33c5f742e5c248a257b50dc6b6ebb9e20e25b308
[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 * This file is part of FFmpeg.
11 *
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.
16 *
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.
21 *
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
25 */
26
27 #include <stdio.h>
28 #include <stddef.h>
29 #include <math.h>
30 #include <string.h>
31
32 #include "libavutil/crc.h"
33 #include "internal.h"
34 #include "aac_ac3_parser.h"
35 #include "ac3_parser.h"
36 #include "ac3dec.h"
37 #include "ac3dec_data.h"
38
39 /** Large enough for maximum possible frame size when the specification limit is ignored */
40 #define AC3_FRAME_BUFFER_SIZE 32768
41
42 /**
43 * table for ungrouping 3 values in 7 bits.
44 * used for exponents and bap=2 mantissas
45 */
46 static uint8_t ungroup_3_in_7_bits_tab[128][3];
47
48
49 /** tables for ungrouping mantissas */
50 static int b1_mantissas[32][3];
51 static int b2_mantissas[128][3];
52 static int b3_mantissas[8];
53 static int b4_mantissas[128][2];
54 static int b5_mantissas[16];
55
56 /**
57 * Quantization table: levels for symmetric. bits for asymmetric.
58 * reference: Table 7.18 Mapping of bap to Quantizer
59 */
60 static const uint8_t quantization_tab[16] = {
61 0, 3, 5, 7, 11, 15,
62 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
63 };
64
65 /** dynamic range table. converts codes to scale factors. */
66 static float dynamic_range_tab[256];
67
68 /** Adjustments in dB gain */
69 #define LEVEL_PLUS_3DB 1.4142135623730950
70 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209
71 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145
72 #define LEVEL_MINUS_3DB 0.7071067811865476
73 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605
74 #define LEVEL_MINUS_6DB 0.5000000000000000
75 #define LEVEL_MINUS_9DB 0.3535533905932738
76 #define LEVEL_ZERO 0.0000000000000000
77 #define LEVEL_ONE 1.0000000000000000
78
79 static const float gain_levels[9] = {
80 LEVEL_PLUS_3DB,
81 LEVEL_PLUS_1POINT5DB,
82 LEVEL_ONE,
83 LEVEL_MINUS_1POINT5DB,
84 LEVEL_MINUS_3DB,
85 LEVEL_MINUS_4POINT5DB,
86 LEVEL_MINUS_6DB,
87 LEVEL_ZERO,
88 LEVEL_MINUS_9DB
89 };
90
91 /**
92 * Table for center mix levels
93 * reference: Section 5.4.2.4 cmixlev
94 */
95 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
96
97 /**
98 * Table for surround mix levels
99 * reference: Section 5.4.2.5 surmixlev
100 */
101 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
102
103 /**
104 * Table for default stereo downmixing coefficients
105 * reference: Section 7.8.2 Downmixing Into Two Channels
106 */
107 static const uint8_t ac3_default_coeffs[8][5][2] = {
108 { { 2, 7 }, { 7, 2 }, },
109 { { 4, 4 }, },
110 { { 2, 7 }, { 7, 2 }, },
111 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
112 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
113 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
114 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
115 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
116 };
117
118 /**
119 * Symmetrical Dequantization
120 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
121 * Tables 7.19 to 7.23
122 */
123 static inline int
124 symmetric_dequant(int code, int levels)
125 {
126 return ((code - (levels >> 1)) << 24) / levels;
127 }
128
129 /*
130 * Initialize tables at runtime.
131 */
132 static av_cold void ac3_tables_init(void)
133 {
134 int i;
135
136 /* generate table for ungrouping 3 values in 7 bits
137 reference: Section 7.1.3 Exponent Decoding */
138 for(i=0; i<128; i++) {
139 ungroup_3_in_7_bits_tab[i][0] = i / 25;
140 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
141 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
142 }
143
144 /* generate grouped mantissa tables
145 reference: Section 7.3.5 Ungrouping of Mantissas */
146 for(i=0; i<32; i++) {
147 /* bap=1 mantissas */
148 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
149 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
150 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
151 }
152 for(i=0; i<128; i++) {
153 /* bap=2 mantissas */
154 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
155 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
156 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
157
158 /* bap=4 mantissas */
159 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
160 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
161 }
162 /* generate ungrouped mantissa tables
163 reference: Tables 7.21 and 7.23 */
164 for(i=0; i<7; i++) {
165 /* bap=3 mantissas */
166 b3_mantissas[i] = symmetric_dequant(i, 7);
167 }
168 for(i=0; i<15; i++) {
169 /* bap=5 mantissas */
170 b5_mantissas[i] = symmetric_dequant(i, 15);
171 }
172
173 /* generate dynamic range table
174 reference: Section 7.7.1 Dynamic Range Control */
175 for(i=0; i<256; i++) {
176 int v = (i >> 5) - ((i >> 7) << 3) - 5;
177 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
178 }
179 }
180
181
182 /**
183 * AVCodec initialization
184 */
185 static av_cold int ac3_decode_init(AVCodecContext *avctx)
186 {
187 AC3DecodeContext *s = avctx->priv_data;
188 s->avctx = avctx;
189
190 ff_ac3_common_init();
191 ac3_tables_init();
192 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
193 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
194 ff_kbd_window_init(s->window, 5.0, 256);
195 dsputil_init(&s->dsp, avctx);
196 av_lfg_init(&s->dith_state, 0);
197
198 /* set bias values for float to int16 conversion */
199 if(s->dsp.float_to_int16_interleave == ff_float_to_int16_interleave_c) {
200 s->add_bias = 385.0f;
201 s->mul_bias = 1.0f;
202 } else {
203 s->add_bias = 0.0f;
204 s->mul_bias = 32767.0f;
205 }
206
207 /* allow downmixing to stereo or mono */
208 if (avctx->channels > 0 && avctx->request_channels > 0 &&
209 avctx->request_channels < avctx->channels &&
210 avctx->request_channels <= 2) {
211 avctx->channels = avctx->request_channels;
212 }
213 s->downmixed = 1;
214
215 /* allocate context input buffer */
216 if (avctx->error_recognition >= FF_ER_CAREFUL) {
217 s->input_buffer = av_mallocz(AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
218 if (!s->input_buffer)
219 return AVERROR(ENOMEM);
220 }
221
222 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
223 return 0;
224 }
225
226 /**
227 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
228 * GetBitContext within AC3DecodeContext must point to
229 * the start of the synchronized AC-3 bitstream.
