 2);
815 start_subband = get_bits(gbc, 3) + 2;
816 if (start_subband > 7)
817 start_subband += start_subband - 7;
818 end_subband = get_bits(gbc, 3) + 5;
820 end_subband += end_subband - 7;
821 dst_start_freq = dst_start_freq * 12 + 25;
822 src_start_freq = start_subband * 12 + 25;
823 dst_end_freq = end_subband * 12 + 25;
825 /* check validity of spx ranges */
826 if (start_subband >= end_subband) {
827 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
828 "range (%d >= %d)\n", start_subband, end_subband);
831 if (dst_start_freq >= src_start_freq) {
832 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
833 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
837 s->spx_dst_start_freq = dst_start_freq;
838 s->spx_src_start_freq = src_start_freq;
839 s->spx_dst_end_freq = dst_end_freq;
841 decode_band_structure(gbc, blk, s->eac3, 0,
842 start_subband, end_subband,
843 ff_eac3_default_spx_band_struct,
847 for (ch = 1; ch <= fbw_channels; ch++) {
848 s->channel_uses_spx[ch] = 0;
849 s->first_spx_coords[ch] = 1;
854 /* spectral extension coordinates */
856 for (ch = 1; ch <= fbw_channels; ch++) {
857 if (s->channel_uses_spx[ch]) {
858 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
860 int bin, master_spx_coord;
862 s->first_spx_coords[ch] = 0;
863 spx_blend = get_bits(gbc, 5) * (1.0f/32);
864 master_spx_coord = get_bits(gbc, 2) * 3;
866 bin = s->spx_src_start_freq;
867 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
869 int spx_coord_exp, spx_coord_mant;
870 float nratio, sblend, nblend, spx_coord;
872 /* calculate blending factors */
873 bandsize = s->spx_band_sizes[bnd];
874 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
875 nratio = av_clipf(nratio, 0.0f, 1.0f);
876 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) to give unity variance
877 sblend = sqrtf(1.0f - nratio);
880 /* decode spx coordinates */
881 spx_coord_exp = get_bits(gbc, 4);
882 spx_coord_mant = get_bits(gbc, 2);
883 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
884 else spx_coord_mant += 4;
885 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
886 spx_coord = spx_coord_mant * (1.0f/(1<<23));
888 /* multiply noise and signal blending factors by spx coordinate */
889 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
890 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
894 s->first_spx_coords[ch] = 1;
899 /* coupling strategy */
900 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
901 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
903 s->cpl_in_use[blk] = get_bits1(gbc);
904 if (s->cpl_in_use[blk]) {
905 /* coupling in use */
906 int cpl_start_subband, cpl_end_subband;
908 if (channel_mode < AC3_CHMODE_STEREO) {
909 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
913 /* check for enhanced coupling */
914 if (s->eac3 && get_bits1(gbc)) {
915 /* TODO: parse enhanced coupling strategy info */
916 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
920 /* determine which channels are coupled */
921 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
922 s->channel_in_cpl[1] = 1;
923 s->channel_in_cpl[2] = 1;
925 for (ch = 1; ch <= fbw_channels; ch++)
926 s->channel_in_cpl[ch] = get_bits1(gbc);
929 /* phase flags in use */
930 if (channel_mode == AC3_CHMODE_STEREO)
931 s->phase_flags_in_use = get_bits1(gbc);
933 /* coupling frequency range */
934 cpl_start_subband = get_bits(gbc, 4);
935 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
936 get_bits(gbc, 4) + 3;
937 if (cpl_start_subband >= cpl_end_subband) {
938 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
939 cpl_start_subband, cpl_end_subband);
942 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
943 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
945 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
947 ff_eac3_default_cpl_band_struct,
948 &s->num_cpl_bands, s->cpl_band_sizes);
950 /* coupling not in use */
951 for (ch = 1; ch <= fbw_channels; ch++) {
952 s->channel_in_cpl[ch] = 0;
953 s->first_cpl_coords[ch] = 1;
955 s->first_cpl_leak = s->eac3;
956 s->phase_flags_in_use = 0;
958 } else if (!s->eac3) {
960 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
963 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
966 cpl_in_use = s->cpl_in_use[blk];
968 /* coupling coordinates */
970 int cpl_coords_exist = 0;
972 for (ch = 1; ch <= fbw_channels; ch++) {
973 if (s->channel_in_cpl[ch]) {
974 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
975 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
976 s->first_cpl_coords[ch] = 0;
977 cpl_coords_exist = 1;
978 master_cpl_coord = 3 * get_bits(gbc, 2);
979 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
980 cpl_coord_exp = get_bits(gbc, 4);
981 cpl_coord_mant = get_bits(gbc, 4);
982 if (cpl_coord_exp == 15)
983 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
985 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
986 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
989 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
993 /* channel not in coupling */
994 s->first_cpl_coords[ch] = 1;
998 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
999 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1000 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1005 /* stereo rematrixing strategy and band structure */
1006 if (channel_mode == AC3_CHMODE_STEREO) {
