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 Libav.
12 * Libav 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 * Libav 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 Libav; 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 avpriv_float_dsp_init(&s->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);
174 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
175 ff_fmt_convert_init(&s->fmt_conv, avctx);
176 av_lfg_init(&s->dith_state, 0);
178 avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
180 /* allow downmixing to stereo or mono */
181 if (avctx->channels > 0 && avctx->request_channels > 0 &&
182 avctx->request_channels < avctx->channels &&
183 avctx->request_channels <= 2) {
184 avctx->channels = avctx->request_channels;
188 avcodec_get_frame_defaults(&s->frame);
189 avctx->coded_frame = &s->frame;
191 for (i = 0; i < AC3_MAX_CHANNELS; i++) {
192 s->xcfptr[i] = s->transform_coeffs[i];
193 s->dlyptr[i] = s->delay[i];
200 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
201 * GetBitContext within AC3DecodeContext must point to
202 * the start of the synchronized AC-3 bitstream.
204 static int ac3_parse_header(AC3DecodeContext *s)
206 GetBitContext *gbc = &s->gbc;
209 /* read the rest of the bsi. read twice for dual mono mode. */
210 i = !s->channel_mode;
212 skip_bits(gbc, 5); // skip dialog normalization
214 skip_bits(gbc, 8); //skip compression
216 skip_bits(gbc, 8); //skip language code
218 skip_bits(gbc, 7); //skip audio production information
221 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
223 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
224 TODO: read & use the xbsi1 downmix levels */
226 skip_bits(gbc, 14); //skip timecode1 / xbsi1
228 skip_bits(gbc, 14); //skip timecode2 / xbsi2
230 /* skip additional bitstream info */
231 if (get_bits1(gbc)) {
232 i = get_bits(gbc, 6);
242 * Common function to parse AC-3 or E-AC-3 frame header
244 static int parse_frame_header(AC3DecodeContext *s)
249 err = avpriv_ac3_parse_header(&s->gbc, &hdr);
253 /* get decoding parameters from header info */
254 s->bit_alloc_params.sr_code = hdr.sr_code;
255 s->bitstream_mode = hdr.bitstream_mode;
256 s->channel_mode = hdr.channel_mode;
257 s->channel_layout = hdr.channel_layout;
258 s->lfe_on = hdr.lfe_on;
259 s->bit_alloc_params.sr_shift = hdr.sr_shift;
260 s->sample_rate = hdr.sample_rate;
261 s->bit_rate = hdr.bit_rate;
262 s->channels = hdr.channels;
263 s->fbw_channels = s->channels - s->lfe_on;
264 s->lfe_ch = s->fbw_channels + 1;
265 s->frame_size = hdr.frame_size;
266 s->center_mix_level = hdr.center_mix_level;
267 s->surround_mix_level = hdr.surround_mix_level;
268 s->num_blocks = hdr.num_blocks;
269 s->frame_type = hdr.frame_type;
270 s->substreamid = hdr.substreamid;
273 s->start_freq[s->lfe_ch] = 0;
274 s->end_freq[s->lfe_ch] = 7;
275 s->num_exp_groups[s->lfe_ch] = 2;
276 s->channel_in_cpl[s->lfe_ch] = 0;
279 if (hdr.bitstream_id <= 10) {
281 s->snr_offset_strategy = 2;
282 s->block_switch_syntax = 1;
283 s->dither_flag_syntax = 1;
284 s->bit_allocation_syntax = 1;
285 s->fast_gain_syntax = 0;
286 s->first_cpl_leak = 0;
289 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
290 return ac3_parse_header(s);
291 } else if (CONFIG_EAC3_DECODER) {
293 return ff_eac3_parse_header(s);
295 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
301 * Set stereo downmixing coefficients based on frame header info.
302 * reference: Section 7.8.2 Downmixing Into Two Channels
304 static void set_downmix_coeffs(AC3DecodeContext *s)
307 float cmix = gain_levels[s-> center_mix_level];
308 float smix = gain_levels[s->surround_mix_level];
311 for (i = 0; i < s->fbw_channels; i++) {
312 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
313 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
315 if (s->channel_mode > 1 && s->channel_mode & 1) {
316 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
318 if (s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
319 int nf = s->channel_mode - 2;
320 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
322 if (s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
323 int nf = s->channel_mode - 4;
324 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
329 for (i = 0; i < s->fbw_channels; i++) {
330 norm0 += s->downmix_coeffs[i][0];
331 norm1 += s->downmix_coeffs[i][1];
333 norm0 = 1.0f / norm0;
334 norm1 = 1.0f / norm1;
335 for (i = 0; i < s->fbw_channels; i++) {
336 s->downmix_coeffs[i][0] *= norm0;
337 s->downmix_coeffs[i][1] *= norm1;
340 if (s->output_mode == AC3_CHMODE_MONO) {
341 for (i = 0; i < s->fbw_channels; i++)
342 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] +
343 s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
348 * Decode the grouped exponents according to exponent strategy.
