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 center mix levels
81 * reference: Section 5.4.2.4 cmixlev
83 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
86 * Table for surround mix levels
87 * reference: Section 5.4.2.5 surmixlev
89 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
92 * Table for default stereo downmixing coefficients
93 * reference: Section 7.8.2 Downmixing Into Two Channels
95 static const uint8_t ac3_default_coeffs[8][5][2] = {
96 { { 2, 7 }, { 7, 2 }, },
98 { { 2, 7 }, { 7, 2 }, },
99 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
100 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
101 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
102 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
103 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
107 * Symmetrical Dequantization
108 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
109 * Tables 7.19 to 7.23
112 symmetric_dequant(int code, int levels)
114 return ((code - (levels >> 1)) << 24) / levels;
118 * Initialize tables at runtime.
120 static av_cold void ac3_tables_init(void)
124 /* generate table for ungrouping 3 values in 7 bits
125 reference: Section 7.1.3 Exponent Decoding */
126 for (i = 0; i < 128; i++) {
127 ungroup_3_in_7_bits_tab[i][0] = i / 25;
128 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
129 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
132 /* generate grouped mantissa tables
133 reference: Section 7.3.5 Ungrouping of Mantissas */
134 for (i = 0; i < 32; i++) {
135 /* bap=1 mantissas */
136 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
137 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
138 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
140 for (i = 0; i < 128; i++) {
141 /* bap=2 mantissas */
142 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
143 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
144 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
146 /* bap=4 mantissas */
147 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
148 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
150 /* generate ungrouped mantissa tables
151 reference: Tables 7.21 and 7.23 */
152 for (i = 0; i < 7; i++) {
153 /* bap=3 mantissas */
154 b3_mantissas[i] = symmetric_dequant(i, 7);
156 for (i = 0; i < 15; i++) {
157 /* bap=5 mantissas */
158 b5_mantissas[i] = symmetric_dequant(i, 15);
161 /* generate dynamic range table
162 reference: Section 7.7.1 Dynamic Range Control */
163 for (i = 0; i < 256; i++) {
164 int v = (i >> 5) - ((i >> 7) << 3) - 5;
165 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
170 * AVCodec initialization
172 static av_cold int ac3_decode_init(AVCodecContext *avctx)
174 AC3DecodeContext *s = avctx->priv_data;
178 if (avctx->drc_scale)
179 s->drc_scale = avctx->drc_scale;
182 ff_ac3_common_init();
184 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
185 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
186 ff_kbd_window_init(s->window, 5.0, 256);
187 dsputil_init(&s->dsp, avctx);
188 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
189 ff_fmt_convert_init(&s->fmt_conv, avctx);
190 av_lfg_init(&s->dith_state, 0);
192 /* set scale value for float to int16 conversion */
193 if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
195 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
197 s->mul_bias = 32767.0f;
198 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
201 /* allow downmixing to stereo or mono */
202 if (avctx->channels > 0 && avctx->request_channels > 0 &&
203 avctx->request_channels < avctx->channels &&
204 avctx->request_channels <= 2) {
205 avctx->channels = avctx->request_channels;
209 avcodec_get_frame_defaults(&s->frame);
210 avctx->coded_frame = &s->frame;
216 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
217 * GetBitContext within AC3DecodeContext must point to
218 * the start of the synchronized AC-3 bitstream.
220 static int ac3_parse_header(AC3DecodeContext *s)
222 GetBitContext *gbc = &s->gbc;
225 /* read the rest of the bsi. read twice for dual mono mode. */
226 i = !(s->channel_mode);
228 skip_bits(gbc, 5); // skip dialog normalization
230 skip_bits(gbc, 8); //skip compression
232 skip_bits(gbc, 8); //skip language code
234 skip_bits(gbc, 7); //skip audio production information
237 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
239 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
240 TODO: read & use the xbsi1 downmix levels */
242 skip_bits(gbc, 14); //skip timecode1 / xbsi1
244 skip_bits(gbc, 14); //skip timecode2 / xbsi2
246 /* skip additional bitstream info */
247 if (get_bits1(gbc)) {
248 i = get_bits(gbc, 6);
258 * Common function to parse AC-3 or E-AC-3 frame header
260 static int parse_frame_header(AC3DecodeContext *s)
265 err = avpriv_ac3_parse_header(&s->gbc, &hdr);
269 /* get decoding parameters from header info */
270 s->bit_alloc_params.sr_code = hdr.sr_code;
271 s->bitstream_mode = hdr.bitstream_mode;
272 s->channel_mode = hdr.channel_mode;
273 s->channel_layout = hdr.channel_layout;
274 s->lfe_on = hdr.lfe_on;
275 s->bit_alloc_params.sr_shift = hdr.sr_shift;
276 s->sample_rate = hdr.sample_rate;
277 s->bit_rate = hdr.bit_rate;
278 s->channels = hdr.channels;
279 s->fbw_channels = s->channels - s->lfe_on;
280 s->lfe_ch = s->fbw_channels + 1;
281 s->frame_size = hdr.frame_size;
282 s->center_mix_level = hdr.center_mix_level;
283 s->surround_mix_level = hdr.surround_mix_level;
284 s->num_blocks = hdr.num_blocks;
285 s->frame_type = hdr.frame_type;
286 s->substreamid = hdr.substreamid;
289 s->start_freq[s->lfe_ch] = 0;
290 s->end_freq[s->lfe_ch] = 7;
291 s->num_exp_groups[s->lfe_ch] = 2;
292 s->channel_in_cpl[s->lfe_ch] = 0;
295 if (hdr.bitstream_id <= 10) {
297 s->snr_offset_strategy = 2;
298 s->block_switch_syntax = 1;
299 s->dither_flag_syntax = 1;
300 s->bit_allocation_syntax = 1;
301 s->fast_gain_syntax = 0;
302 s->first_cpl_leak = 0;
305 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
306 return ac3_parse_header(s);
307 } else if (CONFIG_EAC3_DECODER) {
309 return ff_eac3_parse_header(s);
311 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
317 * Set stereo downmixing coefficients based on frame header info.
