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];
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 default stereo downmixing coefficients
81 * reference: Section 7.8.2 Downmixing Into Two Channels
83 static const uint8_t ac3_default_coeffs[8][5][2] = {
84 { { 2, 7 }, { 7, 2 }, },
86 { { 2, 7 }, { 7, 2 }, },
87 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
88 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
89 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
90 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
91 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
95 * Symmetrical Dequantization
96 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
100 symmetric_dequant(int code, int levels)
102 return ((code - (levels >> 1)) << 24) / levels;
106 * Initialize tables at runtime.
108 static av_cold void ac3_tables_init(void)
112 /* generate table for ungrouping 3 values in 7 bits
113 reference: Section 7.1.3 Exponent Decoding */
114 for (i = 0; i < 128; i++) {
115 ungroup_3_in_7_bits_tab[i][0] = i / 25;
116 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
117 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
120 /* generate grouped mantissa tables
121 reference: Section 7.3.5 Ungrouping of Mantissas */
122 for (i = 0; i < 32; i++) {
123 /* bap=1 mantissas */
124 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
125 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
126 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
128 for (i = 0; i < 128; i++) {
129 /* bap=2 mantissas */
130 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
131 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
132 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
134 /* bap=4 mantissas */
135 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
136 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
138 /* generate ungrouped mantissa tables
139 reference: Tables 7.21 and 7.23 */
140 for (i = 0; i < 7; i++) {
141 /* bap=3 mantissas */
142 b3_mantissas[i] = symmetric_dequant(i, 7);
144 for (i = 0; i < 15; i++) {
145 /* bap=5 mantissas */
146 b5_mantissas[i] = symmetric_dequant(i, 15);
149 /* generate dynamic range table
150 reference: Section 7.7.1 Dynamic Range Control */
151 for (i = 0; i < 256; i++) {
152 int v = (i >> 5) - ((i >> 7) << 3) - 5;
153 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
158 * AVCodec initialization
160 static av_cold int ac3_decode_init(AVCodecContext *avctx)
162 AC3DecodeContext *s = avctx->priv_data;
167 ff_ac3_common_init();
169 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
170 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
171 ff_kbd_window_init(s->window, 5.0, 256);
172 ff_dsputil_init(&s->dsp, avctx);
173 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
174 ff_fmt_convert_init(&s->fmt_conv, avctx);
175 av_lfg_init(&s->dith_state, 0);
177 avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
179 /* allow downmixing to stereo or mono */
180 if (avctx->channels > 0 && avctx->request_channels > 0 &&
181 avctx->request_channels < avctx->channels &&
182 avctx->request_channels <= 2) {
183 avctx->channels = avctx->request_channels;
187 avcodec_get_frame_defaults(&s->frame);
188 avctx->coded_frame = &s->frame;
190 for (i = 0; i < AC3_MAX_CHANNELS; i++) {
191 s->xcfptr[i] = s->transform_coeffs[i];
192 s->dlyptr[i] = s->delay[i];
199 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
200 * GetBitContext within AC3DecodeContext must point to
201 * the start of the synchronized AC-3 bitstream.
203 static int ac3_parse_header(AC3DecodeContext *s)
205 GetBitContext *gbc = &s->gbc;
208 /* read the rest of the bsi. read twice for dual mono mode. */
209 i = !s->channel_mode;
211 skip_bits(gbc, 5); // skip dialog normalization
213 skip_bits(gbc, 8); //skip compression
215 skip_bits(gbc, 8); //skip language code
217 skip_bits(gbc, 7); //skip audio production information
220 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
222 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
223 TODO: read & use the xbsi1 downmix levels */
225 skip_bits(gbc, 14); //skip timecode1 / xbsi1
227 skip_bits(gbc, 14); //skip timecode2 / xbsi2
229 /* skip additional bitstream info */
230 if (get_bits1(gbc)) {
231 i = get_bits(gbc, 6);
241 * Common function to parse AC-3 or E-AC-3 frame header
243 static int parse_frame_header(AC3DecodeContext *s)
248 err = avpriv_ac3_parse_header(&s->gbc, &hdr);
252 /* get decoding parameters from header info */
253 s->bit_alloc_params.sr_code = hdr.sr_code;
254 s->bitstream_mode = hdr.bitstream_mode;
255 s->channel_mode = hdr.channel_mode;
256 s->channel_layout = hdr.channel_layout;
257 s->lfe_on = hdr.lfe_on;
258 s->bit_alloc_params.sr_shift = hdr.sr_shift;
259 s->sample_rate = hdr.sample_rate;
260 s->bit_rate = hdr.bit_rate;
261 s->channels = hdr.channels;
262 s->fbw_channels = s->channels - s->lfe_on;
263 s->lfe_ch = s->fbw_channels + 1;
264 s->frame_size = hdr.frame_size;
265 s->center_mix_level = hdr.center_mix_level;
266 s->surround_mix_level = hdr.surround_mix_level;
267 s->num_blocks = hdr.num_blocks;
268 s->frame_type = hdr.frame_type;
269 s->substreamid = hdr.substreamid;
272 s->start_freq[s->lfe_ch] = 0;
273 s->end_freq[s->lfe_ch] = 7;
274 s->num_exp_groups[s->lfe_ch] = 2;
275 s->channel_in_cpl[s->lfe_ch] = 0;
278 if (hdr.bitstream_id <= 10) {
280 s->snr_offset_strategy = 2;
281 s->block_switch_syntax = 1;
282 s->dither_flag_syntax = 1;
283 s->bit_allocation_syntax = 1;
284 s->fast_gain_syntax = 0;
285 s->first_cpl_leak = 0;
288 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
289 return ac3_parse_header(s);
290 } else if (CONFIG_EAC3_DECODER) {
292 return ff_eac3_parse_header(s);
294 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
300 * Set stereo downmixing coefficients based on frame header info.