349 * reference: Section 7.1.3 Exponent Decoding
351 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
352 uint8_t absexp, int8_t *dexps)
354 int i, j, grp, group_size;
359 group_size = exp_strategy + (exp_strategy == EXP_D45);
360 for (grp = 0, i = 0; grp < ngrps; grp++) {
361 expacc = get_bits(gbc, 7);
362 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
363 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
364 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
367 /* convert to absolute exps and expand groups */
369 for (i = 0, j = 0; i < ngrps * 3; i++) {
370 prevexp += dexp[i] - 2;
373 switch (group_size) {
374 case 4: dexps[j++] = prevexp;
375 dexps[j++] = prevexp;
376 case 2: dexps[j++] = prevexp;
377 case 1: dexps[j++] = prevexp;
384 * Generate transform coefficients for each coupled channel in the coupling
385 * range using the coupling coefficients and coupling coordinates.
386 * reference: Section 7.4.3 Coupling Coordinate Format
388 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
392 bin = s->start_freq[CPL_CH];
393 for (band = 0; band < s->num_cpl_bands; band++) {
394 int band_start = bin;
395 int band_end = bin + s->cpl_band_sizes[band];
396 for (ch = 1; ch <= s->fbw_channels; ch++) {
397 if (s->channel_in_cpl[ch]) {
398 int cpl_coord = s->cpl_coords[ch][band] << 5;
399 for (bin = band_start; bin < band_end; bin++) {
400 s->fixed_coeffs[ch][bin] =
401 MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
403 if (ch == 2 && s->phase_flags[band]) {
404 for (bin = band_start; bin < band_end; bin++)
405 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
414 * Grouped mantissas for 3-level 5-level and 11-level quantization
426 * Decode the transform coefficients for a particular channel
427 * reference: Section 7.3 Quantization and Decoding of Mantissas
429 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
431 int start_freq = s->start_freq[ch_index];
432 int end_freq = s->end_freq[ch_index];
433 uint8_t *baps = s->bap[ch_index];
434 int8_t *exps = s->dexps[ch_index];
435 int *coeffs = s->fixed_coeffs[ch_index];
436 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
437 GetBitContext *gbc = &s->gbc;
440 for (freq = start_freq; freq < end_freq; freq++) {
441 int bap = baps[freq];
446 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
453 mantissa = m->b1_mant[m->b1];
455 int bits = get_bits(gbc, 5);
456 mantissa = b1_mantissas[bits][0];
457 m->b1_mant[1] = b1_mantissas[bits][1];
458 m->b1_mant[0] = b1_mantissas[bits][2];
465 mantissa = m->b2_mant[m->b2];
467 int bits = get_bits(gbc, 7);
468 mantissa = b2_mantissas[bits][0];
469 m->b2_mant[1] = b2_mantissas[bits][1];
470 m->b2_mant[0] = b2_mantissas[bits][2];
475 mantissa = b3_mantissas[get_bits(gbc, 3)];
480 mantissa = m->b4_mant;
482 int bits = get_bits(gbc, 7);
483 mantissa = b4_mantissas[bits][0];
484 m->b4_mant = b4_mantissas[bits][1];
489 mantissa = b5_mantissas[get_bits(gbc, 4)];
491 default: /* 6 to 15 */
492 /* Shift mantissa and sign-extend it. */
493 mantissa = get_sbits(gbc, quantization_tab[bap]);
494 mantissa <<= 24 - quantization_tab[bap];
497 coeffs[freq] = mantissa >> exps[freq];
502 * Remove random dithering from coupling range coefficients with zero-bit
503 * mantissas for coupled channels which do not use dithering.
