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;
165 ff_ac3_common_init();
167 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
168 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
169 ff_kbd_window_init(s->window, 5.0, 256);
170 ff_dsputil_init(&s->dsp, avctx);
171 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
172 ff_fmt_convert_init(&s->fmt_conv, avctx);
173 av_lfg_init(&s->dith_state, 0);
175 avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
177 /* allow downmixing to stereo or mono */
178 if (avctx->channels > 0 && avctx->request_channels > 0 &&
179 avctx->request_channels < avctx->channels &&
180 avctx->request_channels <= 2) {
181 avctx->channels = avctx->request_channels;
185 avcodec_get_frame_defaults(&s->frame);
186 avctx->coded_frame = &s->frame;
192 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
193 * GetBitContext within AC3DecodeContext must point to
194 * the start of the synchronized AC-3 bitstream.
196 static int ac3_parse_header(AC3DecodeContext *s)
198 GetBitContext *gbc = &s->gbc;
201 /* read the rest of the bsi. read twice for dual mono mode. */
202 i = !s->channel_mode;
204 skip_bits(gbc, 5); // skip dialog normalization
206 skip_bits(gbc, 8); //skip compression
208 skip_bits(gbc, 8); //skip language code
210 skip_bits(gbc, 7); //skip audio production information
213 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
215 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
216 TODO: read & use the xbsi1 downmix levels */
218 skip_bits(gbc, 14); //skip timecode1 / xbsi1
220 skip_bits(gbc, 14); //skip timecode2 / xbsi2
222 /* skip additional bitstream info */
223 if (get_bits1(gbc)) {
224 i = get_bits(gbc, 6);
234 * Common function to parse AC-3 or E-AC-3 frame header
236 static int parse_frame_header(AC3DecodeContext *s)
241 err = avpriv_ac3_parse_header(&s->gbc, &hdr);
245 /* get decoding parameters from header info */
246 s->bit_alloc_params.sr_code = hdr.sr_code;
247 s->bitstream_mode = hdr.bitstream_mode;
248 s->channel_mode = hdr.channel_mode;
249 s->channel_layout = hdr.channel_layout;
250 s->lfe_on = hdr.lfe_on;
251 s->bit_alloc_params.sr_shift = hdr.sr_shift;
252 s->sample_rate = hdr.sample_rate;
253 s->bit_rate = hdr.bit_rate;
254 s->channels = hdr.channels;
255 s->fbw_channels = s->channels - s->lfe_on;
256 s->lfe_ch = s->fbw_channels + 1;
257 s->frame_size = hdr.frame_size;
258 s->center_mix_level = hdr.center_mix_level;
259 s->surround_mix_level = hdr.surround_mix_level;
260 s->num_blocks = hdr.num_blocks;
261 s->frame_type = hdr.frame_type;
262 s->substreamid = hdr.substreamid;
265 s->start_freq[s->lfe_ch] = 0;
266 s->end_freq[s->lfe_ch] = 7;
267 s->num_exp_groups[s->lfe_ch] = 2;
268 s->channel_in_cpl[s->lfe_ch] = 0;
271 if (hdr.bitstream_id <= 10) {
273 s->snr_offset_strategy = 2;
274 s->block_switch_syntax = 1;
275 s->dither_flag_syntax = 1;
276 s->bit_allocation_syntax = 1;
277 s->fast_gain_syntax = 0;
278 s->first_cpl_leak = 0;
281 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
282 return ac3_parse_header(s);
283 } else if (CONFIG_EAC3_DECODER) {
285 return ff_eac3_parse_header(s);
287 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
293 * Set stereo downmixing coefficients based on frame header info.
294 * reference: Section 7.8.2 Downmixing Into Two Channels
296 static void set_downmix_coeffs(AC3DecodeContext *s)
299 float cmix = gain_levels[s-> center_mix_level];
300 float smix = gain_levels[s->surround_mix_level];
303 for (i = 0; i < s->fbw_channels; i++) {
304 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
305 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
307 if (s->channel_mode > 1 && s->channel_mode & 1) {
308 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
310 if (s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
311 int nf = s->channel_mode - 2;
312 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
314 if (s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
315 int nf = s->channel_mode - 4;
316 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
321 for (i = 0; i < s->fbw_channels; i++) {
322 norm0 += s->downmix_coeffs[i][0];
323 norm1 += s->downmix_coeffs[i][1];
325 norm0 = 1.0f / norm0;
326 norm1 = 1.0f / norm1;
327 for (i = 0; i < s->fbw_channels; i++) {
328 s->downmix_coeffs[i][0] *= norm0;
329 s->downmix_coeffs[i][1] *= norm1;
332 if (s->output_mode == AC3_CHMODE_MONO) {
333 for (i = 0; i < s->fbw_channels; i++)
334 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] +
335 s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
340 * Decode the grouped exponents according to exponent strategy.