301 * reference: Section 7.8.2 Downmixing Into Two Channels
303 static void set_downmix_coeffs(AC3DecodeContext *s)
306 float cmix = gain_levels[s-> center_mix_level];
307 float smix = gain_levels[s->surround_mix_level];
310 for (i = 0; i < s->fbw_channels; i++) {
311 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
312 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
314 if (s->channel_mode > 1 && s->channel_mode & 1) {
315 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
317 if (s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
318 int nf = s->channel_mode - 2;
319 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
321 if (s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
322 int nf = s->channel_mode - 4;
323 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
328 for (i = 0; i < s->fbw_channels; i++) {
329 norm0 += s->downmix_coeffs[i][0];
330 norm1 += s->downmix_coeffs[i][1];
332 norm0 = 1.0f / norm0;
333 norm1 = 1.0f / norm1;
334 for (i = 0; i < s->fbw_channels; i++) {
335 s->downmix_coeffs[i][0] *= norm0;
336 s->downmix_coeffs[i][1] *= norm1;
339 if (s->output_mode == AC3_CHMODE_MONO) {
340 for (i = 0; i < s->fbw_channels; i++)
341 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] +
342 s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
347 * Decode the grouped exponents according to exponent strategy.
348 * reference: Section 7.1.3 Exponent Decoding
350 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
351 uint8_t absexp, int8_t *dexps)
353 int i, j, grp, group_size;
358 group_size = exp_strategy + (exp_strategy == EXP_D45);
359 for (grp = 0, i = 0; grp < ngrps; grp++) {
360 expacc = get_bits(gbc, 7);
361 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
362 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
363 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
366 /* convert to absolute exps and expand groups */
368 for (i = 0, j = 0; i < ngrps * 3; i++) {
369 prevexp += dexp[i] - 2;
372 switch (group_size) {
373 case 4: dexps[j++] = prevexp;
374 dexps[j++] = prevexp;
375 case 2: dexps[j++] = prevexp;
376 case 1: dexps[j++] = prevexp;
383 * Generate transform coefficients for each coupled channel in the coupling
384 * range using the coupling coefficients and coupling coordinates.
385 * reference: Section 7.4.3 Coupling Coordinate Format
387 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
391 bin = s->start_freq[CPL_CH];
392 for (band = 0; band < s->num_cpl_bands; band++) {
393 int band_start = bin;
394 int band_end = bin + s->cpl_band_sizes[band];
395 for (ch = 1; ch <= s->fbw_channels; ch++) {
396 if (s->channel_in_cpl[ch]) {
397 int cpl_coord = s->cpl_coords[ch][band] << 5;
398 for (bin = band_start; bin < band_end; bin++) {
399 s->fixed_coeffs[ch][bin] =
400 MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
402 if (ch == 2 && s->phase_flags[band]) {
403 for (bin = band_start; bin < band_end; bin++)
404 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
413 * Grouped mantissas for 3-level 5-level and 11-level quantization
425 * Decode the transform coefficients for a particular channel
426 * reference: Section 7.3 Quantization and Decoding of Mantissas
428 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
430 int start_freq = s->start_freq[ch_index];
431 int end_freq = s->end_freq[ch_index];
432 uint8_t *baps = s->bap[ch_index];
433 int8_t *exps = s->dexps[ch_index];
434 int *coeffs = s->fixed_coeffs[ch_index];
435 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
436 GetBitContext *gbc = &s->gbc;
439 for (freq = start_freq; freq < end_freq; freq++) {
440 int bap = baps[freq];
445 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
452 mantissa = m->b1_mant[m->b1];
454 int bits = get_bits(gbc, 5);
455 mantissa = b1_mantissas[bits][0];
456 m->b1_mant[1] = b1_mantissas[bits][1];
457 m->b1_mant[0] = b1_mantissas[bits][2];
464 mantissa = m->b2_mant[m->b2];
466 int bits = get_bits(gbc, 7);
467 mantissa = b2_mantissas[bits][0];
468 m->b2_mant[1] = b2_mantissas[bits][1];
469 m->b2_mant[0] = b2_mantissas[bits][2];
474 mantissa = b3_mantissas[get_bits(gbc, 3)];
479 mantissa = m->b4_mant;
481 int bits = get_bits(gbc, 7);
482 mantissa = b4_mantissas[bits][0];
483 m->b4_mant = b4_mantissas[bits][1];
488 mantissa = b5_mantissas[get_bits(gbc, 4)];
490 default: /* 6 to 15 */
491 /* Shift mantissa and sign-extend it. */
492 mantissa = get_sbits(gbc, quantization_tab[bap]);
493 mantissa <<= 24 - quantization_tab[bap];
496 coeffs[freq] = mantissa >> exps[freq];
501 * Remove random dithering from coupling range coefficients with zero-bit
502 * mantissas for coupled channels which do not use dithering.
