cosmetics: line wrap and vertical alignment
[libav.git] / libavcodec / ac3dec.c
1 /*
2 * AC-3 Audio Decoder
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.
5 *
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>
9 *
10 * Portions of this code are derived from liba52
11 * http://liba52.sourceforge.net
12 * Copyright (C) 2000-2003 Michel Lespinasse <walken@zoy.org>
13 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
14 *
15 * This file is part of FFmpeg.
16 *
17 * FFmpeg is free software; you can redistribute it and/or
18 * modify it under the terms of the GNU General Public
19 * License as published by the Free Software Foundation; either
20 * version 2 of the License, or (at your option) any later version.
21 *
22 * FFmpeg is distributed in the hope that it will be useful,
23 * but WITHOUT ANY WARRANTY; without even the implied warranty of
24 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
25 * General Public License for more details.
26 *
27 * You should have received a copy of the GNU General Public
28 * License along with FFmpeg; if not, write to the Free Software
29 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
30 */
31
32 #include <stdio.h>
33 #include <stddef.h>
34 #include <math.h>
35 #include <string.h>
36
37 #include "libavutil/crc.h"
38 #include "internal.h"
39 #include "aac_ac3_parser.h"
40 #include "ac3_parser.h"
41 #include "ac3dec.h"
42 #include "ac3dec_data.h"
43
44 /** Large enough for maximum possible frame size when the specification limit is ignored */
45 #define AC3_FRAME_BUFFER_SIZE 32768
46
47 /**
48 * table for ungrouping 3 values in 7 bits.
49 * used for exponents and bap=2 mantissas
50 */
51 static uint8_t ungroup_3_in_7_bits_tab[128][3];
52
53
54 /** tables for ungrouping mantissas */
55 static int b1_mantissas[32][3];
56 static int b2_mantissas[128][3];
57 static int b3_mantissas[8];
58 static int b4_mantissas[128][2];
59 static int b5_mantissas[16];
60
61 /**
62 * Quantization table: levels for symmetric. bits for asymmetric.
63 * reference: Table 7.18 Mapping of bap to Quantizer
64 */
65 static const uint8_t quantization_tab[16] = {
66 0, 3, 5, 7, 11, 15,
67 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
68 };
69
70 /** dynamic range table. converts codes to scale factors. */
71 static float dynamic_range_tab[256];
72
73 /** Adjustments in dB gain */
74 #define LEVEL_PLUS_3DB 1.4142135623730950
75 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209
76 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145
77 #define LEVEL_MINUS_3DB 0.7071067811865476
78 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605
79 #define LEVEL_MINUS_6DB 0.5000000000000000
80 #define LEVEL_MINUS_9DB 0.3535533905932738
81 #define LEVEL_ZERO 0.0000000000000000
82 #define LEVEL_ONE 1.0000000000000000
83
84 static const float gain_levels[9] = {
85 LEVEL_PLUS_3DB,
86 LEVEL_PLUS_1POINT5DB,
87 LEVEL_ONE,
88 LEVEL_MINUS_1POINT5DB,
89 LEVEL_MINUS_3DB,
90 LEVEL_MINUS_4POINT5DB,
91 LEVEL_MINUS_6DB,
92 LEVEL_ZERO,
93 LEVEL_MINUS_9DB
94 };
95
96 /**
97 * Table for center mix levels
98 * reference: Section 5.4.2.4 cmixlev
99 */
100 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
101
102 /**
103 * Table for surround mix levels
104 * reference: Section 5.4.2.5 surmixlev
105 */
106 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
107
108 /**
109 * Table for default stereo downmixing coefficients
110 * reference: Section 7.8.2 Downmixing Into Two Channels
111 */
112 static const uint8_t ac3_default_coeffs[8][5][2] = {
113 { { 2, 7 }, { 7, 2 }, },
114 { { 4, 4 }, },
115 { { 2, 7 }, { 7, 2 }, },
116 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
117 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
118 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
119 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
120 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
121 };
122
123 /**
124 * Symmetrical Dequantization
125 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
126 * Tables 7.19 to 7.23
127 */
128 static inline int
129 symmetric_dequant(int code, int levels)
130 {
131 return ((code - (levels >> 1)) << 24) / levels;
132 }
133
134 /*
135 * Initialize tables at runtime.
