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"
34 #include "aac_ac3_parser.h"
35 #include "ac3_parser.h"
37 #include "ac3dec_data.h"
40 /** Large enough for maximum possible frame size when the specification limit is ignored */
41 #define AC3_FRAME_BUFFER_SIZE 32768
44 * table for ungrouping 3 values in 7 bits.
45 * used for exponents and bap=2 mantissas
47 static uint8_t ungroup_3_in_7_bits_tab[128][3];
50 /** tables for ungrouping mantissas */
51 static int b1_mantissas[32][3];
52 static int b2_mantissas[128][3];
53 static int b3_mantissas[8];
54 static int b4_mantissas[128][2];
55 static int b5_mantissas[16];
58 * Quantization table: levels for symmetric. bits for asymmetric.
59 * reference: Table 7.18 Mapping of bap to Quantizer
61 static const uint8_t quantization_tab[16] = {
63 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
66 /** dynamic range table. converts codes to scale factors. */
67 static float dynamic_range_tab[256];
69 /** Adjustments in dB gain */
70 #define LEVEL_PLUS_3DB 1.4142135623730950
71 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209
72 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145
73 #define LEVEL_MINUS_3DB 0.7071067811865476
74 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605
75 #define LEVEL_MINUS_6DB 0.5000000000000000
76 #define LEVEL_MINUS_9DB 0.3535533905932738
77 #define LEVEL_ZERO 0.0000000000000000
78 #define LEVEL_ONE 1.0000000000000000
80 static const float gain_levels[9] = {
84 LEVEL_MINUS_1POINT5DB,
86 LEVEL_MINUS_4POINT5DB,
93 * Table for center mix levels
94 * reference: Section 5.4.2.4 cmixlev
96 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
99 * Table for surround mix levels
100 * reference: Section 5.4.2.5 surmixlev
102 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
105 * Table for default stereo downmixing coefficients
106 * reference: Section 7.8.2 Downmixing Into Two Channels
108 static const uint8_t ac3_default_coeffs[8][5][2] = {
109 { { 2, 7 }, { 7, 2 }, },
111 { { 2, 7 }, { 7, 2 }, },
112 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
113 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
114 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
115 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
116 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
120 * Symmetrical Dequantization
121 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
122 * Tables 7.19 to 7.23
125 symmetric_dequant(int code, int levels)
127 return ((code - (levels >> 1)) << 24) / levels;
131 * Initialize tables at runtime.
133 static av_cold void ac3_tables_init(void)
137 /* generate table for ungrouping 3 values in 7 bits
138 reference: Section 7.1.3 Exponent Decoding */
139 for(i=0; i<128; i++) {
140 ungroup_3_in_7_bits_tab[i][0] = i / 25;
141 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
142 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
145 /* generate grouped mantissa tables
146 reference: Section 7.3.5 Ungrouping of Mantissas */
147 for(i=0; i<32; i++) {
148 /* bap=1 mantissas */
149 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
150 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
151 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
153 for(i=0; i<128; i++) {
154 /* bap=2 mantissas */
155 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
156 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
157 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
159 /* bap=4 mantissas */
160 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
161 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
163 /* generate ungrouped mantissa tables
164 reference: Tables 7.21 and 7.23 */
166 /* bap=3 mantissas */
167 b3_mantissas[i] = symmetric_dequant(i, 7);
169 for(i=0; i<15; i++) {
170 /* bap=5 mantissas */
171 b5_mantissas[i] = symmetric_dequant(i, 15);
174 /* generate dynamic range table
175 reference: Section 7.7.1 Dynamic Range Control */
176 for(i=0; i<256; i++) {
177 int v = (i >> 5) - ((i >> 7) << 3) - 5;
178 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
184 * AVCodec initialization
186 static av_cold int ac3_decode_init(AVCodecContext *avctx)
188 AC3DecodeContext *s = avctx->priv_data;
191 ff_ac3_common_init();
193 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
194 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
195 ff_kbd_window_init(s->window, 5.0, 256);
196 dsputil_init(&s->dsp, avctx);
197 ff_fmt_convert_init(&s->fmt_conv, avctx);
198 av_lfg_init(&s->dith_state, 0);
200 /* set scale value for float to int16 conversion */
201 s->mul_bias = 32767.0f;
203 /* allow downmixing to stereo or mono */
204 if (avctx->channels > 0 && avctx->request_channels > 0 &&
205 avctx->request_channels < avctx->channels &&
206 avctx->request_channels <= 2) {
207 avctx->channels = avctx->request_channels;
211 /* allocate context input buffer */
212 s->input_buffer = av_mallocz(AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
213 if (!s->input_buffer)
214 return AVERROR(ENOMEM);
216 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
221 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
222 * GetBitContext within AC3DecodeContext must point to
223 * the start of the synchronized AC-3 bitstream.