318 * reference: Section 7.8.2 Downmixing Into Two Channels
320 static void set_downmix_coeffs(AC3DecodeContext *s)
323 float cmix = gain_levels[center_levels[s->center_mix_level]];
324 float smix = gain_levels[surround_levels[s->surround_mix_level]];
327 for (i = 0; i < s->fbw_channels; i++) {
328 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
329 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
331 if (s->channel_mode > 1 && s->channel_mode & 1) {
332 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
334 if (s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
335 int nf = s->channel_mode - 2;
336 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
338 if (s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
339 int nf = s->channel_mode - 4;
340 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
345 for (i = 0; i < s->fbw_channels; i++) {
346 norm0 += s->downmix_coeffs[i][0];
347 norm1 += s->downmix_coeffs[i][1];
349 norm0 = 1.0f / norm0;
350 norm1 = 1.0f / norm1;
351 for (i = 0; i < s->fbw_channels; i++) {
352 s->downmix_coeffs[i][0] *= norm0;
353 s->downmix_coeffs[i][1] *= norm1;
356 if (s->output_mode == AC3_CHMODE_MONO) {
357 for (i = 0; i < s->fbw_channels; i++)
358 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] +
359 s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
364 * Decode the grouped exponents according to exponent strategy.
365 * reference: Section 7.1.3 Exponent Decoding
367 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
368 uint8_t absexp, int8_t *dexps)
370 int i, j, grp, group_size;
375 group_size = exp_strategy + (exp_strategy == EXP_D45);
376 for (grp = 0, i = 0; grp < ngrps; grp++) {
377 expacc = get_bits(gbc, 7);
378 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
379 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
380 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
383 /* convert to absolute exps and expand groups */
385 for (i = 0, j = 0; i < ngrps * 3; i++) {
386 prevexp += dexp[i] - 2;
389 switch (group_size) {
390 case 4: dexps[j++] = prevexp;
391 dexps[j++] = prevexp;
392 case 2: dexps[j++] = prevexp;
393 case 1: dexps[j++] = prevexp;
400 * Generate transform coefficients for each coupled channel in the coupling
401 * range using the coupling coefficients and coupling coordinates.
402 * reference: Section 7.4.3 Coupling Coordinate Format
404 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
408 bin = s->start_freq[CPL_CH];
409 for (band = 0; band < s->num_cpl_bands; band++) {
410 int band_start = bin;
411 int band_end = bin + s->cpl_band_sizes[band];
412 for (ch = 1; ch <= s->fbw_channels; ch++) {
413 if (s->channel_in_cpl[ch]) {
414 int cpl_coord = s->cpl_coords[ch][band] << 5;
415 for (bin = band_start; bin < band_end; bin++) {
416 s->fixed_coeffs[ch][bin] =
417 MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
419 if (ch == 2 && s->phase_flags[band]) {
420 for (bin = band_start; bin < band_end; bin++)
421 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
430 * Grouped mantissas for 3-level 5-level and 11-level quantization
442 * Decode the transform coefficients for a particular channel
443 * reference: Section 7.3 Quantization and Decoding of Mantissas
445 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
447 int start_freq = s->start_freq[ch_index];
448 int end_freq = s->end_freq[ch_index];
449 uint8_t *baps = s->bap[ch_index];
450 int8_t *exps = s->dexps[ch_index];
451 int *coeffs = s->fixed_coeffs[ch_index];
452 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
453 GetBitContext *gbc = &s->gbc;
456 for (freq = start_freq; freq < end_freq; freq++) {
457 int bap = baps[freq];
462 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
469 mantissa = m->b1_mant[m->b1];
471 int bits = get_bits(gbc, 5);
472 mantissa = b1_mantissas[bits][0];
473 m->b1_mant[1] = b1_mantissas[bits][1];
474 m->b1_mant[0] = b1_mantissas[bits][2];
481 mantissa = m->b2_mant[m->b2];
483 int bits = get_bits(gbc, 7);
484 mantissa = b2_mantissas[bits][0];
485 m->b2_mant[1] = b2_mantissas[bits][1];
486 m->b2_mant[0] = b2_mantissas[bits][2];
491 mantissa = b3_mantissas[get_bits(gbc, 3)];
496 mantissa = m->b4_mant;
498 int bits = get_bits(gbc, 7);
499 mantissa = b4_mantissas[bits][0];
500 m->b4_mant = b4_mantissas[bits][1];
505 mantissa = b5_mantissas[get_bits(gbc, 4)];
507 default: /* 6 to 15 */
508 /* Shift mantissa and sign-extend it. */
509 mantissa = get_sbits(gbc, quantization_tab[bap]);
510 mantissa <<= 24 - quantization_tab[bap];
513 coeffs[freq] = mantissa >> exps[freq];
518 * Remove random dithering from coupling range coefficients with zero-bit
519 * mantissas for coupled channels which do not use dithering.