136 */
137 static av_cold void ac3_tables_init(void)
138 {
139 int i;
140
141 /* generate table for ungrouping 3 values in 7 bits
142 reference: Section 7.1.3 Exponent Decoding */
143 for(i=0; i<128; i++) {
144 ungroup_3_in_7_bits_tab[i][0] = i / 25;
145 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
146 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
147 }
148
149 /* generate grouped mantissa tables
150 reference: Section 7.3.5 Ungrouping of Mantissas */
151 for(i=0; i<32; i++) {
152 /* bap=1 mantissas */
153 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
154 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
155 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
156 }
157 for(i=0; i<128; i++) {
158 /* bap=2 mantissas */
159 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
160 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
161 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
162
163 /* bap=4 mantissas */
164 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
165 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
166 }
167 /* generate ungrouped mantissa tables
168 reference: Tables 7.21 and 7.23 */
169 for(i=0; i<7; i++) {
170 /* bap=3 mantissas */
171 b3_mantissas[i] = symmetric_dequant(i, 7);
172 }
173 for(i=0; i<15; i++) {
174 /* bap=5 mantissas */
175 b5_mantissas[i] = symmetric_dequant(i, 15);
176 }
177
178 /* generate dynamic range table
179 reference: Section 7.7.1 Dynamic Range Control */
180 for(i=0; i<256; i++) {
181 int v = (i >> 5) - ((i >> 7) << 3) - 5;
182 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
183 }
184 }
185
186
187 /**
188 * AVCodec initialization
189 */
190 static av_cold int ac3_decode_init(AVCodecContext *avctx)
191 {
192 AC3DecodeContext *s = avctx->priv_data;
193 s->avctx = avctx;
194
195 ac3_common_init();
196 ac3_tables_init();
197 ff_mdct_init(&s->imdct_256, 8, 1);
198 ff_mdct_init(&s->imdct_512, 9, 1);
199 ff_kbd_window_init(s->window, 5.0, 256);
200 dsputil_init(&s->dsp, avctx);
201 av_lfg_init(&s->dith_state, 0);
202
203 /* set bias values for float to int16 conversion */
204 if(s->dsp.float_to_int16_interleave == ff_float_to_int16_interleave_c) {
205 s->add_bias = 385.0f;
206 s->mul_bias = 1.0f;
207 } else {
208 s->add_bias = 0.0f;
209 s->mul_bias = 32767.0f;
210 }
211
212 /* allow downmixing to stereo or mono */
213 if (avctx->channels > 0 && avctx->request_channels > 0 &&
214 avctx->request_channels < avctx->channels &&
215 avctx->request_channels <= 2) {
216 avctx->channels = avctx->request_channels;
217 }
218 s->downmixed = 1;
219
220 /* allocate context input buffer */
221 if (avctx->error_recognition >= FF_ER_CAREFUL) {
222 s->input_buffer = av_mallocz(AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
223 if (!s->input_buffer)
224 return AVERROR_NOMEM;
225 }
226
227 avctx->sample_fmt = SAMPLE_FMT_S16;
228 return 0;
229 }
230
231 /**
232 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
233 * GetBitContext within AC3DecodeContext must point to
234 * the start of the synchronized AC-3 bitstream.
235 */
236 static int ac3_parse_header(AC3DecodeContext *s)
237 {
238 GetBitContext *gbc = &s->gbc;
239 int i;
240
241 /* read the rest of the bsi. read twice for dual mono mode. */
242 i = !(s->channel_mode);
243 do {
244 skip_bits(gbc, 5); // skip dialog normalization
245 if (get_bits1(gbc))
246 skip_bits(gbc, 8); //skip compression
247 if (get_bits1(gbc))
248 skip_bits(gbc, 8); //skip language code
249 if (get_bits1(gbc))
250 skip_bits(gbc, 7); //skip audio production information
251 } while (i--);
252
253 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
254
255 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
256 TODO: read & use the xbsi1 downmix levels */
257 if (get_bits1(gbc))
258 skip_bits(gbc, 14); //skip timecode1 / xbsi1
259 if (get_bits1(gbc))
260 skip_bits(gbc, 14); //skip timecode2 / xbsi2
261
262 /* skip additional bitstream info */
263 if (get_bits1(gbc)) {
264 i = get_bits(gbc, 6);
265 do {
266 skip_bits(gbc, 8);
267 } while(i--);
268 }
269
270 return 0;
271 }
272
273 /**
274 * Common function to parse AC-3 or E-AC-3 frame header
275 */
276 static int parse_frame_header(AC3DecodeContext *s)
277 {
278 AC3HeaderInfo hdr;
279 int err;
280
281 err = ff_ac3_parse_header(&s->gbc, &hdr);
282 if(err)
283 return err;
284
285 /* get decoding parameters from header info */
286 s->bit_alloc_params.sr_code = hdr.sr_code;
287 s->channel_mode = hdr.channel_mode;
288 s->channel_layout = hdr.channel_layout;
289 s->lfe_on = hdr.lfe_on;
290 s->bit_alloc_params.sr_shift = hdr.sr_shift;
291 s->sample_rate = hdr.sample_rate;
292 s->bit_rate = hdr.bit_rate;
293 s->channels = hdr.channels;
294 s->fbw_channels = s->channels - s->lfe_on;
295 s->lfe_ch = s->fbw_channels + 1;
296 s->frame_size = hdr.frame_size;
297 s->center_mix_level = hdr.center_mix_level;
298 s->surround_mix_level = hdr.surround_mix_level;
299 s->num_blocks = hdr.num_blocks;
300 s->frame_type = hdr.frame_type;
301 s->substreamid = hdr.substreamid;
302
303 if(s->lfe_on) {
304 s->start_freq[s->lfe_ch] = 0;
305 s->end_freq[s->lfe_ch] = 7;
306 s->num_exp_groups[s->lfe_ch] = 2;
307 s->channel_in_cpl[s->lfe_ch] = 0;
308 }
309
310 if (hdr.bitstream_id <= 10) {
311 s->eac3 = 0;
312 s->snr_offset_strategy = 2;
313 s->block_switch_syntax = 1;
314 s->dither_flag_syntax = 1;
315 s->bit_allocation_syntax = 1;
316 s->fast_gain_syntax = 0;
317 s->first_cpl_leak = 0;
318 s->dba_syntax = 1;
319 s->skip_syntax = 1;
320 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
321 return ac3_parse_header(s);
322 } else {
323 s->eac3 = 1;
324 return ff_eac3_parse_header(s);
325 }
326 }
327
328 /**
329 * Set stereo downmixing coefficients based on frame header info.