341 * reference: Section 7.1.3 Exponent Decoding
343 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
344 uint8_t absexp, int8_t *dexps)
346 int i, j, grp, group_size;
351 group_size = exp_strategy + (exp_strategy == EXP_D45);
352 for (grp = 0, i = 0; grp < ngrps; grp++) {
353 expacc = get_bits(gbc, 7);
354 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
355 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
356 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
359 /* convert to absolute exps and expand groups */
361 for (i = 0, j = 0; i < ngrps * 3; i++) {
362 prevexp += dexp[i] - 2;
365 switch (group_size) {
366 case 4: dexps[j++] = prevexp;
367 dexps[j++] = prevexp;
368 case 2: dexps[j++] = prevexp;
369 case 1: dexps[j++] = prevexp;
376 * Generate transform coefficients for each coupled channel in the coupling
377 * range using the coupling coefficients and coupling coordinates.
378 * reference: Section 7.4.3 Coupling Coordinate Format
380 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
384 bin = s->start_freq[CPL_CH];
385 for (band = 0; band < s->num_cpl_bands; band++) {
386 int band_start = bin;
387 int band_end = bin + s->cpl_band_sizes[band];
388 for (ch = 1; ch <= s->fbw_channels; ch++) {
389 if (s->channel_in_cpl[ch]) {
390 int cpl_coord = s->cpl_coords[ch][band] << 5;
391 for (bin = band_start; bin < band_end; bin++) {
392 s->fixed_coeffs[ch][bin] =
393 MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
395 if (ch == 2 && s->phase_flags[band]) {
396 for (bin = band_start; bin < band_end; bin++)
397 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
406 * Grouped mantissas for 3-level 5-level and 11-level quantization
418 * Decode the transform coefficients for a particular channel
419 * reference: Section 7.3 Quantization and Decoding of Mantissas
421 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
423 int start_freq = s->start_freq[ch_index];
424 int end_freq = s->end_freq[ch_index];
425 uint8_t *baps = s->bap[ch_index];
426 int8_t *exps = s->dexps[ch_index];
427 int *coeffs = s->fixed_coeffs[ch_index];
428 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
429 GetBitContext *gbc = &s->gbc;
432 for (freq = start_freq; freq < end_freq; freq++) {
433 int bap = baps[freq];
438 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
445 mantissa = m->b1_mant[m->b1];
447 int bits = get_bits(gbc, 5);
448 mantissa = b1_mantissas[bits][0];
449 m->b1_mant[1] = b1_mantissas[bits][1];
450 m->b1_mant[0] = b1_mantissas[bits][2];
457 mantissa = m->b2_mant[m->b2];
459 int bits = get_bits(gbc, 7);
460 mantissa = b2_mantissas[bits][0];
461 m->b2_mant[1] = b2_mantissas[bits][1];
462 m->b2_mant[0] = b2_mantissas[bits][2];
467 mantissa = b3_mantissas[get_bits(gbc, 3)];
472 mantissa = m->b4_mant;
474 int bits = get_bits(gbc, 7);
475 mantissa = b4_mantissas[bits][0];
476 m->b4_mant = b4_mantissas[bits][1];
481 mantissa = b5_mantissas[get_bits(gbc, 4)];
483 default: /* 6 to 15 */
484 /* Shift mantissa and sign-extend it. */
485 mantissa = get_sbits(gbc, quantization_tab[bap]);
486 mantissa <<= 24 - quantization_tab[bap];
489 coeffs[freq] = mantissa >> exps[freq];
494 * Remove random dithering from coupling range coefficients with zero-bit
495 * mantissas for coupled channels which do not use dithering.
496 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
498 static void remove_dithering(AC3DecodeContext *s) {
501 for (ch = 1; ch <= s->fbw_channels; ch++) {
502 if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
503 for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) {
504 if (!s->bap[CPL_CH][i])
505 s->fixed_coeffs[ch][i] = 0;
511 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
514 if (!s->channel_uses_aht[ch]) {
515 ac3_decode_transform_coeffs_ch(s, ch, m);
517 /* if AHT is used, mantissas for all blocks are encoded in the first
518 block of the frame. */
520 if (!blk && CONFIG_EAC3_DECODER)
521 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
522 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
523 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
529 * Decode the transform coefficients.
