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 /* set scale value for float to int16 conversion */
189 if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
191 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
193 s->mul_bias = 32767.0f;
194 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
197 /* allow downmixing to stereo or mono */
198 if (avctx->channels > 0 && avctx->request_channels > 0 &&
199 avctx->request_channels < avctx->channels &&
200 avctx->request_channels <= 2) {
201 avctx->channels = avctx->request_channels;
209 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
210 * GetBitContext within AC3DecodeContext must point to
211 * the start of the synchronized AC-3 bitstream.
213 static int ac3_parse_header(AC3DecodeContext *s)
215 GetBitContext *gbc = &s->gbc;
218 /* read the rest of the bsi. read twice for dual mono mode. */
219 i = !(s->channel_mode);
221 skip_bits(gbc, 5); // skip dialog normalization
223 skip_bits(gbc, 8); //skip compression
225 skip_bits(gbc, 8); //skip language code
227 skip_bits(gbc, 7); //skip audio production information
230 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
232 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
233 TODO: read & use the xbsi1 downmix levels */
235 skip_bits(gbc, 14); //skip timecode1 / xbsi1
237 skip_bits(gbc, 14); //skip timecode2 / xbsi2
239 /* skip additional bitstream info */
240 if (get_bits1(gbc)) {
241 i = get_bits(gbc, 6);
251 * Common function to parse AC-3 or E-AC-3 frame header
253 static int parse_frame_header(AC3DecodeContext *s)
258 err = ff_ac3_parse_header(&s->gbc, &hdr);
262 /* get decoding parameters from header info */
263 s->bit_alloc_params.sr_code = hdr.sr_code;
264 s->bitstream_mode = hdr.bitstream_mode;
265 s->channel_mode = hdr.channel_mode;
266 s->channel_layout = hdr.channel_layout;
267 s->lfe_on = hdr.lfe_on;
268 s->bit_alloc_params.sr_shift = hdr.sr_shift;
269 s->sample_rate = hdr.sample_rate;
270 s->bit_rate = hdr.bit_rate;
271 s->channels = hdr.channels;
272 s->fbw_channels = s->channels - s->lfe_on;
273 s->lfe_ch = s->fbw_channels + 1;
274 s->frame_size = hdr.frame_size;
275 s->center_mix_level = hdr.center_mix_level;
276 s->surround_mix_level = hdr.surround_mix_level;
277 s->num_blocks = hdr.num_blocks;
278 s->frame_type = hdr.frame_type;
279 s->substreamid = hdr.substreamid;
282 s->start_freq[s->lfe_ch] = 0;
283 s->end_freq[s->lfe_ch] = 7;
284 s->num_exp_groups[s->lfe_ch] = 2;
285 s->channel_in_cpl[s->lfe_ch] = 0;
288 if (hdr.bitstream_id <= 10) {
290 s->snr_offset_strategy = 2;
291 s->block_switch_syntax = 1;
292 s->dither_flag_syntax = 1;
293 s->bit_allocation_syntax = 1;
294 s->fast_gain_syntax = 0;
295 s->first_cpl_leak = 0;
298 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
299 return ac3_parse_header(s);
300 } else if (CONFIG_EAC3_DECODER) {
302 return ff_eac3_parse_header(s);
304 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
310 * Set stereo downmixing coefficients based on frame header info.
311 * reference: Section 7.8.2 Downmixing Into Two Channels
313 static void set_downmix_coeffs(AC3DecodeContext *s)
316 float cmix = gain_levels[center_levels[s->center_mix_level]];
317 float smix = gain_levels[surround_levels[s->surround_mix_level]];
320 for(i=0; i<s->fbw_channels; i++) {
321 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
322 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
324 if(s->channel_mode > 1 && s->channel_mode & 1) {
325 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
327 if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
328 int nf = s->channel_mode - 2;
329 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
331 if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
332 int nf = s->channel_mode - 4;
333 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
338 for(i=0; i<s->fbw_channels; i++) {
339 norm0 += s->downmix_coeffs[i][0];
340 norm1 += s->downmix_coeffs[i][1];
342 norm0 = 1.0f / norm0;
343 norm1 = 1.0f / norm1;
344 for(i=0; i<s->fbw_channels; i++) {
345 s->downmix_coeffs[i][0] *= norm0;
346 s->downmix_coeffs[i][1] *= norm1;
349 if(s->output_mode == AC3_CHMODE_MONO) {
350 for(i=0; i<s->fbw_channels; i++)
351 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
356 * Decode the grouped exponents according to exponent strategy.