1007 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1008 s->num_rematrixing_bands = 4;
1009 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1010 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1011 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1012 s->num_rematrixing_bands--;
1014 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
1015 s->rematrixing_flags[bnd] = get_bits1(gbc);
1017 av_log(s->avctx, AV_LOG_WARNING, "Warning: new rematrixing strategy not present in block 0\n");
1018 s->num_rematrixing_bands = 0;
1022 /* exponent strategies for each channel */
1023 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1025 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1026 if(s->exp_strategy[blk][ch] != EXP_REUSE)
1027 bit_alloc_stages[ch] = 3;
1030 /* channel bandwidth */
1031 for (ch = 1; ch <= fbw_channels; ch++) {
1032 s->start_freq[ch] = 0;
1033 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1035 int prev = s->end_freq[ch];
1036 if (s->channel_in_cpl[ch])
1037 s->end_freq[ch] = s->start_freq[CPL_CH];
1038 else if (s->channel_uses_spx[ch])
1039 s->end_freq[ch] = s->spx_src_start_freq;
1041 int bandwidth_code = get_bits(gbc, 6);
1042 if (bandwidth_code > 60) {
1043 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1046 s->end_freq[ch] = bandwidth_code * 3 + 73;
1048 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1049 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
1050 if(blk > 0 && s->end_freq[ch] != prev)
1051 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1054 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1055 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1056 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1059 /* decode exponents for each channel */
1060 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1061 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1062 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1063 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1064 s->num_exp_groups[ch], s->dexps[ch][0],
1065 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1066 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1069 if(ch != CPL_CH && ch != s->lfe_ch)
1070 skip_bits(gbc, 2); /* skip gainrng */
1074 /* bit allocation information */
1075 if (s->bit_allocation_syntax) {
1076 if (get_bits1(gbc)) {
1077 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1078 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1079 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1080 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1081 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1082 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1083 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1085 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1090 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1091 if(!s->eac3 || !blk){
1092 if(s->snr_offset_strategy && get_bits1(gbc)) {
1095 csnr = (get_bits(gbc, 6) - 15) << 4;
1096 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1098 if (ch == i || s->snr_offset_strategy == 2)
1099 snr = (csnr + get_bits(gbc, 4)) << 2;
1100 /* run at least last bit allocation stage if snr offset changes */
1101 if(blk && s->snr_offset[ch] != snr) {
1102 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1104 s->snr_offset[ch] = snr;
1106 /* fast gain (normal AC-3 only) */
1108 int prev = s->fast_gain[ch];
1109 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1110 /* run last 2 bit allocation stages if fast gain changes */
1111 if(blk && prev != s->fast_gain[ch])
1112 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1115 } else if (!s->eac3 && !blk) {
1116 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1121 /* fast gain (E-AC-3 only) */
1122 if (s->fast_gain_syntax && get_bits1(gbc)) {
1123 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1124 int prev = s->fast_gain[ch];
1125 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1126 /* run last 2 bit allocation stages if fast gain changes */
1127 if(blk && prev != s->fast_gain[ch])
1128 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1130 } else if (s->eac3 && !blk) {
1131 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1132 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1135 /* E-AC-3 to AC-3 converter SNR offset */
1136 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1137 skip_bits(gbc, 10); // skip converter snr offset
1140 /* coupling leak information */
1142 if (s->first_cpl_leak || get_bits1(gbc)) {
1143 int fl = get_bits(gbc, 3);
1144 int sl = get_bits(gbc, 3);
1145 /* run last 2 bit allocation stages for coupling channel if
1146 coupling leak changes */
1147 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1148 sl != s->bit_alloc_params.cpl_slow_leak)) {
1149 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1151 s->bit_alloc_params.cpl_fast_leak = fl;
1152 s->bit_alloc_params.cpl_slow_leak = sl;
1153 } else if (!s->eac3 && !blk) {
1154 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1157 s->first_cpl_leak = 0;
1160 /* delta bit allocation information */
1161 if (s->dba_syntax && get_bits1(gbc)) {
1162 /* delta bit allocation exists (strategy) */
1163 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1164 s->dba_mode[ch] = get_bits(gbc, 2);
1165 if (s->dba_mode[ch] == DBA_RESERVED) {