504 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
506 static void remove_dithering(AC3DecodeContext *s) {
509 for (ch = 1; ch <= s->fbw_channels; ch++) {
510 if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
511 for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) {
512 if (!s->bap[CPL_CH][i])
513 s->fixed_coeffs[ch][i] = 0;
519 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
522 if (!s->channel_uses_aht[ch]) {
523 ac3_decode_transform_coeffs_ch(s, ch, m);
525 /* if AHT is used, mantissas for all blocks are encoded in the first
526 block of the frame. */
528 if (!blk && CONFIG_EAC3_DECODER)
529 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
530 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
531 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
537 * Decode the transform coefficients.
539 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
545 m.b1 = m.b2 = m.b4 = 0;
547 for (ch = 1; ch <= s->channels; ch++) {
548 /* transform coefficients for full-bandwidth channel */
549 decode_transform_coeffs_ch(s, blk, ch, &m);
550 /* transform coefficients for coupling channel come right after the
551 coefficients for the first coupled channel*/
552 if (s->channel_in_cpl[ch]) {
554 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
555 calc_transform_coeffs_cpl(s);
558 end = s->end_freq[CPL_CH];
560 end = s->end_freq[ch];
563 s->fixed_coeffs[ch][end] = 0;
567 /* zero the dithered coefficients for appropriate channels */
572 * Stereo rematrixing.
573 * reference: Section 7.5.4 Rematrixing : Decoding Technique
575 static void do_rematrixing(AC3DecodeContext *s)
580 end = FFMIN(s->end_freq[1], s->end_freq[2]);
582 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
583 if (s->rematrixing_flags[bnd]) {
584 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd + 1]);
585 for (i = ff_ac3_rematrix_band_tab[bnd]; i < bndend; i++) {
586 int tmp0 = s->fixed_coeffs[1][i];
587 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
588 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
595 * Inverse MDCT Transform.
596 * Convert frequency domain coefficients to time-domain audio samples.
597 * reference: Section 7.9.4 Transformation Equations
599 static inline void do_imdct(AC3DecodeContext *s, int channels)
603 for (ch = 1; ch <= channels; ch++) {
604 if (s->block_switch[ch]) {
606 float *x = s->tmp_output + 128;
607 for (i = 0; i < 128; i++)
608 x[i] = s->transform_coeffs[ch][2 * i];
609 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
610 s->fdsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
611 s->tmp_output, s->window, 128);
612 for (i = 0; i < 128; i++)
613 x[i] = s->transform_coeffs[ch][2 * i + 1];
614 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x);
616 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
617 s->fdsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1],
618 s->tmp_output, s->window, 128);
619 memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(float));
625 * Upmix delay samples from stereo to original channel layout.
627 static void ac3_upmix_delay(AC3DecodeContext *s)
629 int channel_data_size = sizeof(s->delay[0]);
630 switch (s->channel_mode) {
631 case AC3_CHMODE_DUALMONO:
632 case AC3_CHMODE_STEREO:
633 /* upmix mono to stereo */
634 memcpy(s->delay[1], s->delay[0], channel_data_size);
636 case AC3_CHMODE_2F2R:
637 memset(s->delay[3], 0, channel_data_size);
638 case AC3_CHMODE_2F1R:
639 memset(s->delay[2], 0, channel_data_size);
641 case AC3_CHMODE_3F2R:
642 memset(s->delay[4], 0, channel_data_size);
643 case AC3_CHMODE_3F1R:
644 memset(s->delay[3], 0, channel_data_size);
646 memcpy(s->delay[2], s->delay[1], channel_data_size);
647 memset(s->delay[1], 0, channel_data_size);
653 * Decode band structure for coupling, spectral extension, or enhanced coupling.
654 * The band structure defines how many subbands are in each band. For each
655 * subband in the range, 1 means it is combined with the previous band, and 0
656 * means that it starts a new band.
658 * @param[in] gbc bit reader context
659 * @param[in] blk block number
660 * @param[in] eac3 flag to indicate E-AC-3
661 * @param[in] ecpl flag to indicate enhanced coupling
662 * @param[in] start_subband subband number for start of range
663 * @param[in] end_subband subband number for end of range
664 * @param[in] default_band_struct default band structure table
665 * @param[out] num_bands number of bands (optionally NULL)
666 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
668 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
669 int ecpl, int start_subband, int end_subband,
670 const uint8_t *default_band_struct,
671 int *num_bands, uint8_t *band_sizes)
673 int subbnd, bnd, n_subbands, n_bands=0;
675 uint8_t coded_band_struct[22];
676 const uint8_t *band_struct;
678 n_subbands = end_subband - start_subband;
680 /* decode band structure from bitstream or use default */
681 if (!eac3 || get_bits1(gbc)) {
682 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
683 coded_band_struct[subbnd] = get_bits1(gbc);
685 band_struct = coded_band_struct;
687 band_struct = &default_band_struct[start_subband+1];
689 /* no change in band structure */
693 /* calculate number of bands and band sizes based on band structure.