531 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
537 m.b1 = m.b2 = m.b4 = 0;
539 for (ch = 1; ch <= s->channels; ch++) {
540 /* transform coefficients for full-bandwidth channel */
541 decode_transform_coeffs_ch(s, blk, ch, &m);
542 /* tranform coefficients for coupling channel come right after the
543 coefficients for the first coupled channel*/
544 if (s->channel_in_cpl[ch]) {
546 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
547 calc_transform_coeffs_cpl(s);
550 end = s->end_freq[CPL_CH];
552 end = s->end_freq[ch];
555 s->fixed_coeffs[ch][end] = 0;
559 /* zero the dithered coefficients for appropriate channels */
564 * Stereo rematrixing.
565 * reference: Section 7.5.4 Rematrixing : Decoding Technique
567 static void do_rematrixing(AC3DecodeContext *s)
572 end = FFMIN(s->end_freq[1], s->end_freq[2]);
574 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
575 if (s->rematrixing_flags[bnd]) {
576 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd + 1]);
577 for (i = ff_ac3_rematrix_band_tab[bnd]; i < bndend; i++) {
578 int tmp0 = s->fixed_coeffs[1][i];
579 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
580 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
587 * Inverse MDCT Transform.
588 * Convert frequency domain coefficients to time-domain audio samples.
589 * reference: Section 7.9.4 Transformation Equations
591 static inline void do_imdct(AC3DecodeContext *s, int channels)
595 for (ch = 1; ch <= channels; ch++) {
596 if (s->block_switch[ch]) {
598 float *x = s->tmp_output + 128;
599 for (i = 0; i < 128; i++)
600 x[i] = s->transform_coeffs[ch][2 * i];
601 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
602 s->dsp.vector_fmul_window(s->output[ch - 1], s->delay[ch - 1],
603 s->tmp_output, s->window, 128);
604 for (i = 0; i < 128; i++)
605 x[i] = s->transform_coeffs[ch][2 * i + 1];
606 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x);
608 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
609 s->dsp.vector_fmul_window(s->output[ch - 1], s->delay[ch - 1],
610 s->tmp_output, s->window, 128);
611 memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(float));
617 * Upmix delay samples from stereo to original channel layout.
619 static void ac3_upmix_delay(AC3DecodeContext *s)
621 int channel_data_size = sizeof(s->delay[0]);
622 switch (s->channel_mode) {
623 case AC3_CHMODE_DUALMONO:
624 case AC3_CHMODE_STEREO:
625 /* upmix mono to stereo */
626 memcpy(s->delay[1], s->delay[0], channel_data_size);
628 case AC3_CHMODE_2F2R:
629 memset(s->delay[3], 0, channel_data_size);
630 case AC3_CHMODE_2F1R:
631 memset(s->delay[2], 0, channel_data_size);
633 case AC3_CHMODE_3F2R:
634 memset(s->delay[4], 0, channel_data_size);
635 case AC3_CHMODE_3F1R:
636 memset(s->delay[3], 0, channel_data_size);
638 memcpy(s->delay[2], s->delay[1], channel_data_size);
639 memset(s->delay[1], 0, channel_data_size);
645 * Decode band structure for coupling, spectral extension, or enhanced coupling.
646 * The band structure defines how many subbands are in each band. For each
647 * subband in the range, 1 means it is combined with the previous band, and 0
648 * means that it starts a new band.
650 * @param[in] gbc bit reader context
651 * @param[in] blk block number
652 * @param[in] eac3 flag to indicate E-AC-3
653 * @param[in] ecpl flag to indicate enhanced coupling
654 * @param[in] start_subband subband number for start of range
655 * @param[in] end_subband subband number for end of range
656 * @param[in] default_band_struct default band structure table
657 * @param[out] num_bands number of bands (optionally NULL)
658 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
660 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
661 int ecpl, int start_subband, int end_subband,
662 const uint8_t *default_band_struct,
663 int *num_bands, uint8_t *band_sizes)
665 int subbnd, bnd, n_subbands, n_bands=0;
667 uint8_t coded_band_struct[22];
668 const uint8_t *band_struct;
670 n_subbands = end_subband - start_subband;
672 /* decode band structure from bitstream or use default */
673 if (!eac3 || get_bits1(gbc)) {
674 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
675 coded_band_struct[subbnd] = get_bits1(gbc);
677 band_struct = coded_band_struct;
679 band_struct = &default_band_struct[start_subband+1];
681 /* no change in band structure */
685 /* calculate number of bands and band sizes based on band structure.