330 * reference: Section 7.8.2 Downmixing Into Two Channels
331 */
332 static void set_downmix_coeffs(AC3DecodeContext *s)
333 {
334 int i;
335 float cmix = gain_levels[center_levels[s->center_mix_level]];
336 float smix = gain_levels[surround_levels[s->surround_mix_level]];
337 float norm0, norm1;
338
339 for(i=0; i<s->fbw_channels; i++) {
340 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
341 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
342 }
343 if(s->channel_mode > 1 && s->channel_mode & 1) {
344 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
345 }
346 if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
347 int nf = s->channel_mode - 2;
348 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
349 }
350 if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
351 int nf = s->channel_mode - 4;
352 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
353 }
354
355 /* renormalize */
356 norm0 = norm1 = 0.0;
357 for(i=0; i<s->fbw_channels; i++) {
358 norm0 += s->downmix_coeffs[i][0];
359 norm1 += s->downmix_coeffs[i][1];
360 }
361 norm0 = 1.0f / norm0;
362 norm1 = 1.0f / norm1;
363 for(i=0; i<s->fbw_channels; i++) {
364 s->downmix_coeffs[i][0] *= norm0;
365 s->downmix_coeffs[i][1] *= norm1;
366 }
367
368 if(s->output_mode == AC3_CHMODE_MONO) {
369 for(i=0; i<s->fbw_channels; i++)
370 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
371 }
372 }
373
374 /**
375 * Decode the grouped exponents according to exponent strategy.
376 * reference: Section 7.1.3 Exponent Decoding
377 */
378 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
379 uint8_t absexp, int8_t *dexps)
380 {
381 int i, j, grp, group_size;
382 int dexp[256];
383 int expacc, prevexp;
384
385 /* unpack groups */
386 group_size = exp_strategy + (exp_strategy == EXP_D45);
387 for(grp=0,i=0; grp<ngrps; grp++) {
388 expacc = get_bits(gbc, 7);
389 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
390 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
391 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
392 }
393
394 /* convert to absolute exps and expand groups */
395 prevexp = absexp;
396 for(i=0,j=0; i<ngrps*3; i++) {
397 prevexp += dexp[i] - 2;
398 if (prevexp > 24U)
399 return -1;
400 switch (group_size) {
401 case 4: dexps[j++] = prevexp;
402 dexps[j++] = prevexp;
403 case 2: dexps[j++] = prevexp;
404 case 1: dexps[j++] = prevexp;
405 }
406 }
407 return 0;
408 }
409
410 /**
411 * Generate transform coefficients for each coupled channel in the coupling
412 * range using the coupling coefficients and coupling coordinates.
413 * reference: Section 7.4.3 Coupling Coordinate Format
414 */
415 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
416 {
417 int i, j, ch, bnd, subbnd;
418
419 subbnd = -1;
420 i = s->start_freq[CPL_CH];
421 for(bnd=0; bnd<s->num_cpl_bands; bnd++) {
422 do {
423 subbnd++;
424 for(j=0; j<12; j++) {
425 for(ch=1; ch<=s->fbw_channels; ch++) {
426 if(s->channel_in_cpl[ch]) {
427 s->fixed_coeffs[ch][i] = ((int64_t)s->fixed_coeffs[CPL_CH][i] * (int64_t)s->cpl_coords[ch][bnd]) >> 23;
428 if (ch == 2 && s->phase_flags[bnd])
429 s->fixed_coeffs[ch][i] = -s->fixed_coeffs[ch][i];
430 }
431 }
432 i++;
433 }
434 } while(s->cpl_band_struct[subbnd]);
435 }
436 }
437
438 /**
439 * Grouped mantissas for 3-level 5-level and 11-level quantization
440 */
441 typedef struct {
442 int b1_mant[3];
443 int b2_mant[3];
444 int b4_mant[2];
445 int b1ptr;
446 int b2ptr;
447 int b4ptr;
448 } mant_groups;
449
450 /**
451 * Decode the transform coefficients for a particular channel
452 * reference: Section 7.3 Quantization and Decoding of Mantissas
453 */
454 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
455 {
456 GetBitContext *gbc = &s->gbc;
457 int i, gcode, tbap, start, end;
458 uint8_t *exps;
459 uint8_t *bap;
460 int *coeffs;
461
462 exps = s->dexps[ch_index];
463 bap = s->bap[ch_index];
464 coeffs = s->fixed_coeffs[ch_index];
465 start = s->start_freq[ch_index];
466 end = s->end_freq[ch_index];
467
468 for (i = start; i < end; i++) {
469 tbap = bap[i];
470 switch (tbap) {
471 case 0:
472 coeffs[i] = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
473 break;
474
475 case 1:
476 if(m->b1ptr > 2) {
477 gcode = get_bits(gbc, 5);
478 m->b1_mant[0] = b1_mantissas[gcode][0];
479 m->b1_mant[1] = b1_mantissas[gcode][1];
480 m->b1_mant[2] = b1_mantissas[gcode][2];
481 m->b1ptr = 0;
482 }
483 coeffs[i] = m->b1_mant[m->b1ptr++];
484 break;
485
486 case 2:
487 if(m->b2ptr > 2) {
488 gcode = get_bits(gbc, 7);
489 m->b2_mant[0] = b2_mantissas[gcode][0];
490 m->b2_mant[1] = b2_mantissas[gcode][1];
491 m->b2_mant[2] = b2_mantissas[gcode][2];