357 * reference: Section 7.1.3 Exponent Decoding
359 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
360 uint8_t absexp, int8_t *dexps)
362 int i, j, grp, group_size;
367 group_size = exp_strategy + (exp_strategy == EXP_D45);
368 for(grp=0,i=0; grp<ngrps; grp++) {
369 expacc = get_bits(gbc, 7);
370 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
371 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
372 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
375 /* convert to absolute exps and expand groups */
377 for(i=0,j=0; i<ngrps*3; i++) {
378 prevexp += dexp[i] - 2;
381 switch (group_size) {
382 case 4: dexps[j++] = prevexp;
383 dexps[j++] = prevexp;
384 case 2: dexps[j++] = prevexp;
385 case 1: dexps[j++] = prevexp;
392 * Generate transform coefficients for each coupled channel in the coupling
393 * range using the coupling coefficients and coupling coordinates.
394 * reference: Section 7.4.3 Coupling Coordinate Format
396 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
400 bin = s->start_freq[CPL_CH];
401 for (band = 0; band < s->num_cpl_bands; band++) {
402 int band_start = bin;
403 int band_end = bin + s->cpl_band_sizes[band];
404 for (ch = 1; ch <= s->fbw_channels; ch++) {
405 if (s->channel_in_cpl[ch]) {
406 int cpl_coord = s->cpl_coords[ch][band] << 5;
407 for (bin = band_start; bin < band_end; bin++) {
408 s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
410 if (ch == 2 && s->phase_flags[band]) {
411 for (bin = band_start; bin < band_end; bin++)
412 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
421 * Grouped mantissas for 3-level 5-level and 11-level quantization
433 * Decode the transform coefficients for a particular channel
434 * reference: Section 7.3 Quantization and Decoding of Mantissas
436 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
438 int start_freq = s->start_freq[ch_index];
439 int end_freq = s->end_freq[ch_index];
440 uint8_t *baps = s->bap[ch_index];
441 int8_t *exps = s->dexps[ch_index];
442 int *coeffs = s->fixed_coeffs[ch_index];
443 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
444 GetBitContext *gbc = &s->gbc;
447 for(freq = start_freq; freq < end_freq; freq++){
448 int bap = baps[freq];
453 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
460 mantissa = m->b1_mant[m->b1];
463 int bits = get_bits(gbc, 5);
464 mantissa = b1_mantissas[bits][0];
465 m->b1_mant[1] = b1_mantissas[bits][1];
466 m->b1_mant[0] = b1_mantissas[bits][2];
473 mantissa = m->b2_mant[m->b2];
476 int bits = get_bits(gbc, 7);
477 mantissa = b2_mantissas[bits][0];
478 m->b2_mant[1] = b2_mantissas[bits][1];
479 m->b2_mant[0] = b2_mantissas[bits][2];
484 mantissa = b3_mantissas[get_bits(gbc, 3)];
489 mantissa = m->b4_mant;
492 int bits = get_bits(gbc, 7);
493 mantissa = b4_mantissas[bits][0];
494 m->b4_mant = b4_mantissas[bits][1];
499 mantissa = b5_mantissas[get_bits(gbc, 4)];
501 default: /* 6 to 15 */
502 mantissa = get_bits(gbc, quantization_tab[bap]);
503 /* Shift mantissa and sign-extend it. */
504 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
507 coeffs[freq] = mantissa >> exps[freq];
512 * Remove random dithering from coupling range coefficients with zero-bit
513 * mantissas for coupled channels which do not use dithering.