230 */
231 static int ac3_parse_header(AC3DecodeContext *s)
232 {
233 GetBitContext *gbc = &s->gbc;
234 int i;
235
236 /* read the rest of the bsi. read twice for dual mono mode. */
237 i = !(s->channel_mode);
238 do {
239 skip_bits(gbc, 5); // skip dialog normalization
240 if (get_bits1(gbc))
241 skip_bits(gbc, 8); //skip compression
242 if (get_bits1(gbc))
243 skip_bits(gbc, 8); //skip language code
244 if (get_bits1(gbc))
245 skip_bits(gbc, 7); //skip audio production information
246 } while (i--);
247
248 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
249
250 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
251 TODO: read & use the xbsi1 downmix levels */
252 if (get_bits1(gbc))
253 skip_bits(gbc, 14); //skip timecode1 / xbsi1
254 if (get_bits1(gbc))
255 skip_bits(gbc, 14); //skip timecode2 / xbsi2
256
257 /* skip additional bitstream info */
258 if (get_bits1(gbc)) {
259 i = get_bits(gbc, 6);
260 do {
261 skip_bits(gbc, 8);
262 } while(i--);
263 }
264
265 return 0;
266 }
267
268 /**
269 * Common function to parse AC-3 or E-AC-3 frame header
270 */
271 static int parse_frame_header(AC3DecodeContext *s)
272 {
273 AC3HeaderInfo hdr;
274 int err;
275
276 err = ff_ac3_parse_header(&s->gbc, &hdr);
277 if(err)
278 return err;
279
280 /* get decoding parameters from header info */
281 s->bit_alloc_params.sr_code = hdr.sr_code;
282 s->channel_mode = hdr.channel_mode;
283 s->channel_layout = hdr.channel_layout;
284 s->lfe_on = hdr.lfe_on;
285 s->bit_alloc_params.sr_shift = hdr.sr_shift;
286 s->sample_rate = hdr.sample_rate;
287 s->bit_rate = hdr.bit_rate;
288 s->channels = hdr.channels;
289 s->fbw_channels = s->channels - s->lfe_on;
290 s->lfe_ch = s->fbw_channels + 1;
291 s->frame_size = hdr.frame_size;
292 s->center_mix_level = hdr.center_mix_level;
293 s->surround_mix_level = hdr.surround_mix_level;
294 s->num_blocks = hdr.num_blocks;
295 s->frame_type = hdr.frame_type;
296 s->substreamid = hdr.substreamid;
297
298 if(s->lfe_on) {
299 s->start_freq[s->lfe_ch] = 0;
300 s->end_freq[s->lfe_ch] = 7;
301 s->num_exp_groups[s->lfe_ch] = 2;
302 s->channel_in_cpl[s->lfe_ch] = 0;
303 }
304
305 if (hdr.bitstream_id <= 10) {
306 s->eac3 = 0;
307 s->snr_offset_strategy = 2;
308 s->block_switch_syntax = 1;
309 s->dither_flag_syntax = 1;
310 s->bit_allocation_syntax = 1;
311 s->fast_gain_syntax = 0;
312 s->first_cpl_leak = 0;
313 s->dba_syntax = 1;
314 s->skip_syntax = 1;
315 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
316 return ac3_parse_header(s);
317 } else if (CONFIG_EAC3_DECODER) {
318 s->eac3 = 1;
319 return ff_eac3_parse_header(s);
320 } else {
321 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
322 return -1;
323 }
324 }
325
326 /**
327 * Set stereo downmixing coefficients based on frame header info.
328 * reference: Section 7.8.2 Downmixing Into Two Channels
329 */
330 static void set_downmix_coeffs(AC3DecodeContext *s)
331 {
332 int i;
333 float cmix = gain_levels[center_levels[s->center_mix_level]];
334 float smix = gain_levels[surround_levels[s->surround_mix_level]];
335 float norm0, norm1;
336
337 for(i=0; i<s->fbw_channels; i++) {
338 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
339 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
340 }
341 if(s->channel_mode > 1 && s->channel_mode & 1) {
342 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
343 }
344 if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
345 int nf = s->channel_mode - 2;
346 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
347 }
348 if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
349 int nf = s->channel_mode - 4;
350 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
351 }
352
353 /* renormalize */
354 norm0 = norm1 = 0.0;
355 for(i=0; i<s->fbw_channels; i++) {
356 norm0 += s->downmix_coeffs[i][0];
357 norm1 += s->downmix_coeffs[i][1];
358 }
359 norm0 = 1.0f / norm0;
360 norm1 = 1.0f / norm1;
361 for(i=0; i<s->fbw_channels; i++) {
362 s->downmix_coeffs[i][0] *= norm0;
363 s->downmix_coeffs[i][1] *= norm1;
364 }
365
366 if(s->output_mode == AC3_CHMODE_MONO) {
367 for(i=0; i<s->fbw_channels; i++)
368 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
369 }
370 }
371
372 /**
373 * Decode the grouped exponents according to exponent strategy.
