3 * This code was developed as part of Google Summer of Code 2006.
4 * E-AC-3 support was added as part of Google Summer of Code 2007.
6 * Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com)
7 * Copyright (c) 2007-2008 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
8 * Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com>
10 * This file is part of Libav.
12 * Libav is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Lesser General Public
14 * License as published by the Free Software Foundation; either
15 * version 2.1 of the License, or (at your option) any later version.
17 * Libav is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * Lesser General Public License for more details.
22 * You should have received a copy of the GNU Lesser General Public
23 * License along with Libav; if not, write to the Free Software
24 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
32 #include "libavutil/crc.h"
33 #include "libavutil/opt.h"
35 #include "aac_ac3_parser.h"
36 #include "ac3_parser.h"
38 #include "ac3dec_data.h"
42 * table for ungrouping 3 values in 7 bits.
43 * used for exponents and bap=2 mantissas
45 static uint8_t ungroup_3_in_7_bits_tab[128][3];
47 /** tables for ungrouping mantissas */
48 static int b1_mantissas[32][3];
49 static int b2_mantissas[128][3];
50 static int b3_mantissas[8];
51 static int b4_mantissas[128][2];
52 static int b5_mantissas[16];
55 * Quantization table: levels for symmetric. bits for asymmetric.
56 * reference: Table 7.18 Mapping of bap to Quantizer
58 static const uint8_t quantization_tab[16] = {
60 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
63 /** dynamic range table. converts codes to scale factors. */
64 static float dynamic_range_tab[256];
66 /** Adjustments in dB gain */
67 static const float gain_levels[9] = {
71 LEVEL_MINUS_1POINT5DB,
73 LEVEL_MINUS_4POINT5DB,
80 * Table for 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;
177 ff_ac3_common_init();
179 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
180 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
181 ff_kbd_window_init(s->window, 5.0, 256);
182 dsputil_init(&s->dsp, avctx);
183 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
184 ff_fmt_convert_init(&s->fmt_conv, avctx);
185 av_lfg_init(&s->dith_state, 0);
187 /* set scale value for float to int16 conversion */
188 if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
190 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
192 s->mul_bias = 32767.0f;
193 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
196 /* allow downmixing to stereo or mono */
197 if (avctx->channels > 0 && avctx->request_channels > 0 &&
198 avctx->request_channels < avctx->channels &&
199 avctx->request_channels <= 2) {
200 avctx->channels = avctx->request_channels;
204 avcodec_get_frame_defaults(&s->frame);
205 avctx->coded_frame = &s->frame;
211 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
212 * GetBitContext within AC3DecodeContext must point to
213 * the start of the synchronized AC-3 bitstream.
215 static int ac3_parse_header(AC3DecodeContext *s)
217 GetBitContext *gbc = &s->gbc;
220 /* read the rest of the bsi. read twice for dual mono mode. */
221 i = !s->channel_mode;
223 skip_bits(gbc, 5); // skip dialog normalization
225 skip_bits(gbc, 8); //skip compression
227 skip_bits(gbc, 8); //skip language code
229 skip_bits(gbc, 7); //skip audio production information
232 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
234 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
235 TODO: read & use the xbsi1 downmix levels */
237 skip_bits(gbc, 14); //skip timecode1 / xbsi1
239 skip_bits(gbc, 14); //skip timecode2 / xbsi2
241 /* skip additional bitstream info */
242 if (get_bits1(gbc)) {
243 i = get_bits(gbc, 6);
253 * Common function to parse AC-3 or E-AC-3 frame header
255 static int parse_frame_header(AC3DecodeContext *s)
260 err = avpriv_ac3_parse_header(&s->gbc, &hdr);
264 /* get decoding parameters from header info */
265 s->bit_alloc_params.sr_code = hdr.sr_code;
266 s->bitstream_mode = hdr.bitstream_mode;
267 s->channel_mode = hdr.channel_mode;
268 s->channel_layout = hdr.channel_layout;
269 s->lfe_on = hdr.lfe_on;
270 s->bit_alloc_params.sr_shift = hdr.sr_shift;
271 s->sample_rate = hdr.sample_rate;
272 s->bit_rate = hdr.bit_rate;
273 s->channels = hdr.channels;
274 s->fbw_channels = s->channels - s->lfe_on;
275 s->lfe_ch = s->fbw_channels + 1;
276 s->frame_size = hdr.frame_size;
277 s->center_mix_level = hdr.center_mix_level;
278 s->surround_mix_level = hdr.surround_mix_level;
279 s->num_blocks = hdr.num_blocks;
280 s->frame_type = hdr.frame_type;
281 s->substreamid = hdr.substreamid;
284 s->start_freq[s->lfe_ch] = 0;
285 s->end_freq[s->lfe_ch] = 7;
286 s->num_exp_groups[s->lfe_ch] = 2;
287 s->channel_in_cpl[s->lfe_ch] = 0;
290 if (hdr.bitstream_id <= 10) {
292 s->snr_offset_strategy = 2;
293 s->block_switch_syntax = 1;
294 s->dither_flag_syntax = 1;
295 s->bit_allocation_syntax = 1;
296 s->fast_gain_syntax = 0;
297 s->first_cpl_leak = 0;
300 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
301 return ac3_parse_header(s);
302 } else if (CONFIG_EAC3_DECODER) {
304 return ff_eac3_parse_header(s);
306 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
312 * Set stereo downmixing coefficients based on frame header info.