503 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
505 static void remove_dithering(AC3DecodeContext *s) {
508 for (ch = 1; ch <= s->fbw_channels; ch++) {
509 if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
510 for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) {
511 if (!s->bap[CPL_CH][i])
512 s->fixed_coeffs[ch][i] = 0;
518 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
521 if (!s->channel_uses_aht[ch]) {
522 ac3_decode_transform_coeffs_ch(s, ch, m);
524 /* if AHT is used, mantissas for all blocks are encoded in the first
525 block of the frame. */
527 if (!blk && CONFIG_EAC3_DECODER)
528 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
529 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
530 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
536 * Decode the transform coefficients.
538 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
544 m.b1 = m.b2 = m.b4 = 0;
546 for (ch = 1; ch <= s->channels; ch++) {
547 /* transform coefficients for full-bandwidth channel */
548 decode_transform_coeffs_ch(s, blk, ch, &m);
549 /* tranform coefficients for coupling channel come right after the
550 coefficients for the first coupled channel*/
551 if (s->channel_in_cpl[ch]) {
553 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
554 calc_transform_coeffs_cpl(s);
557 end = s->end_freq[CPL_CH];
559 end = s->end_freq[ch];
562 s->fixed_coeffs[ch][end] = 0;
566 /* zero the dithered coefficients for appropriate channels */
571 * Stereo rematrixing.
572 * reference: Section 7.5.4 Rematrixing : Decoding Technique
574 static void do_rematrixing(AC3DecodeContext *s)
579 end = FFMIN(s->end_freq[1], s->end_freq[2]);
581 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
582 if (s->rematrixing_flags[bnd]) {
583 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd + 1]);
584 for (i = ff_ac3_rematrix_band_tab[bnd]; i < bndend; i++) {
585 int tmp0 = s->fixed_coeffs[1][i];
586 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
587 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
594 * Inverse MDCT Transform.
595 * Convert frequency domain coefficients to time-domain audio samples.
596 * reference: Section 7.9.4 Transformation Equations
598 static inline void do_imdct(AC3DecodeContext *s, int channels)
602 for (ch = 1; ch <= channels; ch++) {
603 if (s->block_switch[ch]) {
605 float *x = s->tmp_output + 128;
606 for (i = 0; i < 128; i++)
607 x[i] = s->transform_coeffs[ch][2 * i];
608 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
609 s->dsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
610 s->tmp_output, s->window, 128);
611 for (i = 0; i < 128; i++)
612 x[i] = s->transform_coeffs[ch][2 * i + 1];
613 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x);
615 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
616 s->dsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
617 s->tmp_output, s->window, 128);
618 memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(float));
624 * Upmix delay samples from stereo to original channel layout.
626 static void ac3_upmix_delay(AC3DecodeContext *s)
628 int channel_data_size = sizeof(s->delay[0]);
629 switch (s->channel_mode) {
630 case AC3_CHMODE_DUALMONO:
631 case AC3_CHMODE_STEREO:
632 /* upmix mono to stereo */
633 memcpy(s->delay[1], s->delay[0], channel_data_size);
635 case AC3_CHMODE_2F2R:
636 memset(s->delay[3], 0, channel_data_size);
637 case AC3_CHMODE_2F1R:
638 memset(s->delay[2], 0, channel_data_size);
640 case AC3_CHMODE_3F2R:
641 memset(s->delay[4], 0, channel_data_size);
642 case AC3_CHMODE_3F1R:
643 memset(s->delay[3], 0, channel_data_size);
645 memcpy(s->delay[2], s->delay[1], channel_data_size);
646 memset(s->delay[1], 0, channel_data_size);
652 * Decode band structure for coupling, spectral extension, or enhanced coupling.