374 * reference: Section 7.1.3 Exponent Decoding
375 */
376 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
377 uint8_t absexp, int8_t *dexps)
378 {
379 int i, j, grp, group_size;
380 int dexp[256];
381 int expacc, prevexp;
382
383 /* unpack groups */
384 group_size = exp_strategy + (exp_strategy == EXP_D45);
385 for(grp=0,i=0; grp<ngrps; grp++) {
386 expacc = get_bits(gbc, 7);
387 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
388 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
389 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
390 }
391
392 /* convert to absolute exps and expand groups */
393 prevexp = absexp;
394 for(i=0,j=0; i<ngrps*3; i++) {
395 prevexp += dexp[i] - 2;
396 if (prevexp > 24U)
397 return -1;
398 switch (group_size) {
399 case 4: dexps[j++] = prevexp;
400 dexps[j++] = prevexp;
401 case 2: dexps[j++] = prevexp;
402 case 1: dexps[j++] = prevexp;
403 }
404 }
405 return 0;
406 }
407
408 /**
409 * Generate transform coefficients for each coupled channel in the coupling
410 * range using the coupling coefficients and coupling coordinates.
411 * reference: Section 7.4.3 Coupling Coordinate Format
412 */
413 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
414 {
415 int bin, band, ch;
416
417 bin = s->start_freq[CPL_CH];
418 for (band = 0; band < s->num_cpl_bands; band++) {
419 int band_start = bin;
420 int band_end = bin + s->cpl_band_sizes[band];
421 for (ch = 1; ch <= s->fbw_channels; ch++) {
422 if (s->channel_in_cpl[ch]) {
423 int cpl_coord = s->cpl_coords[ch][band] << 5;
424 for (bin = band_start; bin < band_end; bin++) {
425 s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
426 }
427 if (ch == 2 && s->phase_flags[band]) {
428 for (bin = band_start; bin < band_end; bin++)
429 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
430 }
431 }
432 }
433 bin = band_end;
434 }
435 }
436
437 /**
438 * Grouped mantissas for 3-level 5-level and 11-level quantization
439 */
440 typedef struct {
441 int b1_mant[2];
442 int b2_mant[2];
443 int b4_mant;
444 int b1;
445 int b2;
446 int b4;
447 } mant_groups;
448
449 /**
450 * Decode the transform coefficients for a particular channel
451 * reference: Section 7.3 Quantization and Decoding of Mantissas
452 */
453 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
454 {
455 int start_freq = s->start_freq[ch_index];
456 int end_freq = s->end_freq[ch_index];
457 uint8_t *baps = s->bap[ch_index];
458 int8_t *exps = s->dexps[ch_index];
459 int *coeffs = s->fixed_coeffs[ch_index];
460 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
461 GetBitContext *gbc = &s->gbc;
462 int freq;
463
464 for(freq = start_freq; freq < end_freq; freq++){
465 int bap = baps[freq];
466 int mantissa;
467 switch(bap){
468 case 0:
469 if (dither)
470 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
471 else
472 mantissa = 0;
473 break;
474 case 1:
475 if(m->b1){
476 m->b1--;
477 mantissa = m->b1_mant[m->b1];
478 }
479 else{
480 int bits = get_bits(gbc, 5);
481 mantissa = b1_mantissas[bits][0];
482 m->b1_mant[1] = b1_mantissas[bits][1];
483 m->b1_mant[0] = b1_mantissas[bits][2];
484 m->b1 = 2;
485 }
486 break;
487 case 2:
488 if(m->b2){
489 m->b2--;
490 mantissa = m->b2_mant[m->b2];
491 }
492 else{
493 int bits = get_bits(gbc, 7);
494 mantissa = b2_mantissas[bits][0];
495 m->b2_mant[1] = b2_mantissas[bits][1];
496 m->b2_mant[0] = b2_mantissas[bits][2];
497 m->b2 = 2;
498 }
499 break;
500 case 3:
501 mantissa = b3_mantissas[get_bits(gbc, 3)];
502 break;
503 case 4:
504 if(m->b4){
505 m->b4 = 0;
506 mantissa = m->b4_mant;
507 }
508 else{
509 int bits = get_bits(gbc, 7);
510 mantissa = b4_mantissas[bits][0];
511 m->b4_mant = b4_mantissas[bits][1];
512 m->b4 = 1;
513 }
514 break;
515 case 5:
516 mantissa = b5_mantissas[get_bits(gbc, 4)];
517 break;
518 default: /* 6 to 15 */
519 mantissa = get_bits(gbc, quantization_tab[bap]);
520 /* Shift mantissa and sign-extend it. */
521 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
522 break;
523 }
524 coeffs[freq] = mantissa >> exps[freq];
525 }
526 }
527
528 /**
529 * Remove random dithering from coupling range coefficients with zero-bit
530 * mantissas for coupled channels which do not use dithering.
531 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
532 */
533 static void remove_dithering(AC3DecodeContext *s) {
534 int ch, i;
535
536 for(ch=1; ch<=s->fbw_channels; ch++) {
537 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
538 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
539 if(!s->bap[CPL_CH][i])
540 s->fixed_coeffs[ch][i] = 0;
541 }
542 }
543 }
544 }
545
546 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
547 mant_groups *m)
548 {
549 if (!s->channel_uses_aht[ch]) {
550 ac3_decode_transform_coeffs_ch(s, ch, m);
551 } else {
552 /* if AHT is used, mantissas for all blocks are encoded in the first
553 block of the frame. */
554 int bin;
555 if (!blk && CONFIG_EAC3_DECODER)
556 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
557 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
558 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
559 }
560 }
561 }
562
563 /**
564 * Decode the transform coefficients.