514 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
516 static void remove_dithering(AC3DecodeContext *s) {
519 for(ch=1; ch<=s->fbw_channels; ch++) {
520 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
521 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
522 if(!s->bap[CPL_CH][i])
523 s->fixed_coeffs[ch][i] = 0;
529 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
532 if (!s->channel_uses_aht[ch]) {
533 ac3_decode_transform_coeffs_ch(s, ch, m);
535 /* if AHT is used, mantissas for all blocks are encoded in the first
536 block of the frame. */
538 if (!blk && CONFIG_EAC3_DECODER)
539 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
540 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
541 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
547 * Decode the transform coefficients.
549 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
555 m.b1 = m.b2 = m.b4 = 0;
557 for (ch = 1; ch <= s->channels; ch++) {
558 /* transform coefficients for full-bandwidth channel */
559 decode_transform_coeffs_ch(s, blk, ch, &m);
560 /* tranform coefficients for coupling channel come right after the
561 coefficients for the first coupled channel*/
562 if (s->channel_in_cpl[ch]) {
564 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
565 calc_transform_coeffs_cpl(s);
568 end = s->end_freq[CPL_CH];
570 end = s->end_freq[ch];
573 s->fixed_coeffs[ch][end] = 0;
577 /* zero the dithered coefficients for appropriate channels */
582 * Stereo rematrixing.
583 * reference: Section 7.5.4 Rematrixing : Decoding Technique
585 static void do_rematrixing(AC3DecodeContext *s)
590 end = FFMIN(s->end_freq[1], s->end_freq[2]);
592 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
593 if(s->rematrixing_flags[bnd]) {
594 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
595 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
596 int tmp0 = s->fixed_coeffs[1][i];
597 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
598 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
605 * Inverse MDCT Transform.
606 * Convert frequency domain coefficients to time-domain audio samples.
607 * reference: Section 7.9.4 Transformation Equations
609 static inline void do_imdct(AC3DecodeContext *s, int channels)
613 for (ch=1; ch<=channels; ch++) {
614 if (s->block_switch[ch]) {
616 float *x = s->tmp_output+128;
618 x[i] = s->transform_coeffs[ch][2*i];
619 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
620 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
622 x[i] = s->transform_coeffs[ch][2*i+1];
623 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch-1], x);
625 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
626 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
627 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
633 * Downmix the output to mono or stereo.
635 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
640 for(i=0; i<len; i++) {
642 for(j=0; j<in_ch; j++) {
643 v0 += samples[j][i] * matrix[j][0];
644 v1 += samples[j][i] * matrix[j][1];
649 } else if(out_ch == 1) {
650 for(i=0; i<len; i++) {
652 for(j=0; j<in_ch; j++)
653 v0 += samples[j][i] * matrix[j][0];
660 * Upmix delay samples from stereo to original channel layout.
662 static void ac3_upmix_delay(AC3DecodeContext *s)
664 int channel_data_size = sizeof(s->delay[0]);
665 switch(s->channel_mode) {
666 case AC3_CHMODE_DUALMONO:
667 case AC3_CHMODE_STEREO:
668 /* upmix mono to stereo */
669 memcpy(s->delay[1], s->delay[0], channel_data_size);
671 case AC3_CHMODE_2F2R:
672 memset(s->delay[3], 0, channel_data_size);
673 case AC3_CHMODE_2F1R:
674 memset(s->delay[2], 0, channel_data_size);
676 case AC3_CHMODE_3F2R:
677 memset(s->delay[4], 0, channel_data_size);
678 case AC3_CHMODE_3F1R:
679 memset(s->delay[3], 0, channel_data_size);
681 memcpy(s->delay[2], s->delay[1], channel_data_size);
682 memset(s->delay[1], 0, channel_data_size);
688 * Decode band structure for coupling, spectral extension, or enhanced coupling.
689 * The band structure defines how many subbands are in each band. For each
690 * subband in the range, 1 means it is combined with the previous band, and 0
691 * means that it starts a new band.