686 note that the first 4 subbands in enhanced coupling span only 6 bins
688 if (num_bands || band_sizes ) {
689 n_bands = n_subbands;
690 bnd_sz[0] = ecpl ? 6 : 12;
691 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
692 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
693 if (band_struct[subbnd - 1]) {
695 bnd_sz[bnd] += subbnd_size;
697 bnd_sz[++bnd] = subbnd_size;
702 /* set optional output params */
704 *num_bands = n_bands;
706 memcpy(band_sizes, bnd_sz, n_bands);
710 * Decode a single audio block from the AC-3 bitstream.
712 static int decode_audio_block(AC3DecodeContext *s, int blk)
714 int fbw_channels = s->fbw_channels;
715 int channel_mode = s->channel_mode;
717 int different_transforms;
720 GetBitContext *gbc = &s->gbc;
721 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
723 /* block switch flags */
724 different_transforms = 0;
725 if (s->block_switch_syntax) {
726 for (ch = 1; ch <= fbw_channels; ch++) {
727 s->block_switch[ch] = get_bits1(gbc);
728 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
729 different_transforms = 1;
733 /* dithering flags */
734 if (s->dither_flag_syntax) {
735 for (ch = 1; ch <= fbw_channels; ch++) {
736 s->dither_flag[ch] = get_bits1(gbc);
741 i = !s->channel_mode;
743 if (get_bits1(gbc)) {
744 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)] - 1.0) *
746 } else if (blk == 0) {
747 s->dynamic_range[i] = 1.0f;
751 /* spectral extension strategy */
752 if (s->eac3 && (!blk || get_bits1(gbc))) {
753 s->spx_in_use = get_bits1(gbc);
755 int dst_start_freq, dst_end_freq, src_start_freq,
756 start_subband, end_subband;
758 /* determine which channels use spx */
759 if (s->channel_mode == AC3_CHMODE_MONO) {
760 s->channel_uses_spx[1] = 1;
762 for (ch = 1; ch <= fbw_channels; ch++)
763 s->channel_uses_spx[ch] = get_bits1(gbc);
766 /* get the frequency bins of the spx copy region and the spx start
768 dst_start_freq = get_bits(gbc, 2);
769 start_subband = get_bits(gbc, 3) + 2;
770 if (start_subband > 7)
771 start_subband += start_subband - 7;
772 end_subband = get_bits(gbc, 3) + 5;
774 end_subband += end_subband - 7;
775 dst_start_freq = dst_start_freq * 12 + 25;
776 src_start_freq = start_subband * 12 + 25;
777 dst_end_freq = end_subband * 12 + 25;
779 /* check validity of spx ranges */
780 if (start_subband >= end_subband) {
781 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
782 "range (%d >= %d)\n", start_subband, end_subband);
785 if (dst_start_freq >= src_start_freq) {
786 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
787 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
791 s->spx_dst_start_freq = dst_start_freq;
792 s->spx_src_start_freq = src_start_freq;
793 s->spx_dst_end_freq = dst_end_freq;
795 decode_band_structure(gbc, blk, s->eac3, 0,
796 start_subband, end_subband,
797 ff_eac3_default_spx_band_struct,
801 for (ch = 1; ch <= fbw_channels; ch++) {
802 s->channel_uses_spx[ch] = 0;
803 s->first_spx_coords[ch] = 1;
808 /* spectral extension coordinates */
810 for (ch = 1; ch <= fbw_channels; ch++) {
811 if (s->channel_uses_spx[ch]) {
812 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
814 int bin, master_spx_coord;
816 s->first_spx_coords[ch] = 0;
817 spx_blend = get_bits(gbc, 5) * (1.0f/32);
818 master_spx_coord = get_bits(gbc, 2) * 3;
820 bin = s->spx_src_start_freq;
821 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
823 int spx_coord_exp, spx_coord_mant;
824 float nratio, sblend, nblend, spx_coord;
826 /* calculate blending factors */
827 bandsize = s->spx_band_sizes[bnd];
828 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
829 nratio = av_clipf(nratio, 0.0f, 1.0f);
830 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
831 // to give unity variance
832 sblend = sqrtf(1.0f - nratio);
835 /* decode spx coordinates */
836 spx_coord_exp = get_bits(gbc, 4);
837 spx_coord_mant = get_bits(gbc, 2);
838 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
839 else spx_coord_mant += 4;
840 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
841 spx_coord = spx_coord_mant * (1.0f / (1 << 23));
843 /* multiply noise and signal blending factors by spx coordinate */
844 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
845 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
849 s->first_spx_coords[ch] = 1;
854 /* coupling strategy */
855 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
856 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
858 s->cpl_in_use[blk] = get_bits1(gbc);
859 if (s->cpl_in_use[blk]) {
860 /* coupling in use */
861 int cpl_start_subband, cpl_end_subband;
863 if (channel_mode < AC3_CHMODE_STEREO) {
864 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