653 * The band structure defines how many subbands are in each band. For each
654 * subband in the range, 1 means it is combined with the previous band, and 0
655 * means that it starts a new band.
657 * @param[in] gbc bit reader context
658 * @param[in] blk block number
659 * @param[in] eac3 flag to indicate E-AC-3
660 * @param[in] ecpl flag to indicate enhanced coupling
661 * @param[in] start_subband subband number for start of range
662 * @param[in] end_subband subband number for end of range
663 * @param[in] default_band_struct default band structure table
664 * @param[out] num_bands number of bands (optionally NULL)
665 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
667 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
668 int ecpl, int start_subband, int end_subband,
669 const uint8_t *default_band_struct,
670 int *num_bands, uint8_t *band_sizes)
672 int subbnd, bnd, n_subbands, n_bands=0;
674 uint8_t coded_band_struct[22];
675 const uint8_t *band_struct;
677 n_subbands = end_subband - start_subband;
679 /* decode band structure from bitstream or use default */
680 if (!eac3 || get_bits1(gbc)) {
681 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
682 coded_band_struct[subbnd] = get_bits1(gbc);
684 band_struct = coded_band_struct;
686 band_struct = &default_band_struct[start_subband+1];
688 /* no change in band structure */
692 /* calculate number of bands and band sizes based on band structure.
693 note that the first 4 subbands in enhanced coupling span only 6 bins
695 if (num_bands || band_sizes ) {
696 n_bands = n_subbands;
697 bnd_sz[0] = ecpl ? 6 : 12;
698 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
699 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
700 if (band_struct[subbnd - 1]) {
702 bnd_sz[bnd] += subbnd_size;
704 bnd_sz[++bnd] = subbnd_size;
709 /* set optional output params */
711 *num_bands = n_bands;
713 memcpy(band_sizes, bnd_sz, n_bands);
717 * Decode a single audio block from the AC-3 bitstream.
719 static int decode_audio_block(AC3DecodeContext *s, int blk)
721 int fbw_channels = s->fbw_channels;
722 int channel_mode = s->channel_mode;
724 int different_transforms;
727 GetBitContext *gbc = &s->gbc;
728 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
730 /* block switch flags */
731 different_transforms = 0;
732 if (s->block_switch_syntax) {
733 for (ch = 1; ch <= fbw_channels; ch++) {
734 s->block_switch[ch] = get_bits1(gbc);
735 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
736 different_transforms = 1;
740 /* dithering flags */
741 if (s->dither_flag_syntax) {
742 for (ch = 1; ch <= fbw_channels; ch++) {
743 s->dither_flag[ch] = get_bits1(gbc);
748 i = !s->channel_mode;
750 if (get_bits1(gbc)) {
751 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)] - 1.0) *
753 } else if (blk == 0) {
754 s->dynamic_range[i] = 1.0f;
758 /* spectral extension strategy */
759 if (s->eac3 && (!blk || get_bits1(gbc))) {
760 s->spx_in_use = get_bits1(gbc);
762 int dst_start_freq, dst_end_freq, src_start_freq,
763 start_subband, end_subband;
765 /* determine which channels use spx */
766 if (s->channel_mode == AC3_CHMODE_MONO) {
767 s->channel_uses_spx[1] = 1;
769 for (ch = 1; ch <= fbw_channels; ch++)
770 s->channel_uses_spx[ch] = get_bits1(gbc);
773 /* get the frequency bins of the spx copy region and the spx start
775 dst_start_freq = get_bits(gbc, 2);
776 start_subband = get_bits(gbc, 3) + 2;
777 if (start_subband > 7)
778 start_subband += start_subband - 7;
779 end_subband = get_bits(gbc, 3) + 5;
781 end_subband += end_subband - 7;
782 dst_start_freq = dst_start_freq * 12 + 25;
783 src_start_freq = start_subband * 12 + 25;
784 dst_end_freq = end_subband * 12 + 25;
786 /* check validity of spx ranges */
787 if (start_subband >= end_subband) {
788 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
789 "range (%d >= %d)\n", start_subband, end_subband);
792 if (dst_start_freq >= src_start_freq) {
793 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
794 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
798 s->spx_dst_start_freq = dst_start_freq;
799 s->spx_src_start_freq = src_start_freq;
800 s->spx_dst_end_freq = dst_end_freq;
802 decode_band_structure(gbc, blk, s->eac3, 0,
803 start_subband, end_subband,
804 ff_eac3_default_spx_band_struct,
808 for (ch = 1; ch <= fbw_channels; ch++) {
809 s->channel_uses_spx[ch] = 0;
810 s->first_spx_coords[ch] = 1;
815 /* spectral extension coordinates */
817 for (ch = 1; ch <= fbw_channels; ch++) {
818 if (s->channel_uses_spx[ch]) {
819 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
821 int bin, master_spx_coord;
823 s->first_spx_coords[ch] = 0;
824 spx_blend = get_bits(gbc, 5) * (1.0f/32);
825 master_spx_coord = get_bits(gbc, 2) * 3;
827 bin = s->spx_src_start_freq;
828 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
830 int spx_coord_exp, spx_coord_mant;
831 float nratio, sblend, nblend, spx_coord;
833 /* calculate blending factors */
834 bandsize = s->spx_band_sizes[bnd];
835 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
836 nratio = av_clipf(nratio, 0.0f, 1.0f);
837 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