693 * @param[in] gbc bit reader context
694 * @param[in] blk block number
695 * @param[in] eac3 flag to indicate E-AC-3
696 * @param[in] ecpl flag to indicate enhanced coupling
697 * @param[in] start_subband subband number for start of range
698 * @param[in] end_subband subband number for end of range
699 * @param[in] default_band_struct default band structure table
700 * @param[out] num_bands number of bands (optionally NULL)
701 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
703 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
704 int ecpl, int start_subband, int end_subband,
705 const uint8_t *default_band_struct,
706 int *num_bands, uint8_t *band_sizes)
708 int subbnd, bnd, n_subbands, n_bands=0;
710 uint8_t coded_band_struct[22];
711 const uint8_t *band_struct;
713 n_subbands = end_subband - start_subband;
715 /* decode band structure from bitstream or use default */
716 if (!eac3 || get_bits1(gbc)) {
717 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
718 coded_band_struct[subbnd] = get_bits1(gbc);
720 band_struct = coded_band_struct;
722 band_struct = &default_band_struct[start_subband+1];
724 /* no change in band structure */
728 /* calculate number of bands and band sizes based on band structure.
729 note that the first 4 subbands in enhanced coupling span only 6 bins
731 if (num_bands || band_sizes ) {
732 n_bands = n_subbands;
733 bnd_sz[0] = ecpl ? 6 : 12;
734 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
735 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
736 if (band_struct[subbnd-1]) {
738 bnd_sz[bnd] += subbnd_size;
740 bnd_sz[++bnd] = subbnd_size;
745 /* set optional output params */
747 *num_bands = n_bands;
749 memcpy(band_sizes, bnd_sz, n_bands);
753 * Decode a single audio block from the AC-3 bitstream.
755 static int decode_audio_block(AC3DecodeContext *s, int blk)
757 int fbw_channels = s->fbw_channels;
758 int channel_mode = s->channel_mode;
760 int different_transforms;
763 GetBitContext *gbc = &s->gbc;
764 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
766 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
768 /* block switch flags */
769 different_transforms = 0;
770 if (s->block_switch_syntax) {
771 for (ch = 1; ch <= fbw_channels; ch++) {
772 s->block_switch[ch] = get_bits1(gbc);
773 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
774 different_transforms = 1;
778 /* dithering flags */
779 if (s->dither_flag_syntax) {
780 for (ch = 1; ch <= fbw_channels; ch++) {
781 s->dither_flag[ch] = get_bits1(gbc);
786 i = !(s->channel_mode);
789 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
790 s->avctx->drc_scale)+1.0;
791 } else if(blk == 0) {
792 s->dynamic_range[i] = 1.0f;
796 /* spectral extension strategy */
797 if (s->eac3 && (!blk || get_bits1(gbc))) {
798 s->spx_in_use = get_bits1(gbc);
800 int dst_start_freq, dst_end_freq, src_start_freq,
801 start_subband, end_subband;
803 /* determine which channels use spx */
804 if (s->channel_mode == AC3_CHMODE_MONO) {
805 s->channel_uses_spx[1] = 1;
807 for (ch = 1; ch <= fbw_channels; ch++)
808 s->channel_uses_spx[ch] = get_bits1(gbc);
811 /* get the frequency bins of the spx copy region and the spx start
813 dst_start_freq = get_bits(gbc, 2);
814 start_subband = get_bits(gbc, 3) + 2;
815 if (start_subband > 7)
816 start_subband += start_subband - 7;
817 end_subband = get_bits(gbc, 3) + 5;
819 end_subband += end_subband - 7;
820 dst_start_freq = dst_start_freq * 12 + 25;
821 src_start_freq = start_subband * 12 + 25;
822 dst_end_freq = end_subband * 12 + 25;
824 /* check validity of spx ranges */
825 if (start_subband >= end_subband) {
826 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
827 "range (%d >= %d)\n", start_subband, end_subband);
830 if (dst_start_freq >= src_start_freq) {
831 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
832 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
836 s->spx_dst_start_freq = dst_start_freq;
837 s->spx_src_start_freq = src_start_freq;
838 s->spx_dst_end_freq = dst_end_freq;
840 decode_band_structure(gbc, blk, s->eac3, 0,
841 start_subband, end_subband,
842 ff_eac3_default_spx_band_struct,
846 for (ch = 1; ch <= fbw_channels; ch++) {
847 s->channel_uses_spx[ch] = 0;
848 s->first_spx_coords[ch] = 1;
853 /* spectral extension coordinates */
855 for (ch = 1; ch <= fbw_channels; ch++) {
856 if (s->channel_uses_spx[ch]) {