694 note that the first 4 subbands in enhanced coupling span only 6 bins
696 if (num_bands || band_sizes ) {
697 n_bands = n_subbands;
698 bnd_sz[0] = ecpl ? 6 : 12;
699 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
700 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
701 if (band_struct[subbnd - 1]) {
703 bnd_sz[bnd] += subbnd_size;
705 bnd_sz[++bnd] = subbnd_size;
710 /* set optional output params */
712 *num_bands = n_bands;
714 memcpy(band_sizes, bnd_sz, n_bands);
718 * Decode a single audio block from the AC-3 bitstream.
720 static int decode_audio_block(AC3DecodeContext *s, int blk)
722 int fbw_channels = s->fbw_channels;
723 int channel_mode = s->channel_mode;
725 int different_transforms;
728 GetBitContext *gbc = &s->gbc;
729 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
731 /* block switch flags */
732 different_transforms = 0;
733 if (s->block_switch_syntax) {
734 for (ch = 1; ch <= fbw_channels; ch++) {
735 s->block_switch[ch] = get_bits1(gbc);
736 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
737 different_transforms = 1;
741 /* dithering flags */
742 if (s->dither_flag_syntax) {
743 for (ch = 1; ch <= fbw_channels; ch++) {
744 s->dither_flag[ch] = get_bits1(gbc);
749 i = !s->channel_mode;
751 if (get_bits1(gbc)) {
752 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)] - 1.0) *
754 } else if (blk == 0) {
755 s->dynamic_range[i] = 1.0f;
759 /* spectral extension strategy */
760 if (s->eac3 && (!blk || get_bits1(gbc))) {
761 s->spx_in_use = get_bits1(gbc);
763 int dst_start_freq, dst_end_freq, src_start_freq,
764 start_subband, end_subband;
766 /* determine which channels use spx */
767 if (s->channel_mode == AC3_CHMODE_MONO) {
768 s->channel_uses_spx[1] = 1;
770 for (ch = 1; ch <= fbw_channels; ch++)
771 s->channel_uses_spx[ch] = get_bits1(gbc);
774 /* get the frequency bins of the spx copy region and the spx start
776 dst_start_freq = get_bits(gbc, 2);
777 start_subband = get_bits(gbc, 3) + 2;
778 if (start_subband > 7)
779 start_subband += start_subband - 7;
780 end_subband = get_bits(gbc, 3) + 5;
782 end_subband += end_subband - 7;
783 dst_start_freq = dst_start_freq * 12 + 25;
784 src_start_freq = start_subband * 12 + 25;
785 dst_end_freq = end_subband * 12 + 25;
787 /* check validity of spx ranges */
788 if (start_subband >= end_subband) {
789 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
790 "range (%d >= %d)\n", start_subband, end_subband);
793 if (dst_start_freq >= src_start_freq) {
794 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
795 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
799 s->spx_dst_start_freq = dst_start_freq;
800 s->spx_src_start_freq = src_start_freq;
801 s->spx_dst_end_freq = dst_end_freq;
803 decode_band_structure(gbc, blk, s->eac3, 0,
804 start_subband, end_subband,
805 ff_eac3_default_spx_band_struct,
809 for (ch = 1; ch <= fbw_channels; ch++) {
810 s->channel_uses_spx[ch] = 0;
811 s->first_spx_coords[ch] = 1;
816 /* spectral extension coordinates */
818 for (ch = 1; ch <= fbw_channels; ch++) {
819 if (s->channel_uses_spx[ch]) {
820 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
822 int bin, master_spx_coord;
824 s->first_spx_coords[ch] = 0;
825 spx_blend = get_bits(gbc, 5) * (1.0f/32);
826 master_spx_coord = get_bits(gbc, 2) * 3;
828 bin = s->spx_src_start_freq;
829 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
831 int spx_coord_exp, spx_coord_mant;
832 float nratio, sblend, nblend, spx_coord;
834 /* calculate blending factors */
835 bandsize = s->spx_band_sizes[bnd];
836 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
837 nratio = av_clipf(nratio, 0.0f, 1.0f);
838 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
839 // to give unity variance
840 sblend = sqrtf(1.0f - nratio);
843 /* decode spx coordinates */
844 spx_coord_exp = get_bits(gbc, 4);
845 spx_coord_mant = get_bits(gbc, 2);
846 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
847 else spx_coord_mant += 4;
848 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
849 spx_coord = spx_coord_mant * (1.0f / (1 << 23));
851 /* multiply noise and signal blending factors by spx coordinate */
852 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
853 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
857 s->first_spx_coords[ch] = 1;
862 /* coupling strategy */
863 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
864 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
866 s->cpl_in_use[blk] = get_bits1(gbc);
867 if (s->cpl_in_use[blk]) {
868 /* coupling in use */
869 int cpl_start_subband, cpl_end_subband;
871 if (channel_mode < AC3_CHMODE_STEREO) {