313 * reference: Section 7.8.2 Downmixing Into Two Channels
315 static void set_downmix_coeffs(AC3DecodeContext *s)
318 float cmix = gain_levels[center_levels[s->center_mix_level]];
319 float smix = gain_levels[surround_levels[s->surround_mix_level]];
322 for (i = 0; i < s->fbw_channels; i++) {
323 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
324 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
326 if (s->channel_mode > 1 && s->channel_mode & 1) {
327 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
329 if (s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
330 int nf = s->channel_mode - 2;
331 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
333 if (s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
334 int nf = s->channel_mode - 4;
335 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
340 for (i = 0; i < s->fbw_channels; i++) {
341 norm0 += s->downmix_coeffs[i][0];
342 norm1 += s->downmix_coeffs[i][1];
344 norm0 = 1.0f / norm0;
345 norm1 = 1.0f / norm1;
346 for (i = 0; i < s->fbw_channels; i++) {
347 s->downmix_coeffs[i][0] *= norm0;
348 s->downmix_coeffs[i][1] *= norm1;
351 if (s->output_mode == AC3_CHMODE_MONO) {
352 for (i = 0; i < s->fbw_channels; i++)
353 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] +
354 s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
359 * Decode the grouped exponents according to exponent strategy.
360 * reference: Section 7.1.3 Exponent Decoding
362 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
363 uint8_t absexp, int8_t *dexps)
365 int i, j, grp, group_size;
370 group_size = exp_strategy + (exp_strategy == EXP_D45);
371 for (grp = 0, i = 0; grp < ngrps; grp++) {
372 expacc = get_bits(gbc, 7);
373 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
374 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
375 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
378 /* convert to absolute exps and expand groups */
380 for (i = 0, j = 0; i < ngrps * 3; i++) {
381 prevexp += dexp[i] - 2;
384 switch (group_size) {
385 case 4: dexps[j++] = prevexp;
386 dexps[j++] = prevexp;
387 case 2: dexps[j++] = prevexp;
388 case 1: dexps[j++] = prevexp;
395 * Generate transform coefficients for each coupled channel in the coupling
396 * range using the coupling coefficients and coupling coordinates.
397 * reference: Section 7.4.3 Coupling Coordinate Format
399 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
403 bin = s->start_freq[CPL_CH];
404 for (band = 0; band < s->num_cpl_bands; band++) {
405 int band_start = bin;
406 int band_end = bin + s->cpl_band_sizes[band];
407 for (ch = 1; ch <= s->fbw_channels; ch++) {
408 if (s->channel_in_cpl[ch]) {
409 int cpl_coord = s->cpl_coords[ch][band] << 5;
410 for (bin = band_start; bin < band_end; bin++) {
411 s->fixed_coeffs[ch][bin] =
412 MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
414 if (ch == 2 && s->phase_flags[band]) {
415 for (bin = band_start; bin < band_end; bin++)
416 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
425 * Grouped mantissas for 3-level 5-level and 11-level quantization
437 * Decode the transform coefficients for a particular channel
438 * reference: Section 7.3 Quantization and Decoding of Mantissas
440 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
442 int start_freq = s->start_freq[ch_index];
443 int end_freq = s->end_freq[ch_index];
444 uint8_t *baps = s->bap[ch_index];
445 int8_t *exps = s->dexps[ch_index];
446 int *coeffs = s->fixed_coeffs[ch_index];
447 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
448 GetBitContext *gbc = &s->gbc;
451 for (freq = start_freq; freq < end_freq; freq++) {
452 int bap = baps[freq];
457 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
464 mantissa = m->b1_mant[m->b1];
466 int bits = get_bits(gbc, 5);
467 mantissa = b1_mantissas[bits][0];
468 m->b1_mant[1] = b1_mantissas[bits][1];
469 m->b1_mant[0] = b1_mantissas[bits][2];
476 mantissa = m->b2_mant[m->b2];
478 int bits = get_bits(gbc, 7);
479 mantissa = b2_mantissas[bits][0];
480 m->b2_mant[1] = b2_mantissas[bits][1];
481 m->b2_mant[0] = b2_mantissas[bits][2];
486 mantissa = b3_mantissas[get_bits(gbc, 3)];
491 mantissa = m->b4_mant;
493 int bits = get_bits(gbc, 7);
494 mantissa = b4_mantissas[bits][0];
495 m->b4_mant = b4_mantissas[bits][1];
500 mantissa = b5_mantissas[get_bits(gbc, 4)];
502 default: /* 6 to 15 */
503 /* Shift mantissa and sign-extend it. */
504 mantissa = get_sbits(gbc, quantization_tab[bap]);
505 mantissa <<= 24 - quantization_tab[bap];
508 coeffs[freq] = mantissa >> exps[freq];
513 * Remove random dithering from coupling range coefficients with zero-bit
514 * mantissas for coupled channels which do not use dithering.