838 // to give unity variance
839 sblend = sqrtf(1.0f - nratio);
842 /* decode spx coordinates */
843 spx_coord_exp = get_bits(gbc, 4);
844 spx_coord_mant = get_bits(gbc, 2);
845 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
846 else spx_coord_mant += 4;
847 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
848 spx_coord = spx_coord_mant * (1.0f / (1 << 23));
850 /* multiply noise and signal blending factors by spx coordinate */
851 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
852 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
856 s->first_spx_coords[ch] = 1;
861 /* coupling strategy */
862 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
863 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
865 s->cpl_in_use[blk] = get_bits1(gbc);
866 if (s->cpl_in_use[blk]) {
867 /* coupling in use */
868 int cpl_start_subband, cpl_end_subband;
870 if (channel_mode < AC3_CHMODE_STEREO) {
871 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
875 /* check for enhanced coupling */
876 if (s->eac3 && get_bits1(gbc)) {
877 /* TODO: parse enhanced coupling strategy info */
878 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
879 return AVERROR_PATCHWELCOME;
882 /* determine which channels are coupled */
883 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
884 s->channel_in_cpl[1] = 1;
885 s->channel_in_cpl[2] = 1;
887 for (ch = 1; ch <= fbw_channels; ch++)
888 s->channel_in_cpl[ch] = get_bits1(gbc);
891 /* phase flags in use */
892 if (channel_mode == AC3_CHMODE_STEREO)
893 s->phase_flags_in_use = get_bits1(gbc);
895 /* coupling frequency range */
896 cpl_start_subband = get_bits(gbc, 4);
897 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
898 get_bits(gbc, 4) + 3;
899 if (cpl_start_subband >= cpl_end_subband) {
900 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
901 cpl_start_subband, cpl_end_subband);
904 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
905 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
907 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
909 ff_eac3_default_cpl_band_struct,
910 &s->num_cpl_bands, s->cpl_band_sizes);
912 /* coupling not in use */
913 for (ch = 1; ch <= fbw_channels; ch++) {
914 s->channel_in_cpl[ch] = 0;
915 s->first_cpl_coords[ch] = 1;
917 s->first_cpl_leak = s->eac3;
918 s->phase_flags_in_use = 0;
920 } else if (!s->eac3) {
922 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
923 "be present in block 0\n");
926 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
929 cpl_in_use = s->cpl_in_use[blk];
931 /* coupling coordinates */
933 int cpl_coords_exist = 0;
935 for (ch = 1; ch <= fbw_channels; ch++) {
936 if (s->channel_in_cpl[ch]) {
937 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
938 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
939 s->first_cpl_coords[ch] = 0;
940 cpl_coords_exist = 1;
941 master_cpl_coord = 3 * get_bits(gbc, 2);
942 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
943 cpl_coord_exp = get_bits(gbc, 4);
944 cpl_coord_mant = get_bits(gbc, 4);
945 if (cpl_coord_exp == 15)
946 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
948 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
949 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
952 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
953 "be present in block 0\n");
957 /* channel not in coupling */
958 s->first_cpl_coords[ch] = 1;
962 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
963 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
964 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
969 /* stereo rematrixing strategy and band structure */
970 if (channel_mode == AC3_CHMODE_STEREO) {
971 if ((s->eac3 && !blk) || get_bits1(gbc)) {
972 s->num_rematrixing_bands = 4;
973 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
974 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
975 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
976 s->num_rematrixing_bands--;
978 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
979 s->rematrixing_flags[bnd] = get_bits1(gbc);
981 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
982 "new rematrixing strategy not present in block 0\n");
983 s->num_rematrixing_bands = 0;
987 /* exponent strategies for each channel */
988 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
990 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
991 if (s->exp_strategy[blk][ch] != EXP_REUSE)
992 bit_alloc_stages[ch] = 3;
995 /* channel bandwidth */
996 for (ch = 1; ch <= fbw_channels; ch++) {
997 s->start_freq[ch] = 0;
998 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1000 int prev = s->end_freq[ch];
1001 if (s->channel_in_cpl[ch])
1002 s->end_freq[ch] = s->start_freq[CPL_CH];
1003 else if (s->channel_uses_spx[ch])
1004 s->end_freq[ch] = s->spx_src_start_freq;
1006 int bandwidth_code = get_bits(gbc, 6);
1007 if (bandwidth_code > 60) {
1008 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1011 s->end_freq[ch] = bandwidth_code * 3 + 73;
1013 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1014 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1015 if (blk > 0 && s->end_freq[ch] != prev)