492 m->b2ptr = 0;
493 }
494 coeffs[i] = m->b2_mant[m->b2ptr++];
495 break;
496
497 case 3:
498 coeffs[i] = b3_mantissas[get_bits(gbc, 3)];
499 break;
500
501 case 4:
502 if(m->b4ptr > 1) {
503 gcode = get_bits(gbc, 7);
504 m->b4_mant[0] = b4_mantissas[gcode][0];
505 m->b4_mant[1] = b4_mantissas[gcode][1];
506 m->b4ptr = 0;
507 }
508 coeffs[i] = m->b4_mant[m->b4ptr++];
509 break;
510
511 case 5:
512 coeffs[i] = b5_mantissas[get_bits(gbc, 4)];
513 break;
514
515 default: {
516 /* asymmetric dequantization */
517 int qlevel = quantization_tab[tbap];
518 coeffs[i] = get_sbits(gbc, qlevel) << (24 - qlevel);
519 break;
520 }
521 }
522 coeffs[i] >>= exps[i];
523 }
524 }
525
526 /**
527 * Remove random dithering from coefficients with zero-bit mantissas
528 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
529 */
530 static void remove_dithering(AC3DecodeContext *s) {
531 int ch, i;
532 int end=0;
533 int *coeffs;
534 uint8_t *bap;
535
536 for(ch=1; ch<=s->fbw_channels; ch++) {
537 if(!s->dither_flag[ch]) {
538 coeffs = s->fixed_coeffs[ch];
539 bap = s->bap[ch];
540 if(s->channel_in_cpl[ch])
541 end = s->start_freq[CPL_CH];
542 else
543 end = s->end_freq[ch];
544 for(i=0; i<end; i++) {
545 if(!bap[i])
546 coeffs[i] = 0;
547 }
548 if(s->channel_in_cpl[ch]) {
549 bap = s->bap[CPL_CH];
550 for(; i<s->end_freq[CPL_CH]; i++) {
551 if(!bap[i])
552 coeffs[i] = 0;
553 }
554 }
555 }
556 }
557 }
558
559 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
560 mant_groups *m)
561 {
562 if (!s->channel_uses_aht[ch]) {
563 ac3_decode_transform_coeffs_ch(s, ch, m);
564 } else {
565 /* if AHT is used, mantissas for all blocks are encoded in the first
566 block of the frame. */
567 int bin;
568 if (!blk)
569 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
570 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
571 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
572 }
573 }
574 }
575
576 /**
577 * Decode the transform coefficients.
578 */
579 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
580 {
581 int ch, end;
582 int got_cplchan = 0;
583 mant_groups m;
584
585 m.b1ptr = m.b2ptr = m.b4ptr = 3;
586
587 for (ch = 1; ch <= s->channels; ch++) {
588 /* transform coefficients for full-bandwidth channel */
589 decode_transform_coeffs_ch(s, blk, ch, &m);
590 /* tranform coefficients for coupling channel come right after the
591 coefficients for the first coupled channel*/
592 if (s->channel_in_cpl[ch]) {
593 if (!got_cplchan) {
594 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
595 calc_transform_coeffs_cpl(s);
596 got_cplchan = 1;
597 }
598 end = s->end_freq[CPL_CH];
599 } else {
600 end = s->end_freq[ch];
601 }
602 do
603 s->fixed_coeffs[ch][end] = 0;
604 while(++end < 256);
605 }
606
607 /* zero the dithered coefficients for appropriate channels */
608 remove_dithering(s);
609 }
610
611 /**
612 * Stereo rematrixing.
613 * reference: Section 7.5.4 Rematrixing : Decoding Technique
614 */
615 static void do_rematrixing(AC3DecodeContext *s)
616 {
617 int bnd, i;
618 int end, bndend;
619 int tmp0, tmp1;
620
621 end = FFMIN(s->end_freq[1], s->end_freq[2]);
622
623 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
624 if(s->rematrixing_flags[bnd]) {
625 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
626 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
627 tmp0 = s->fixed_coeffs[1][i];
628 tmp1 = s->fixed_coeffs[2][i];
629 s->fixed_coeffs[1][i] = tmp0 + tmp1;
630 s->fixed_coeffs[2][i] = tmp0 - tmp1;
631 }
632 }
633 }
634 }
635
636 /**
637 * Inverse MDCT Transform.
638 * Convert frequency domain coefficients to time-domain audio samples.
639 * reference: Section 7.9.4 Transformation Equations
640 */
641 static inline void do_imdct(AC3DecodeContext *s, int channels)
642 {
643 int ch;
644 float add_bias = s->add_bias;
645 if(s->out_channels==1 && channels>1)
646 add_bias *= LEVEL_MINUS_3DB; // compensate for the gain in downmix
647
648 for (ch=1; ch<=channels; ch++) {
649 if (s->block_switch[ch]) {
650 int i;
651 float *x = s->tmp_output+128;
652 for(i=0; i<128; i++)
653 x[i] = s->transform_coeffs[ch][2*i];
654 ff_imdct_half(&s->imdct_256, s->tmp_output, x);
655 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
656 for(i=0; i<128; i++)
657 x[i] = s->transform_coeffs[ch][2*i+1];
658 ff_imdct_half(&s->imdct_256, s->delay[ch-1], x);
659 } else {
660 ff_imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
661 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
662 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
663 }
664 }
665 }
666
667 /**
668 * Downmix the output to mono or stereo.