515 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
517 static void remove_dithering(AC3DecodeContext *s) {
520 for (ch = 1; ch <= s->fbw_channels; ch++) {
521 if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
522 for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) {
523 if (!s->bap[CPL_CH][i])
524 s->fixed_coeffs[ch][i] = 0;
530 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
533 if (!s->channel_uses_aht[ch]) {
534 ac3_decode_transform_coeffs_ch(s, ch, m);
536 /* if AHT is used, mantissas for all blocks are encoded in the first
537 block of the frame. */
539 if (!blk && CONFIG_EAC3_DECODER)
540 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
541 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
542 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
548 * Decode the transform coefficients.
550 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
556 m.b1 = m.b2 = m.b4 = 0;
558 for (ch = 1; ch <= s->channels; ch++) {
559 /* transform coefficients for full-bandwidth channel */
560 decode_transform_coeffs_ch(s, blk, ch, &m);
561 /* tranform coefficients for coupling channel come right after the
562 coefficients for the first coupled channel*/
563 if (s->channel_in_cpl[ch]) {
565 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
566 calc_transform_coeffs_cpl(s);
569 end = s->end_freq[CPL_CH];
571 end = s->end_freq[ch];
574 s->fixed_coeffs[ch][end] = 0;
578 /* zero the dithered coefficients for appropriate channels */
583 * Stereo rematrixing.
584 * reference: Section 7.5.4 Rematrixing : Decoding Technique
586 static void do_rematrixing(AC3DecodeContext *s)
591 end = FFMIN(s->end_freq[1], s->end_freq[2]);
593 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
594 if (s->rematrixing_flags[bnd]) {
595 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd + 1]);
596 for (i = ff_ac3_rematrix_band_tab[bnd]; i < bndend; i++) {
597 int tmp0 = s->fixed_coeffs[1][i];
598 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
599 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
606 * Inverse MDCT Transform.
607 * Convert frequency domain coefficients to time-domain audio samples.
608 * reference: Section 7.9.4 Transformation Equations
610 static inline void do_imdct(AC3DecodeContext *s, int channels)
614 for (ch = 1; ch <= channels; ch++) {
615 if (s->block_switch[ch]) {
617 float *x = s->tmp_output + 128;
618 for (i = 0; i < 128; i++)
619 x[i] = s->transform_coeffs[ch][2 * i];
620 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
621 s->dsp.vector_fmul_window(s->output[ch - 1], s->delay[ch - 1],
622 s->tmp_output, s->window, 128);
623 for (i = 0; i < 128; i++)
624 x[i] = s->transform_coeffs[ch][2 * i + 1];
625 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x);
627 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
628 s->dsp.vector_fmul_window(s->output[ch - 1], s->delay[ch - 1],
629 s->tmp_output, s->window, 128);
630 memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(float));
636 * Downmix the output to mono or stereo.
638 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2],
639 int out_ch, int in_ch, int len)
644 for (i = 0; i < len; i++) {
646 for (j = 0; j < in_ch; j++) {
647 v0 += samples[j][i] * matrix[j][0];
648 v1 += samples[j][i] * matrix[j][1];
653 } else if (out_ch == 1) {
654 for (i = 0; i < len; i++) {
656 for (j = 0; j < in_ch; j++)
657 v0 += samples[j][i] * matrix[j][0];
664 * Upmix delay samples from stereo to original channel layout.