868 /* check for enhanced coupling */
869 if (s->eac3 && get_bits1(gbc)) {
870 /* TODO: parse enhanced coupling strategy info */
871 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
872 return AVERROR_PATCHWELCOME;
875 /* determine which channels are coupled */
876 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
877 s->channel_in_cpl[1] = 1;
878 s->channel_in_cpl[2] = 1;
880 for (ch = 1; ch <= fbw_channels; ch++)
881 s->channel_in_cpl[ch] = get_bits1(gbc);
884 /* phase flags in use */
885 if (channel_mode == AC3_CHMODE_STEREO)
886 s->phase_flags_in_use = get_bits1(gbc);
888 /* coupling frequency range */
889 cpl_start_subband = get_bits(gbc, 4);
890 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
891 get_bits(gbc, 4) + 3;
892 if (cpl_start_subband >= cpl_end_subband) {
893 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
894 cpl_start_subband, cpl_end_subband);
897 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
898 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
900 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
902 ff_eac3_default_cpl_band_struct,
903 &s->num_cpl_bands, s->cpl_band_sizes);
905 /* coupling not in use */
906 for (ch = 1; ch <= fbw_channels; ch++) {
907 s->channel_in_cpl[ch] = 0;
908 s->first_cpl_coords[ch] = 1;
910 s->first_cpl_leak = s->eac3;
911 s->phase_flags_in_use = 0;
913 } else if (!s->eac3) {
915 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
916 "be present in block 0\n");
919 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
922 cpl_in_use = s->cpl_in_use[blk];
924 /* coupling coordinates */
926 int cpl_coords_exist = 0;
928 for (ch = 1; ch <= fbw_channels; ch++) {
929 if (s->channel_in_cpl[ch]) {
930 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
931 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
932 s->first_cpl_coords[ch] = 0;
933 cpl_coords_exist = 1;
934 master_cpl_coord = 3 * get_bits(gbc, 2);
935 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
936 cpl_coord_exp = get_bits(gbc, 4);
937 cpl_coord_mant = get_bits(gbc, 4);
938 if (cpl_coord_exp == 15)
939 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
941 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
942 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
945 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
946 "be present in block 0\n");
950 /* channel not in coupling */
951 s->first_cpl_coords[ch] = 1;
955 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
956 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
957 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
962 /* stereo rematrixing strategy and band structure */
963 if (channel_mode == AC3_CHMODE_STEREO) {
964 if ((s->eac3 && !blk) || get_bits1(gbc)) {
965 s->num_rematrixing_bands = 4;
966 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
967 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
968 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
969 s->num_rematrixing_bands--;
971 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
972 s->rematrixing_flags[bnd] = get_bits1(gbc);
974 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
975 "new rematrixing strategy not present in block 0\n");
976 s->num_rematrixing_bands = 0;
980 /* exponent strategies for each channel */
981 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
983 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
984 if (s->exp_strategy[blk][ch] != EXP_REUSE)
985 bit_alloc_stages[ch] = 3;
988 /* channel bandwidth */
989 for (ch = 1; ch <= fbw_channels; ch++) {
990 s->start_freq[ch] = 0;
991 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
993 int prev = s->end_freq[ch];
994 if (s->channel_in_cpl[ch])
995 s->end_freq[ch] = s->start_freq[CPL_CH];
996 else if (s->channel_uses_spx[ch])
997 s->end_freq[ch] = s->spx_src_start_freq;
999 int bandwidth_code = get_bits(gbc, 6);
1000 if (bandwidth_code > 60) {
1001 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1004 s->end_freq[ch] = bandwidth_code * 3 + 73;
1006 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1007 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1008 if (blk > 0 && s->end_freq[ch] != prev)
1009 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1012 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1013 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1014 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1017 /* decode exponents for each channel */
1018 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1019 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1020 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1021 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1022 s->num_exp_groups[ch], s->dexps[ch][0],