1016 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1019 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1020 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1021 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1024 /* decode exponents for each channel */
1025 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1026 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1027 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1028 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1029 s->num_exp_groups[ch], s->dexps[ch][0],
1030 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1031 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1034 if (ch != CPL_CH && ch != s->lfe_ch)
1035 skip_bits(gbc, 2); /* skip gainrng */
1039 /* bit allocation information */
1040 if (s->bit_allocation_syntax) {
1041 if (get_bits1(gbc)) {
1042 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1043 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1044 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1045 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1046 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1047 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1048 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1050 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1051 "be present in block 0\n");
1056 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1057 if (!s->eac3 || !blk) {
1058 if (s->snr_offset_strategy && get_bits1(gbc)) {
1061 csnr = (get_bits(gbc, 6) - 15) << 4;
1062 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1064 if (ch == i || s->snr_offset_strategy == 2)
1065 snr = (csnr + get_bits(gbc, 4)) << 2;
1066 /* run at least last bit allocation stage if snr offset changes */
1067 if (blk && s->snr_offset[ch] != snr) {
1068 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1070 s->snr_offset[ch] = snr;
1072 /* fast gain (normal AC-3 only) */
1074 int prev = s->fast_gain[ch];
1075 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1076 /* run last 2 bit allocation stages if fast gain changes */
1077 if (blk && prev != s->fast_gain[ch])
1078 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1081 } else if (!s->eac3 && !blk) {
1082 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1087 /* fast gain (E-AC-3 only) */
1088 if (s->fast_gain_syntax && get_bits1(gbc)) {
1089 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1090 int prev = s->fast_gain[ch];
1091 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1092 /* run last 2 bit allocation stages if fast gain changes */
1093 if (blk && prev != s->fast_gain[ch])
1094 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1096 } else if (s->eac3 && !blk) {
1097 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1098 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1101 /* E-AC-3 to AC-3 converter SNR offset */
1102 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1103 skip_bits(gbc, 10); // skip converter snr offset
1106 /* coupling leak information */
1108 if (s->first_cpl_leak || get_bits1(gbc)) {
1109 int fl = get_bits(gbc, 3);
1110 int sl = get_bits(gbc, 3);
1111 /* run last 2 bit allocation stages for coupling channel if
1112 coupling leak changes */
1113 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1114 sl != s->bit_alloc_params.cpl_slow_leak)) {
1115 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1117 s->bit_alloc_params.cpl_fast_leak = fl;
1118 s->bit_alloc_params.cpl_slow_leak = sl;
1119 } else if (!s->eac3 && !blk) {
1120 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1121 "be present in block 0\n");
1124 s->first_cpl_leak = 0;
1127 /* delta bit allocation information */
1128 if (s->dba_syntax && get_bits1(gbc)) {
1129 /* delta bit allocation exists (strategy) */
1130 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1131 s->dba_mode[ch] = get_bits(gbc, 2);
1132 if (s->dba_mode[ch] == DBA_RESERVED) {
1133 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1136 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1138 /* channel delta offset, len and bit allocation */
1139 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1140 if (s->dba_mode[ch] == DBA_NEW) {
1141 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1142 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1143 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1144 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1145 s->dba_values[ch][seg] = get_bits(gbc, 3);
1147 /* run last 2 bit allocation stages if new dba values */
1148 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1151 } else if (blk == 0) {
1152 for (ch = 0; ch <= s->channels; ch++) {
1153 s->dba_mode[ch] = DBA_NONE;
1157 /* Bit allocation */
1158 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1159 if (bit_alloc_stages[ch] > 2) {
1160 /* Exponent mapping into PSD and PSD integration */
1161 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1162 s->start_freq[ch], s->end_freq[ch],
1163 s->psd[ch], s->band_psd[ch]);
1165 if (bit_alloc_stages[ch] > 1) {
1166 /* Compute excitation function, Compute masking curve, and
1167 Apply delta bit allocation */