666 static void ac3_upmix_delay(AC3DecodeContext *s)
668 int channel_data_size = sizeof(s->delay[0]);
669 switch (s->channel_mode) {
670 case AC3_CHMODE_DUALMONO:
671 case AC3_CHMODE_STEREO:
672 /* upmix mono to stereo */
673 memcpy(s->delay[1], s->delay[0], channel_data_size);
675 case AC3_CHMODE_2F2R:
676 memset(s->delay[3], 0, channel_data_size);
677 case AC3_CHMODE_2F1R:
678 memset(s->delay[2], 0, channel_data_size);
680 case AC3_CHMODE_3F2R:
681 memset(s->delay[4], 0, channel_data_size);
682 case AC3_CHMODE_3F1R:
683 memset(s->delay[3], 0, channel_data_size);
685 memcpy(s->delay[2], s->delay[1], channel_data_size);
686 memset(s->delay[1], 0, channel_data_size);
692 * Decode band structure for coupling, spectral extension, or enhanced coupling.
693 * The band structure defines how many subbands are in each band. For each
694 * subband in the range, 1 means it is combined with the previous band, and 0
695 * means that it starts a new band.
697 * @param[in] gbc bit reader context
698 * @param[in] blk block number
699 * @param[in] eac3 flag to indicate E-AC-3
700 * @param[in] ecpl flag to indicate enhanced coupling
701 * @param[in] start_subband subband number for start of range
702 * @param[in] end_subband subband number for end of range
703 * @param[in] default_band_struct default band structure table
704 * @param[out] num_bands number of bands (optionally NULL)
705 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
707 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
708 int ecpl, int start_subband, int end_subband,
709 const uint8_t *default_band_struct,
710 int *num_bands, uint8_t *band_sizes)
712 int subbnd, bnd, n_subbands, n_bands=0;
714 uint8_t coded_band_struct[22];
715 const uint8_t *band_struct;
717 n_subbands = end_subband - start_subband;
719 /* decode band structure from bitstream or use default */
720 if (!eac3 || get_bits1(gbc)) {
721 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
722 coded_band_struct[subbnd] = get_bits1(gbc);
724 band_struct = coded_band_struct;
726 band_struct = &default_band_struct[start_subband+1];
728 /* no change in band structure */
732 /* calculate number of bands and band sizes based on band structure.
733 note that the first 4 subbands in enhanced coupling span only 6 bins
735 if (num_bands || band_sizes ) {
736 n_bands = n_subbands;
737 bnd_sz[0] = ecpl ? 6 : 12;
738 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
739 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
740 if (band_struct[subbnd - 1]) {
742 bnd_sz[bnd] += subbnd_size;
744 bnd_sz[++bnd] = subbnd_size;
749 /* set optional output params */
751 *num_bands = n_bands;
753 memcpy(band_sizes, bnd_sz, n_bands);
757 * Decode a single audio block from the AC-3 bitstream.
759 static int decode_audio_block(AC3DecodeContext *s, int blk)
761 int fbw_channels = s->fbw_channels;
762 int channel_mode = s->channel_mode;
764 int different_transforms;
767 GetBitContext *gbc = &s->gbc;
768 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
770 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
772 /* block switch flags */
773 different_transforms = 0;
774 if (s->block_switch_syntax) {
775 for (ch = 1; ch <= fbw_channels; ch++) {
776 s->block_switch[ch] = get_bits1(gbc);
777 if (ch > 1 && s->block_switch[ch] != s->block_switch[1])
778 different_transforms = 1;
782 /* dithering flags */
783 if (s->dither_flag_syntax) {
784 for (ch = 1; ch <= fbw_channels; ch++) {
785 s->dither_flag[ch] = get_bits1(gbc);
790 i = !s->channel_mode;
792 if (get_bits1(gbc)) {
793 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)] - 1.0) *
795 } else if (blk == 0) {
796 s->dynamic_range[i] = 1.0f;
800 /* spectral extension strategy */
801 if (s->eac3 && (!blk || get_bits1(gbc))) {
802 s->spx_in_use = get_bits1(gbc);
804 int dst_start_freq, dst_end_freq, src_start_freq,
805 start_subband, end_subband;
807 /* determine which channels use spx */
808 if (s->channel_mode == AC3_CHMODE_MONO) {
809 s->channel_uses_spx[1] = 1;
811 for (ch = 1; ch <= fbw_channels; ch++)
812 s->channel_uses_spx[ch] = get_bits1(gbc);
815 /* get the frequency bins of the spx copy region and the spx start
817 dst_start_freq = get_bits(gbc, 2);
818 start_subband = get_bits(gbc, 3) + 2;
819 if (start_subband > 7)
820 start_subband += start_subband - 7;
821 end_subband = get_bits(gbc, 3) + 5;
823 end_subband += end_subband - 7;
824 dst_start_freq = dst_start_freq * 12 + 25;
825 src_start_freq = start_subband * 12 + 25;
826 dst_end_freq = end_subband * 12 + 25;
828 /* check validity of spx ranges */
829 if (start_subband >= end_subband) {
830 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
831 "range (%d >= %d)\n", start_subband, end_subband);
834 if (dst_start_freq >= src_start_freq) {