565 */
566 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
567 {
568 int ch, end;
569 int got_cplchan = 0;
570 mant_groups m;
571
572 m.b1 = m.b2 = m.b4 = 0;
573
574 for (ch = 1; ch <= s->channels; ch++) {
575 /* transform coefficients for full-bandwidth channel */
576 decode_transform_coeffs_ch(s, blk, ch, &m);
577 /* tranform coefficients for coupling channel come right after the
578 coefficients for the first coupled channel*/
579 if (s->channel_in_cpl[ch]) {
580 if (!got_cplchan) {
581 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
582 calc_transform_coeffs_cpl(s);
583 got_cplchan = 1;
584 }
585 end = s->end_freq[CPL_CH];
586 } else {
587 end = s->end_freq[ch];
588 }
589 do
590 s->fixed_coeffs[ch][end] = 0;
591 while(++end < 256);
592 }
593
594 /* zero the dithered coefficients for appropriate channels */
595 remove_dithering(s);
596 }
597
598 /**
599 * Stereo rematrixing.
600 * reference: Section 7.5.4 Rematrixing : Decoding Technique
601 */
602 static void do_rematrixing(AC3DecodeContext *s)
603 {
604 int bnd, i;
605 int end, bndend;
606
607 end = FFMIN(s->end_freq[1], s->end_freq[2]);
608
609 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
610 if(s->rematrixing_flags[bnd]) {
611 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
612 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
613 int tmp0 = s->fixed_coeffs[1][i];
614 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
615 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
616 }
617 }
618 }
619 }
620
621 /**
622 * Inverse MDCT Transform.
623 * Convert frequency domain coefficients to time-domain audio samples.
624 * reference: Section 7.9.4 Transformation Equations
625 */
626 static inline void do_imdct(AC3DecodeContext *s, int channels)
627 {
628 int ch;
629 float add_bias = s->add_bias;
630 if(s->out_channels==1 && channels>1)
631 add_bias *= LEVEL_MINUS_3DB; // compensate for the gain in downmix
632
633 for (ch=1; ch<=channels; ch++) {
634 if (s->block_switch[ch]) {
635 int i;
636 float *x = s->tmp_output+128;
637 for(i=0; i<128; i++)
638 x[i] = s->transform_coeffs[ch][2*i];
639 ff_imdct_half(&s->imdct_256, s->tmp_output, x);
640 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
641 for(i=0; i<128; i++)
642 x[i] = s->transform_coeffs[ch][2*i+1];
643 ff_imdct_half(&s->imdct_256, s->delay[ch-1], x);
644 } else {
645 ff_imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
646 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
647 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
648 }
649 }
650 }
651
652 /**
653 * Downmix the output to mono or stereo.
654 */
655 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
656 {
657 int i, j;
658 float v0, v1;
659 if(out_ch == 2) {
660 for(i=0; i<len; i++) {
661 v0 = v1 = 0.0f;
662 for(j=0; j<in_ch; j++) {
663 v0 += samples[j][i] * matrix[j][0];
664 v1 += samples[j][i] * matrix[j][1];
665 }
666 samples[0][i] = v0;
667 samples[1][i] = v1;
668 }
669 } else if(out_ch == 1) {
670 for(i=0; i<len; i++) {
671 v0 = 0.0f;
672 for(j=0; j<in_ch; j++)
673 v0 += samples[j][i] * matrix[j][0];
674 samples[0][i] = v0;
675 }
676 }
677 }
678
679 /**
680 * Upmix delay samples from stereo to original channel layout.
681 */
682 static void ac3_upmix_delay(AC3DecodeContext *s)
683 {
684 int channel_data_size = sizeof(s->delay[0]);
685 switch(s->channel_mode) {
686 case AC3_CHMODE_DUALMONO:
687 case AC3_CHMODE_STEREO:
688 /* upmix mono to stereo */
689 memcpy(s->delay[1], s->delay[0], channel_data_size);
690 break;
691 case AC3_CHMODE_2F2R:
692 memset(s->delay[3], 0, channel_data_size);
693 case AC3_CHMODE_2F1R:
694 memset(s->delay[2], 0, channel_data_size);
695 break;
696 case AC3_CHMODE_3F2R:
697 memset(s->delay[4], 0, channel_data_size);
698 case AC3_CHMODE_3F1R:
699 memset(s->delay[3], 0, channel_data_size);
700 case AC3_CHMODE_3F:
701 memcpy(s->delay[2], s->delay[1], channel_data_size);
702 memset(s->delay[1], 0, channel_data_size);
703 break;
704 }
705 }
706
707 /**
708 * Decode band structure for coupling, spectral extension, or enhanced coupling.
709 * The band structure defines how many subbands are in each band. For each
710 * subband in the range, 1 means it is combined with the previous band, and 0
711 * means that it starts a new band.
712 *
713 * @param[in] gbc bit reader context
714 * @param[in] blk block number
715 * @param[in] eac3 flag to indicate E-AC-3
716 * @param[in] ecpl flag to indicate enhanced coupling
717 * @param[in] start_subband subband number for start of range
718 * @param[in] end_subband subband number for end of range
719 * @param[in] default_band_struct default band structure table
720 * @param[out] num_bands number of bands (optionally NULL)
721 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
722 */
723 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
724 int ecpl, int start_subband, int end_subband,
725 const uint8_t *default_band_struct,
726 int *num_bands, uint8_t *band_sizes)
727 {
728 int subbnd, bnd, n_subbands, n_bands=0;
729 uint8_t bnd_sz[22];
730 uint8_t coded_band_struct[22];
731 const uint8_t *band_struct;
732
733 n_subbands = end_subband - start_subband;
734
735 /* decode band structure from bitstream or use default */
736 if (!eac3 || get_bits1(gbc)) {
737 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
738 coded_band_struct[subbnd] = get_bits1(gbc);
739 }
740 band_struct = coded_band_struct;
741 } else if (!blk) {
742 band_struct = &default_band_struct[start_subband+1];
743 } else {
744 /* no change in band structure */
745 return;
746 }
747
748 /* calculate number of bands and band sizes based on band structure.