520 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
522 static void remove_dithering(AC3DecodeContext *s) {
525 for (ch = 1; ch <= s->fbw_channels; ch++) {
526 if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
527 for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) {
528 if (!s->bap[CPL_CH][i])
529 s->fixed_coeffs[ch][i] = 0;
535 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
538 if (!s->channel_uses_aht[ch]) {
539 ac3_decode_transform_coeffs_ch(s, ch, m);
541 /* if AHT is used, mantissas for all blocks are encoded in the first
542 block of the frame. */
544 if (!blk && CONFIG_EAC3_DECODER)
545 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
546 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
547 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
553 * Decode the transform coefficients.
555 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
561 m.b1 = m.b2 = m.b4 = 0;
563 for (ch = 1; ch <= s->channels; ch++) {
564 /* transform coefficients for full-bandwidth channel */
565 decode_transform_coeffs_ch(s, blk, ch, &m);
566 /* tranform coefficients for coupling channel come right after the
567 coefficients for the first coupled channel*/
568 if (s->channel_in_cpl[ch]) {
570 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
571 calc_transform_coeffs_cpl(s);
574 end = s->end_freq[CPL_CH];
576 end = s->end_freq[ch];
579 s->fixed_coeffs[ch][end] = 0;
583 /* zero the dithered coefficients for appropriate channels */
588 * Stereo rematrixing.
589 * reference: Section 7.5.4 Rematrixing : Decoding Technique
591 static void do_rematrixing(AC3DecodeContext *s)
596 end = FFMIN(s->end_freq[1], s->end_freq[2]);
598 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
599 if (s->rematrixing_flags[bnd]) {
600 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd + 1]);
601 for (i = ff_ac3_rematrix_band_tab[bnd]; i < bndend; i++) {
602 int tmp0 = s->fixed_coeffs[1][i];
603 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
604 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
611 * Inverse MDCT Transform.
612 * Convert frequency domain coefficients to time-domain audio samples.
613 * reference: Section 7.9.4 Transformation Equations
615 static inline void do_imdct(AC3DecodeContext *s, int channels)
619 for (ch = 1; ch <= channels; ch++) {
620 if (s->block_switch[ch]) {
622 float *x = s->tmp_output + 128;
623 for (i = 0; i < 128; i++)
624 x[i] = s->transform_coeffs[ch][2 * i];
625 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
626 s->dsp.vector_fmul_window(s->output[ch - 1], s->delay[ch - 1],
627 s->tmp_output, s->window, 128);
628 for (i = 0; i < 128; i++)
629 x[i] = s->transform_coeffs[ch][2 * i + 1];
630 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x);
632 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
633 s->dsp.vector_fmul_window(s->output[ch - 1], s->delay[ch - 1],
634 s->tmp_output, s->window, 128);
635 memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(float));
641 * Downmix the output to mono or stereo.
643 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2],
644 int out_ch, int in_ch, int len)
649 for (i = 0; i < len; i++) {
651 for (j = 0; j < in_ch; j++) {
652 v0 += samples[j][i] * matrix[j][0];
653 v1 += samples[j][i] * matrix[j][1];
658 } else if (out_ch == 1) {
659 for (i = 0; i < len; i++) {
661 for (j = 0; j < in_ch; j++)
662 v0 += samples[j][i] * matrix[j][0];
669 * Upmix delay samples from stereo to original channel layout.