835 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
836 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
840 s->spx_dst_start_freq = dst_start_freq;
841 s->spx_src_start_freq = src_start_freq;
842 s->spx_dst_end_freq = dst_end_freq;
844 decode_band_structure(gbc, blk, s->eac3, 0,
845 start_subband, end_subband,
846 ff_eac3_default_spx_band_struct,
850 for (ch = 1; ch <= fbw_channels; ch++) {
851 s->channel_uses_spx[ch] = 0;
852 s->first_spx_coords[ch] = 1;
857 /* spectral extension coordinates */
859 for (ch = 1; ch <= fbw_channels; ch++) {
860 if (s->channel_uses_spx[ch]) {
861 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
863 int bin, master_spx_coord;
865 s->first_spx_coords[ch] = 0;
866 spx_blend = get_bits(gbc, 5) * (1.0f/32);
867 master_spx_coord = get_bits(gbc, 2) * 3;
869 bin = s->spx_src_start_freq;
870 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
872 int spx_coord_exp, spx_coord_mant;
873 float nratio, sblend, nblend, spx_coord;
875 /* calculate blending factors */
876 bandsize = s->spx_band_sizes[bnd];
877 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
878 nratio = av_clipf(nratio, 0.0f, 1.0f);
879 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
880 // to give unity variance
881 sblend = sqrtf(1.0f - nratio);
884 /* decode spx coordinates */
885 spx_coord_exp = get_bits(gbc, 4);
886 spx_coord_mant = get_bits(gbc, 2);
887 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
888 else spx_coord_mant += 4;
889 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
890 spx_coord = spx_coord_mant * (1.0f / (1 << 23));
892 /* multiply noise and signal blending factors by spx coordinate */
893 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
894 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
898 s->first_spx_coords[ch] = 1;
903 /* coupling strategy */
904 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
905 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
907 s->cpl_in_use[blk] = get_bits1(gbc);
908 if (s->cpl_in_use[blk]) {
909 /* coupling in use */
910 int cpl_start_subband, cpl_end_subband;
912 if (channel_mode < AC3_CHMODE_STEREO) {
913 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
917 /* check for enhanced coupling */
918 if (s->eac3 && get_bits1(gbc)) {
919 /* TODO: parse enhanced coupling strategy info */
920 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
924 /* determine which channels are coupled */
925 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
926 s->channel_in_cpl[1] = 1;
927 s->channel_in_cpl[2] = 1;
929 for (ch = 1; ch <= fbw_channels; ch++)
930 s->channel_in_cpl[ch] = get_bits1(gbc);
933 /* phase flags in use */
934 if (channel_mode == AC3_CHMODE_STEREO)
935 s->phase_flags_in_use = get_bits1(gbc);
937 /* coupling frequency range */
938 cpl_start_subband = get_bits(gbc, 4);
939 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
940 get_bits(gbc, 4) + 3;
941 if (cpl_start_subband >= cpl_end_subband) {
942 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
943 cpl_start_subband, cpl_end_subband);
946 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
947 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
949 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
951 ff_eac3_default_cpl_band_struct,
952 &s->num_cpl_bands, s->cpl_band_sizes);
954 /* coupling not in use */
955 for (ch = 1; ch <= fbw_channels; ch++) {
956 s->channel_in_cpl[ch] = 0;
957 s->first_cpl_coords[ch] = 1;
959 s->first_cpl_leak = s->eac3;
960 s->phase_flags_in_use = 0;
962 } else if (!s->eac3) {
964 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must "
965 "be present in block 0\n");
968 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
971 cpl_in_use = s->cpl_in_use[blk];
973 /* coupling coordinates */
975 int cpl_coords_exist = 0;
977 for (ch = 1; ch <= fbw_channels; ch++) {
978 if (s->channel_in_cpl[ch]) {
979 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
980 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
981 s->first_cpl_coords[ch] = 0;
982 cpl_coords_exist = 1;
983 master_cpl_coord = 3 * get_bits(gbc, 2);
984 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
985 cpl_coord_exp = get_bits(gbc, 4);
986 cpl_coord_mant = get_bits(gbc, 4);
987 if (cpl_coord_exp == 15)
988 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
990 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
991 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
994 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must "
995 "be present in block 0\n");
999 /* channel not in coupling */
1000 s->first_cpl_coords[ch] = 1;
1004 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1005 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1006 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1011 /* stereo rematrixing strategy and band structure */