225 static int ac3_parse_header(AC3DecodeContext *s)
227 GetBitContext *gbc = &s->gbc;
230 /* read the rest of the bsi. read twice for dual mono mode. */
231 i = !(s->channel_mode);
233 skip_bits(gbc, 5); // skip dialog normalization
235 skip_bits(gbc, 8); //skip compression
237 skip_bits(gbc, 8); //skip language code
239 skip_bits(gbc, 7); //skip audio production information
242 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
244 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
245 TODO: read & use the xbsi1 downmix levels */
247 skip_bits(gbc, 14); //skip timecode1 / xbsi1
249 skip_bits(gbc, 14); //skip timecode2 / xbsi2
251 /* skip additional bitstream info */
252 if (get_bits1(gbc)) {
253 i = get_bits(gbc, 6);
263 * Common function to parse AC-3 or E-AC-3 frame header
265 static int parse_frame_header(AC3DecodeContext *s)
270 err = ff_ac3_parse_header(&s->gbc, &hdr);
274 /* get decoding parameters from header info */
275 s->bit_alloc_params.sr_code = hdr.sr_code;
276 s->channel_mode = hdr.channel_mode;
277 s->channel_layout = hdr.channel_layout;
278 s->lfe_on = hdr.lfe_on;
279 s->bit_alloc_params.sr_shift = hdr.sr_shift;
280 s->sample_rate = hdr.sample_rate;
281 s->bit_rate = hdr.bit_rate;
282 s->channels = hdr.channels;
283 s->fbw_channels = s->channels - s->lfe_on;
284 s->lfe_ch = s->fbw_channels + 1;
285 s->frame_size = hdr.frame_size;
286 s->center_mix_level = hdr.center_mix_level;
287 s->surround_mix_level = hdr.surround_mix_level;
288 s->num_blocks = hdr.num_blocks;
289 s->frame_type = hdr.frame_type;
290 s->substreamid = hdr.substreamid;
293 s->start_freq[s->lfe_ch] = 0;
294 s->end_freq[s->lfe_ch] = 7;
295 s->num_exp_groups[s->lfe_ch] = 2;
296 s->channel_in_cpl[s->lfe_ch] = 0;
299 if (hdr.bitstream_id <= 10) {
301 s->snr_offset_strategy = 2;
302 s->block_switch_syntax = 1;
303 s->dither_flag_syntax = 1;
304 s->bit_allocation_syntax = 1;
305 s->fast_gain_syntax = 0;
306 s->first_cpl_leak = 0;
309 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
310 return ac3_parse_header(s);
311 } else if (CONFIG_EAC3_DECODER) {
313 return ff_eac3_parse_header(s);
315 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
321 * Set stereo downmixing coefficients based on frame header info.
322 * reference: Section 7.8.2 Downmixing Into Two Channels
324 static void set_downmix_coeffs(AC3DecodeContext *s)
327 float cmix = gain_levels[center_levels[s->center_mix_level]];
328 float smix = gain_levels[surround_levels[s->surround_mix_level]];
331 for(i=0; i<s->fbw_channels; i++) {
332 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
333 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
335 if(s->channel_mode > 1 && s->channel_mode & 1) {
336 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
338 if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
339 int nf = s->channel_mode - 2;
340 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
342 if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
343 int nf = s->channel_mode - 4;
344 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
349 for(i=0; i<s->fbw_channels; i++) {
350 norm0 += s->downmix_coeffs[i][0];
351 norm1 += s->downmix_coeffs[i][1];
353 norm0 = 1.0f / norm0;
354 norm1 = 1.0f / norm1;
355 for(i=0; i<s->fbw_channels; i++) {
356 s->downmix_coeffs[i][0] *= norm0;
357 s->downmix_coeffs[i][1] *= norm1;
360 if(s->output_mode == AC3_CHMODE_MONO) {
361 for(i=0; i<s->fbw_channels; i++)
362 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
367 * Decode the grouped exponents according to exponent strategy.