669 */
670 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
671 {
672 int i, j;
673 float v0, v1;
674 if(out_ch == 2) {
675 for(i=0; i<len; i++) {
676 v0 = v1 = 0.0f;
677 for(j=0; j<in_ch; j++) {
678 v0 += samples[j][i] * matrix[j][0];
679 v1 += samples[j][i] * matrix[j][1];
680 }
681 samples[0][i] = v0;
682 samples[1][i] = v1;
683 }
684 } else if(out_ch == 1) {
685 for(i=0; i<len; i++) {
686 v0 = 0.0f;
687 for(j=0; j<in_ch; j++)
688 v0 += samples[j][i] * matrix[j][0];
689 samples[0][i] = v0;
690 }
691 }
692 }
693
694 /**
695 * Upmix delay samples from stereo to original channel layout.
696 */
697 static void ac3_upmix_delay(AC3DecodeContext *s)
698 {
699 int channel_data_size = sizeof(s->delay[0]);
700 switch(s->channel_mode) {
701 case AC3_CHMODE_DUALMONO:
702 case AC3_CHMODE_STEREO:
703 /* upmix mono to stereo */
704 memcpy(s->delay[1], s->delay[0], channel_data_size);
705 break;
706 case AC3_CHMODE_2F2R:
707 memset(s->delay[3], 0, channel_data_size);
708 case AC3_CHMODE_2F1R:
709 memset(s->delay[2], 0, channel_data_size);
710 break;
711 case AC3_CHMODE_3F2R:
712 memset(s->delay[4], 0, channel_data_size);
713 case AC3_CHMODE_3F1R:
714 memset(s->delay[3], 0, channel_data_size);
715 case AC3_CHMODE_3F:
716 memcpy(s->delay[2], s->delay[1], channel_data_size);
717 memset(s->delay[1], 0, channel_data_size);
718 break;
719 }
720 }
721
722 /**
723 * Decode band structure for coupling, spectral extension, or enhanced coupling.
724 * @param[in] gbc bit reader context
725 * @param[in] blk block number
726 * @param[in] eac3 flag to indicate E-AC-3
727 * @param[in] ecpl flag to indicate enhanced coupling
728 * @param[in] start_subband subband number for start of range
729 * @param[in] end_subband subband number for end of range
730 * @param[in] default_band_struct default band structure table
731 * @param[out] band_struct decoded band structure
732 * @param[out] num_bands number of bands (optionally NULL)
733 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
734 */
735 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
736 int ecpl, int start_subband, int end_subband,
737 const uint8_t *default_band_struct,
738 uint8_t *band_struct, int *num_bands,
739 uint8_t *band_sizes)
740 {
741 int subbnd, bnd, n_subbands, n_bands=0;
742 uint8_t bnd_sz[22];
743
744 n_subbands = end_subband - start_subband;
745
746 /* decode band structure from bitstream or use default */
747 if (!eac3 || get_bits1(gbc)) {
748 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
749 band_struct[subbnd] = get_bits1(gbc);
750 }
751 } else if (!blk) {
752 memcpy(band_struct,
753 &default_band_struct[start_subband+1],
754 n_subbands-1);
755 }
756 band_struct[n_subbands-1] = 0;
757
758 /* calculate number of bands and band sizes based on band structure.
759 note that the first 4 subbands in enhanced coupling span only 6 bins
760 instead of 12. */
761 if (num_bands || band_sizes ) {
762 n_bands = n_subbands;
763 bnd_sz[0] = ecpl ? 6 : 12;
764 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
765 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
766 if (band_struct[subbnd-1]) {
767 n_bands--;
768 bnd_sz[bnd] += subbnd_size;
769 } else {
770 bnd_sz[++bnd] = subbnd_size;
771 }
772 }
773 }
774
775 /* set optional output params */
776 if (num_bands)
777 *num_bands = n_bands;
778 if (band_sizes)
779 memcpy(band_sizes, bnd_sz, n_bands);
780 }
781
782 /**
783 * Decode a single audio block from the AC-3 bitstream.
784 */
785 static int decode_audio_block(AC3DecodeContext *s, int blk)
786 {
787 int fbw_channels = s->fbw_channels;
788 int channel_mode = s->channel_mode;
789 int i, bnd, seg, ch;
790 int different_transforms;
791 int downmix_output;
792 int cpl_in_use;
793 GetBitContext *gbc = &s->gbc;
794 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
795
796 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
797
798 /* block switch flags */
799 different_transforms = 0;
800 if (s->block_switch_syntax) {
801 for (ch = 1; ch <= fbw_channels; ch++) {
802 s->block_switch[ch] = get_bits1(gbc);
803 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
804 different_transforms = 1;
805 }
806 }
807
808 /* dithering flags */
809 if (s->dither_flag_syntax) {
810 for (ch = 1; ch <= fbw_channels; ch++) {
811 s->dither_flag[ch] = get_bits1(gbc);
812 }
813 }
814
815 /* dynamic range */
816 i = !(s->channel_mode);
817 do {
818 if(get_bits1(gbc)) {
819 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
820 s->avctx->drc_scale)+1.0;
821 } else if(blk == 0) {
822 s->dynamic_range[i] = 1.0f;
823 }
824 } while(i--);
825
826 /* spectral extension strategy */
827 if (s->eac3 && (!blk || get_bits1(gbc))) {
828 if (get_bits1(gbc)) {
829 ff_log_missing_feature(s->avctx, "Spectral extension", 1);
830 return -1;
831 }
832 /* TODO: parse spectral extension strategy info */
833 }
834
835 /* TODO: spectral extension coordinates */
836
837 /* coupling strategy */
838 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
839 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
840 if (!s->eac3)
841 s->cpl_in_use[blk] = get_bits1(gbc);
842 if (s->cpl_in_use[blk]) {
843 /* coupling in use */
844 int cpl_start_subband, cpl_end_subband;
845
846 if (channel_mode < AC3_CHMODE_STEREO) {
847 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
848 return -1;
849 }
850
851 /* check for enhanced coupling */
852 if (s->eac3 && get_bits1(gbc)) {
853 /* TODO: parse enhanced coupling strategy info */
854 ff_log_missing_feature(s->avctx, "Enhanced coupling", 1);
855 return -1;
856 }
857
858 /* determine which channels are coupled */
859 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
860 s->channel_in_cpl[1] = 1;
861 s->channel_in_cpl[2] = 1;
862 } else {
863 for (ch = 1; ch <= fbw_channels; ch++)
864 s->channel_in_cpl[ch] = get_bits1(gbc);
865 }
866
867 /* phase flags in use */
868 if (channel_mode == AC3_CHMODE_STEREO)
869 s->phase_flags_in_use = get_bits1(gbc);
870
871 /* coupling frequency range */