1012 if (channel_mode == AC3_CHMODE_STEREO) {
1013 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1014 s->num_rematrixing_bands = 4;
1015 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1016 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1017 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1018 s->num_rematrixing_bands--;
1020 for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++)
1021 s->rematrixing_flags[bnd] = get_bits1(gbc);
1023 av_log(s->avctx, AV_LOG_WARNING, "Warning: "
1024 "new rematrixing strategy not present in block 0\n");
1025 s->num_rematrixing_bands = 0;
1029 /* exponent strategies for each channel */
1030 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1032 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1033 if (s->exp_strategy[blk][ch] != EXP_REUSE)
1034 bit_alloc_stages[ch] = 3;
1037 /* channel bandwidth */
1038 for (ch = 1; ch <= fbw_channels; ch++) {
1039 s->start_freq[ch] = 0;
1040 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1042 int prev = s->end_freq[ch];
1043 if (s->channel_in_cpl[ch])
1044 s->end_freq[ch] = s->start_freq[CPL_CH];
1045 else if (s->channel_uses_spx[ch])
1046 s->end_freq[ch] = s->spx_src_start_freq;
1048 int bandwidth_code = get_bits(gbc, 6);
1049 if (bandwidth_code > 60) {
1050 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1053 s->end_freq[ch] = bandwidth_code * 3 + 73;
1055 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1056 s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size;
1057 if (blk > 0 && s->end_freq[ch] != prev)
1058 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1061 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1062 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1063 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1066 /* decode exponents for each channel */
1067 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1068 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1069 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1070 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1071 s->num_exp_groups[ch], s->dexps[ch][0],
1072 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1073 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1076 if (ch != CPL_CH && ch != s->lfe_ch)
1077 skip_bits(gbc, 2); /* skip gainrng */
1081 /* bit allocation information */
1082 if (s->bit_allocation_syntax) {
1083 if (get_bits1(gbc)) {
1084 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1085 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1086 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1087 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1088 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1089 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1090 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1092 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must "
1093 "be present in block 0\n");
1098 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1099 if (!s->eac3 || !blk) {
1100 if (s->snr_offset_strategy && get_bits1(gbc)) {
1103 csnr = (get_bits(gbc, 6) - 15) << 4;
1104 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1106 if (ch == i || s->snr_offset_strategy == 2)
1107 snr = (csnr + get_bits(gbc, 4)) << 2;
1108 /* run at least last bit allocation stage if snr offset changes */
1109 if (blk && s->snr_offset[ch] != snr) {
1110 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1112 s->snr_offset[ch] = snr;
1114 /* fast gain (normal AC-3 only) */
1116 int prev = s->fast_gain[ch];
1117 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1118 /* run last 2 bit allocation stages if fast gain changes */
1119 if (blk && prev != s->fast_gain[ch])
1120 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1123 } else if (!s->eac3 && !blk) {
1124 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1129 /* fast gain (E-AC-3 only) */
1130 if (s->fast_gain_syntax && get_bits1(gbc)) {
1131 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1132 int prev = s->fast_gain[ch];
1133 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1134 /* run last 2 bit allocation stages if fast gain changes */
1135 if (blk && prev != s->fast_gain[ch])
1136 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1138 } else if (s->eac3 && !blk) {
1139 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1140 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1143 /* E-AC-3 to AC-3 converter SNR offset */
1144 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1145 skip_bits(gbc, 10); // skip converter snr offset
1148 /* coupling leak information */
1150 if (s->first_cpl_leak || get_bits1(gbc)) {