368 * reference: Section 7.1.3 Exponent Decoding
370 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
371 uint8_t absexp, int8_t *dexps)
373 int i, j, grp, group_size;
378 group_size = exp_strategy + (exp_strategy == EXP_D45);
379 for(grp=0,i=0; grp<ngrps; grp++) {
380 expacc = get_bits(gbc, 7);
381 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
382 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
383 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
386 /* convert to absolute exps and expand groups */
388 for(i=0,j=0; i<ngrps*3; i++) {
389 prevexp += dexp[i] - 2;
392 switch (group_size) {
393 case 4: dexps[j++] = prevexp;
394 dexps[j++] = prevexp;
395 case 2: dexps[j++] = prevexp;
396 case 1: dexps[j++] = prevexp;
403 * Generate transform coefficients for each coupled channel in the coupling
404 * range using the coupling coefficients and coupling coordinates.
405 * reference: Section 7.4.3 Coupling Coordinate Format
407 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
411 bin = s->start_freq[CPL_CH];
412 for (band = 0; band < s->num_cpl_bands; band++) {
413 int band_start = bin;
414 int band_end = bin + s->cpl_band_sizes[band];
415 for (ch = 1; ch <= s->fbw_channels; ch++) {
416 if (s->channel_in_cpl[ch]) {
417 int cpl_coord = s->cpl_coords[ch][band] << 5;
418 for (bin = band_start; bin < band_end; bin++) {
419 s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
421 if (ch == 2 && s->phase_flags[band]) {
422 for (bin = band_start; bin < band_end; bin++)
423 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
432 * Grouped mantissas for 3-level 5-level and 11-level quantization
444 * Decode the transform coefficients for a particular channel
445 * reference: Section 7.3 Quantization and Decoding of Mantissas
447 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
449 int start_freq = s->start_freq[ch_index];
450 int end_freq = s->end_freq[ch_index];
451 uint8_t *baps = s->bap[ch_index];
452 int8_t *exps = s->dexps[ch_index];
453 int *coeffs = s->fixed_coeffs[ch_index];
454 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
455 GetBitContext *gbc = &s->gbc;
458 for(freq = start_freq; freq < end_freq; freq++){
459 int bap = baps[freq];
464 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
471 mantissa = m->b1_mant[m->b1];
474 int bits = get_bits(gbc, 5);
475 mantissa = b1_mantissas[bits][0];
476 m->b1_mant[1] = b1_mantissas[bits][1];
477 m->b1_mant[0] = b1_mantissas[bits][2];
484 mantissa = m->b2_mant[m->b2];
487 int bits = get_bits(gbc, 7);
488 mantissa = b2_mantissas[bits][0];
489 m->b2_mant[1] = b2_mantissas[bits][1];
490 m->b2_mant[0] = b2_mantissas[bits][2];
495 mantissa = b3_mantissas[get_bits(gbc, 3)];
500 mantissa = m->b4_mant;
503 int bits = get_bits(gbc, 7);
504 mantissa = b4_mantissas[bits][0];
505 m->b4_mant = b4_mantissas[bits][1];
510 mantissa = b5_mantissas[get_bits(gbc, 4)];
512 default: /* 6 to 15 */
513 mantissa = get_bits(gbc, quantization_tab[bap]);
514 /* Shift mantissa and sign-extend it. */
515 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
518 coeffs[freq] = mantissa >> exps[freq];
523 * Remove random dithering from coupling range coefficients with zero-bit
524 * mantissas for coupled channels which do not use dithering.
525 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
527 static void remove_dithering(AC3DecodeContext *s) {
530 for(ch=1; ch<=s->fbw_channels; ch++) {
531 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
532 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
533 if(!s->bap[CPL_CH][i])
534 s->fixed_coeffs[ch][i] = 0;
540 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
543 if (!s->channel_uses_aht[ch]) {
544 ac3_decode_transform_coeffs_ch(s, ch, m);
546 /* if AHT is used, mantissas for all blocks are encoded in the first
547 block of the frame. */
549 if (!blk && CONFIG_EAC3_DECODER)
550 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
551 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
552 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
558 * Decode the transform coefficients.