857 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
859 int bin, master_spx_coord;
861 s->first_spx_coords[ch] = 0;
862 spx_blend = get_bits(gbc, 5) * (1.0f/32);
863 master_spx_coord = get_bits(gbc, 2) * 3;
865 bin = s->spx_src_start_freq;
866 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
868 int spx_coord_exp, spx_coord_mant;
869 float nratio, sblend, nblend, spx_coord;
871 /* calculate blending factors */
872 bandsize = s->spx_band_sizes[bnd];
873 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
874 nratio = av_clipf(nratio, 0.0f, 1.0f);
875 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) to give unity variance
876 sblend = sqrtf(1.0f - nratio);
879 /* decode spx coordinates */
880 spx_coord_exp = get_bits(gbc, 4);
881 spx_coord_mant = get_bits(gbc, 2);
882 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
883 else spx_coord_mant += 4;
884 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
885 spx_coord = spx_coord_mant * (1.0f/(1<<23));
887 /* multiply noise and signal blending factors by spx coordinate */
888 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
889 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
893 s->first_spx_coords[ch] = 1;
898 /* coupling strategy */
899 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
900 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
902 s->cpl_in_use[blk] = get_bits1(gbc);
903 if (s->cpl_in_use[blk]) {
904 /* coupling in use */
905 int cpl_start_subband, cpl_end_subband;
907 if (channel_mode < AC3_CHMODE_STEREO) {
908 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
912 /* check for enhanced coupling */
913 if (s->eac3 && get_bits1(gbc)) {
914 /* TODO: parse enhanced coupling strategy info */
915 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
919 /* determine which channels are coupled */
920 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
921 s->channel_in_cpl[1] = 1;
922 s->channel_in_cpl[2] = 1;
924 for (ch = 1; ch <= fbw_channels; ch++)
925 s->channel_in_cpl[ch] = get_bits1(gbc);
928 /* phase flags in use */
929 if (channel_mode == AC3_CHMODE_STEREO)
930 s->phase_flags_in_use = get_bits1(gbc);
932 /* coupling frequency range */
933 cpl_start_subband = get_bits(gbc, 4);
934 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
935 get_bits(gbc, 4) + 3;
936 if (cpl_start_subband >= cpl_end_subband) {
937 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
938 cpl_start_subband, cpl_end_subband);
941 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
942 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
944 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
946 ff_eac3_default_cpl_band_struct,
947 &s->num_cpl_bands, s->cpl_band_sizes);
949 /* coupling not in use */
950 for (ch = 1; ch <= fbw_channels; ch++) {
951 s->channel_in_cpl[ch] = 0;
952 s->first_cpl_coords[ch] = 1;
954 s->first_cpl_leak = s->eac3;
955 s->phase_flags_in_use = 0;
957 } else if (!s->eac3) {
959 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
962 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
965 cpl_in_use = s->cpl_in_use[blk];
967 /* coupling coordinates */
969 int cpl_coords_exist = 0;
971 for (ch = 1; ch <= fbw_channels; ch++) {
972 if (s->channel_in_cpl[ch]) {
973 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
974 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
975 s->first_cpl_coords[ch] = 0;
976 cpl_coords_exist = 1;
977 master_cpl_coord = 3 * get_bits(gbc, 2);
978 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
979 cpl_coord_exp = get_bits(gbc, 4);
980 cpl_coord_mant = get_bits(gbc, 4);
981 if (cpl_coord_exp == 15)
982 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
984 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
985 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
988 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
992 /* channel not in coupling */
993 s->first_cpl_coords[ch] = 1;
997 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
998 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
999 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1004 /* stereo rematrixing strategy and band structure */
1005 if (channel_mode == AC3_CHMODE_STEREO) {
1006 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1007 s->num_rematrixing_bands = 4;
1008 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1009 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1010 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1011 s->num_rematrixing_bands--;