872 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
876 /* check for enhanced coupling */
877 if (s->eac3 && get_bits1(gbc)) {
878 /* TODO: parse enhanced coupling strategy info */
879 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
880 return AVERROR_PATCHWELCOME;
883 /* determine which channels are coupled */
884 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
885 s->channel_in_cpl[1] = 1;
886 s->channel_in_cpl[2] = 1;
888 for (ch = 1; ch <= fbw_channels; ch++)
889 s->channel_in_cpl[ch] = get_bits1(gbc);
892 /* phase flags in use */
893 if (channel_mode == AC3_CHMODE_STEREO)
894 s->phase_flags_in_use = get_bits1(gbc);
896 /* coupling frequency range */
897 cpl_start_subband = get_bits(gbc, 4);
898 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
899 get_bits(gbc, 4) + 3;
900 if (cpl_start_subband >= cpl_end_subband) {
901 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
902 cpl_start_subband, cpl_end_subband);
905 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
906 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
908 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
910 ff_eac3_default_cpl_band_struct,
911 &s->num_cpl_bands, s->cpl_band_sizes);
913 /* coupling not in use */
914 for (ch = 1; ch <= fbw_channels; ch++) {
915 s->channel_in_cpl[ch] = 0;
916 s->first_cpl_coords[ch] = 1;
918 s->first_cpl_leak = s->eac3;
919 s->phase_flags_in_use = 0;
921 } else if (!s->eac3) {
923 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
924 "be present in block 0\n");
927 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
930 cpl_in_use = s->cpl_in_use[blk];
932 /* coupling coordinates */
934 int cpl_coords_exist = 0;
936 for (ch = 1; ch <= fbw_channels; ch++) {
937 if (s->channel_in_cpl[ch]) {
938 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
939 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
940 s->first_cpl_coords[ch] = 0;
941 cpl_coords_exist = 1;
942 master_cpl_coord = 3 * get_bits(gbc, 2);
943 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
944 cpl_coord_exp = get_bits(gbc, 4);
945 cpl_coord_mant = get_bits(gbc, 4);
946 if (cpl_coord_exp == 15)
947 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
949 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
950 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
953 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
954 "be present in block 0\n");
958 /* channel not in coupling */
959 s->first_cpl_coords[ch] = 1;
963 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
964 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
965 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
970 /* stereo rematrixing strategy and band structure */
971 if (channel_mode == AC3_CHMODE_STEREO) {
972 if ((s->eac3 && !blk) || get_bits1(gbc)) {
973 s->num_rematrixing_bands = 4;
974 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
975 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
976 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
977 s->num_rematrixing_bands--;
979 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
980 s->rematrixing_flags[bnd] = get_bits1(gbc);
982 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
983 "new rematrixing strategy not present in block 0\n");
984 s->num_rematrixing_bands = 0;
988 /* exponent strategies for each channel */
989 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
991 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
992 if (s->exp_strategy[blk][ch] != EXP_REUSE)
993 bit_alloc_stages[ch] = 3;
996 /* channel bandwidth */
997 for (ch = 1; ch <= fbw_channels; ch++) {
998 s->start_freq[ch] = 0;
999 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1001 int prev = s->end_freq[ch];
1002 if (s->channel_in_cpl[ch])
1003 s->end_freq[ch] = s->start_freq[CPL_CH];
1004 else if (s->channel_uses_spx[ch])
1005 s->end_freq[ch] = s->spx_src_start_freq;
1007 int bandwidth_code = get_bits(gbc, 6);
1008 if (bandwidth_code > 60) {
1009 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1012 s->end_freq[ch] = bandwidth_code * 3 + 73;
1014 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1015 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1016 if (blk > 0 && s->end_freq[ch] != prev)
1017 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1020 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1021 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1022 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1025 /* decode exponents for each channel */