671 static void ac3_upmix_delay(AC3DecodeContext *s)
673 int channel_data_size = sizeof(s->delay[0]);
674 switch (s->channel_mode) {
675 case AC3_CHMODE_DUALMONO:
676 case AC3_CHMODE_STEREO:
677 /* upmix mono to stereo */
678 memcpy(s->delay[1], s->delay[0], channel_data_size);
680 case AC3_CHMODE_2F2R:
681 memset(s->delay[3], 0, channel_data_size);
682 case AC3_CHMODE_2F1R:
683 memset(s->delay[2], 0, channel_data_size);
685 case AC3_CHMODE_3F2R:
686 memset(s->delay[4], 0, channel_data_size);
687 case AC3_CHMODE_3F1R:
688 memset(s->delay[3], 0, channel_data_size);
690 memcpy(s->delay[2], s->delay[1], channel_data_size);
691 memset(s->delay[1], 0, channel_data_size);
697 * Decode band structure for coupling, spectral extension, or enhanced coupling.
698 * The band structure defines how many subbands are in each band. For each
699 * subband in the range, 1 means it is combined with the previous band, and 0
700 * means that it starts a new band.
702 * @param[in] gbc bit reader context
703 * @param[in] blk block number
704 * @param[in] eac3 flag to indicate E-AC-3
705 * @param[in] ecpl flag to indicate enhanced coupling
706 * @param[in] start_subband subband number for start of range
707 * @param[in] end_subband subband number for end of range
708 * @param[in] default_band_struct default band structure table
709 * @param[out] num_bands number of bands (optionally NULL)
710 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
712 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
713 int ecpl, int start_subband, int end_subband,
714 const uint8_t *default_band_struct,
715 int *num_bands, uint8_t *band_sizes)
717 int subbnd, bnd, n_subbands, n_bands=0;
719 uint8_t coded_band_struct[22];
720 const uint8_t *band_struct;
722 n_subbands = end_subband - start_subband;
724 /* decode band structure from bitstream or use default */
725 if (!eac3 || get_bits1(gbc)) {
726 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
727 coded_band_struct[subbnd] = get_bits1(gbc);
729 band_struct = coded_band_struct;
731 band_struct = &default_band_struct[start_subband+1];
733 /* no change in band structure */
737 /* calculate number of bands and band sizes based on band structure.
738 note that the first 4 subbands in enhanced coupling span only 6 bins
740 if (num_bands || band_sizes ) {
741 n_bands = n_subbands;
742 bnd_sz[0] = ecpl ? 6 : 12;
743 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
744 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
745 if (band_struct[subbnd - 1]) {
747 bnd_sz[bnd] += subbnd_size;
749 bnd_sz[++bnd] = subbnd_size;
754 /* set optional output params */
756 *num_bands = n_bands;
758 memcpy(band_sizes, bnd_sz, n_bands);
762 * Decode a single audio block from the AC-3 bitstream.
764 static int decode_audio_block(AC3DecodeContext *s, int blk)
766 int fbw_channels = s->fbw_channels;
767 int channel_mode = s->channel_mode;
769 int different_transforms;
772 GetBitContext *gbc = &s->gbc;
773 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
775 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
777 /* block switch flags */
778 different_transforms = 0;
779 if (s->block_switch_syntax) {
780 for (ch = 1; ch <= fbw_channels; ch++) {
781 s->block_switch[ch] = get_bits1(gbc);
782 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
783 different_transforms = 1;
787 /* dithering flags */
788 if (s->dither_flag_syntax) {
789 for (ch = 1; ch <= fbw_channels; ch++) {
790 s->dither_flag[ch] = get_bits1(gbc);
795 i = !(s->channel_mode);
797 if (get_bits1(gbc)) {
798 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)] - 1.0) *
800 } else if (blk == 0) {
801 s->dynamic_range[i] = 1.0f;
805 /* spectral extension strategy */
806 if (s->eac3 && (!blk || get_bits1(gbc))) {
807 s->spx_in_use = get_bits1(gbc);
809 int dst_start_freq, dst_end_freq, src_start_freq,
810 start_subband, end_subband;
812 /* determine which channels use spx */
813 if (s->channel_mode == AC3_CHMODE_MONO) {
814 s->channel_uses_spx[1] = 1;
816 for (ch = 1; ch <= fbw_channels; ch++)
817 s->channel_uses_spx[ch] = get_bits1(gbc);
820 /* get the frequency bins of the spx copy region and the spx start
822 dst_start_freq = get_bits(gbc, 2);
823 start_subband = get_bits(gbc, 3) + 2;
824 if (start_subband > 7)
825 start_subband += start_subband - 7;
826 end_subband = get_bits(gbc, 3) + 5;
828 end_subband += end_subband - 7;
829 dst_start_freq = dst_start_freq * 12 + 25;
830 src_start_freq = start_subband * 12 + 25;
831 dst_end_freq = end_subband * 12 + 25;
833 /* check validity of spx ranges */
834 if (start_subband >= end_subband) {
835 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
836 "range (%d >= %d)\n", start_subband, end_subband);
839 if (dst_start_freq >= src_start_freq) {
840 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
841 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
845 s->spx_dst_start_freq = dst_start_freq;
846 s->spx_src_start_freq = src_start_freq;
847 s->spx_dst_end_freq = dst_end_freq;
849 decode_band_structure(gbc, blk, s->eac3, 0,
850 start_subband, end_subband,
851 ff_eac3_default_spx_band_struct,
855 for (ch = 1; ch <= fbw_channels; ch++) {
856 s->channel_uses_spx[ch] = 0;
857 s->first_spx_coords[ch] = 1;