1168 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1169 s->start_freq[ch], s->end_freq[ch],
1170 s->fast_gain[ch], (ch == s->lfe_ch),
1171 s->dba_mode[ch], s->dba_nsegs[ch],
1172 s->dba_offsets[ch], s->dba_lengths[ch],
1173 s->dba_values[ch], s->mask[ch])) {
1174 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1178 if (bit_alloc_stages[ch] > 0) {
1179 /* Compute bit allocation */
1180 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1181 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1182 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1183 s->start_freq[ch], s->end_freq[ch],
1185 s->bit_alloc_params.floor,
1186 bap_tab, s->bap[ch]);
1190 /* unused dummy data */
1191 if (s->skip_syntax && get_bits1(gbc)) {
1192 int skipl = get_bits(gbc, 9);
1197 /* unpack the transform coefficients
1198 this also uncouples channels if coupling is in use. */
1199 decode_transform_coeffs(s, blk);
1201 /* TODO: generate enhanced coupling coordinates and uncouple */
1203 /* recover coefficients if rematrixing is in use */
1204 if (s->channel_mode == AC3_CHMODE_STEREO)
1207 /* apply scaling to coefficients (headroom, dynrng) */
1208 for (ch = 1; ch <= s->channels; ch++) {
1209 float gain = 1.0 / 4194304.0f;
1210 if (s->channel_mode == AC3_CHMODE_DUALMONO) {
1211 gain *= s->dynamic_range[2 - ch];
1213 gain *= s->dynamic_range[0];
1215 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1216 s->fixed_coeffs[ch], gain, 256);
1219 /* apply spectral extension to high frequency bins */
1220 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1221 ff_eac3_apply_spectral_extension(s);
1224 /* downmix and MDCT. order depends on whether block switching is used for
1225 any channel in this block. this is because coefficients for the long
1226 and short transforms cannot be mixed. */
1227 downmix_output = s->channels != s->out_channels &&
1228 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1229 s->fbw_channels == s->out_channels);
1230 if (different_transforms) {
1231 /* the delay samples have already been downmixed, so we upmix the delay
1232 samples in order to reconstruct all channels before downmixing. */
1238 do_imdct(s, s->channels);
1240 if (downmix_output) {
1241 s->ac3dsp.downmix(s->outptr, s->downmix_coeffs,
1242 s->out_channels, s->fbw_channels, 256);
1245 if (downmix_output) {
1246 s->ac3dsp.downmix(s->xcfptr + 1, s->downmix_coeffs,
1247 s->out_channels, s->fbw_channels, 256);
1250 if (downmix_output && !s->downmixed) {
1252 s->ac3dsp.downmix(s->dlyptr, s->downmix_coeffs, s->out_channels,
1253 s->fbw_channels, 128);
1256 do_imdct(s, s->out_channels);
1263 * Decode a single AC-3 frame.
1265 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1266 int *got_frame_ptr, AVPacket *avpkt)
1268 const uint8_t *buf = avpkt->data;
1269 int buf_size = avpkt->size;
1270 AC3DecodeContext *s = avctx->priv_data;
1271 int blk, ch, err, ret;
1272 const uint8_t *channel_map;
1273 const float *output[AC3_MAX_CHANNELS];
1275 /* copy input buffer to decoder context to avoid reading past the end
1276 of the buffer, which can be caused by a damaged input stream. */
1277 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1278 // seems to be byte-swapped AC-3
1279 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1280 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1282 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1283 buf = s->input_buffer;
1284 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1285 init_get_bits(&s->gbc, buf, buf_size * 8);
1287 /* parse the syncinfo */
1288 err = parse_frame_header(s);
1292 case AAC_AC3_PARSE_ERROR_SYNC:
1293 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1295 case AAC_AC3_PARSE_ERROR_BSID:
1296 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1298 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1299 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1301 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1302 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1304 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1305 /* skip frame if CRC is ok. otherwise use error concealment. */
1306 /* TODO: add support for substreams and dependent frames */
1307 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1308 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : "
1309 "skipping frame\n");
1311 return s->frame_size;
1313 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1317 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1321 /* check that reported frame size fits in input buffer */
1322 if (s->frame_size > buf_size) {
1323 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1324 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1325 } else if (avctx->err_recognition & (AV_EF_CRCCHECK|AV_EF_CAREFUL)) {
1326 /* check for crc mismatch */
1327 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1328 s->frame_size - 2)) {
1329 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1330 err = AAC_AC3_PARSE_ERROR_CRC;
1335 /* if frame is ok, set audio parameters */
1337 avctx->sample_rate = s->sample_rate;
1338 avctx->bit_rate = s->bit_rate;
1340 /* channel config */
1341 s->out_channels = s->channels;