749 note that the first 4 subbands in enhanced coupling span only 6 bins
750 instead of 12. */
751 if (num_bands || band_sizes ) {
752 n_bands = n_subbands;
753 bnd_sz[0] = ecpl ? 6 : 12;
754 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
755 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
756 if (band_struct[subbnd-1]) {
757 n_bands--;
758 bnd_sz[bnd] += subbnd_size;
759 } else {
760 bnd_sz[++bnd] = subbnd_size;
761 }
762 }
763 }
764
765 /* set optional output params */
766 if (num_bands)
767 *num_bands = n_bands;
768 if (band_sizes)
769 memcpy(band_sizes, bnd_sz, n_bands);
770 }
771
772 /**
773 * Decode a single audio block from the AC-3 bitstream.
774 */
775 static int decode_audio_block(AC3DecodeContext *s, int blk)
776 {
777 int fbw_channels = s->fbw_channels;
778 int channel_mode = s->channel_mode;
779 int i, bnd, seg, ch;
780 int different_transforms;
781 int downmix_output;
782 int cpl_in_use;
783 GetBitContext *gbc = &s->gbc;
784 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
785
786 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
787
788 /* block switch flags */
789 different_transforms = 0;
790 if (s->block_switch_syntax) {
791 for (ch = 1; ch <= fbw_channels; ch++) {
792 s->block_switch[ch] = get_bits1(gbc);
793 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
794 different_transforms = 1;
795 }
796 }
797
798 /* dithering flags */
799 if (s->dither_flag_syntax) {
800 for (ch = 1; ch <= fbw_channels; ch++) {
801 s->dither_flag[ch] = get_bits1(gbc);
802 }
803 }
804
805 /* dynamic range */
806 i = !(s->channel_mode);
807 do {
808 if(get_bits1(gbc)) {
809 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
810 s->avctx->drc_scale)+1.0;
811 } else if(blk == 0) {
812 s->dynamic_range[i] = 1.0f;
813 }
814 } while(i--);
815
816 /* spectral extension strategy */
817 if (s->eac3 && (!blk || get_bits1(gbc))) {
818 s->spx_in_use = get_bits1(gbc);
819 if (s->spx_in_use) {
820 int dst_start_freq, dst_end_freq, src_start_freq,
821 start_subband, end_subband;
822
823 /* determine which channels use spx */
824 if (s->channel_mode == AC3_CHMODE_MONO) {
825 s->channel_uses_spx[1] = 1;
826 } else {
827 for (ch = 1; ch <= fbw_channels; ch++)
828 s->channel_uses_spx[ch] = get_bits1(gbc);
829 }
830
831 /* get the frequency bins of the spx copy region and the spx start
832 and end subbands */
833 dst_start_freq = get_bits(gbc, 2);
834 start_subband = get_bits(gbc, 3) + 2;
835 if (start_subband > 7)
836 start_subband += start_subband - 7;
837 end_subband = get_bits(gbc, 3) + 5;
838 if (end_subband > 7)
839 end_subband += end_subband - 7;
840 dst_start_freq = dst_start_freq * 12 + 25;
841 src_start_freq = start_subband * 12 + 25;
842 dst_end_freq = end_subband * 12 + 25;
843
844 /* check validity of spx ranges */
845 if (start_subband >= end_subband) {
846 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
847 "range (%d >= %d)\n", start_subband, end_subband);
848 return -1;
849 }
850 if (dst_start_freq >= src_start_freq) {
851 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
852 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
853 return -1;
854 }
855
856 s->spx_dst_start_freq = dst_start_freq;
857 s->spx_src_start_freq = src_start_freq;
858 s->spx_dst_end_freq = dst_end_freq;
859
860 decode_band_structure(gbc, blk, s->eac3, 0,
861 start_subband, end_subband,
862 ff_eac3_default_spx_band_struct,
863 &s->num_spx_bands,
864 s->spx_band_sizes);
865 } else {
866 for (ch = 1; ch <= fbw_channels; ch++) {
867 s->channel_uses_spx[ch] = 0;
868 s->first_spx_coords[ch] = 1;
869 }
870 }
871 }
872
873 /* spectral extension coordinates */
874 if (s->spx_in_use) {
875 for (ch = 1; ch <= fbw_channels; ch++) {
876 if (s->channel_uses_spx[ch]) {
877 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
878 float spx_blend;
879 int bin, master_spx_coord;
880
881 s->first_spx_coords[ch] = 0;
882 spx_blend = get_bits(gbc, 5) * (1.0f/32);
883 master_spx_coord = get_bits(gbc, 2) * 3;
884
885 bin = s->spx_src_start_freq;
886 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
887 int bandsize;
888 int spx_coord_exp, spx_coord_mant;
889 float nratio, sblend, nblend, spx_coord;
890
891 /* calculate blending factors */
892 bandsize = s->spx_band_sizes[bnd];
893 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
894 nratio = av_clipf(nratio, 0.0f, 1.0f);
895 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) to give unity variance
896 sblend = sqrtf(1.0f - nratio);
897 bin += bandsize;
898
899 /* decode spx coordinates */
900 spx_coord_exp = get_bits(gbc, 4);
901 spx_coord_mant = get_bits(gbc, 2);
902 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
903 else spx_coord_mant += 4;
904 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
905 spx_coord = spx_coord_mant * (1.0f/(1<<23));
906
907 /* multiply noise and signal blending factors by spx coordinate */
908 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
909 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
910 }
911 }
912 } else {
913 s->first_spx_coords[ch] = 1;
914 }
915 }
916 }
917
918 /* coupling strategy */
919 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
920 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
921 if (!s->eac3)
922 s->cpl_in_use[blk] = get_bits1(gbc);
923 if (s->cpl_in_use[blk]) {
924 /* coupling in use */
925 int cpl_start_subband, cpl_end_subband;
926
927 if (channel_mode < AC3_CHMODE_STEREO) {
928 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
929 return -1;
930 }
931
932 /* check for enhanced coupling */
933 if (s->eac3 && get_bits1(gbc)) {
934 /* TODO: parse enhanced coupling strategy info */
935 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
936 return -1;
937 }
938
939 /* determine which channels are coupled */
940 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
941 s->channel_in_cpl[1] = 1;
942 s->channel_in_cpl[2] = 1;
943 } else {
944 for (ch = 1; ch <= fbw_channels; ch++)
945 s->channel_in_cpl[ch] = get_bits1(gbc);
946 }
947
948 /* phase flags in use */
949 if (channel_mode == AC3_CHMODE_STEREO)
950 s->phase_flags_in_use = get_bits1(gbc);
951
952 /* coupling frequency range */