1151 int fl = get_bits(gbc, 3);
1152 int sl = get_bits(gbc, 3);
1153 /* run last 2 bit allocation stages for coupling channel if
1154 coupling leak changes */
1155 if (blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1156 sl != s->bit_alloc_params.cpl_slow_leak)) {
1157 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1159 s->bit_alloc_params.cpl_fast_leak = fl;
1160 s->bit_alloc_params.cpl_slow_leak = sl;
1161 } else if (!s->eac3 && !blk) {
1162 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must "
1163 "be present in block 0\n");
1166 s->first_cpl_leak = 0;
1169 /* delta bit allocation information */
1170 if (s->dba_syntax && get_bits1(gbc)) {
1171 /* delta bit allocation exists (strategy) */
1172 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1173 s->dba_mode[ch] = get_bits(gbc, 2);
1174 if (s->dba_mode[ch] == DBA_RESERVED) {
1175 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1178 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1180 /* channel delta offset, len and bit allocation */
1181 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1182 if (s->dba_mode[ch] == DBA_NEW) {
1183 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1184 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1185 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1186 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1187 s->dba_values[ch][seg] = get_bits(gbc, 3);
1189 /* run last 2 bit allocation stages if new dba values */
1190 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1193 } else if (blk == 0) {
1194 for (ch = 0; ch <= s->channels; ch++) {
1195 s->dba_mode[ch] = DBA_NONE;
1199 /* Bit allocation */
1200 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1201 if (bit_alloc_stages[ch] > 2) {
1202 /* Exponent mapping into PSD and PSD integration */
1203 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1204 s->start_freq[ch], s->end_freq[ch],
1205 s->psd[ch], s->band_psd[ch]);
1207 if (bit_alloc_stages[ch] > 1) {
1208 /* Compute excitation function, Compute masking curve, and
1209 Apply delta bit allocation */
1210 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1211 s->start_freq[ch], s->end_freq[ch],
1212 s->fast_gain[ch], (ch == s->lfe_ch),
1213 s->dba_mode[ch], s->dba_nsegs[ch],
1214 s->dba_offsets[ch], s->dba_lengths[ch],
1215 s->dba_values[ch], s->mask[ch])) {
1216 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1220 if (bit_alloc_stages[ch] > 0) {
1221 /* Compute bit allocation */
1222 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1223 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1224 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1225 s->start_freq[ch], s->end_freq[ch],
1227 s->bit_alloc_params.floor,
1228 bap_tab, s->bap[ch]);
1232 /* unused dummy data */
1233 if (s->skip_syntax && get_bits1(gbc)) {
1234 int skipl = get_bits(gbc, 9);
1239 /* unpack the transform coefficients
1240 this also uncouples channels if coupling is in use. */
1241 decode_transform_coeffs(s, blk);
1243 /* TODO: generate enhanced coupling coordinates and uncouple */
1245 /* recover coefficients if rematrixing is in use */
1246 if (s->channel_mode == AC3_CHMODE_STEREO)
1249 /* apply scaling to coefficients (headroom, dynrng) */
1250 for (ch = 1; ch <= s->channels; ch++) {
1251 float gain = s->mul_bias / 4194304.0f;
1252 if (s->channel_mode == AC3_CHMODE_DUALMONO) {
1253 gain *= s->dynamic_range[2 - ch];
1255 gain *= s->dynamic_range[0];
1257 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch],
1258 s->fixed_coeffs[ch], gain, 256);
1261 /* apply spectral extension to high frequency bins */
1262 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1263 ff_eac3_apply_spectral_extension(s);
1266 /* downmix and MDCT. order depends on whether block switching is used for
1267 any channel in this block. this is because coefficients for the long
1268 and short transforms cannot be mixed. */
1269 downmix_output = s->channels != s->out_channels &&
1270 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1271 s->fbw_channels == s->out_channels);
1272 if (different_transforms) {
1273 /* the delay samples have already been downmixed, so we upmix the delay
1274 samples in order to reconstruct all channels before downmixing. */
1280 do_imdct(s, s->channels);
1282 if (downmix_output) {
1283 s->dsp.ac3_downmix(s->output, s->downmix_coeffs,
1284 s->out_channels, s->fbw_channels, 256);
1287 if (downmix_output) {
1288 s->dsp.ac3_downmix(s->transform_coeffs + 1, s->downmix_coeffs,
1289 s->out_channels, s->fbw_channels, 256);
1292 if (downmix_output && !s->downmixed) {
1294 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels,
1295 s->fbw_channels, 128);
1298 do_imdct(s, s->out_channels);
1305 * Decode a single AC-3 frame.