1023 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1024 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1027 if (ch != CPL_CH && ch != s->lfe_ch)
1028 skip_bits(gbc, 2); /* skip gainrng */
1032 /* bit allocation information */
1033 if (s->bit_allocation_syntax) {
1034 if (get_bits1(gbc)) {
1035 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1036 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1037 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1038 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1039 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1040 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1041 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1043 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1044 "be present in block 0\n");
1049 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1050 if (!s->eac3 || !blk) {
1051 if (s->snr_offset_strategy && get_bits1(gbc)) {
1054 csnr = (get_bits(gbc, 6) - 15) << 4;
1055 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1057 if (ch == i || s->snr_offset_strategy == 2)
1058 snr = (csnr + get_bits(gbc, 4)) << 2;
1059 /* run at least last bit allocation stage if snr offset changes */
1060 if (blk && s->snr_offset[ch] != snr) {
1061 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1063 s->snr_offset[ch] = snr;
1065 /* fast gain (normal AC-3 only) */
1067 int prev = s->fast_gain[ch];
1068 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1069 /* run last 2 bit allocation stages if fast gain changes */
1070 if (blk && prev != s->fast_gain[ch])
1071 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1074 } else if (!s->eac3 && !blk) {
1075 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1080 /* fast gain (E-AC-3 only) */
1081 if (s->fast_gain_syntax && get_bits1(gbc)) {
1082 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1083 int prev = s->fast_gain[ch];
1084 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1085 /* run last 2 bit allocation stages if fast gain changes */
1086 if (blk && prev != s->fast_gain[ch])
1087 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1089 } else if (s->eac3 && !blk) {
1090 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1091 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1094 /* E-AC-3 to AC-3 converter SNR offset */
1095 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1096 skip_bits(gbc, 10); // skip converter snr offset
1099 /* coupling leak information */
1101 if (s->first_cpl_leak || get_bits1(gbc)) {
1102 int fl = get_bits(gbc, 3);
1103 int sl = get_bits(gbc, 3);
1104 /* run last 2 bit allocation stages for coupling channel if
1105 coupling leak changes */
1106 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1107 sl != s->bit_alloc_params.cpl_slow_leak)) {
1108 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1110 s->bit_alloc_params.cpl_fast_leak = fl;
1111 s->bit_alloc_params.cpl_slow_leak = sl;
1112 } else if (!s->eac3 && !blk) {
1113 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1114 "be present in block 0\n");
1117 s->first_cpl_leak = 0;
1120 /* delta bit allocation information */
1121 if (s->dba_syntax && get_bits1(gbc)) {
1122 /* delta bit allocation exists (strategy) */
1123 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1124 s->dba_mode[ch] = get_bits(gbc, 2);
1125 if (s->dba_mode[ch] == DBA_RESERVED) {
1126 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1129 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1131 /* channel delta offset, len and bit allocation */
1132 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1133 if (s->dba_mode[ch] == DBA_NEW) {
1134 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1135 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1136 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1137 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1138 s->dba_values[ch][seg] = get_bits(gbc, 3);
1140 /* run last 2 bit allocation stages if new dba values */
1141 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1144 } else if (blk == 0) {
1145 for (ch = 0; ch <= s->channels; ch++) {
1146 s->dba_mode[ch] = DBA_NONE;
1150 /* Bit allocation */
1151 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1152 if (bit_alloc_stages[ch] > 2) {
1153 /* Exponent mapping into PSD and PSD integration */
1154 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1155 s->start_freq[ch], s->end_freq[ch],
1156 s->psd[ch], s->band_psd[ch]);
1158 if (bit_alloc_stages[ch] > 1) {
1159 /* Compute excitation function, Compute masking curve, and