953 cpl_start_subband = get_bits(gbc, 4);
954 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
955 get_bits(gbc, 4) + 3;
956 if (cpl_start_subband >= cpl_end_subband) {
957 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
958 cpl_start_subband, cpl_end_subband);
959 return -1;
960 }
961 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
962 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
963
964 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
965 cpl_end_subband,
966 ff_eac3_default_cpl_band_struct,
967 &s->num_cpl_bands, s->cpl_band_sizes);
968 } else {
969 /* coupling not in use */
970 for (ch = 1; ch <= fbw_channels; ch++) {
971 s->channel_in_cpl[ch] = 0;
972 s->first_cpl_coords[ch] = 1;
973 }
974 s->first_cpl_leak = s->eac3;
975 s->phase_flags_in_use = 0;
976 }
977 } else if (!s->eac3) {
978 if(!blk) {
979 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
980 return -1;
981 } else {
982 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
983 }
984 }
985 cpl_in_use = s->cpl_in_use[blk];
986
987 /* coupling coordinates */
988 if (cpl_in_use) {
989 int cpl_coords_exist = 0;
990
991 for (ch = 1; ch <= fbw_channels; ch++) {
992 if (s->channel_in_cpl[ch]) {
993 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
994 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
995 s->first_cpl_coords[ch] = 0;
996 cpl_coords_exist = 1;
997 master_cpl_coord = 3 * get_bits(gbc, 2);
998 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
999 cpl_coord_exp = get_bits(gbc, 4);
1000 cpl_coord_mant = get_bits(gbc, 4);
1001 if (cpl_coord_exp == 15)
1002 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
1003 else
1004 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
1005 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
1006 }
1007 } else if (!blk) {
1008 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
1009 return -1;
1010 }
1011 } else {
1012 /* channel not in coupling */
1013 s->first_cpl_coords[ch] = 1;
1014 }
1015 }
1016 /* phase flags */
1017 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1018 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1019 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1020 }
1021 }
1022 }
1023
1024 /* stereo rematrixing strategy and band structure */
1025 if (channel_mode == AC3_CHMODE_STEREO) {
1026 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1027 s->num_rematrixing_bands = 4;
1028 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1029 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1030 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1031 s->num_rematrixing_bands--;
1032 }
1033 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
1034 s->rematrixing_flags[bnd] = get_bits1(gbc);
1035 } else if (!blk) {
1036 av_log(s->avctx, AV_LOG_WARNING, "Warning: new rematrixing strategy not present in block 0\n");
1037 s->num_rematrixing_bands = 0;
1038 }
1039 }
1040
1041 /* exponent strategies for each channel */
1042 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1043 if (!s->eac3)
1044 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1045 if(s->exp_strategy[blk][ch] != EXP_REUSE)
1046 bit_alloc_stages[ch] = 3;
1047 }
1048
1049 /* channel bandwidth */
1050 for (ch = 1; ch <= fbw_channels; ch++) {
1051 s->start_freq[ch] = 0;
1052 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1053 int group_size;
1054 int prev = s->end_freq[ch];
1055 if (s->channel_in_cpl[ch])
1056 s->end_freq[ch] = s->start_freq[CPL_CH];
1057 else if (s->channel_uses_spx[ch])
1058 s->end_freq[ch] = s->spx_src_start_freq;
1059 else {
1060 int bandwidth_code = get_bits(gbc, 6);
1061 if (bandwidth_code > 60) {
1062 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1063 return -1;
1064 }
1065 s->end_freq[ch] = bandwidth_code * 3 + 73;
1066 }
1067 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1068 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
1069 if(blk > 0 && s->end_freq[ch] != prev)
1070 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1071 }
1072 }
1073 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1074 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1075 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1076 }
1077
1078 /* decode exponents for each channel */
1079 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1080 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1081 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1082 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1083 s->num_exp_groups[ch], s->dexps[ch][0],
1084 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1085 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1086 return -1;
1087 }
1088 if(ch != CPL_CH && ch != s->lfe_ch)
1089 skip_bits(gbc, 2); /* skip gainrng */
1090 }
1091 }
1092
1093 /* bit allocation information */
1094 if (s->bit_allocation_syntax) {
1095 if (get_bits1(gbc)) {
1096 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1097 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1098 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1099 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1100 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1101 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1102 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1103 } else if (!blk) {
1104 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1105 return -1;
1106 }
1107 }
1108
1109 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1110 if(!s->eac3 || !blk){
1111 if(s->snr_offset_strategy && get_bits1(gbc)) {
1112 int snr = 0;
1113 int csnr;
1114 csnr = (get_bits(gbc, 6) - 15) << 4;
1115 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1116 /* snr offset */
1117 if (ch == i || s->snr_offset_strategy == 2)
1118 snr = (csnr + get_bits(gbc, 4)) << 2;
1119 /* run at least last bit allocation stage if snr offset changes */
1120 if(blk && s->snr_offset[ch] != snr) {
1121 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1122 }
1123 s->snr_offset[ch] = snr;
1124
1125 /* fast gain (normal AC-3 only) */
1126 if (!s->eac3) {
1127 int prev = s->fast_gain[ch];
1128 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1129 /* run last 2 bit allocation stages if fast gain changes */