560 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
566 m.b1 = m.b2 = m.b4 = 0;
568 for (ch = 1; ch <= s->channels; ch++) {
569 /* transform coefficients for full-bandwidth channel */
570 decode_transform_coeffs_ch(s, blk, ch, &m);
571 /* tranform coefficients for coupling channel come right after the
572 coefficients for the first coupled channel*/
573 if (s->channel_in_cpl[ch]) {
575 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
576 calc_transform_coeffs_cpl(s);
579 end = s->end_freq[CPL_CH];
581 end = s->end_freq[ch];
584 s->fixed_coeffs[ch][end] = 0;
588 /* zero the dithered coefficients for appropriate channels */
593 * Stereo rematrixing.
594 * reference: Section 7.5.4 Rematrixing : Decoding Technique
596 static void do_rematrixing(AC3DecodeContext *s)
601 end = FFMIN(s->end_freq[1], s->end_freq[2]);
603 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
604 if(s->rematrixing_flags[bnd]) {
605 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
606 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
607 int tmp0 = s->fixed_coeffs[1][i];
608 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
609 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
616 * Inverse MDCT Transform.
617 * Convert frequency domain coefficients to time-domain audio samples.
618 * reference: Section 7.9.4 Transformation Equations
620 static inline void do_imdct(AC3DecodeContext *s, int channels)
624 for (ch=1; ch<=channels; ch++) {
625 if (s->block_switch[ch]) {
627 float *x = s->tmp_output+128;
629 x[i] = s->transform_coeffs[ch][2*i];
630 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
631 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
633 x[i] = s->transform_coeffs[ch][2*i+1];
634 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch-1], x);
636 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
637 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
638 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
644 * Downmix the output to mono or stereo.
646 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
651 for(i=0; i<len; i++) {
653 for(j=0; j<in_ch; j++) {
654 v0 += samples[j][i] * matrix[j][0];
655 v1 += samples[j][i] * matrix[j][1];
660 } else if(out_ch == 1) {
661 for(i=0; i<len; i++) {
663 for(j=0; j<in_ch; j++)
664 v0 += samples[j][i] * matrix[j][0];
671 * Upmix delay samples from stereo to original channel layout.
673 static void ac3_upmix_delay(AC3DecodeContext *s)
675 int channel_data_size = sizeof(s->delay[0]);
676 switch(s->channel_mode) {
677 case AC3_CHMODE_DUALMONO:
678 case AC3_CHMODE_STEREO:
679 /* upmix mono to stereo */
680 memcpy(s->delay[1], s->delay[0], channel_data_size);
682 case AC3_CHMODE_2F2R:
683 memset(s->delay[3], 0, channel_data_size);
684 case AC3_CHMODE_2F1R:
685 memset(s->delay[2], 0, channel_data_size);
687 case AC3_CHMODE_3F2R:
688 memset(s->delay[4], 0, channel_data_size);
689 case AC3_CHMODE_3F1R:
690 memset(s->delay[3], 0, channel_data_size);
692 memcpy(s->delay[2], s->delay[1], channel_data_size);
693 memset(s->delay[1], 0, channel_data_size);
699 * Decode band structure for coupling, spectral extension, or enhanced coupling.
700 * The band structure defines how many subbands are in each band. For each
701 * subband in the range, 1 means it is combined with the previous band, and 0
702 * means that it starts a new band.
704 * @param[in] gbc bit reader context
705 * @param[in] blk block number
706 * @param[in] eac3 flag to indicate E-AC-3
707 * @param[in] ecpl flag to indicate enhanced coupling
708 * @param[in] start_subband subband number for start of range
709 * @param[in] end_subband subband number for end of range
710 * @param[in] default_band_struct default band structure table
711 * @param[out] num_bands number of bands (optionally NULL)
712 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
714 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
715 int ecpl, int start_subband, int end_subband,
716 const uint8_t *default_band_struct,
717 int *num_bands, uint8_t *band_sizes)
719 int subbnd, bnd, n_subbands, n_bands=0;
721 uint8_t coded_band_struct[22];
722 const uint8_t *band_struct;
724 n_subbands = end_subband - start_subband;
726 /* decode band structure from bitstream or use default */
727 if (!eac3 || get_bits1(gbc)) {
728 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
729 coded_band_struct[subbnd] = get_bits1(gbc);
731 band_struct = coded_band_struct;
733 band_struct = &default_band_struct[start_subband+1];
735 /* no change in band structure */
739 /* calculate number of bands and band sizes based on band structure.