1342 s->output_mode = s->channel_mode;
1344 s->output_mode |= AC3_OUTPUT_LFEON;
1345 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1346 avctx->request_channels < s->channels) {
1347 s->out_channels = avctx->request_channels;
1348 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1349 s->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode];
1351 avctx->channels = s->out_channels;
1352 avctx->channel_layout = s->channel_layout;
1354 s->loro_center_mix_level = gain_levels[s-> center_mix_level];
1355 s->loro_surround_mix_level = gain_levels[s->surround_mix_level];
1356 s->ltrt_center_mix_level = LEVEL_MINUS_3DB;
1357 s->ltrt_surround_mix_level = LEVEL_MINUS_3DB;
1358 /* set downmixing coefficients if needed */
1359 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1360 s->fbw_channels == s->out_channels)) {
1361 set_downmix_coeffs(s);
1363 } else if (!s->out_channels) {
1364 s->out_channels = avctx->channels;
1365 if (s->out_channels < s->channels)
1366 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1368 if (avctx->channels != s->out_channels) {
1369 av_log(avctx, AV_LOG_ERROR, "channel number mismatching on damaged frame\n");
1370 return AVERROR_INVALIDDATA;
1372 /* set audio service type based on bitstream mode for AC-3 */
1373 avctx->audio_service_type = s->bitstream_mode;
1374 if (s->bitstream_mode == 0x7 && s->channels > 1)
1375 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1377 /* get output buffer */
1378 avctx->channels = s->out_channels;
1379 s->frame.nb_samples = s->num_blocks * 256;
1380 if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {
1381 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
1385 /* decode the audio blocks */
1386 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1387 for (ch = 0; ch < AC3_MAX_CHANNELS; ch++) {
1388 output[ch] = s->output[ch];
1389 s->outptr[ch] = s->output[ch];
1391 for (ch = 0; ch < s->channels; ch++) {
1392 if (ch < s->out_channels)
1393 s->outptr[channel_map[ch]] = (float *)s->frame.data[ch];
1395 for (blk = 0; blk < s->num_blocks; blk++) {
1396 if (!err && decode_audio_block(s, blk)) {
1397 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1401 for (ch = 0; ch < s->out_channels; ch++)
1402 memcpy(((float*)s->frame.data[ch]) + AC3_BLOCK_SIZE*blk, output[ch], 1024);
1403 for (ch = 0; ch < s->out_channels; ch++) {
1404 output[ch] = s->outptr[channel_map[ch]];
1406 for (ch = 0; ch < s->channels; ch++) {
1407 s->outptr[ch] += AC3_BLOCK_SIZE;
1411 s->frame.decode_error_flags = err ? FF_DECODE_ERROR_INVALID_BITSTREAM : 0;
1413 /* keep last block for error concealment in next frame */
1414 for (ch = 0; ch < s->out_channels; ch++)
1415 memcpy(s->output[ch], output[ch], 1024);
1418 *(AVFrame *)data = s->frame;
1420 return FFMIN(buf_size, s->frame_size);
1424 * Uninitialize the AC-3 decoder.
1426 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1428 AC3DecodeContext *s = avctx->priv_data;
1429 ff_mdct_end(&s->imdct_512);
1430 ff_mdct_end(&s->imdct_256);
1435 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1436 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)
1437 static const AVOption options[] = {
1438 { "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), AV_OPT_TYPE_FLOAT, {.dbl = 1.0}, 0.0, 1.0, PAR },
1440 {"dmix_mode", "Preferred Stereo Downmix Mode", OFFSET(preferred_stereo_downmix), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, 2, 0, "dmix_mode"},
1441 {"ltrt_cmixlev", "Lt/Rt Center Mix Level", OFFSET(ltrt_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1442 {"ltrt_surmixlev", "Lt/Rt Surround Mix Level", OFFSET(ltrt_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1443 {"loro_cmixlev", "Lo/Ro Center Mix Level", OFFSET(loro_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1444 {"loro_surmixlev", "Lo/Ro Surround Mix Level", OFFSET(loro_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1449 static const AVClass ac3_decoder_class = {
1450 .class_name = "AC3 decoder",
1451 .item_name = av_default_item_name,
1453 .version = LIBAVUTIL_VERSION_INT,
1456 AVCodec ff_ac3_decoder = {
1458 .type = AVMEDIA_TYPE_AUDIO,
1459 .id = AV_CODEC_ID_AC3,
1460 .priv_data_size = sizeof (AC3DecodeContext),
1461 .init = ac3_decode_init,
1462 .close = ac3_decode_end,
1463 .decode = ac3_decode_frame,
1464 .capabilities = CODEC_CAP_DR1,
1465 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1466 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
1467 AV_SAMPLE_FMT_NONE },
1468 .priv_class = &ac3_decoder_class,
1471 #if CONFIG_EAC3_DECODER
1472 static const AVClass eac3_decoder_class = {
1473 .class_name = "E-AC3 decoder",
1474 .item_name = av_default_item_name,
1476 .version = LIBAVUTIL_VERSION_INT,
1479 AVCodec ff_eac3_decoder = {
1481 .type = AVMEDIA_TYPE_AUDIO,
1482 .id = AV_CODEC_ID_EAC3,
1483 .priv_data_size = sizeof (AC3DecodeContext),
1484 .init = ac3_decode_init,
1485 .close = ac3_decode_end,
1486 .decode = ac3_decode_frame,
1487 .capabilities = CODEC_CAP_DR1,
1488 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1489 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
1490 AV_SAMPLE_FMT_NONE },
1491 .priv_class = &eac3_decoder_class,