1166 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1169 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1171 /* channel delta offset, len and bit allocation */
1172 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1173 if (s->dba_mode[ch] == DBA_NEW) {
1174 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1175 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1176 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1177 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1178 s->dba_values[ch][seg] = get_bits(gbc, 3);
1180 /* run last 2 bit allocation stages if new dba values */
1181 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1184 } else if(blk == 0) {
1185 for(ch=0; ch<=s->channels; ch++) {
1186 s->dba_mode[ch] = DBA_NONE;
1190 /* Bit allocation */
1191 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1192 if(bit_alloc_stages[ch] > 2) {
1193 /* Exponent mapping into PSD and PSD integration */
1194 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1195 s->start_freq[ch], s->end_freq[ch],
1196 s->psd[ch], s->band_psd[ch]);
1198 if(bit_alloc_stages[ch] > 1) {
1199 /* Compute excitation function, Compute masking curve, and
1200 Apply delta bit allocation */
1201 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1202 s->start_freq[ch], s->end_freq[ch],
1203 s->fast_gain[ch], (ch == s->lfe_ch),
1204 s->dba_mode[ch], s->dba_nsegs[ch],
1205 s->dba_offsets[ch], s->dba_lengths[ch],
1206 s->dba_values[ch], s->mask[ch])) {
1207 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1211 if(bit_alloc_stages[ch] > 0) {
1212 /* Compute bit allocation */
1213 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1214 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1215 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1216 s->start_freq[ch], s->end_freq[ch],
1218 s->bit_alloc_params.floor,
1219 bap_tab, s->bap[ch]);
1223 /* unused dummy data */
1224 if (s->skip_syntax && get_bits1(gbc)) {
1225 int skipl = get_bits(gbc, 9);
1230 /* unpack the transform coefficients
1231 this also uncouples channels if coupling is in use. */
1232 decode_transform_coeffs(s, blk);
1234 /* TODO: generate enhanced coupling coordinates and uncouple */
1236 /* recover coefficients if rematrixing is in use */
1237 if(s->channel_mode == AC3_CHMODE_STEREO)
1240 /* apply scaling to coefficients (headroom, dynrng) */
1241 for(ch=1; ch<=s->channels; ch++) {
1242 float gain = s->mul_bias / 4194304.0f;
1243 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1244 gain *= s->dynamic_range[2-ch];
1246 gain *= s->dynamic_range[0];
1248 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1251 /* apply spectral extension to high frequency bins */
1252 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1253 ff_eac3_apply_spectral_extension(s);
1256 /* downmix and MDCT. order depends on whether block switching is used for
1257 any channel in this block. this is because coefficients for the long
1258 and short transforms cannot be mixed. */
1259 downmix_output = s->channels != s->out_channels &&
1260 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1261 s->fbw_channels == s->out_channels);
1262 if(different_transforms) {
1263 /* the delay samples have already been downmixed, so we upmix the delay
1264 samples in order to reconstruct all channels before downmixing. */
1270 do_imdct(s, s->channels);
1272 if(downmix_output) {
1273 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1276 if(downmix_output) {
1277 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1280 if(downmix_output && !s->downmixed) {
1282 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1285 do_imdct(s, s->out_channels);
1292 * Decode a single AC-3 frame.
1294 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1297 const uint8_t *buf = avpkt->data;
1298 int buf_size = avpkt->size;
1299 AC3DecodeContext *s = avctx->priv_data;
1300 float *out_samples_flt = data;
1301 int16_t *out_samples_s16 = data;
1303 int data_size_orig, data_size_tmp;
1304 const uint8_t *channel_map;
1305 const float *output[AC3_MAX_CHANNELS];
1307 /* copy input buffer to decoder context to avoid reading past the end
1308 of the buffer, which can be caused by a damaged input stream. */
1309 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1310 // seems to be byte-swapped AC-3
1311 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1312 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1314 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1315 buf = s->input_buffer;
1316 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1317 init_get_bits(&s->gbc, buf, buf_size * 8);
1319 /* parse the syncinfo */
1320 data_size_orig = *data_size;
1322 err = parse_frame_header(s);
1326 case AAC_AC3_PARSE_ERROR_SYNC:
1327 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1329 case AAC_AC3_PARSE_ERROR_BSID:
1330 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1332 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1333 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1335 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1336 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1338 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1339 /* skip frame if CRC is ok. otherwise use error concealment. */
1340 /* TODO: add support for substreams and dependent frames */
1341 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1342 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1343 return s->frame_size;