1160 Apply delta bit allocation */
1161 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1162 s->start_freq[ch], s->end_freq[ch],
1163 s->fast_gain[ch], (ch == s->lfe_ch),
1164 s->dba_mode[ch], s->dba_nsegs[ch],
1165 s->dba_offsets[ch], s->dba_lengths[ch],
1166 s->dba_values[ch], s->mask[ch])) {
1167 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1171 if (bit_alloc_stages[ch] > 0) {
1172 /* Compute bit allocation */
1173 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1174 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1175 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1176 s->start_freq[ch], s->end_freq[ch],
1178 s->bit_alloc_params.floor,
1179 bap_tab, s->bap[ch]);
1183 /* unused dummy data */
1184 if (s->skip_syntax && get_bits1(gbc)) {
1185 int skipl = get_bits(gbc, 9);
1190 /* unpack the transform coefficients
1191 this also uncouples channels if coupling is in use. */
1192 decode_transform_coeffs(s, blk);
1194 /* TODO: generate enhanced coupling coordinates and uncouple */
1196 /* recover coefficients if rematrixing is in use */
1197 if (s->channel_mode == AC3_CHMODE_STEREO)
1200 /* apply scaling to coefficients (headroom, dynrng) */
1201 for (ch = 1; ch <= s->channels; ch++) {
1202 float gain = 1.0 / 4194304.0f;
1203 if (s->channel_mode == AC3_CHMODE_DUALMONO) {
1204 gain *= s->dynamic_range[2 - ch];
1206 gain *= s->dynamic_range[0];
1208 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1209 s->fixed_coeffs[ch], gain, 256);
1212 /* apply spectral extension to high frequency bins */
1213 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1214 ff_eac3_apply_spectral_extension(s);
1217 /* downmix and MDCT. order depends on whether block switching is used for
1218 any channel in this block. this is because coefficients for the long
1219 and short transforms cannot be mixed. */
1220 downmix_output = s->channels != s->out_channels &&
1221 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1222 s->fbw_channels == s->out_channels);
1223 if (different_transforms) {
1224 /* the delay samples have already been downmixed, so we upmix the delay
1225 samples in order to reconstruct all channels before downmixing. */
1231 do_imdct(s, s->channels);
1233 if (downmix_output) {
1234 s->ac3dsp.downmix(s->output, s->downmix_coeffs,
1235 s->out_channels, s->fbw_channels, 256);
1238 if (downmix_output) {
1239 s->ac3dsp.downmix(s->transform_coeffs + 1, s->downmix_coeffs,
1240 s->out_channels, s->fbw_channels, 256);
1243 if (downmix_output && !s->downmixed) {
1245 s->ac3dsp.downmix(s->delay, s->downmix_coeffs, s->out_channels,
1246 s->fbw_channels, 128);
1249 do_imdct(s, s->out_channels);
1256 * Decode a single AC-3 frame.
1258 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1259 int *got_frame_ptr, AVPacket *avpkt)
1261 const uint8_t *buf = avpkt->data;
1262 int buf_size = avpkt->size;
1263 AC3DecodeContext *s = avctx->priv_data;
1264 int blk, ch, err, ret;
1265 const uint8_t *channel_map;
1266 const float *output[AC3_MAX_CHANNELS];
1268 /* copy input buffer to decoder context to avoid reading past the end
1269 of the buffer, which can be caused by a damaged input stream. */
1270 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1271 // seems to be byte-swapped AC-3
1272 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1273 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1275 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1276 buf = s->input_buffer;
1277 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1278 init_get_bits(&s->gbc, buf, buf_size * 8);
1280 /* parse the syncinfo */
1281 err = parse_frame_header(s);
1285 case AAC_AC3_PARSE_ERROR_SYNC:
1286 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1288 case AAC_AC3_PARSE_ERROR_BSID:
1289 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1291 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1292 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1294 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1295 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1297 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1298 /* skip frame if CRC is ok. otherwise use error concealment. */
1299 /* TODO: add support for substreams and dependent frames */
1300 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1301 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : "
1302 "skipping frame\n");
1304 return s->frame_size;
1306 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1310 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1314 /* check that reported frame size fits in input buffer */
1315 if (s->frame_size > buf_size) {