1307 static int ac3_decode_frame(AVCodecContext * avctx, void *data,
1308 int *got_frame_ptr, AVPacket *avpkt)
1310 const uint8_t *buf = avpkt->data;
1311 int buf_size = avpkt->size;
1312 AC3DecodeContext *s = avctx->priv_data;
1313 float *out_samples_flt;
1314 int16_t *out_samples_s16;
1315 int blk, ch, err, ret;
1316 const uint8_t *channel_map;
1317 const float *output[AC3_MAX_CHANNELS];
1319 /* copy input buffer to decoder context to avoid reading past the end
1320 of the buffer, which can be caused by a damaged input stream. */
1321 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1322 // seems to be byte-swapped AC-3
1323 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1324 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1326 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1327 buf = s->input_buffer;
1328 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1329 init_get_bits(&s->gbc, buf, buf_size * 8);
1331 /* parse the syncinfo */
1332 err = parse_frame_header(s);
1336 case AAC_AC3_PARSE_ERROR_SYNC:
1337 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1339 case AAC_AC3_PARSE_ERROR_BSID:
1340 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1342 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1343 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1345 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1346 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1348 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1349 /* skip frame if CRC is ok. otherwise use error concealment. */
1350 /* TODO: add support for substreams and dependent frames */
1351 if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1352 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : "
1353 "skipping frame\n");
1355 return s->frame_size;
1357 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1361 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1365 /* check that reported frame size fits in input buffer */
1366 if (s->frame_size > buf_size) {
1367 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1368 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1369 } else if (avctx->err_recognition & AV_EF_CRCCHECK) {
1370 /* check for crc mismatch */
1371 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2],
1372 s->frame_size - 2)) {
1373 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1374 err = AAC_AC3_PARSE_ERROR_CRC;
1379 /* if frame is ok, set audio parameters */
1381 avctx->sample_rate = s->sample_rate;
1382 avctx->bit_rate = s->bit_rate;
1384 /* channel config */
1385 s->out_channels = s->channels;
1386 s->output_mode = s->channel_mode;
1388 s->output_mode |= AC3_OUTPUT_LFEON;
1389 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1390 avctx->request_channels < s->channels) {
1391 s->out_channels = avctx->request_channels;
1392 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1393 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1395 avctx->channels = s->out_channels;
1396 avctx->channel_layout = s->channel_layout;
1398 /* set downmixing coefficients if needed */
1399 if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1400 s->fbw_channels == s->out_channels)) {
1401 set_downmix_coeffs(s);
1403 } else if (!s->out_channels) {
1404 s->out_channels = avctx->channels;
1405 if (s->out_channels < s->channels)
1406 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1408 /* set audio service type based on bitstream mode for AC-3 */
1409 avctx->audio_service_type = s->bitstream_mode;
1410 if (s->bitstream_mode == 0x7 && s->channels > 1)
1411 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1413 /* get output buffer */
1414 s->frame.nb_samples = s->num_blocks * 256;
1415 if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
1416 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
1419 out_samples_flt = (float *)s->frame.data[0];
1420 out_samples_s16 = (int16_t *)s->frame.data[0];
1422 /* decode the audio blocks */
1423 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1424 for (ch = 0; ch < s->out_channels; ch++)
1425 output[ch] = s->output[channel_map[ch]];
1426 for (blk = 0; blk < s->num_blocks; blk++) {
1427 if (!err && decode_audio_block(s, blk)) {
1428 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1431 if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT) {
1432 s->fmt_conv.float_interleave(out_samples_flt, output, 256,
1434 out_samples_flt += 256 * s->out_channels;
1436 s->fmt_conv.float_to_int16_interleave(out_samples_s16, output, 256,
1438 out_samples_s16 += 256 * s->out_channels;
1443 *(AVFrame *)data = s->frame;
1445 return FFMIN(buf_size, s->frame_size);
1449 * Uninitialize the AC-3 decoder.
1451 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1453 AC3DecodeContext *s = avctx->priv_data;
1454 ff_mdct_end(&s->imdct_512);
1455 ff_mdct_end(&s->imdct_256);
1460 #define OFFSET(x) offsetof(AC3DecodeContext, x)
1461 #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)
1462 static const AVOption options[] = {
1463 { "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), AV_OPT_TYPE_FLOAT, {1.0}, 0.0, 1.0, PAR },
1467 static const AVClass ac3_decoder_class = {
1468 .class_name = "AC3 decoder",
1469 .item_name = av_default_item_name,
1471 .version = LIBAVUTIL_VERSION_INT,
1474 AVCodec ff_ac3_decoder = {
1476 .type = AVMEDIA_TYPE_AUDIO,
1478 .priv_data_size = sizeof (AC3DecodeContext),
1479 .init = ac3_decode_init,
1480 .close = ac3_decode_end,
1481 .decode = ac3_decode_frame,
1482 .capabilities = CODEC_CAP_DR1,
1483 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1484 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT,
1486 AV_SAMPLE_FMT_NONE },
1487 .priv_class = &ac3_decoder_class,
1490 #if CONFIG_EAC3_DECODER
1491 static const AVClass eac3_decoder_class = {
1492 .class_name = "E-AC3 decoder",
1493 .item_name = av_default_item_name,
1495 .version = LIBAVUTIL_VERSION_INT,
1498 AVCodec ff_eac3_decoder = {
1500 .type = AVMEDIA_TYPE_AUDIO,
1501 .id = CODEC_ID_EAC3,
1502 .priv_data_size = sizeof (AC3DecodeContext),
1503 .init = ac3_decode_init,
1504 .close = ac3_decode_end,
1505 .decode = ac3_decode_frame,
1506 .capabilities = CODEC_CAP_DR1,
1507 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1508 .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT,
1510 AV_SAMPLE_FMT_NONE },
1511 .priv_class = &eac3_decoder_class,