862 /* spectral extension coordinates */
864 for (ch = 1; ch <= fbw_channels; ch++) {
865 if (s->channel_uses_spx[ch]) {
866 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
868 int bin, master_spx_coord;
870 s->first_spx_coords[ch] = 0;
871 spx_blend = get_bits(gbc, 5) * (1.0f/32);
872 master_spx_coord = get_bits(gbc, 2) * 3;
874 bin = s->spx_src_start_freq;
875 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
877 int spx_coord_exp, spx_coord_mant;
878 float nratio, sblend, nblend, spx_coord;
880 /* calculate blending factors */
881 bandsize = s->spx_band_sizes[bnd];
882 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
883 nratio = av_clipf(nratio, 0.0f, 1.0f);
884 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
885 // to give unity variance
886 sblend = sqrtf(1.0f - nratio);
889 /* decode spx coordinates */
890 spx_coord_exp = get_bits(gbc, 4);
891 spx_coord_mant = get_bits(gbc, 2);
892 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
893 else spx_coord_mant += 4;
894 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
895 spx_coord = spx_coord_mant * (1.0f / (1 << 23));
897 /* multiply noise and signal blending factors by spx coordinate */
898 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
899 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
903 s->first_spx_coords[ch] = 1;
908 /* coupling strategy */
909 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
910 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
912 s->cpl_in_use[blk] = get_bits1(gbc);
913 if (s->cpl_in_use[blk]) {
914 /* coupling in use */
915 int cpl_start_subband, cpl_end_subband;
917 if (channel_mode < AC3_CHMODE_STEREO) {
918 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
922 /* check for enhanced coupling */
923 if (s->eac3 && get_bits1(gbc)) {
924 /* TODO: parse enhanced coupling strategy info */
925 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
929 /* determine which channels are coupled */
930 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
931 s->channel_in_cpl[1] = 1;
932 s->channel_in_cpl[2] = 1;
934 for (ch = 1; ch <= fbw_channels; ch++)
935 s->channel_in_cpl[ch] = get_bits1(gbc);
938 /* phase flags in use */
939 if (channel_mode == AC3_CHMODE_STEREO)
940 s->phase_flags_in_use = get_bits1(gbc);
942 /* coupling frequency range */
943 cpl_start_subband = get_bits(gbc, 4);
944 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
945 get_bits(gbc, 4) + 3;
946 if (cpl_start_subband >= cpl_end_subband) {
947 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
948 cpl_start_subband, cpl_end_subband);
951 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
952 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
954 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
956 ff_eac3_default_cpl_band_struct,
957 &s->num_cpl_bands, s->cpl_band_sizes);
959 /* coupling not in use */
960 for (ch = 1; ch <= fbw_channels; ch++) {
961 s->channel_in_cpl[ch] = 0;
962 s->first_cpl_coords[ch] = 1;
964 s->first_cpl_leak = s->eac3;
965 s->phase_flags_in_use = 0;
967 } else if (!s->eac3) {
969 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
970 "be present in block 0\n");
973 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
976 cpl_in_use = s->cpl_in_use[blk];
978 /* coupling coordinates */
980 int cpl_coords_exist = 0;
982 for (ch = 1; ch <= fbw_channels; ch++) {
983 if (s->channel_in_cpl[ch]) {
984 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
985 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
986 s->first_cpl_coords[ch] = 0;
987 cpl_coords_exist = 1;
988 master_cpl_coord = 3 * get_bits(gbc, 2);
989 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
990 cpl_coord_exp = get_bits(gbc, 4);
991 cpl_coord_mant = get_bits(gbc, 4);
992 if (cpl_coord_exp == 15)
993 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
995 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
996 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
999 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
1000 "be present in block 0\n");
1004 /* channel not in coupling */
1005 s->first_cpl_coords[ch] = 1;
1009 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1010 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1011 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1016 /* stereo rematrixing strategy and band structure */
1017 if (channel_mode == AC3_CHMODE_STEREO) {
1018 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1019 s->num_rematrixing_bands = 4;
1020 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1021 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1022 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1023 s->num_rematrixing_bands--;
1025 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
1026 s->rematrixing_flags[bnd] = get_bits1(gbc);
1028 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
1029 "new rematrixing strategy not present in block 0\n");
1030 s->num_rematrixing_bands = 0;
1034 /* exponent strategies for each channel */
1035 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1037 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1038 if (s->exp_strategy[blk][ch] != EXP_REUSE)
1039 bit_alloc_stages[ch] = 3;
1042 /* channel bandwidth */