872 /* TODO: modify coupling end freq if spectral extension is used */
873 cpl_start_subband = get_bits(gbc, 4);
874 cpl_end_subband = get_bits(gbc, 4) + 3;
875 if (cpl_start_subband > cpl_end_subband) {
876 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d > %d)\n",
877 cpl_start_subband, cpl_end_subband);
878 return -1;
879 }
880 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
881 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
882
883 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
884 cpl_end_subband,
885 ff_eac3_default_cpl_band_struct,
886 s->cpl_band_struct, &s->num_cpl_bands, NULL);
887 } else {
888 /* coupling not in use */
889 for (ch = 1; ch <= fbw_channels; ch++) {
890 s->channel_in_cpl[ch] = 0;
891 s->first_cpl_coords[ch] = 1;
892 }
893 s->first_cpl_leak = s->eac3;
894 s->phase_flags_in_use = 0;
895 }
896 } else if (!s->eac3) {
897 if(!blk) {
898 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
899 return -1;
900 } else {
901 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
902 }
903 }
904 cpl_in_use = s->cpl_in_use[blk];
905
906 /* coupling coordinates */
907 if (cpl_in_use) {
908 int cpl_coords_exist = 0;
909
910 for (ch = 1; ch <= fbw_channels; ch++) {
911 if (s->channel_in_cpl[ch]) {
912 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
913 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
914 s->first_cpl_coords[ch] = 0;
915 cpl_coords_exist = 1;
916 master_cpl_coord = 3 * get_bits(gbc, 2);
917 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
918 cpl_coord_exp = get_bits(gbc, 4);
919 cpl_coord_mant = get_bits(gbc, 4);
920 if (cpl_coord_exp == 15)
921 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
922 else
923 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
924 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
925 }
926 } else if (!blk) {
927 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
928 return -1;
929 }
930 } else {
931 /* channel not in coupling */
932 s->first_cpl_coords[ch] = 1;
933 }
934 }
935 /* phase flags */
936 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
937 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
938 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
939 }
940 }
941 }
942
943 /* stereo rematrixing strategy and band structure */
944 if (channel_mode == AC3_CHMODE_STEREO) {
945 if ((s->eac3 && !blk) || get_bits1(gbc)) {
946 s->num_rematrixing_bands = 4;
947 if(cpl_in_use && s->start_freq[CPL_CH] <= 61)
948 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
949 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
950 s->rematrixing_flags[bnd] = get_bits1(gbc);
951 } else if (!blk) {
952 av_log(s->avctx, AV_LOG_ERROR, "new rematrixing strategy must be present in block 0\n");
953 return -1;
954 }
955 }
956
957 /* exponent strategies for each channel */
958 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
959 if (!s->eac3)
960 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
961 if(s->exp_strategy[blk][ch] != EXP_REUSE)
962 bit_alloc_stages[ch] = 3;
963 }
964
965 /* channel bandwidth */
966 for (ch = 1; ch <= fbw_channels; ch++) {
967 s->start_freq[ch] = 0;
968 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
969 int group_size;
970 int prev = s->end_freq[ch];
971 if (s->channel_in_cpl[ch])
972 s->end_freq[ch] = s->start_freq[CPL_CH];
973 else {
974 int bandwidth_code = get_bits(gbc, 6);
975 if (bandwidth_code > 60) {
976 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
977 return -1;
978 }
979 s->end_freq[ch] = bandwidth_code * 3 + 73;
980 }
981 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
982 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
983 if(blk > 0 && s->end_freq[ch] != prev)
984 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
985 }
986 }
987 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
988 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
989 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
990 }
991
992 /* decode exponents for each channel */
993 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
994 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
995 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
996 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
997 s->num_exp_groups[ch], s->dexps[ch][0],
998 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
999 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1000 return -1;
1001 }
1002 if(ch != CPL_CH && ch != s->lfe_ch)
1003 skip_bits(gbc, 2); /* skip gainrng */
1004 }
1005 }
1006
1007 /* bit allocation information */
1008 if (s->bit_allocation_syntax) {
1009 if (get_bits1(gbc)) {
1010 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1011 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1012 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1013 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1014 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1015 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1016 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1017 } else if (!blk) {
1018 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1019 return -1;
1020 }
1021 }
1022
1023 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1024 if(!s->eac3 || !blk){
1025 if(s->snr_offset_strategy && get_bits1(gbc)) {
1026 int snr = 0;
1027 int csnr;
1028 csnr = (get_bits(gbc, 6) - 15) << 4;
1029 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1030 /* snr offset */
1031 if (ch == i || s->snr_offset_strategy == 2)
1032 snr = (csnr + get_bits(gbc, 4)) << 2;
1033 /* run at least last bit allocation stage if snr offset changes */
1034 if(blk && s->snr_offset[ch] != snr) {
1035 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1036 }
1037 s->snr_offset[ch] = snr;
1038
1039 /* fast gain (normal AC-3 only) */
1040 if (!s->eac3) {
1041 int prev = s->fast_gain[ch];
1042 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1043 /* run last 2 bit allocation stages if fast gain changes */
1044 if(blk && prev != s->fast_gain[ch])