1316 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1317 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1318 } else if (avctx->err_recognition & (AV_EF_CRCCHECK|AV_EF_CAREFUL)) {
1319 /* check for crc mismatch */
1320 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1321 s->frame_size - 2)) {
1322 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1323 err = AAC_AC3_PARSE_ERROR_CRC;
1328 /* if frame is ok, set audio parameters */
1330 avctx->sample_rate = s->sample_rate;
1331 avctx->bit_rate = s->bit_rate;
1333 /* channel config */
1334 s->out_channels = s->channels;
1335 s->output_mode = s->channel_mode;
1337 s->output_mode |= AC3_OUTPUT_LFEON;
1338 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1339 avctx->request_channels < s->channels) {
1340 s->out_channels = avctx->request_channels;
1341 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1342 s->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode];
1344 avctx->channels = s->out_channels;
1345 avctx->channel_layout = s->channel_layout;
1347 s->loro_center_mix_level = gain_levels[s-> center_mix_level];
1348 s->loro_surround_mix_level = gain_levels[s->surround_mix_level];
1349 s->ltrt_center_mix_level = LEVEL_MINUS_3DB;
1350 s->ltrt_surround_mix_level = LEVEL_MINUS_3DB;
1351 /* set downmixing coefficients if needed */
1352 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1353 s->fbw_channels == s->out_channels)) {
1354 set_downmix_coeffs(s);
1356 } else if (!s->out_channels) {
1357 s->out_channels = avctx->channels;
1358 if (s->out_channels < s->channels)
1359 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1361 if (avctx->channels != s->out_channels) {
1362 av_log(avctx, AV_LOG_ERROR, "channel number mismatching on damaged frame\n");
1363 return AVERROR_INVALIDDATA;
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->out_channels; ch++)
1381 output[ch] = s->output[channel_map[ch]];
1382 for (blk = 0; blk < s->num_blocks; blk++) {
1383 if (!err && decode_audio_block(s, blk)) {
1384 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1387 for (ch = 0; ch < s->out_channels; ch++)
1388 memcpy(s->frame.data[ch] + blk * 1024, output[ch], 1024);
1391 s->frame.decode_error_flags = err ? FF_DECODE_ERROR_INVALID_BITSTREAM : 0;
1394 *(AVFrame *)data = s->frame;
1396 return FFMIN(buf_size, s->frame_size);
1400 * Uninitialize the AC-3 decoder.
1402 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1404 AC3DecodeContext *s = avctx->priv_data;
1405 ff_mdct_end(&s->imdct_512);
1406 ff_mdct_end(&s->imdct_256);
1411 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1412 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)
1413 static const AVOption options[] = {
1414 { "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), AV_OPT_TYPE_FLOAT, {.dbl = 1.0}, 0.0, 1.0, PAR },
1416 {"dmix_mode", "Preferred Stereo Downmix Mode", OFFSET(preferred_stereo_downmix), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, 2, 0, "dmix_mode"},
1417 {"ltrt_cmixlev", "Lt/Rt Center Mix Level", OFFSET(ltrt_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1418 {"ltrt_surmixlev", "Lt/Rt Surround Mix Level", OFFSET(ltrt_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1419 {"loro_cmixlev", "Lo/Ro Center Mix Level", OFFSET(loro_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1420 {"loro_surmixlev", "Lo/Ro Surround Mix Level", OFFSET(loro_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1425 static const AVClass ac3_decoder_class = {
1426 .class_name = "AC3 decoder",
1427 .item_name = av_default_item_name,
1429 .version = LIBAVUTIL_VERSION_INT,
1432 AVCodec ff_ac3_decoder = {
1434 .type = AVMEDIA_TYPE_AUDIO,
1435 .id = AV_CODEC_ID_AC3,
1436 .priv_data_size = sizeof (AC3DecodeContext),
1437 .init = ac3_decode_init,
1438 .close = ac3_decode_end,
1439 .decode = ac3_decode_frame,
1440 .capabilities = CODEC_CAP_DR1,
1441 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1442 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
1443 AV_SAMPLE_FMT_NONE },
1444 .priv_class = &ac3_decoder_class,
1447 #if CONFIG_EAC3_DECODER
1448 static const AVClass eac3_decoder_class = {
1449 .class_name = "E-AC3 decoder",
1450 .item_name = av_default_item_name,
1452 .version = LIBAVUTIL_VERSION_INT,
1455 AVCodec ff_eac3_decoder = {
1457 .type = AVMEDIA_TYPE_AUDIO,
1458 .id = AV_CODEC_ID_EAC3,
1459 .priv_data_size = sizeof (AC3DecodeContext),
1460 .init = ac3_decode_init,
1461 .close = ac3_decode_end,
1462 .decode = ac3_decode_frame,
1463 .capabilities = CODEC_CAP_DR1,
1464 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1465 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
1466 AV_SAMPLE_FMT_NONE },
1467 .priv_class = &eac3_decoder_class,