740 note that the first 4 subbands in enhanced coupling span only 6 bins
742 if (num_bands || band_sizes ) {
743 n_bands = n_subbands;
744 bnd_sz[0] = ecpl ? 6 : 12;
745 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
746 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
747 if (band_struct[subbnd-1]) {
749 bnd_sz[bnd] += subbnd_size;
751 bnd_sz[++bnd] = subbnd_size;
756 /* set optional output params */
758 *num_bands = n_bands;
760 memcpy(band_sizes, bnd_sz, n_bands);
764 * Decode a single audio block from the AC-3 bitstream.
766 static int decode_audio_block(AC3DecodeContext *s, int blk)
768 int fbw_channels = s->fbw_channels;
769 int channel_mode = s->channel_mode;
771 int different_transforms;
774 GetBitContext *gbc = &s->gbc;
775 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
777 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
779 /* block switch flags */
780 different_transforms = 0;
781 if (s->block_switch_syntax) {
782 for (ch = 1; ch <= fbw_channels; ch++) {
783 s->block_switch[ch] = get_bits1(gbc);
784 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
785 different_transforms = 1;
789 /* dithering flags */
790 if (s->dither_flag_syntax) {
791 for (ch = 1; ch <= fbw_channels; ch++) {
792 s->dither_flag[ch] = get_bits1(gbc);
797 i = !(s->channel_mode);
800 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
801 s->avctx->drc_scale)+1.0;
802 } else if(blk == 0) {
803 s->dynamic_range[i] = 1.0f;
807 /* spectral extension strategy */
808 if (s->eac3 && (!blk || get_bits1(gbc))) {
809 s->spx_in_use = get_bits1(gbc);
811 int dst_start_freq, dst_end_freq, src_start_freq,
812 start_subband, end_subband;
814 /* determine which channels use spx */
815 if (s->channel_mode == AC3_CHMODE_MONO) {
816 s->channel_uses_spx[1] = 1;
818 for (ch = 1; ch <= fbw_channels; ch++)
819 s->channel_uses_spx[ch] = get_bits1(gbc);
822 /* get the frequency bins of the spx copy region and the spx start
824 dst_start_freq = get_bits(gbc, 2);
825 start_subband = get_bits(gbc, 3) + 2;
826 if (start_subband > 7)
827 start_subband += start_subband - 7;
828 end_subband = get_bits(gbc, 3) + 5;
830 end_subband += end_subband - 7;
831 dst_start_freq = dst_start_freq * 12 + 25;
832 src_start_freq = start_subband * 12 + 25;
833 dst_end_freq = end_subband * 12 + 25;
835 /* check validity of spx ranges */
836 if (start_subband >= end_subband) {
837 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
838 "range (%d >= %d)\n", start_subband, end_subband);
841 if (dst_start_freq >= src_start_freq) {
842 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
843 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
847 s->spx_dst_start_freq = dst_start_freq;
848 s->spx_src_start_freq = src_start_freq;
849 s->spx_dst_end_freq = dst_end_freq;
851 decode_band_structure(gbc, blk, s->eac3, 0,
852 start_subband, end_subband,
853 ff_eac3_default_spx_band_struct,
857 for (ch = 1; ch <= fbw_channels; ch++) {
858 s->channel_uses_spx[ch] = 0;
859 s->first_spx_coords[ch] = 1;
864 /* spectral extension coordinates */
866 for (ch = 1; ch <= fbw_channels; ch++) {
867 if (s->channel_uses_spx[ch]) {
868 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
870 int bin, master_spx_coord;
872 s->first_spx_coords[ch] = 0;
873 spx_blend = get_bits(gbc, 5) * (1.0f/32);
874 master_spx_coord = get_bits(gbc, 2) * 3;
876 bin = s->spx_src_start_freq;
877 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
879 int spx_coord_exp, spx_coord_mant;
880 float nratio, sblend, nblend, spx_coord;
882 /* calculate blending factors */
883 bandsize = s->spx_band_sizes[bnd];
884 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
885 nratio = av_clipf(nratio, 0.0f, 1.0f);
886 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) to give unity variance
887 sblend = sqrtf(1.0f - nratio);
890 /* decode spx coordinates */
891 spx_coord_exp = get_bits(gbc, 4);
892 spx_coord_mant = get_bits(gbc, 2);
893 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
894 else spx_coord_mant += 4;
895 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
896 spx_coord = spx_coord_mant * (1.0f/(1<<23));
898 /* multiply noise and signal blending factors by spx coordinate */
899 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
900 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
904 s->first_spx_coords[ch] = 1;
909 /* coupling strategy */
910 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
911 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
913 s->cpl_in_use[blk] = get_bits1(gbc);
914 if (s->cpl_in_use[blk]) {
915 /* coupling in use */
916 int cpl_start_subband, cpl_end_subband;
918 if (channel_mode < AC3_CHMODE_STEREO) {
919 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
923 /* check for enhanced coupling */
924 if (s->eac3 && get_bits1(gbc)) {
925 /* TODO: parse enhanced coupling strategy info */
926 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