1045 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1046 }
1047 }
1048 } else if (!s->eac3 && !blk) {
1049 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1050 return -1;
1051 }
1052 }
1053
1054 /* fast gain (E-AC-3 only) */
1055 if (s->fast_gain_syntax && get_bits1(gbc)) {
1056 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1057 int prev = s->fast_gain[ch];
1058 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1059 /* run last 2 bit allocation stages if fast gain changes */
1060 if(blk && prev != s->fast_gain[ch])
1061 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1062 }
1063 } else if (s->eac3 && !blk) {
1064 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1065 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1066 }
1067
1068 /* E-AC-3 to AC-3 converter SNR offset */
1069 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1070 skip_bits(gbc, 10); // skip converter snr offset
1071 }
1072
1073 /* coupling leak information */
1074 if (cpl_in_use) {
1075 if (s->first_cpl_leak || get_bits1(gbc)) {
1076 int fl = get_bits(gbc, 3);
1077 int sl = get_bits(gbc, 3);
1078 /* run last 2 bit allocation stages for coupling channel if
1079 coupling leak changes */
1080 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1081 sl != s->bit_alloc_params.cpl_slow_leak)) {
1082 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1083 }
1084 s->bit_alloc_params.cpl_fast_leak = fl;
1085 s->bit_alloc_params.cpl_slow_leak = sl;
1086 } else if (!s->eac3 && !blk) {
1087 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1088 return -1;
1089 }
1090 s->first_cpl_leak = 0;
1091 }
1092
1093 /* delta bit allocation information */
1094 if (s->dba_syntax && get_bits1(gbc)) {
1095 /* delta bit allocation exists (strategy) */
1096 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1097 s->dba_mode[ch] = get_bits(gbc, 2);
1098 if (s->dba_mode[ch] == DBA_RESERVED) {
1099 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1100 return -1;
1101 }
1102 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1103 }
1104 /* channel delta offset, len and bit allocation */
1105 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1106 if (s->dba_mode[ch] == DBA_NEW) {
1107 s->dba_nsegs[ch] = get_bits(gbc, 3);
1108 for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1109 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1110 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1111 s->dba_values[ch][seg] = get_bits(gbc, 3);
1112 }
1113 /* run last 2 bit allocation stages if new dba values */
1114 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1115 }
1116 }
1117 } else if(blk == 0) {
1118 for(ch=0; ch<=s->channels; ch++) {
1119 s->dba_mode[ch] = DBA_NONE;
1120 }
1121 }
1122
1123 /* Bit allocation */
1124 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1125 if(bit_alloc_stages[ch] > 2) {
1126 /* Exponent mapping into PSD and PSD integration */
1127 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1128 s->start_freq[ch], s->end_freq[ch],
1129 s->psd[ch], s->band_psd[ch]);
1130 }
1131 if(bit_alloc_stages[ch] > 1) {
1132 /* Compute excitation function, Compute masking curve, and
1133 Apply delta bit allocation */
1134 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1135 s->start_freq[ch], s->end_freq[ch],
1136 s->fast_gain[ch], (ch == s->lfe_ch),
1137 s->dba_mode[ch], s->dba_nsegs[ch],
1138 s->dba_offsets[ch], s->dba_lengths[ch],
1139 s->dba_values[ch], s->mask[ch])) {
1140 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1141 return -1;
1142 }
1143 }
1144 if(bit_alloc_stages[ch] > 0) {
1145 /* Compute bit allocation */
1146 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1147 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1148 ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1149 s->start_freq[ch], s->end_freq[ch],
1150 s->snr_offset[ch],
1151 s->bit_alloc_params.floor,
1152 bap_tab, s->bap[ch]);
1153 }
1154 }
1155
1156 /* unused dummy data */
1157 if (s->skip_syntax && get_bits1(gbc)) {
1158 int skipl = get_bits(gbc, 9);
1159 while(skipl--)
1160 skip_bits(gbc, 8);
1161 }
1162
1163 /* unpack the transform coefficients
1164 this also uncouples channels if coupling is in use. */
1165 decode_transform_coeffs(s, blk);
1166
1167 /* TODO: generate enhanced coupling coordinates and uncouple */
1168
1169 /* TODO: apply spectral extension */
1170
1171 /* recover coefficients if rematrixing is in use */
1172 if(s->channel_mode == AC3_CHMODE_STEREO)
1173 do_rematrixing(s);
1174
1175 /* apply scaling to coefficients (headroom, dynrng) */
1176 for(ch=1; ch<=s->channels; ch++) {
1177 float gain = s->mul_bias / 4194304.0f;
1178 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1179 gain *= s->dynamic_range[ch-1];
1180 } else {
1181 gain *= s->dynamic_range[0];
1182 }
1183 s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1184 }
1185
1186 /* downmix and MDCT. order depends on whether block switching is used for
1187 any channel in this block. this is because coefficients for the long
1188 and short transforms cannot be mixed. */
1189 downmix_output = s->channels != s->out_channels &&
1190 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1191 s->fbw_channels == s->out_channels);
1192 if(different_transforms) {
1193 /* the delay samples have already been downmixed, so we upmix the delay
1194 samples in order to reconstruct all channels before downmixing. */
1195 if(s->downmixed) {
1196 s->downmixed = 0;
1197 ac3_upmix_delay(s);
1198 }
1199
1200 do_imdct(s, s->channels);
1201
1202 if(downmix_output) {
1203 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1204 }
1205 } else {
1206 if(downmix_output) {
1207 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1208 }
1209
1210 if(downmix_output && !s->downmixed) {
1211 s->downmixed = 1;
1212 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1213 }
1214
1215 do_imdct(s, s->out_channels);
1216 }
1217
1218 return 0;
1219 }
1220
1221 /**
1222 * Decode a single AC-3 frame.