1026 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1027 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1028 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1029 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1030 s->num_exp_groups[ch], s->dexps[ch][0],
1031 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1032 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1035 if (ch != CPL_CH && ch != s->lfe_ch)
1036 skip_bits(gbc, 2); /* skip gainrng */
1040 /* bit allocation information */
1041 if (s->bit_allocation_syntax) {
1042 if (get_bits1(gbc)) {
1043 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1044 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1045 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1046 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1047 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1048 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1049 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1051 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1052 "be present in block 0\n");
1057 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1058 if (!s->eac3 || !blk) {
1059 if (s->snr_offset_strategy && get_bits1(gbc)) {
1062 csnr = (get_bits(gbc, 6) - 15) << 4;
1063 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1065 if (ch == i || s->snr_offset_strategy == 2)
1066 snr = (csnr + get_bits(gbc, 4)) << 2;
1067 /* run at least last bit allocation stage if snr offset changes */
1068 if (blk && s->snr_offset[ch] != snr) {
1069 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1071 s->snr_offset[ch] = snr;
1073 /* fast gain (normal AC-3 only) */
1075 int prev = s->fast_gain[ch];
1076 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1077 /* run last 2 bit allocation stages if fast gain changes */
1078 if (blk && prev != s->fast_gain[ch])
1079 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1082 } else if (!s->eac3 && !blk) {
1083 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1088 /* fast gain (E-AC-3 only) */
1089 if (s->fast_gain_syntax && get_bits1(gbc)) {
1090 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1091 int prev = s->fast_gain[ch];
1092 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1093 /* run last 2 bit allocation stages if fast gain changes */
1094 if (blk && prev != s->fast_gain[ch])
1095 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1097 } else if (s->eac3 && !blk) {
1098 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1099 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1102 /* E-AC-3 to AC-3 converter SNR offset */
1103 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1104 skip_bits(gbc, 10); // skip converter snr offset
1107 /* coupling leak information */
1109 if (s->first_cpl_leak || get_bits1(gbc)) {
1110 int fl = get_bits(gbc, 3);
1111 int sl = get_bits(gbc, 3);
1112 /* run last 2 bit allocation stages for coupling channel if
1113 coupling leak changes */
1114 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1115 sl != s->bit_alloc_params.cpl_slow_leak)) {
1116 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1118 s->bit_alloc_params.cpl_fast_leak = fl;
1119 s->bit_alloc_params.cpl_slow_leak = sl;
1120 } else if (!s->eac3 && !blk) {
1121 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1122 "be present in block 0\n");
1125 s->first_cpl_leak = 0;
1128 /* delta bit allocation information */
1129 if (s->dba_syntax && get_bits1(gbc)) {
1130 /* delta bit allocation exists (strategy) */
1131 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1132 s->dba_mode[ch] = get_bits(gbc, 2);
1133 if (s->dba_mode[ch] == DBA_RESERVED) {
1134 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1137 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1139 /* channel delta offset, len and bit allocation */
1140 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1141 if (s->dba_mode[ch] == DBA_NEW) {
1142 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1143 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1144 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1145 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1146 s->dba_values[ch][seg] = get_bits(gbc, 3);
1148 /* run last 2 bit allocation stages if new dba values */
1149 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1152 } else if (blk == 0) {
1153 for (ch = 0; ch <= s->channels; ch++) {
1154 s->dba_mode[ch] = DBA_NONE;
1158 /* Bit allocation */
1159 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1160 if (bit_alloc_stages[ch] > 2) {
1161 /* Exponent mapping into PSD and PSD integration */
1162 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1163 s->start_freq[ch], s->end_freq[ch],
1164 s->psd[ch], s->band_psd[ch]);