930 /* determine which channels are coupled */
931 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
932 s->channel_in_cpl[1] = 1;
933 s->channel_in_cpl[2] = 1;
935 for (ch = 1; ch <= fbw_channels; ch++)
936 s->channel_in_cpl[ch] = get_bits1(gbc);
939 /* phase flags in use */
940 if (channel_mode == AC3_CHMODE_STEREO)
941 s->phase_flags_in_use = get_bits1(gbc);
943 /* coupling frequency range */
944 cpl_start_subband = get_bits(gbc, 4);
945 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
946 get_bits(gbc, 4) + 3;
947 if (cpl_start_subband >= cpl_end_subband) {
948 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
949 cpl_start_subband, cpl_end_subband);
952 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
953 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
955 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
957 ff_eac3_default_cpl_band_struct,
958 &s->num_cpl_bands, s->cpl_band_sizes);
960 /* coupling not in use */
961 for (ch = 1; ch <= fbw_channels; ch++) {
962 s->channel_in_cpl[ch] = 0;
963 s->first_cpl_coords[ch] = 1;
965 s->first_cpl_leak = s->eac3;
966 s->phase_flags_in_use = 0;
968 } else if (!s->eac3) {
970 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must 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 be present in block 0\n");
1003 /* channel not in coupling */
1004 s->first_cpl_coords[ch] = 1;
1008 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1009 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1010 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1015 /* stereo rematrixing strategy and band structure */
1016 if (channel_mode == AC3_CHMODE_STEREO) {
1017 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1018 s->num_rematrixing_bands = 4;
1019 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1020 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1021 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1022 s->num_rematrixing_bands--;
1024 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
1025 s->rematrixing_flags[bnd] = get_bits1(gbc);
1027 av_log(s->avctx, AV_LOG_WARNING, "Warning: new rematrixing strategy not present in block 0\n");
1028 s->num_rematrixing_bands = 0;
1032 /* exponent strategies for each channel */
1033 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1035 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1036 if(s->exp_strategy[blk][ch] != EXP_REUSE)
1037 bit_alloc_stages[ch] = 3;
1040 /* channel bandwidth */
1041 for (ch = 1; ch <= fbw_channels; ch++) {
1042 s->start_freq[ch] = 0;
1043 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1045 int prev = s->end_freq[ch];
1046 if (s->channel_in_cpl[ch])
1047 s->end_freq[ch] = s->start_freq[CPL_CH];
1048 else if (s->channel_uses_spx[ch])
1049 s->end_freq[ch] = s->spx_src_start_freq;
1051 int bandwidth_code = get_bits(gbc, 6);
1052 if (bandwidth_code > 60) {
1053 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1056 s->end_freq[ch] = bandwidth_code * 3 + 73;
1058 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1059 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
1060 if(blk > 0 && s->end_freq[ch] != prev)
1061 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1064 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1065 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1066 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1069 /* decode exponents for each channel */
1070 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1071 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1072 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1073 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1074 s->num_exp_groups[ch], s->dexps[ch][0],
1075 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1076 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1079 if(ch != CPL_CH && ch != s->lfe_ch)
1080 skip_bits(gbc, 2); /* skip gainrng */
1084 /* bit allocation information */
1085 if (s->bit_allocation_syntax) {
1086 if (get_bits1(gbc)) {
1087 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1088 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1089 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1090 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1091 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1092 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1093 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1095 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1100 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1101 if(!s->eac3 || !blk){
1102 if(s->snr_offset_strategy && get_bits1(gbc)) {
1105 csnr = (get_bits(gbc, 6) - 15) << 4;
1106 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1108 if (ch == i || s->snr_offset_strategy == 2)
1109 snr = (csnr + get_bits(gbc, 4)) << 2;
1110 /* run at least last bit allocation stage if snr offset changes */