1043 for (ch = 1; ch <= fbw_channels; ch++) {
1044 s->start_freq[ch] = 0;
1045 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1047 int prev = s->end_freq[ch];
1048 if (s->channel_in_cpl[ch])
1049 s->end_freq[ch] = s->start_freq[CPL_CH];
1050 else if (s->channel_uses_spx[ch])
1051 s->end_freq[ch] = s->spx_src_start_freq;
1053 int bandwidth_code = get_bits(gbc, 6);
1054 if (bandwidth_code > 60) {
1055 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1058 s->end_freq[ch] = bandwidth_code * 3 + 73;
1060 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1061 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1062 if (blk > 0 && s->end_freq[ch] != prev)
1063 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1066 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1067 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1068 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1071 /* decode exponents for each channel */
1072 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1073 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1074 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1075 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1076 s->num_exp_groups[ch], s->dexps[ch][0],
1077 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1078 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1081 if (ch != CPL_CH && ch != s->lfe_ch)
1082 skip_bits(gbc, 2); /* skip gainrng */
1086 /* bit allocation information */
1087 if (s->bit_allocation_syntax) {
1088 if (get_bits1(gbc)) {
1089 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1090 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1091 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1092 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1093 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1094 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1095 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1097 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1098 "be present in block 0\n");
1103 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1104 if (!s->eac3 || !blk) {
1105 if (s->snr_offset_strategy && get_bits1(gbc)) {
1108 csnr = (get_bits(gbc, 6) - 15) << 4;
1109 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1111 if (ch == i || s->snr_offset_strategy == 2)
1112 snr = (csnr + get_bits(gbc, 4)) << 2;
1113 /* run at least last bit allocation stage if snr offset changes */
1114 if (blk && s->snr_offset[ch] != snr) {
1115 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1117 s->snr_offset[ch] = snr;
1119 /* fast gain (normal AC-3 only) */
1121 int prev = s->fast_gain[ch];
1122 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1123 /* run last 2 bit allocation stages if fast gain changes */
1124 if (blk && prev != s->fast_gain[ch])
1125 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1128 } else if (!s->eac3 && !blk) {
1129 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1134 /* fast gain (E-AC-3 only) */
1135 if (s->fast_gain_syntax && get_bits1(gbc)) {
1136 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1137 int prev = s->fast_gain[ch];
1138 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1139 /* run last 2 bit allocation stages if fast gain changes */
1140 if (blk && prev != s->fast_gain[ch])
1141 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1143 } else if (s->eac3 && !blk) {
1144 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1145 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1148 /* E-AC-3 to AC-3 converter SNR offset */
1149 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1150 skip_bits(gbc, 10); // skip converter snr offset
1153 /* coupling leak information */
1155 if (s->first_cpl_leak || get_bits1(gbc)) {
1156 int fl = get_bits(gbc, 3);
1157 int sl = get_bits(gbc, 3);
1158 /* run last 2 bit allocation stages for coupling channel if
1159 coupling leak changes */
1160 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1161 sl != s->bit_alloc_params.cpl_slow_leak)) {
1162 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1164 s->bit_alloc_params.cpl_fast_leak = fl;
1165 s->bit_alloc_params.cpl_slow_leak = sl;
1166 } else if (!s->eac3 && !blk) {
1167 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1168 "be present in block 0\n");
1171 s->first_cpl_leak = 0;
1174 /* delta bit allocation information */
1175 if (s->dba_syntax && get_bits1(gbc)) {
1176 /* delta bit allocation exists (strategy) */
1177 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1178 s->dba_mode[ch] = get_bits(gbc, 2);
1179 if (s->dba_mode[ch] == DBA_RESERVED) {
1180 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1183 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1185 /* channel delta offset, len and bit allocation */
1186 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1187 if (s->dba_mode[ch] == DBA_NEW) {
1188 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1189 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1190 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1191 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1192 s->dba_values[ch][seg] = get_bits(gbc, 3);
1194 /* run last 2 bit allocation stages if new dba values */