1166 if (bit_alloc_stages[ch] > 1) {
1167 /* Compute excitation function, Compute masking curve, and
1168 Apply delta bit allocation */
1169 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1170 s->start_freq[ch], s->end_freq[ch],
1171 s->fast_gain[ch], (ch == s->lfe_ch),
1172 s->dba_mode[ch], s->dba_nsegs[ch],
1173 s->dba_offsets[ch], s->dba_lengths[ch],
1174 s->dba_values[ch], s->mask[ch])) {
1175 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1179 if (bit_alloc_stages[ch] > 0) {
1180 /* Compute bit allocation */
1181 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1182 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1183 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1184 s->start_freq[ch], s->end_freq[ch],
1186 s->bit_alloc_params.floor,
1187 bap_tab, s->bap[ch]);
1191 /* unused dummy data */
1192 if (s->skip_syntax && get_bits1(gbc)) {
1193 int skipl = get_bits(gbc, 9);
1198 /* unpack the transform coefficients
1199 this also uncouples channels if coupling is in use. */
1200 decode_transform_coeffs(s, blk);
1202 /* TODO: generate enhanced coupling coordinates and uncouple */
1204 /* recover coefficients if rematrixing is in use */
1205 if (s->channel_mode == AC3_CHMODE_STEREO)
1208 /* apply scaling to coefficients (headroom, dynrng) */
1209 for (ch = 1; ch <= s->channels; ch++) {
1210 float gain = 1.0 / 4194304.0f;
1211 if (s->channel_mode == AC3_CHMODE_DUALMONO) {
1212 gain *= s->dynamic_range[2 - ch];
1214 gain *= s->dynamic_range[0];
1216 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1217 s->fixed_coeffs[ch], gain, 256);
1220 /* apply spectral extension to high frequency bins */
1221 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1222 ff_eac3_apply_spectral_extension(s);
1225 /* downmix and MDCT. order depends on whether block switching is used for
1226 any channel in this block. this is because coefficients for the long
1227 and short transforms cannot be mixed. */
1228 downmix_output = s->channels != s->out_channels &&
1229 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1230 s->fbw_channels == s->out_channels);
1231 if (different_transforms) {
1232 /* the delay samples have already been downmixed, so we upmix the delay
1233 samples in order to reconstruct all channels before downmixing. */
1239 do_imdct(s, s->channels);
1241 if (downmix_output) {
1242 s->ac3dsp.downmix(s->outptr, s->downmix_coeffs,
1243 s->out_channels, s->fbw_channels, 256);
1246 if (downmix_output) {
1247 s->ac3dsp.downmix(s->xcfptr + 1, s->downmix_coeffs,
1248 s->out_channels, s->fbw_channels, 256);
1251 if (downmix_output && !s->downmixed) {
1253 s->ac3dsp.downmix(s->dlyptr, s->downmix_coeffs, s->out_channels,
1254 s->fbw_channels, 128);
1257 do_imdct(s, s->out_channels);
1264 * Decode a single AC-3 frame.
1266 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1267 int *got_frame_ptr, AVPacket *avpkt)
1269 const uint8_t *buf = avpkt->data;
1270 int buf_size = avpkt->size;
1271 AC3DecodeContext *s = avctx->priv_data;
1272 int blk, ch, err, ret;
1273 const uint8_t *channel_map;
1274 const float *output[AC3_MAX_CHANNELS];
1276 /* copy input buffer to decoder context to avoid reading past the end
1277 of the buffer, which can be caused by a damaged input stream. */
1278 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1279 // seems to be byte-swapped AC-3
1280 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1281 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1283 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1284 buf = s->input_buffer;
1285 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1286 init_get_bits(&s->gbc, buf, buf_size * 8);
1288 /* parse the syncinfo */
1289 err = parse_frame_header(s);
1293 case AAC_AC3_PARSE_ERROR_SYNC:
1294 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1296 case AAC_AC3_PARSE_ERROR_BSID:
1297 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1299 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1300 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1302 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1303 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1305 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1306 /* skip frame if CRC is ok. otherwise use error concealment. */
1307 /* TODO: add support for substreams and dependent frames */
1308 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1309 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : "
1310 "skipping frame\n");
1312 return s->frame_size;
1314 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1318 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1322 /* check that reported frame size fits in input buffer */