1111 if(blk && s->snr_offset[ch] != snr) {
1112 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1114 s->snr_offset[ch] = snr;
1116 /* fast gain (normal AC-3 only) */
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);
1125 } else if (!s->eac3 && !blk) {
1126 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1131 /* fast gain (E-AC-3 only) */
1132 if (s->fast_gain_syntax && get_bits1(gbc)) {
1133 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1134 int prev = s->fast_gain[ch];
1135 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1136 /* run last 2 bit allocation stages if fast gain changes */
1137 if(blk && prev != s->fast_gain[ch])
1138 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1140 } else if (s->eac3 && !blk) {
1141 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1142 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1145 /* E-AC-3 to AC-3 converter SNR offset */
1146 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1147 skip_bits(gbc, 10); // skip converter snr offset
1150 /* coupling leak information */
1152 if (s->first_cpl_leak || get_bits1(gbc)) {
1153 int fl = get_bits(gbc, 3);
1154 int sl = get_bits(gbc, 3);
1155 /* run last 2 bit allocation stages for coupling channel if
1156 coupling leak changes */
1157 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1158 sl != s->bit_alloc_params.cpl_slow_leak)) {
1159 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1161 s->bit_alloc_params.cpl_fast_leak = fl;
1162 s->bit_alloc_params.cpl_slow_leak = sl;
1163 } else if (!s->eac3 && !blk) {
1164 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1167 s->first_cpl_leak = 0;
1170 /* delta bit allocation information */
1171 if (s->dba_syntax && get_bits1(gbc)) {
1172 /* delta bit allocation exists (strategy) */
1173 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1174 s->dba_mode[ch] = get_bits(gbc, 2);
1175 if (s->dba_mode[ch] == DBA_RESERVED) {
1176 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1179 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1181 /* channel delta offset, len and bit allocation */
1182 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1183 if (s->dba_mode[ch] == DBA_NEW) {
1184 s->dba_nsegs[ch] = get_bits(gbc, 3);
1185 for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1186 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1187 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1188 s->dba_values[ch][seg] = get_bits(gbc, 3);
1190 /* run last 2 bit allocation stages if new dba values */
1191 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1194 } else if(blk == 0) {
1195 for(ch=0; ch<=s->channels; ch++) {
1196 s->dba_mode[ch] = DBA_NONE;
1200 /* Bit allocation */
1201 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1202 if(bit_alloc_stages[ch] > 2) {
1203 /* Exponent mapping into PSD and PSD integration */
1204 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1205 s->start_freq[ch], s->end_freq[ch],
1206 s->psd[ch], s->band_psd[ch]);
1208 if(bit_alloc_stages[ch] > 1) {
1209 /* Compute excitation function, Compute masking curve, and
1210 Apply delta bit allocation */
1211 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1212 s->start_freq[ch], s->end_freq[ch],
1213 s->fast_gain[ch], (ch == s->lfe_ch),
1214 s->dba_mode[ch], s->dba_nsegs[ch],
1215 s->dba_offsets[ch], s->dba_lengths[ch],
1216 s->dba_values[ch], s->mask[ch])) {
1217 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1221 if(bit_alloc_stages[ch] > 0) {
1222 /* Compute bit allocation */
1223 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1224 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1225 ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1226 s->start_freq[ch], s->end_freq[ch],
1228 s->bit_alloc_params.floor,
1229 bap_tab, s->bap[ch]);
1233 /* unused dummy data */
1234 if (s->skip_syntax && get_bits1(gbc)) {
1235 int skipl = get_bits(gbc, 9);
1240 /* unpack the transform coefficients
1241 this also uncouples channels if coupling is in use. */
1242 decode_transform_coeffs(s, blk);
1244 /* TODO: generate enhanced coupling coordinates and uncouple */
1246 /* recover coefficients if rematrixing is in use */
1247 if(s->channel_mode == AC3_CHMODE_STEREO)
1250 /* apply scaling to coefficients (headroom, dynrng) */
1251 for(ch=1; ch<=s->channels; ch++) {
1252 float gain = s->mul_bias / 4194304.0f;
1253 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1254 gain *= s->dynamic_range[2-ch];
1256 gain *= s->dynamic_range[0];
1258 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch], 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, s->out_channels, s->fbw_channels, 256);
1286 if(downmix_output) {
1287 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1290 if(downmix_output && !s->downmixed) {
1292 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1295 do_imdct(s, s->out_channels);
1302 * Decode a single AC-3 frame.