1013 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
1014 s->rematrixing_flags[bnd] = get_bits1(gbc);
1016 av_log(s->avctx, AV_LOG_WARNING, "Warning: new rematrixing strategy not present in block 0\n");
1017 s->num_rematrixing_bands = 0;
1021 /* exponent strategies for each channel */
1022 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1024 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1025 if(s->exp_strategy[blk][ch] != EXP_REUSE)
1026 bit_alloc_stages[ch] = 3;
1029 /* channel bandwidth */
1030 for (ch = 1; ch <= fbw_channels; ch++) {
1031 s->start_freq[ch] = 0;
1032 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1034 int prev = s->end_freq[ch];
1035 if (s->channel_in_cpl[ch])
1036 s->end_freq[ch] = s->start_freq[CPL_CH];
1037 else if (s->channel_uses_spx[ch])
1038 s->end_freq[ch] = s->spx_src_start_freq;
1040 int bandwidth_code = get_bits(gbc, 6);
1041 if (bandwidth_code > 60) {
1042 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1045 s->end_freq[ch] = bandwidth_code * 3 + 73;
1047 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1048 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
1049 if(blk > 0 && s->end_freq[ch] != prev)
1050 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1053 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1054 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1055 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1058 /* decode exponents for each channel */
1059 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1060 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1061 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1062 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1063 s->num_exp_groups[ch], s->dexps[ch][0],
1064 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1065 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1068 if(ch != CPL_CH && ch != s->lfe_ch)
1069 skip_bits(gbc, 2); /* skip gainrng */
1073 /* bit allocation information */
1074 if (s->bit_allocation_syntax) {
1075 if (get_bits1(gbc)) {
1076 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1077 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1078 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1079 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1080 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1081 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1082 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1084 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1089 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1090 if(!s->eac3 || !blk){
1091 if(s->snr_offset_strategy && get_bits1(gbc)) {
1094 csnr = (get_bits(gbc, 6) - 15) << 4;
1095 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1097 if (ch == i || s->snr_offset_strategy == 2)
1098 snr = (csnr + get_bits(gbc, 4)) << 2;
1099 /* run at least last bit allocation stage if snr offset changes */
1100 if(blk && s->snr_offset[ch] != snr) {
1101 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1103 s->snr_offset[ch] = snr;
1105 /* fast gain (normal AC-3 only) */
1107 int prev = s->fast_gain[ch];
1108 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1109 /* run last 2 bit allocation stages if fast gain changes */
1110 if(blk && prev != s->fast_gain[ch])
1111 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1114 } else if (!s->eac3 && !blk) {
1115 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1120 /* fast gain (E-AC-3 only) */
1121 if (s->fast_gain_syntax && get_bits1(gbc)) {
1122 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1123 int prev = s->fast_gain[ch];
1124 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1125 /* run last 2 bit allocation stages if fast gain changes */
1126 if(blk && prev != s->fast_gain[ch])
1127 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1129 } else if (s->eac3 && !blk) {
1130 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1131 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1134 /* E-AC-3 to AC-3 converter SNR offset */
1135 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1136 skip_bits(gbc, 10); // skip converter snr offset
1139 /* coupling leak information */
1141 if (s->first_cpl_leak || get_bits1(gbc)) {
1142 int fl = get_bits(gbc, 3);
1143 int sl = get_bits(gbc, 3);
1144 /* run last 2 bit allocation stages for coupling channel if