1195 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1198 } else if (blk == 0) {
1199 for (ch = 0; ch <= s->channels; ch++) {
1200 s->dba_mode[ch] = DBA_NONE;
1204 /* Bit allocation */
1205 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1206 if (bit_alloc_stages[ch] > 2) {
1207 /* Exponent mapping into PSD and PSD integration */
1208 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1209 s->start_freq[ch], s->end_freq[ch],
1210 s->psd[ch], s->band_psd[ch]);
1212 if (bit_alloc_stages[ch] > 1) {
1213 /* Compute excitation function, Compute masking curve, and
1214 Apply delta bit allocation */
1215 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1216 s->start_freq[ch], s->end_freq[ch],
1217 s->fast_gain[ch], (ch == s->lfe_ch),
1218 s->dba_mode[ch], s->dba_nsegs[ch],
1219 s->dba_offsets[ch], s->dba_lengths[ch],
1220 s->dba_values[ch], s->mask[ch])) {
1221 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1225 if (bit_alloc_stages[ch] > 0) {
1226 /* Compute bit allocation */
1227 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1228 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1229 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1230 s->start_freq[ch], s->end_freq[ch],
1232 s->bit_alloc_params.floor,
1233 bap_tab, s->bap[ch]);
1237 /* unused dummy data */
1238 if (s->skip_syntax && get_bits1(gbc)) {
1239 int skipl = get_bits(gbc, 9);
1244 /* unpack the transform coefficients
1245 this also uncouples channels if coupling is in use. */
1246 decode_transform_coeffs(s, blk);
1248 /* TODO: generate enhanced coupling coordinates and uncouple */
1250 /* recover coefficients if rematrixing is in use */
1251 if (s->channel_mode == AC3_CHMODE_STEREO)
1254 /* apply scaling to coefficients (headroom, dynrng) */
1255 for (ch = 1; ch <= s->channels; ch++) {
1256 float gain = s->mul_bias / 4194304.0f;
1257 if (s->channel_mode == AC3_CHMODE_DUALMONO) {
1258 gain *= s->dynamic_range[2 - ch];
1260 gain *= s->dynamic_range[0];
1262 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1263 s->fixed_coeffs[ch], gain, 256);
1266 /* apply spectral extension to high frequency bins */
1267 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1268 ff_eac3_apply_spectral_extension(s);
1271 /* downmix and MDCT. order depends on whether block switching is used for
1272 any channel in this block. this is because coefficients for the long
1273 and short transforms cannot be mixed. */
1274 downmix_output = s->channels != s->out_channels &&
1275 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1276 s->fbw_channels == s->out_channels);
1277 if (different_transforms) {
1278 /* the delay samples have already been downmixed, so we upmix the delay
1279 samples in order to reconstruct all channels before downmixing. */
1285 do_imdct(s, s->channels);
1287 if (downmix_output) {
1288 s->dsp.ac3_downmix(s->output, s->downmix_coeffs,
1289 s->out_channels, s->fbw_channels, 256);
1292 if (downmix_output) {
1293 s->dsp.ac3_downmix(s->transform_coeffs + 1, s->downmix_coeffs,
1294 s->out_channels, s->fbw_channels, 256);
1297 if (downmix_output && !s->downmixed) {
1299 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels,
1300 s->fbw_channels, 128);
1303 do_imdct(s, s->out_channels);
1310 * Decode a single AC-3 frame.
1312 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1313 int *got_frame_ptr, AVPacket *avpkt)
1315 const uint8_t *buf = avpkt->data;
1316 int buf_size = avpkt->size;
1317 AC3DecodeContext *s = avctx->priv_data;
1318 float *out_samples_flt;
1319 int16_t *out_samples_s16;
1320 int blk, ch, err, ret;
1321 const uint8_t *channel_map;
1322 const float *output[AC3_MAX_CHANNELS];
1324 /* copy input buffer to decoder context to avoid reading past the end
1325 of the buffer, which can be caused by a damaged input stream. */
1326 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1327 // seems to be byte-swapped AC-3
1328 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1329 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1331 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1332 buf = s->input_buffer;
1333 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1334 init_get_bits(&s->gbc, buf, buf_size * 8);
1336 /* parse the syncinfo */
1337 err = parse_frame_header(s);
1341 case AAC_AC3_PARSE_ERROR_SYNC:
1342 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1344 case AAC_AC3_PARSE_ERROR_BSID:
1345 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1347 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1348 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1350 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1351 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1353 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1354 /* skip frame if CRC is ok. otherwise use error concealment. */
1355 /* TODO: add support for substreams and dependent frames */
1356 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1357 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : "
1358 "skipping frame\n");
1360 return s->frame_size;
1362 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1366 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1370 /* check that reported frame size fits in input buffer */
1371 if (s->frame_size > buf_size) {