1223 */
1224 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1225 AVPacket *avpkt)
1226 {
1227 const uint8_t *buf = avpkt->data;
1228 int buf_size = avpkt->size;
1229 AC3DecodeContext *s = avctx->priv_data;
1230 int16_t *out_samples = (int16_t *)data;
1231 int blk, ch, err;
1232 const uint8_t *channel_map;
1233 const float *output[AC3_MAX_CHANNELS];
1234
1235 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1236 if (s->input_buffer) {
1237 /* copy input buffer to decoder context to avoid reading past the end
1238 of the buffer, which can be caused by a damaged input stream. */
1239 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1240 init_get_bits(&s->gbc, s->input_buffer, buf_size * 8);
1241 } else {
1242 init_get_bits(&s->gbc, buf, buf_size * 8);
1243 }
1244
1245 /* parse the syncinfo */
1246 *data_size = 0;
1247 err = parse_frame_header(s);
1248
1249 /* check that reported frame size fits in input buffer */
1250 if(s->frame_size > buf_size) {
1251 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1252 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1253 }
1254
1255 /* check for crc mismatch */
1256 if(err != AAC_AC3_PARSE_ERROR_FRAME_SIZE && avctx->error_recognition >= FF_ER_CAREFUL) {
1257 if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1258 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1259 err = AAC_AC3_PARSE_ERROR_CRC;
1260 }
1261 }
1262
1263 if(err && err != AAC_AC3_PARSE_ERROR_CRC) {
1264 switch(err) {
1265 case AAC_AC3_PARSE_ERROR_SYNC:
1266 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1267 return -1;
1268 case AAC_AC3_PARSE_ERROR_BSID:
1269 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1270 break;
1271 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1272 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1273 break;
1274 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1275 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1276 break;
1277 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1278 /* skip frame if CRC is ok. otherwise use error concealment. */
1279 /* TODO: add support for substreams and dependent frames */
1280 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1281 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1282 return s->frame_size;
1283 } else {
1284 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1285 }
1286 break;
1287 default:
1288 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1289 break;
1290 }
1291 }
1292
1293 /* if frame is ok, set audio parameters */
1294 if (!err) {
1295 avctx->sample_rate = s->sample_rate;
1296 avctx->bit_rate = s->bit_rate;
1297
1298 /* channel config */
1299 s->out_channels = s->channels;
1300 s->output_mode = s->channel_mode;
1301 if(s->lfe_on)
1302 s->output_mode |= AC3_OUTPUT_LFEON;
1303 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1304 avctx->request_channels < s->channels) {
1305 s->out_channels = avctx->request_channels;
1306 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1307 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1308 }
1309 avctx->channels = s->out_channels;
1310 avctx->channel_layout = s->channel_layout;
1311
1312 /* set downmixing coefficients if needed */
1313 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1314 s->fbw_channels == s->out_channels)) {
1315 set_downmix_coeffs(s);
1316 }
1317 } else if (!s->out_channels) {
1318 s->out_channels = avctx->channels;
1319 if(s->out_channels < s->channels)
1320 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1321 }
1322
1323 /* decode the audio blocks */
1324 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1325 for (ch = 0; ch < s->out_channels; ch++)
1326 output[ch] = s->output[channel_map[ch]];
1327 for (blk = 0; blk < s->num_blocks; blk++) {
1328 if (!err && decode_audio_block(s, blk)) {
1329 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1330 err = 1;
1331 }
1332 s->dsp.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1333 out_samples += 256 * s->out_channels;
1334 }
1335 *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1336 return s->frame_size;
1337 }
1338
1339 /**
1340 * Uninitialize the AC-3 decoder.
1341 */
1342 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1343 {
1344 AC3DecodeContext *s = avctx->priv_data;
1345 ff_mdct_end(&s->imdct_512);
1346 ff_mdct_end(&s->imdct_256);
1347
1348 av_freep(&s->input_buffer);
1349
1350 return 0;
1351 }
1352
1353 AVCodec ac3_decoder = {
1354 .name = "ac3",
1355 .type = CODEC_TYPE_AUDIO,
1356 .id = CODEC_ID_AC3,
1357 .priv_data_size = sizeof (AC3DecodeContext),
1358 .init = ac3_decode_init,
1359 .close = ac3_decode_end,
1360 .decode = ac3_decode_frame,
1361 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1362 };
1363
1364 AVCodec eac3_decoder = {
1365 .name = "eac3",
1366 .type = CODEC_TYPE_AUDIO,
1367 .id = CODEC_ID_EAC3,
1368 .priv_data_size = sizeof (AC3DecodeContext),
1369 .init = ac3_decode_init,
1370 .close = ac3_decode_end,
1371 .decode = ac3_decode_frame,
1372 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1373 };