1145 coupling leak changes */
1146 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1147 sl != s->bit_alloc_params.cpl_slow_leak)) {
1148 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1150 s->bit_alloc_params.cpl_fast_leak = fl;
1151 s->bit_alloc_params.cpl_slow_leak = sl;
1152 } else if (!s->eac3 && !blk) {
1153 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1156 s->first_cpl_leak = 0;
1159 /* delta bit allocation information */
1160 if (s->dba_syntax && get_bits1(gbc)) {
1161 /* delta bit allocation exists (strategy) */
1162 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1163 s->dba_mode[ch] = get_bits(gbc, 2);
1164 if (s->dba_mode[ch] == DBA_RESERVED) {
1165 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1168 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1170 /* channel delta offset, len and bit allocation */
1171 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1172 if (s->dba_mode[ch] == DBA_NEW) {
1173 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1174 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1175 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1176 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1177 s->dba_values[ch][seg] = get_bits(gbc, 3);
1179 /* run last 2 bit allocation stages if new dba values */
1180 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1183 } else if(blk == 0) {
1184 for(ch=0; ch<=s->channels; ch++) {
1185 s->dba_mode[ch] = DBA_NONE;
1189 /* Bit allocation */
1190 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1191 if(bit_alloc_stages[ch] > 2) {
1192 /* Exponent mapping into PSD and PSD integration */
1193 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1194 s->start_freq[ch], s->end_freq[ch],
1195 s->psd[ch], s->band_psd[ch]);
1197 if(bit_alloc_stages[ch] > 1) {
1198 /* Compute excitation function, Compute masking curve, and
1199 Apply delta bit allocation */
1200 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1201 s->start_freq[ch], s->end_freq[ch],
1202 s->fast_gain[ch], (ch == s->lfe_ch),
1203 s->dba_mode[ch], s->dba_nsegs[ch],
1204 s->dba_offsets[ch], s->dba_lengths[ch],
1205 s->dba_values[ch], s->mask[ch])) {
1206 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1210 if(bit_alloc_stages[ch] > 0) {
1211 /* Compute bit allocation */
1212 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1213 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1214 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1215 s->start_freq[ch], s->end_freq[ch],
1217 s->bit_alloc_params.floor,
1218 bap_tab, s->bap[ch]);
1222 /* unused dummy data */
1223 if (s->skip_syntax && get_bits1(gbc)) {
1224 int skipl = get_bits(gbc, 9);
1229 /* unpack the transform coefficients
1230 this also uncouples channels if coupling is in use. */
1231 decode_transform_coeffs(s, blk);
1233 /* TODO: generate enhanced coupling coordinates and uncouple */
1235 /* recover coefficients if rematrixing is in use */
1236 if(s->channel_mode == AC3_CHMODE_STEREO)
1239 /* apply scaling to coefficients (headroom, dynrng) */
1240 for(ch=1; ch<=s->channels; ch++) {
1241 float gain = s->mul_bias / 4194304.0f;
1242 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1243 gain *= s->dynamic_range[2-ch];
1245 gain *= s->dynamic_range[0];
1247 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1250 /* apply spectral extension to high frequency bins */
1251 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1252 ff_eac3_apply_spectral_extension(s);
1255 /* downmix and MDCT. order depends on whether block switching is used for
1256 any channel in this block. this is because coefficients for the long
1257 and short transforms cannot be mixed. */
1258 downmix_output = s->channels != s->out_channels &&
1259 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1260 s->fbw_channels == s->out_channels);
1261 if(different_transforms) {
1262 /* the delay samples have already been downmixed, so we upmix the delay
1263 samples in order to reconstruct all channels before downmixing. */
1269 do_imdct(s, s->channels);
1271 if(downmix_output) {
1272 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1275 if(downmix_output) {
1276 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1279 if(downmix_output && !s->downmixed) {
1281 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1284 do_imdct(s, s->out_channels);
1291 * Decode a single AC-3 frame.