1372 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1373 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1374 } else if (avctx->err_recognition & (AV_EF_CRCCHECK|AV_EF_CAREFUL)) {
1375 /* check for crc mismatch */
1376 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1377 s->frame_size - 2)) {
1378 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1379 err = AAC_AC3_PARSE_ERROR_CRC;
1384 /* if frame is ok, set audio parameters */
1386 avctx->sample_rate = s->sample_rate;
1387 avctx->bit_rate = s->bit_rate;
1389 /* channel config */
1390 s->out_channels = s->channels;
1391 s->output_mode = s->channel_mode;
1393 s->output_mode |= AC3_OUTPUT_LFEON;
1394 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1395 avctx->request_channels < s->channels) {
1396 s->out_channels = avctx->request_channels;
1397 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1398 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1400 avctx->channels = s->out_channels;
1401 avctx->channel_layout = s->channel_layout;
1403 s->loro_center_mix_level = gain_levels[ center_levels[s-> center_mix_level]];
1404 s->loro_surround_mix_level = gain_levels[surround_levels[s->surround_mix_level]];
1405 s->ltrt_center_mix_level = LEVEL_MINUS_3DB;
1406 s->ltrt_surround_mix_level = LEVEL_MINUS_3DB;
1407 /* set downmixing coefficients if needed */
1408 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1409 s->fbw_channels == s->out_channels)) {
1410 set_downmix_coeffs(s);
1412 } else if (!s->out_channels) {
1413 s->out_channels = avctx->channels;
1414 if (s->out_channels < s->channels)
1415 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1417 /* set audio service type based on bitstream mode for AC-3 */
1418 avctx->audio_service_type = s->bitstream_mode;
1419 if (s->bitstream_mode == 0x7 && s->channels > 1)
1420 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1422 /* get output buffer */
1423 s->frame.nb_samples = s->num_blocks * 256;
1424 if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
1425 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
1428 out_samples_flt = (float *)s->frame.data[0];
1429 out_samples_s16 = (int16_t *)s->frame.data[0];
1431 /* decode the audio blocks */
1432 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1433 for (ch = 0; ch < s->out_channels; ch++)
1434 output[ch] = s->output[channel_map[ch]];
1435 for (blk = 0; blk < s->num_blocks; blk++) {
1436 if (!err && decode_audio_block(s, blk)) {
1437 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1440 if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT) {
1441 s->fmt_conv.float_interleave(out_samples_flt, output, 256,
1443 out_samples_flt += 256 * s->out_channels;
1445 s->fmt_conv.float_to_int16_interleave(out_samples_s16, output, 256,
1447 out_samples_s16 += 256 * s->out_channels;
1452 *(AVFrame *)data = s->frame;
1454 return FFMIN(buf_size, s->frame_size);
1458 * Uninitialize the AC-3 decoder.
1460 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1462 AC3DecodeContext *s = avctx->priv_data;
1463 ff_mdct_end(&s->imdct_512);
1464 ff_mdct_end(&s->imdct_256);
1469 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1470 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)
1471 static const AVOption options[] = {
1472 { "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), AV_OPT_TYPE_FLOAT, {1.0}, 0.0, 1.0, PAR },
1474 {"dmix_mode", "Preferred Stereo Downmix Mode", OFFSET(preferred_stereo_downmix), AV_OPT_TYPE_INT, {.dbl = -1 }, -1, 2, 0, "dmix_mode"},
1475 {"ltrt_cmixlev", "Lt/Rt Center Mix Level", OFFSET(ltrt_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1476 {"ltrt_surmixlev", "Lt/Rt Surround Mix Level", OFFSET(ltrt_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1477 {"loro_cmixlev", "Lo/Ro Center Mix Level", OFFSET(loro_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1478 {"loro_surmixlev", "Lo/Ro Surround Mix Level", OFFSET(loro_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0},
1483 static const AVClass ac3_decoder_class = {
1484 .class_name = "AC3 decoder",
1485 .item_name = av_default_item_name,
1487 .version = LIBAVUTIL_VERSION_INT,
1490 AVCodec ff_ac3_decoder = {
1492 .type = AVMEDIA_TYPE_AUDIO,
1494 .priv_data_size = sizeof (AC3DecodeContext),
1495 .init = ac3_decode_init,
1496 .close = ac3_decode_end,
1497 .decode = ac3_decode_frame,
1498 .capabilities = CODEC_CAP_DR1,
1499 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1500 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT,
1502 AV_SAMPLE_FMT_NONE },
1503 .priv_class = &ac3_decoder_class,
1506 #if CONFIG_EAC3_DECODER
1507 static const AVClass eac3_decoder_class = {
1508 .class_name = "E-AC3 decoder",
1509 .item_name = av_default_item_name,
1511 .version = LIBAVUTIL_VERSION_INT,
1514 AVCodec ff_eac3_decoder = {
1516 .type = AVMEDIA_TYPE_AUDIO,
1517 .id = CODEC_ID_EAC3,
1518 .priv_data_size = sizeof (AC3DecodeContext),
1519 .init = ac3_decode_init,
1520 .close = ac3_decode_end,
1521 .decode = ac3_decode_frame,
1522 .capabilities = CODEC_CAP_DR1,
1523 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1524 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT,
1526 AV_SAMPLE_FMT_NONE },
1527 .priv_class = &eac3_decoder_class,