1130 if(blk && prev != s->fast_gain[ch])
1131 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1132 }
1133 }
1134 } else if (!s->eac3 && !blk) {
1135 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1136 return -1;
1137 }
1138 }
1139
1140 /* fast gain (E-AC-3 only) */
1141 if (s->fast_gain_syntax && get_bits1(gbc)) {
1142 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1143 int prev = s->fast_gain[ch];
1144 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1145 /* run last 2 bit allocation stages if fast gain changes */
1146 if(blk && prev != s->fast_gain[ch])
1147 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1148 }
1149 } else if (s->eac3 && !blk) {
1150 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1151 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1152 }
1153
1154 /* E-AC-3 to AC-3 converter SNR offset */
1155 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1156 skip_bits(gbc, 10); // skip converter snr offset
1157 }
1158
1159 /* coupling leak information */
1160 if (cpl_in_use) {
1161 if (s->first_cpl_leak || get_bits1(gbc)) {
1162 int fl = get_bits(gbc, 3);
1163 int sl = get_bits(gbc, 3);
1164 /* run last 2 bit allocation stages for coupling channel if
1165 coupling leak changes */
1166 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1167 sl != s->bit_alloc_params.cpl_slow_leak)) {
1168 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1169 }
1170 s->bit_alloc_params.cpl_fast_leak = fl;
1171 s->bit_alloc_params.cpl_slow_leak = sl;
1172 } else if (!s->eac3 && !blk) {
1173 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1174 return -1;
1175 }
1176 s->first_cpl_leak = 0;
1177 }
1178
1179 /* delta bit allocation information */
1180 if (s->dba_syntax && get_bits1(gbc)) {
1181 /* delta bit allocation exists (strategy) */
1182 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1183 s->dba_mode[ch] = get_bits(gbc, 2);
1184 if (s->dba_mode[ch] == DBA_RESERVED) {
1185 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1186 return -1;
1187 }
1188 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1189 }
1190 /* channel delta offset, len and bit allocation */
1191 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1192 if (s->dba_mode[ch] == DBA_NEW) {
1193 s->dba_nsegs[ch] = get_bits(gbc, 3);
1194 for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1195 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1196 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1197 s->dba_values[ch][seg] = get_bits(gbc, 3);
1198 }
1199 /* run last 2 bit allocation stages if new dba values */
1200 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1201 }
1202 }
1203 } else if(blk == 0) {
1204 for(ch=0; ch<=s->channels; ch++) {
1205 s->dba_mode[ch] = DBA_NONE;
1206 }
1207 }
1208
1209 /* Bit allocation */
1210 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1211 if(bit_alloc_stages[ch] > 2) {
1212 /* Exponent mapping into PSD and PSD integration */
1213 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1214 s->start_freq[ch], s->end_freq[ch],
1215 s->psd[ch], s->band_psd[ch]);
1216 }
1217 if(bit_alloc_stages[ch] > 1) {
1218 /* Compute excitation function, Compute masking curve, and
1219 Apply delta bit allocation */
1220 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1221 s->start_freq[ch], s->end_freq[ch],
1222 s->fast_gain[ch], (ch == s->lfe_ch),
1223 s->dba_mode[ch], s->dba_nsegs[ch],
1224 s->dba_offsets[ch], s->dba_lengths[ch],
1225 s->dba_values[ch], s->mask[ch])) {
1226 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1227 return -1;
1228 }
1229 }
1230 if(bit_alloc_stages[ch] > 0) {
1231 /* Compute bit allocation */
1232 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1233 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1234 ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1235 s->start_freq[ch], s->end_freq[ch],
1236 s->snr_offset[ch],
1237 s->bit_alloc_params.floor,
1238 bap_tab, s->bap[ch]);
1239 }
1240 }
1241
1242 /* unused dummy data */
1243 if (s->skip_syntax && get_bits1(gbc)) {
1244 int skipl = get_bits(gbc, 9);
1245 while(skipl--)
1246 skip_bits(gbc, 8);
1247 }
1248
1249 /* unpack the transform coefficients
1250 this also uncouples channels if coupling is in use. */
1251 decode_transform_coeffs(s, blk);
1252
1253 /* TODO: generate enhanced coupling coordinates and uncouple */
1254
1255 /* recover coefficients if rematrixing is in use */
1256 if(s->channel_mode == AC3_CHMODE_STEREO)
1257 do_rematrixing(s);
1258
1259 /* apply scaling to coefficients (headroom, dynrng) */
1260 for(ch=1; ch<=s->channels; ch++) {
1261 float gain = s->mul_bias / 4194304.0f;
1262 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1263 gain *= s->dynamic_range[2-ch];
1264 } else {
1265 gain *= s->dynamic_range[0];
1266 }
1267 s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1268 }
1269
1270 /* apply spectral extension to high frequency bins */
1271 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1272 ff_eac3_apply_spectral_extension(s);
1273 }
1274
1275 /* downmix and MDCT. order depends on whether block switching is used for
1276 any channel in this block. this is because coefficients for the long
1277 and short transforms cannot be mixed. */
1278 downmix_output = s->channels != s->out_channels &&
1279 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1280 s->fbw_channels == s->out_channels);
1281 if(different_transforms) {
1282 /* the delay samples have already been downmixed, so we upmix the delay
1283 samples in order to reconstruct all channels before downmixing. */
1284 if(s->downmixed) {
1285 s->downmixed = 0;
1286 ac3_upmix_delay(s);
1287 }
1288
1289 do_imdct(s, s->channels);
1290
1291 if(downmix_output) {
1292 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1293 }
1294 } else {
1295 if(downmix_output) {
1296 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1297 }
1298
1299 if(downmix_output && !s->downmixed) {
1300 s->downmixed = 1;
1301 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1302 }
1303
1304 do_imdct(s, s->out_channels);
1305 }
1306
1307 return 0;
1308 }
1309
1310 /**
1311 * Decode a single AC-3 frame.