1345 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1349 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1353 /* check that reported frame size fits in input buffer */
1354 if (s->frame_size > buf_size) {
1355 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1356 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1357 } else if (avctx->error_recognition >= FF_ER_CAREFUL) {
1358 /* check for crc mismatch */
1359 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1360 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1361 err = AAC_AC3_PARSE_ERROR_CRC;
1366 /* if frame is ok, set audio parameters */
1368 avctx->sample_rate = s->sample_rate;
1369 avctx->bit_rate = s->bit_rate;
1371 /* channel config */
1372 s->out_channels = s->channels;
1373 s->output_mode = s->channel_mode;
1375 s->output_mode |= AC3_OUTPUT_LFEON;
1376 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1377 avctx->request_channels < s->channels) {
1378 s->out_channels = avctx->request_channels;
1379 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1380 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1382 avctx->channels = s->out_channels;
1383 avctx->channel_layout = s->channel_layout;
1385 s->loro_center_mix_level = gain_levels[ center_levels[s-> center_mix_level]];
1386 s->loro_surround_mix_level = gain_levels[surround_levels[s->surround_mix_level]];
1387 s->ltrt_center_mix_level = LEVEL_MINUS_3DB;
1388 s->ltrt_surround_mix_level = LEVEL_MINUS_3DB;
1389 /* set downmixing coefficients if needed */
1390 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1391 s->fbw_channels == s->out_channels)) {
1392 set_downmix_coeffs(s);
1394 } else if (!s->out_channels) {
1395 s->out_channels = avctx->channels;
1396 if(s->out_channels < s->channels)
1397 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1399 /* set audio service type based on bitstream mode for AC-3 */
1400 avctx->audio_service_type = s->bitstream_mode;
1401 if (s->bitstream_mode == 0x7 && s->channels > 1)
1402 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1404 /* decode the audio blocks */
1405 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1406 for (ch = 0; ch < s->out_channels; ch++)
1407 output[ch] = s->output[channel_map[ch]];
1408 data_size_tmp = s->num_blocks * 256 * avctx->channels;
1409 data_size_tmp *= avctx->sample_fmt == AV_SAMPLE_FMT_FLT ? sizeof(*out_samples_flt) : sizeof(*out_samples_s16);
1410 if (data_size_orig < data_size_tmp)
1412 *data_size = data_size_tmp;
1413 for (blk = 0; blk < s->num_blocks; blk++) {
1414 if (!err && decode_audio_block(s, blk)) {
1415 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1419 if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT) {
1420 s->fmt_conv.float_interleave(out_samples_flt, output, 256,
1422 out_samples_flt += 256 * s->out_channels;
1424 s->fmt_conv.float_to_int16_interleave(out_samples_s16, output, 256,
1426 out_samples_s16 += 256 * s->out_channels;
1429 *data_size = s->num_blocks * 256 * avctx->channels *
1430 av_get_bytes_per_sample(avctx->sample_fmt);
1431 return FFMIN(buf_size, s->frame_size);
1435 * Uninitialize the AC-3 decoder.
1437 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1439 AC3DecodeContext *s = avctx->priv_data;
1440 ff_mdct_end(&s->imdct_512);
1441 ff_mdct_end(&s->imdct_256);
1446 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1447 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)
1448 static const AVOption options[] = {
1449 { "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), FF_OPT_TYPE_FLOAT, {1.0}, 0.0, 1.0, PAR },
1451 {"dmix_mode", "Preferred Stereo Downmix Mode", OFFSET(preferred_stereo_downmix), FF_OPT_TYPE_INT, {.dbl = -1 }, -1, 2, 0, "dmix_mode"},
1452 {"ltrt_cmixlev", "Lt/Rt Center Mix Level", OFFSET(ltrt_center_mix_level), FF_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1453 {"ltrt_surmixlev", "Lt/Rt Surround Mix Level", OFFSET(ltrt_surround_mix_level), FF_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1454 {"loro_cmixlev", "Lo/Ro Center Mix Level", OFFSET(loro_center_mix_level), FF_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1455 {"loro_surmixlev", "Lo/Ro Surround Mix Level", OFFSET(loro_surround_mix_level), FF_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1460 static const AVClass ac3_decoder_class = {
1461 .class_name = "(E-)AC3 decoder",
1462 .item_name = av_default_item_name,
1464 .version = LIBAVUTIL_VERSION_INT,
1467 AVCodec ff_ac3_decoder = {
1469 .type = AVMEDIA_TYPE_AUDIO,
1471 .priv_data_size = sizeof (AC3DecodeContext),
1472 .init = ac3_decode_init,
1473 .close = ac3_decode_end,
1474 .decode = ac3_decode_frame,
1475 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1476 .sample_fmts = (const enum AVSampleFormat[]) {
1477 AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE
1479 .priv_class = &ac3_decoder_class,
1482 #if CONFIG_EAC3_DECODER
1483 AVCodec ff_eac3_decoder = {
1485 .type = AVMEDIA_TYPE_AUDIO,
1486 .id = CODEC_ID_EAC3,
1487 .priv_data_size = sizeof (AC3DecodeContext),
1488 .init = ac3_decode_init,
1489 .close = ac3_decode_end,
1490 .decode = ac3_decode_frame,
1491 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1492 .sample_fmts = (const enum AVSampleFormat[]) {
1493 AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE
1495 .priv_class = &ac3_decoder_class,