1323 if (s->frame_size > buf_size) {
1324 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1325 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1326 } else if (avctx->err_recognition & AV_EF_CRCCHECK) {
1327 /* check for crc mismatch */
1328 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1329 s->frame_size - 2)) {
1330 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1331 err = AAC_AC3_PARSE_ERROR_CRC;
1336 /* if frame is ok, set audio parameters */
1338 avctx->sample_rate = s->sample_rate;
1339 avctx->bit_rate = s->bit_rate;
1341 /* channel config */
1342 s->out_channels = s->channels;
1343 s->output_mode = s->channel_mode;
1345 s->output_mode |= AC3_OUTPUT_LFEON;
1346 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1347 avctx->request_channels < s->channels) {
1348 s->out_channels = avctx->request_channels;
1349 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1350 s->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode];
1352 avctx->channels = s->out_channels;
1353 avctx->channel_layout = s->channel_layout;
1355 /* set downmixing coefficients if needed */
1356 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1357 s->fbw_channels == s->out_channels)) {
1358 set_downmix_coeffs(s);
1360 } else if (!s->out_channels) {
1361 s->out_channels = avctx->channels;
1362 if (s->out_channels < s->channels)
1363 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1365 /* set audio service type based on bitstream mode for AC-3 */
1366 avctx->audio_service_type = s->bitstream_mode;
1367 if (s->bitstream_mode == 0x7 && s->channels > 1)
1368 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1370 /* get output buffer */
1371 avctx->channels = s->out_channels;
1372 s->frame.nb_samples = s->num_blocks * 256;
1373 if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {
1374 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
1378 /* decode the audio blocks */
1379 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1380 for (ch = 0; ch < s->channels; ch++) {
1381 if (ch < s->out_channels)
1382 s->outptr[channel_map[ch]] = (float *)s->frame.data[ch];
1384 s->outptr[ch] = s->output[ch];
1385 output[ch] = s->output[ch];
1387 for (blk = 0; blk < s->num_blocks; blk++) {
1388 if (!err && decode_audio_block(s, blk)) {
1389 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1393 for (ch = 0; ch < s->out_channels; ch++)
1394 memcpy(s->outptr[channel_map[ch]], output[ch], 1024);
1395 for (ch = 0; ch < s->out_channels; ch++) {
1396 output[ch] = s->outptr[channel_map[ch]];
1397 s->outptr[channel_map[ch]] += AC3_BLOCK_SIZE;
1401 /* keep last block for error concealment in next frame */
1402 for (ch = 0; ch < s->out_channels; ch++)
1403 memcpy(s->output[ch], output[ch], 1024);
1406 *(AVFrame *)data = s->frame;
1408 return FFMIN(buf_size, s->frame_size);
1412 * Uninitialize the AC-3 decoder.
1414 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1416 AC3DecodeContext *s = avctx->priv_data;
1417 ff_mdct_end(&s->imdct_512);
1418 ff_mdct_end(&s->imdct_256);
1423 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1424 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)
1425 static const AVOption options[] = {
1426 { "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), AV_OPT_TYPE_FLOAT, {.dbl = 1.0}, 0.0, 1.0, PAR },
1430 static const AVClass ac3_decoder_class = {
1431 .class_name = "AC3 decoder",
1432 .item_name = av_default_item_name,
1434 .version = LIBAVUTIL_VERSION_INT,
1437 AVCodec ff_ac3_decoder = {
1439 .type = AVMEDIA_TYPE_AUDIO,
1440 .id = AV_CODEC_ID_AC3,
1441 .priv_data_size = sizeof (AC3DecodeContext),
1442 .init = ac3_decode_init,
1443 .close = ac3_decode_end,
1444 .decode = ac3_decode_frame,
1445 .capabilities = CODEC_CAP_DR1,
1446 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1447 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
1448 AV_SAMPLE_FMT_NONE },
1449 .priv_class = &ac3_decoder_class,
1452 #if CONFIG_EAC3_DECODER
1453 static const AVClass eac3_decoder_class = {
1454 .class_name = "E-AC3 decoder",
1455 .item_name = av_default_item_name,
1457 .version = LIBAVUTIL_VERSION_INT,
1460 AVCodec ff_eac3_decoder = {
1462 .type = AVMEDIA_TYPE_AUDIO,
1463 .id = AV_CODEC_ID_EAC3,
1464 .priv_data_size = sizeof (AC3DecodeContext),
1465 .init = ac3_decode_init,
1466 .close = ac3_decode_end,
1467 .decode = ac3_decode_frame,
1468 .capabilities = CODEC_CAP_DR1,
1469 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1470 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
1471 AV_SAMPLE_FMT_NONE },
1472 .priv_class = &eac3_decoder_class,