1293 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1296 const uint8_t *buf = avpkt->data;
1297 int buf_size = avpkt->size;
1298 AC3DecodeContext *s = avctx->priv_data;
1299 float *out_samples_flt = data;
1300 int16_t *out_samples_s16 = data;
1302 int data_size_orig, data_size_tmp;
1303 const uint8_t *channel_map;
1304 const float *output[AC3_MAX_CHANNELS];
1306 /* copy input buffer to decoder context to avoid reading past the end
1307 of the buffer, which can be caused by a damaged input stream. */
1308 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1309 // seems to be byte-swapped AC-3
1310 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1311 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1313 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1314 buf = s->input_buffer;
1315 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1316 init_get_bits(&s->gbc, buf, buf_size * 8);
1318 /* parse the syncinfo */
1319 data_size_orig = *data_size;
1321 err = parse_frame_header(s);
1325 case AAC_AC3_PARSE_ERROR_SYNC:
1326 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1328 case AAC_AC3_PARSE_ERROR_BSID:
1329 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1331 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1332 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1334 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1335 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1337 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1338 /* skip frame if CRC is ok. otherwise use error concealment. */
1339 /* TODO: add support for substreams and dependent frames */
1340 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1341 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1342 return s->frame_size;
1344 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1348 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1352 /* check that reported frame size fits in input buffer */
1353 if (s->frame_size > buf_size) {
1354 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1355 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1356 } else if (avctx->error_recognition >= FF_ER_CAREFUL) {
1357 /* check for crc mismatch */
1358 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1359 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1360 err = AAC_AC3_PARSE_ERROR_CRC;
1365 /* if frame is ok, set audio parameters */
1367 avctx->sample_rate = s->sample_rate;
1368 avctx->bit_rate = s->bit_rate;
1370 /* channel config */
1371 s->out_channels = s->channels;
1372 s->output_mode = s->channel_mode;
1374 s->output_mode |= AC3_OUTPUT_LFEON;
1375 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1376 avctx->request_channels < s->channels) {
1377 s->out_channels = avctx->request_channels;
1378 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1379 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1381 avctx->channels = s->out_channels;
1382 avctx->channel_layout = s->channel_layout;
1384 /* set downmixing coefficients if needed */
1385 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1386 s->fbw_channels == s->out_channels)) {
1387 set_downmix_coeffs(s);
1389 } else if (!s->out_channels) {
1390 s->out_channels = avctx->channels;
1391 if(s->out_channels < s->channels)
1392 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1394 /* set audio service type based on bitstream mode for AC-3 */
1395 avctx->audio_service_type = s->bitstream_mode;
1396 if (s->bitstream_mode == 0x7 && s->channels > 1)
1397 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1399 /* decode the audio blocks */
1400 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1401 for (ch = 0; ch < s->out_channels; ch++)
1402 output[ch] = s->output[channel_map[ch]];
1403 data_size_tmp = s->num_blocks * 256 * avctx->channels;
1404 data_size_tmp *= avctx->sample_fmt == AV_SAMPLE_FMT_FLT ? sizeof(*out_samples_flt) : sizeof(*out_samples_s16);
1405 if (data_size_orig < data_size_tmp)
1407 *data_size = data_size_tmp;
1408 for (blk = 0; blk < s->num_blocks; blk++) {
1409 if (!err && decode_audio_block(s, blk)) {
1410 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1414 if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT) {
1415 s->fmt_conv.float_interleave(out_samples_flt, output, 256,
1417 out_samples_flt += 256 * s->out_channels;
1419 s->fmt_conv.float_to_int16_interleave(out_samples_s16, output, 256,
1421 out_samples_s16 += 256 * s->out_channels;
1424 *data_size = s->num_blocks * 256 * avctx->channels *
1425 (av_get_bits_per_sample_fmt(avctx->sample_fmt) / 8);
1426 return FFMIN(buf_size, s->frame_size);
1430 * Uninitialize the AC-3 decoder.
1432 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1434 AC3DecodeContext *s = avctx->priv_data;
1435 ff_mdct_end(&s->imdct_512);
1436 ff_mdct_end(&s->imdct_256);
1441 AVCodec ff_ac3_decoder = {
1443 .type = AVMEDIA_TYPE_AUDIO,
1445 .priv_data_size = sizeof (AC3DecodeContext),
1446 .init = ac3_decode_init,
1447 .close = ac3_decode_end,
1448 .decode = ac3_decode_frame,
1449 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1450 .sample_fmts = (const enum AVSampleFormat[]) {
1451 AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE
1455 #if CONFIG_EAC3_DECODER
1456 AVCodec ff_eac3_decoder = {
1458 .type = AVMEDIA_TYPE_AUDIO,
1459 .id = CODEC_ID_EAC3,
1460 .priv_data_size = sizeof (AC3DecodeContext),
1461 .init = ac3_decode_init,
1462 .close = ac3_decode_end,
1463 .decode = ac3_decode_frame,
1464 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1465 .sample_fmts = (const enum AVSampleFormat[]) {
1466 AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE