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 /* set scale value for float to int16 conversion */
176 if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
178 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
180 s->mul_bias = 32767.0f;
181 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
184 /* allow downmixing to stereo or mono */
185 if (avctx->channels > 0 && avctx->request_channels > 0 &&
186 avctx->request_channels < avctx->channels &&
187 avctx->request_channels <= 2) {
188 avctx->channels = avctx->request_channels;
192 avcodec_get_frame_defaults(&s->frame);
193 avctx->coded_frame = &s->frame;
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->output[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->output[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 * Downmix the output to mono or stereo.
626 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2],
627 int out_ch, int in_ch, int len)
632 for (i = 0; i < len; i++) {
634 for (j = 0; j < in_ch; j++) {
635 v0 += samples[j][i] * matrix[j][0];
636 v1 += samples[j][i] * matrix[j][1];
641 } else if (out_ch == 1) {
642 for (i = 0; i < len; i++) {
644 for (j = 0; j < in_ch; j++)
645 v0 += samples[j][i] * matrix[j][0];
652 * Upmix delay samples from stereo to original channel layout.
654 static void ac3_upmix_delay(AC3DecodeContext *s)
656 int channel_data_size = sizeof(s->delay[0]);
657 switch (s->channel_mode) {
658 case AC3_CHMODE_DUALMONO:
659 case AC3_CHMODE_STEREO:
660 /* upmix mono to stereo */
661 memcpy(s->delay[1], s->delay[0], channel_data_size);
663 case AC3_CHMODE_2F2R:
664 memset(s->delay[3], 0, channel_data_size);
665 case AC3_CHMODE_2F1R:
666 memset(s->delay[2], 0, channel_data_size);
668 case AC3_CHMODE_3F2R:
669 memset(s->delay[4], 0, channel_data_size);
670 case AC3_CHMODE_3F1R:
671 memset(s->delay[3], 0, channel_data_size);
673 memcpy(s->delay[2], s->delay[1], channel_data_size);
674 memset(s->delay[1], 0, channel_data_size);
680 * Decode band structure for coupling, spectral extension, or enhanced coupling.
681 * The band structure defines how many subbands are in each band. For each
682 * subband in the range, 1 means it is combined with the previous band, and 0
683 * means that it starts a new band.
685 * @param[in] gbc bit reader context
686 * @param[in] blk block number
687 * @param[in] eac3 flag to indicate E-AC-3
688 * @param[in] ecpl flag to indicate enhanced coupling
689 * @param[in] start_subband subband number for start of range
690 * @param[in] end_subband subband number for end of range
691 * @param[in] default_band_struct default band structure table
692 * @param[out] num_bands number of bands (optionally NULL)
693 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
695 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
696 int ecpl, int start_subband, int end_subband,
697 const uint8_t *default_band_struct,
698 int *num_bands, uint8_t *band_sizes)
700 int subbnd, bnd, n_subbands, n_bands=0;
702 uint8_t coded_band_struct[22];
703 const uint8_t *band_struct;
705 n_subbands = end_subband - start_subband;
707 /* decode band structure from bitstream or use default */
708 if (!eac3 || get_bits1(gbc)) {
709 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
710 coded_band_struct[subbnd] = get_bits1(gbc);
712 band_struct = coded_band_struct;
714 band_struct = &default_band_struct[start_subband+1];
716 /* no change in band structure */
720 /* calculate number of bands and band sizes based on band structure.
721 note that the first 4 subbands in enhanced coupling span only 6 bins
723 if (num_bands || band_sizes ) {
724 n_bands = n_subbands;
725 bnd_sz[0] = ecpl ? 6 : 12;
726 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
727 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
728 if (band_struct[subbnd - 1]) {
730 bnd_sz[bnd] += subbnd_size;
732 bnd_sz[++bnd] = subbnd_size;
737 /* set optional output params */
739 *num_bands = n_bands;
741 memcpy(band_sizes, bnd_sz, n_bands);
745 * Decode a single audio block from the AC-3 bitstream.
747 static int decode_audio_block(AC3DecodeContext *s, int blk)
749 int fbw_channels = s->fbw_channels;
750 int channel_mode = s->channel_mode;
752 int different_transforms;
755 GetBitContext *gbc = &s->gbc;
756 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 };
758 /* block switch flags */
759 different_transforms = 0;
760 if (s->block_switch_syntax) {
761 for (ch = 1; ch <= fbw_channels; ch++) {
762 s->block_switch[ch] = get_bits1(gbc);
763 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
764 different_transforms = 1;
768 /* dithering flags */
769 if (s->dither_flag_syntax) {
770 for (ch = 1; ch <= fbw_channels; ch++) {
771 s->dither_flag[ch] = get_bits1(gbc);
776 i = !s->channel_mode;
778 if (get_bits1(gbc)) {
779 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)] - 1.0) *
781 } else if (blk == 0) {
782 s->dynamic_range[i] = 1.0f;
786 /* spectral extension strategy */
787 if (s->eac3 && (!blk || get_bits1(gbc))) {
788 s->spx_in_use = get_bits1(gbc);
790 int dst_start_freq, dst_end_freq, src_start_freq,
791 start_subband, end_subband;
793 /* determine which channels use spx */
794 if (s->channel_mode == AC3_CHMODE_MONO) {
795 s->channel_uses_spx[1] = 1;
797 for (ch = 1; ch <= fbw_channels; ch++)
798 s->channel_uses_spx[ch] = get_bits1(gbc);
801 /* get the frequency bins of the spx copy region and the spx start
803 dst_start_freq = get_bits(gbc, 2);
804 start_subband = get_bits(gbc, 3) + 2;
805 if (start_subband > 7)
806 start_subband += start_subband - 7;
807 end_subband = get_bits(gbc, 3) + 5;
809 end_subband += end_subband - 7;
810 dst_start_freq = dst_start_freq * 12 + 25;
811 src_start_freq = start_subband * 12 + 25;
812 dst_end_freq = end_subband * 12 + 25;
814 /* check validity of spx ranges */
815 if (start_subband >= end_subband) {
816 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
817 "range (%d >= %d)\n", start_subband, end_subband);
820 if (dst_start_freq >= src_start_freq) {
821 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
822 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
826 s->spx_dst_start_freq = dst_start_freq;
827 s->spx_src_start_freq = src_start_freq;
828 s->spx_dst_end_freq = dst_end_freq;
830 decode_band_structure(gbc, blk, s->eac3, 0,
831 start_subband, end_subband,
832 ff_eac3_default_spx_band_struct,
836 for (ch = 1; ch <= fbw_channels; ch++) {
837 s->channel_uses_spx[ch] = 0;
838 s->first_spx_coords[ch] = 1;
843 /* spectral extension coordinates */
845 for (ch = 1; ch <= fbw_channels; ch++) {
846 if (s->channel_uses_spx[ch]) {
847 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
849 int bin, master_spx_coord;
851 s->first_spx_coords[ch] = 0;
852 spx_blend = get_bits(gbc, 5) * (1.0f/32);
853 master_spx_coord = get_bits(gbc, 2) * 3;
855 bin = s->spx_src_start_freq;
856 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
858 int spx_coord_exp, spx_coord_mant;
859 float nratio, sblend, nblend, spx_coord;
861 /* calculate blending factors */
862 bandsize = s->spx_band_sizes[bnd];
863 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
864 nratio = av_clipf(nratio, 0.0f, 1.0f);
865 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
866 // to give unity variance
867 sblend = sqrtf(1.0f - nratio);
870 /* decode spx coordinates */
871 spx_coord_exp = get_bits(gbc, 4);
872 spx_coord_mant = get_bits(gbc, 2);
873 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
874 else spx_coord_mant += 4;
875 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
876 spx_coord = spx_coord_mant * (1.0f / (1 << 23));
878 /* multiply noise and signal blending factors by spx coordinate */
879 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
880 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
884 s->first_spx_coords[ch] = 1;
889 /* coupling strategy */
890 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
891 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
893 s->cpl_in_use[blk] = get_bits1(gbc);
894 if (s->cpl_in_use[blk]) {
895 /* coupling in use */
896 int cpl_start_subband, cpl_end_subband;
898 if (channel_mode < AC3_CHMODE_STEREO) {
899 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
903 /* check for enhanced coupling */
904 if (s->eac3 && get_bits1(gbc)) {
905 /* TODO: parse enhanced coupling strategy info */
906 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
910 /* determine which channels are coupled */
911 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
912 s->channel_in_cpl[1] = 1;
913 s->channel_in_cpl[2] = 1;
915 for (ch = 1; ch <= fbw_channels; ch++)
916 s->channel_in_cpl[ch] = get_bits1(gbc);
919 /* phase flags in use */
920 if (channel_mode == AC3_CHMODE_STEREO)
921 s->phase_flags_in_use = get_bits1(gbc);
923 /* coupling frequency range */
924 cpl_start_subband = get_bits(gbc, 4);
925 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
926 get_bits(gbc, 4) + 3;
927 if (cpl_start_subband >= cpl_end_subband) {
928 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
929 cpl_start_subband, cpl_end_subband);
932 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
933 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
935 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
937 ff_eac3_default_cpl_band_struct,
938 &s->num_cpl_bands, s->cpl_band_sizes);
940 /* coupling not in use */
941 for (ch = 1; ch <= fbw_channels; ch++) {
942 s->channel_in_cpl[ch] = 0;
943 s->first_cpl_coords[ch] = 1;
945 s->first_cpl_leak = s->eac3;
946 s->phase_flags_in_use = 0;
948 } else if (!s->eac3) {
950 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
951 "be present in block 0\n");
954 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
957 cpl_in_use = s->cpl_in_use[blk];
959 /* coupling coordinates */
961 int cpl_coords_exist = 0;
963 for (ch = 1; ch <= fbw_channels; ch++) {
964 if (s->channel_in_cpl[ch]) {
965 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
966 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
967 s->first_cpl_coords[ch] = 0;
968 cpl_coords_exist = 1;
969 master_cpl_coord = 3 * get_bits(gbc, 2);
970 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
971 cpl_coord_exp = get_bits(gbc, 4);
972 cpl_coord_mant = get_bits(gbc, 4);
973 if (cpl_coord_exp == 15)
974 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
976 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
977 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
980 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
981 "be present in block 0\n");
985 /* channel not in coupling */
986 s->first_cpl_coords[ch] = 1;
990 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
991 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
992 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
997 /* stereo rematrixing strategy and band structure */
998 if (channel_mode == AC3_CHMODE_STEREO) {
999 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1000 s->num_rematrixing_bands = 4;
1001 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1002 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1003 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1004 s->num_rematrixing_bands--;
1006 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
1007 s->rematrixing_flags[bnd] = get_bits1(gbc);
1009 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
1010 "new rematrixing strategy not present in block 0\n");
1011 s->num_rematrixing_bands = 0;
1015 /* exponent strategies for each channel */
1016 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1018 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1019 if (s->exp_strategy[blk][ch] != EXP_REUSE)
1020 bit_alloc_stages[ch] = 3;
1023 /* channel bandwidth */
1024 for (ch = 1; ch <= fbw_channels; ch++) {
1025 s->start_freq[ch] = 0;
1026 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1028 int prev = s->end_freq[ch];
1029 if (s->channel_in_cpl[ch])
1030 s->end_freq[ch] = s->start_freq[CPL_CH];
1031 else if (s->channel_uses_spx[ch])
1032 s->end_freq[ch] = s->spx_src_start_freq;
1034 int bandwidth_code = get_bits(gbc, 6);
1035 if (bandwidth_code > 60) {
1036 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1039 s->end_freq[ch] = bandwidth_code * 3 + 73;
1041 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1042 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1043 if (blk > 0 && s->end_freq[ch] != prev)
1044 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1047 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1048 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1049 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1052 /* decode exponents for each channel */
1053 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1054 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1055 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1056 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1057 s->num_exp_groups[ch], s->dexps[ch][0],
1058 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1059 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1062 if (ch != CPL_CH && ch != s->lfe_ch)
1063 skip_bits(gbc, 2); /* skip gainrng */
1067 /* bit allocation information */
1068 if (s->bit_allocation_syntax) {
1069 if (get_bits1(gbc)) {
1070 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1071 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1072 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1073 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1074 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1075 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1076 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1078 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1079 "be present in block 0\n");
1084 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1085 if (!s->eac3 || !blk) {
1086 if (s->snr_offset_strategy && get_bits1(gbc)) {
1089 csnr = (get_bits(gbc, 6) - 15) << 4;
1090 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1092 if (ch == i || s->snr_offset_strategy == 2)
1093 snr = (csnr + get_bits(gbc, 4)) << 2;
1094 /* run at least last bit allocation stage if snr offset changes */
1095 if (blk && s->snr_offset[ch] != snr) {
1096 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1098 s->snr_offset[ch] = snr;
1100 /* fast gain (normal AC-3 only) */
1102 int prev = s->fast_gain[ch];
1103 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1104 /* run last 2 bit allocation stages if fast gain changes */
1105 if (blk && prev != s->fast_gain[ch])
1106 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1109 } else if (!s->eac3 && !blk) {
1110 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1115 /* fast gain (E-AC-3 only) */
1116 if (s->fast_gain_syntax && get_bits1(gbc)) {
1117 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1118 int prev = s->fast_gain[ch];
1119 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1120 /* run last 2 bit allocation stages if fast gain changes */
1121 if (blk && prev != s->fast_gain[ch])
1122 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1124 } else if (s->eac3 && !blk) {
1125 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1126 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1129 /* E-AC-3 to AC-3 converter SNR offset */
1130 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1131 skip_bits(gbc, 10); // skip converter snr offset
1134 /* coupling leak information */
1136 if (s->first_cpl_leak || get_bits1(gbc)) {
1137 int fl = get_bits(gbc, 3);
1138 int sl = get_bits(gbc, 3);
1139 /* run last 2 bit allocation stages for coupling channel if
1140 coupling leak changes */
1141 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1142 sl != s->bit_alloc_params.cpl_slow_leak)) {
1143 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1145 s->bit_alloc_params.cpl_fast_leak = fl;
1146 s->bit_alloc_params.cpl_slow_leak = sl;
1147 } else if (!s->eac3 && !blk) {
1148 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1149 "be present in block 0\n");
1152 s->first_cpl_leak = 0;
1155 /* delta bit allocation information */
1156 if (s->dba_syntax && get_bits1(gbc)) {
1157 /* delta bit allocation exists (strategy) */
1158 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1159 s->dba_mode[ch] = get_bits(gbc, 2);
1160 if (s->dba_mode[ch] == DBA_RESERVED) {
1161 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1164 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1166 /* channel delta offset, len and bit allocation */
1167 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1168 if (s->dba_mode[ch] == DBA_NEW) {
1169 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1170 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1171 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1172 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1173 s->dba_values[ch][seg] = get_bits(gbc, 3);
1175 /* run last 2 bit allocation stages if new dba values */
1176 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1179 } else if (blk == 0) {
1180 for (ch = 0; ch <= s->channels; ch++) {
1181 s->dba_mode[ch] = DBA_NONE;
1185 /* Bit allocation */
1186 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1187 if (bit_alloc_stages[ch] > 2) {
1188 /* Exponent mapping into PSD and PSD integration */
1189 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1190 s->start_freq[ch], s->end_freq[ch],
1191 s->psd[ch], s->band_psd[ch]);
1193 if (bit_alloc_stages[ch] > 1) {
1194 /* Compute excitation function, Compute masking curve, and
1195 Apply delta bit allocation */
1196 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1197 s->start_freq[ch], s->end_freq[ch],
1198 s->fast_gain[ch], (ch == s->lfe_ch),
1199 s->dba_mode[ch], s->dba_nsegs[ch],
1200 s->dba_offsets[ch], s->dba_lengths[ch],
1201 s->dba_values[ch], s->mask[ch])) {
1202 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1206 if (bit_alloc_stages[ch] > 0) {
1207 /* Compute bit allocation */
1208 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1209 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1210 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1211 s->start_freq[ch], s->end_freq[ch],
1213 s->bit_alloc_params.floor,
1214 bap_tab, s->bap[ch]);
1218 /* unused dummy data */
1219 if (s->skip_syntax && get_bits1(gbc)) {
1220 int skipl = get_bits(gbc, 9);
1225 /* unpack the transform coefficients
1226 this also uncouples channels if coupling is in use. */
1227 decode_transform_coeffs(s, blk);
1229 /* TODO: generate enhanced coupling coordinates and uncouple */
1231 /* recover coefficients if rematrixing is in use */
1232 if (s->channel_mode == AC3_CHMODE_STEREO)
1235 /* apply scaling to coefficients (headroom, dynrng) */
1236 for (ch = 1; ch <= s->channels; ch++) {
1237 float gain = s->mul_bias / 4194304.0f;
1238 if (s->channel_mode == AC3_CHMODE_DUALMONO) {
1239 gain *= s->dynamic_range[2 - ch];
1241 gain *= s->dynamic_range[0];
1243 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1244 s->fixed_coeffs[ch], gain, 256);
1247 /* apply spectral extension to high frequency bins */
1248 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1249 ff_eac3_apply_spectral_extension(s);
1252 /* downmix and MDCT. order depends on whether block switching is used for
1253 any channel in this block. this is because coefficients for the long
1254 and short transforms cannot be mixed. */
1255 downmix_output = s->channels != s->out_channels &&
1256 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1257 s->fbw_channels == s->out_channels);
1258 if (different_transforms) {
1259 /* the delay samples have already been downmixed, so we upmix the delay
1260 samples in order to reconstruct all channels before downmixing. */
1266 do_imdct(s, s->channels);
1268 if (downmix_output) {
1269 s->dsp.ac3_downmix(s->output, s->downmix_coeffs,
1270 s->out_channels, s->fbw_channels, 256);
1273 if (downmix_output) {
1274 s->dsp.ac3_downmix(s->transform_coeffs + 1, s->downmix_coeffs,
1275 s->out_channels, s->fbw_channels, 256);
1278 if (downmix_output && !s->downmixed) {
1280 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels,
1281 s->fbw_channels, 128);
1284 do_imdct(s, s->out_channels);
1291 * Decode a single AC-3 frame.
1293 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1294 int *got_frame_ptr, AVPacket *avpkt)
1296 const uint8_t *buf = avpkt->data;
1297 int buf_size = avpkt->size;
1298 AC3DecodeContext *s = avctx->priv_data;
1299 float *out_samples_flt;
1300 int16_t *out_samples_s16;
1301 int blk, ch, err, ret;
1302 const uint8_t *channel_map;
1303 const float *output[AC3_MAX_CHANNELS];
1305 /* copy input buffer to decoder context to avoid reading past the end
1306 of the buffer, which can be caused by a damaged input stream. */
1307 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1308 // seems to be byte-swapped AC-3
1309 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1310 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1312 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1313 buf = s->input_buffer;
1314 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1315 init_get_bits(&s->gbc, buf, buf_size * 8);
1317 /* parse the syncinfo */
1318 err = parse_frame_header(s);
1322 case AAC_AC3_PARSE_ERROR_SYNC:
1323 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1325 case AAC_AC3_PARSE_ERROR_BSID:
1326 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1328 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1329 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1331 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1332 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1334 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1335 /* skip frame if CRC is ok. otherwise use error concealment. */
1336 /* TODO: add support for substreams and dependent frames */
1337 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1338 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : "
1339 "skipping frame\n");
1341 return s->frame_size;
1343 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1347 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1351 /* check that reported frame size fits in input buffer */
1352 if (s->frame_size > buf_size) {
1353 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1354 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1355 } else if (avctx->err_recognition & (AV_EF_CRCCHECK|AV_EF_CAREFUL)) {
1356 /* check for crc mismatch */
1357 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1358 s->frame_size - 2)) {
1359 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1360 err = AAC_AC3_PARSE_ERROR_CRC;
1365 /* if frame is ok, set audio parameters */
1367 avctx->sample_rate = s->sample_rate;
1368 avctx->bit_rate = s->bit_rate;
1370 /* channel config */
1371 s->out_channels = s->channels;
1372 s->output_mode = s->channel_mode;
1374 s->output_mode |= AC3_OUTPUT_LFEON;
1375 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1376 avctx->request_channels < s->channels) {
1377 s->out_channels = avctx->request_channels;
1378 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1379 s->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode];
1381 avctx->channels = s->out_channels;
1382 avctx->channel_layout = s->channel_layout;
1384 s->loro_center_mix_level = gain_levels[s-> center_mix_level];
1385 s->loro_surround_mix_level = gain_levels[s->surround_mix_level];
1386 s->ltrt_center_mix_level = LEVEL_MINUS_3DB;
1387 s->ltrt_surround_mix_level = LEVEL_MINUS_3DB;
1388 /* set downmixing coefficients if needed */
1389 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1390 s->fbw_channels == s->out_channels)) {
1391 set_downmix_coeffs(s);
1393 } else if (!s->out_channels) {
1394 s->out_channels = avctx->channels;
1395 if (s->out_channels < s->channels)
1396 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1398 if (avctx->channels != s->out_channels) {
1399 av_log(avctx, AV_LOG_ERROR, "channel number mismatching on damaged frame\n");
1400 return AVERROR_INVALIDDATA;
1402 /* set audio service type based on bitstream mode for AC-3 */
1403 avctx->audio_service_type = s->bitstream_mode;
1404 if (s->bitstream_mode == 0x7 && s->channels > 1)
1405 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1407 /* get output buffer */
1408 s->frame.nb_samples = s->num_blocks * 256;
1409 if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
1410 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
1413 out_samples_flt = (float *)s->frame.data[0];
1414 out_samples_s16 = (int16_t *)s->frame.data[0];
1416 /* decode the audio blocks */
1417 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1418 for (ch = 0; ch < s->out_channels; ch++)
1419 output[ch] = s->output[channel_map[ch]];
1420 for (blk = 0; blk < s->num_blocks; blk++) {
1421 if (!err && decode_audio_block(s, blk)) {
1422 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1425 if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT) {
1426 s->fmt_conv.float_interleave(out_samples_flt, output, 256,
1428 out_samples_flt += 256 * s->out_channels;
1430 s->fmt_conv.float_to_int16_interleave(out_samples_s16, output, 256,
1432 out_samples_s16 += 256 * s->out_channels;
1437 *(AVFrame *)data = s->frame;
1439 return FFMIN(buf_size, s->frame_size);
1443 * Uninitialize the AC-3 decoder.
1445 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1447 AC3DecodeContext *s = avctx->priv_data;
1448 ff_mdct_end(&s->imdct_512);
1449 ff_mdct_end(&s->imdct_256);
1454 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1455 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)
1456 static const AVOption options[] = {
1457 { "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), AV_OPT_TYPE_FLOAT, {1.0}, 0.0, 1.0, PAR },
1459 {"dmix_mode", "Preferred Stereo Downmix Mode", OFFSET(preferred_stereo_downmix), AV_OPT_TYPE_INT, {.dbl = -1 }, -1, 2, 0, "dmix_mode"},
1460 {"ltrt_cmixlev", "Lt/Rt Center Mix Level", OFFSET(ltrt_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1461 {"ltrt_surmixlev", "Lt/Rt Surround Mix Level", OFFSET(ltrt_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1462 {"loro_cmixlev", "Lo/Ro Center Mix Level", OFFSET(loro_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1463 {"loro_surmixlev", "Lo/Ro Surround Mix Level", OFFSET(loro_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1468 static const AVClass ac3_decoder_class = {
1469 .class_name = "AC3 decoder",
1470 .item_name = av_default_item_name,
1472 .version = LIBAVUTIL_VERSION_INT,
1475 AVCodec ff_ac3_decoder = {
1477 .type = AVMEDIA_TYPE_AUDIO,
1479 .priv_data_size = sizeof (AC3DecodeContext),
1480 .init = ac3_decode_init,
1481 .close = ac3_decode_end,
1482 .decode = ac3_decode_frame,
1483 .capabilities = CODEC_CAP_DR1,
1484 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1485 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT,
1487 AV_SAMPLE_FMT_NONE },
1488 .priv_class = &ac3_decoder_class,
1491 #if CONFIG_EAC3_DECODER
1492 static const AVClass eac3_decoder_class = {
1493 .class_name = "E-AC3 decoder",
1494 .item_name = av_default_item_name,
1496 .version = LIBAVUTIL_VERSION_INT,
1499 AVCodec ff_eac3_decoder = {
1501 .type = AVMEDIA_TYPE_AUDIO,
1502 .id = CODEC_ID_EAC3,
1503 .priv_data_size = sizeof (AC3DecodeContext),
1504 .init = ac3_decode_init,
1505 .close = ac3_decode_end,
1506 .decode = ac3_decode_frame,
1507 .capabilities = CODEC_CAP_DR1,
1508 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1509 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT,
1511 AV_SAMPLE_FMT_NONE },
1512 .priv_class = &eac3_decoder_class,