1304 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1307 const uint8_t *buf = avpkt->data;
1308 int buf_size = avpkt->size;
1309 AC3DecodeContext *s = avctx->priv_data;
1310 int16_t *out_samples = (int16_t *)data;
1312 const uint8_t *channel_map;
1313 const float *output[AC3_MAX_CHANNELS];
1315 /* copy input buffer to decoder context to avoid reading past the end
1316 of the buffer, which can be caused by a damaged input stream. */
1317 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1318 // seems to be byte-swapped AC-3
1319 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1320 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1322 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1323 buf = s->input_buffer;
1324 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1325 init_get_bits(&s->gbc, buf, buf_size * 8);
1327 /* parse the syncinfo */
1329 err = parse_frame_header(s);
1333 case AAC_AC3_PARSE_ERROR_SYNC:
1334 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1336 case AAC_AC3_PARSE_ERROR_BSID:
1337 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1339 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1340 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1342 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1343 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1345 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1346 /* skip frame if CRC is ok. otherwise use error concealment. */
1347 /* TODO: add support for substreams and dependent frames */
1348 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1349 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1350 return s->frame_size;
1352 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1356 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1360 /* check that reported frame size fits in input buffer */
1361 if (s->frame_size > buf_size) {
1362 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1363 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1364 } else if (avctx->error_recognition >= FF_ER_CAREFUL) {
1365 /* check for crc mismatch */
1366 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1367 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1368 err = AAC_AC3_PARSE_ERROR_CRC;
1373 /* if frame is ok, set audio parameters */
1375 avctx->sample_rate = s->sample_rate;
1376 avctx->bit_rate = s->bit_rate;
1378 /* channel config */
1379 s->out_channels = s->channels;
1380 s->output_mode = s->channel_mode;
1382 s->output_mode |= AC3_OUTPUT_LFEON;
1383 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1384 avctx->request_channels < s->channels) {
1385 s->out_channels = avctx->request_channels;
1386 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1387 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1389 avctx->channels = s->out_channels;
1390 avctx->channel_layout = s->channel_layout;
1392 /* set downmixing coefficients if needed */
1393 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1394 s->fbw_channels == s->out_channels)) {
1395 set_downmix_coeffs(s);
1397 } else if (!s->out_channels) {
1398 s->out_channels = avctx->channels;
1399 if(s->out_channels < s->channels)
1400 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1403 /* decode the audio blocks */
1404 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1405 for (ch = 0; ch < s->out_channels; ch++)
1406 output[ch] = s->output[channel_map[ch]];
1407 for (blk = 0; blk < s->num_blocks; blk++) {
1408 if (!err && decode_audio_block(s, blk)) {
1409 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1412 s->fmt_conv.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1413 out_samples += 256 * s->out_channels;
1415 *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1416 return FFMIN(buf_size, s->frame_size);
1420 * Uninitialize the AC-3 decoder.
1422 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1424 AC3DecodeContext *s = avctx->priv_data;
1425 ff_mdct_end(&s->imdct_512);
1426 ff_mdct_end(&s->imdct_256);
1428 av_freep(&s->input_buffer);
1433 AVCodec ff_ac3_decoder = {
1435 .type = AVMEDIA_TYPE_AUDIO,
1437 .priv_data_size = sizeof (AC3DecodeContext),
1438 .init = ac3_decode_init,
1439 .close = ac3_decode_end,
1440 .decode = ac3_decode_frame,
1441 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1444 #if CONFIG_EAC3_DECODER
1445 AVCodec ff_eac3_decoder = {
1447 .type = AVMEDIA_TYPE_AUDIO,
1448 .id = CODEC_ID_EAC3,
1449 .priv_data_size = sizeof (AC3DecodeContext),
1450 .init = ac3_decode_init,
1451 .close = ac3_decode_end,
1452 .decode = ac3_decode_frame,
1453 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),