1312 */
1313 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1314 AVPacket *avpkt)
1315 {
1316 const uint8_t *buf = avpkt->data;
1317 int buf_size = avpkt->size;
1318 AC3DecodeContext *s = avctx->priv_data;
1319 int16_t *out_samples = (int16_t *)data;
1320 int blk, ch, err;
1321 const uint8_t *channel_map;
1322 const float *output[AC3_MAX_CHANNELS];
1323
1324 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1325 if (s->input_buffer) {
1326 /* copy input buffer to decoder context to avoid reading past the end
1327 of the buffer, which can be caused by a damaged input stream. */
1328 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1329 init_get_bits(&s->gbc, s->input_buffer, buf_size * 8);
1330 } else {
1331 init_get_bits(&s->gbc, buf, buf_size * 8);
1332 }
1333
1334 /* parse the syncinfo */
1335 *data_size = 0;
1336 err = parse_frame_header(s);
1337
1338 if (err) {
1339 switch(err) {
1340 case AAC_AC3_PARSE_ERROR_SYNC:
1341 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1342 return -1;
1343 case AAC_AC3_PARSE_ERROR_BSID:
1344 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1345 break;
1346 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1347 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1348 break;
1349 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1350 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1351 break;
1352 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1353 /* skip frame if CRC is ok. otherwise use error concealment. */
1354 /* TODO: add support for substreams and dependent frames */
1355 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1356 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1357 return s->frame_size;
1358 } else {
1359 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1360 }
1361 break;
1362 default:
1363 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1364 break;
1365 }
1366 } else {
1367 /* check that reported frame size fits in input buffer */
1368 if (s->frame_size > buf_size) {
1369 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1370 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1371 } else if (avctx->error_recognition >= FF_ER_CAREFUL) {
1372 /* check for crc mismatch */
1373 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1374 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1375 err = AAC_AC3_PARSE_ERROR_CRC;
1376 }
1377 }
1378 }
1379
1380 /* if frame is ok, set audio parameters */
1381 if (!err) {
1382 avctx->sample_rate = s->sample_rate;
1383 avctx->bit_rate = s->bit_rate;
1384
1385 /* channel config */
1386 s->out_channels = s->channels;
1387 s->output_mode = s->channel_mode;
1388 if(s->lfe_on)
1389 s->output_mode |= AC3_OUTPUT_LFEON;
1390 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1391 avctx->request_channels < s->channels) {
1392 s->out_channels = avctx->request_channels;
1393 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1394 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1395 }
1396 avctx->channels = s->out_channels;
1397 avctx->channel_layout = s->channel_layout;
1398
1399 /* set downmixing coefficients if needed */
1400 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1401 s->fbw_channels == s->out_channels)) {
1402 set_downmix_coeffs(s);
1403 }
1404 } else if (!s->out_channels) {
1405 s->out_channels = avctx->channels;
1406 if(s->out_channels < s->channels)
1407 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1408 }
1409
1410 /* decode the audio blocks */
1411 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1412 for (ch = 0; ch < s->out_channels; ch++)
1413 output[ch] = s->output[channel_map[ch]];
1414 for (blk = 0; blk < s->num_blocks; blk++) {
1415 if (!err && decode_audio_block(s, blk)) {
1416 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1417 err = 1;
1418 }
1419 s->dsp.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1420 out_samples += 256 * s->out_channels;
1421 }
1422 *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1423 return FFMIN(buf_size, s->frame_size);
1424 }
1425
1426 /**
1427 * Uninitialize the AC-3 decoder.
1428 */
1429 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1430 {
1431 AC3DecodeContext *s = avctx->priv_data;
1432 ff_mdct_end(&s->imdct_512);
1433 ff_mdct_end(&s->imdct_256);
1434
1435 av_freep(&s->input_buffer);
1436
1437 return 0;
1438 }
1439
1440 AVCodec ac3_decoder = {
1441 .name = "ac3",
1442 .type = AVMEDIA_TYPE_AUDIO,
1443 .id = CODEC_ID_AC3,
1444 .priv_data_size = sizeof (AC3DecodeContext),
1445 .init = ac3_decode_init,
1446 .close = ac3_decode_end,
1447 .decode = ac3_decode_frame,
1448 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1449 };
1450
1451 #if CONFIG_EAC3_DECODER
1452 AVCodec eac3_decoder = {
1453 .name = "eac3",
1454 .type = AVMEDIA_TYPE_AUDIO,
1455 .id = CODEC_ID_EAC3,
1456 .priv_data_size = sizeof (AC3DecodeContext),
1457 .init = ac3_decode_init,
1458 .close = ac3_decode_end,
1459 .decode = ac3_decode_frame,
1460 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1461 };
1462 #endif