cbeac311c3bc56cd43714adcb9640dd4b1613173
[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 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_NOMEM;
220 }
221
222 avctx->sample_fmt = 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, band_end;
416
417 bin = s->start_freq[CPL_CH];
418 for (band = 0; band < s->num_cpl_bands; band++) {
419 band_end = bin + s->cpl_band_sizes[band];
420 for (; bin < band_end; bin++) {
421 for (ch = 1; ch <= s->fbw_channels; ch++) {
422 if (s->channel_in_cpl[ch]) {
423 s->fixed_coeffs[ch][bin] = ((int64_t)s->fixed_coeffs[CPL_CH][bin] *
424 (int64_t)s->cpl_coords[ch][band]) >> 23;
425 if (ch == 2 && s->phase_flags[band])
426 s->fixed_coeffs[ch][bin] = -s->fixed_coeffs[ch][bin];
427 }
428 }
429 }
430 }
431 }
432
433 /**
434 * Grouped mantissas for 3-level 5-level and 11-level quantization
435 */
436 typedef struct {
437 int b1_mant[2];
438 int b2_mant[2];
439 int b4_mant;
440 int b1;
441 int b2;
442 int b4;
443 } mant_groups;
444
445 /**
446 * Decode the transform coefficients for a particular channel
447 * reference: Section 7.3 Quantization and Decoding of Mantissas
448 */
449 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
450 {
451 int start_freq = s->start_freq[ch_index];
452 int end_freq = s->end_freq[ch_index];
453 uint8_t *baps = s->bap[ch_index];
454 int8_t *exps = s->dexps[ch_index];
455 int *coeffs = s->fixed_coeffs[ch_index];
456 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
457 GetBitContext *gbc = &s->gbc;
458 int freq;
459
460 for(freq = start_freq; freq < end_freq; freq++){
461 int bap = baps[freq];
462 int mantissa;
463 switch(bap){
464 case 0:
465 if (dither)
466 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
467 else
468 mantissa = 0;
469 break;
470 case 1:
471 if(m->b1){
472 m->b1--;
473 mantissa = m->b1_mant[m->b1];
474 }
475 else{
476 int bits = get_bits(gbc, 5);
477 mantissa = b1_mantissas[bits][0];
478 m->b1_mant[1] = b1_mantissas[bits][1];
479 m->b1_mant[0] = b1_mantissas[bits][2];
480 m->b1 = 2;
481 }
482 break;
483 case 2:
484 if(m->b2){
485 m->b2--;
486 mantissa = m->b2_mant[m->b2];
487 }
488 else{
489 int bits = get_bits(gbc, 7);
490 mantissa = b2_mantissas[bits][0];
491 m->b2_mant[1] = b2_mantissas[bits][1];
492 m->b2_mant[0] = b2_mantissas[bits][2];
493 m->b2 = 2;
494 }
495 break;
496 case 3:
497 mantissa = b3_mantissas[get_bits(gbc, 3)];
498 break;
499 case 4:
500 if(m->b4){
501 m->b4 = 0;
502 mantissa = m->b4_mant;
503 }
504 else{
505 int bits = get_bits(gbc, 7);
506 mantissa = b4_mantissas[bits][0];
507 m->b4_mant = b4_mantissas[bits][1];
508 m->b4 = 1;
509 }
510 break;
511 case 5:
512 mantissa = b5_mantissas[get_bits(gbc, 4)];
513 break;
514 default: /* 6 to 15 */
515 mantissa = get_bits(gbc, quantization_tab[bap]);
516 /* Shift mantissa and sign-extend it. */
517 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
518 break;
519 }
520 coeffs[freq] = mantissa >> exps[freq];
521 }
522 }
523
524 /**
525 * Remove random dithering from coupling range coefficients with zero-bit
526 * mantissas for coupled channels which do not use dithering.
527 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
528 */
529 static void remove_dithering(AC3DecodeContext *s) {
530 int ch, i;
531
532 for(ch=1; ch<=s->fbw_channels; ch++) {
533 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
534 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
535 if(!s->bap[CPL_CH][i])
536 s->fixed_coeffs[ch][i] = 0;
537 }
538 }
539 }
540 }
541
542 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
543 mant_groups *m)
544 {
545 if (!s->channel_uses_aht[ch]) {
546 ac3_decode_transform_coeffs_ch(s, ch, m);
547 } else {
548 /* if AHT is used, mantissas for all blocks are encoded in the first
549 block of the frame. */
550 int bin;
551 if (!blk && CONFIG_EAC3_DECODER)
552 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
553 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
554 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
555 }
556 }
557 }
558
559 /**
560 * Decode the transform coefficients.
561 */
562 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
563 {
564 int ch, end;
565 int got_cplchan = 0;
566 mant_groups m;
567
568 m.b1 = m.b2 = m.b4 = 0;
569
570 for (ch = 1; ch <= s->channels; ch++) {
571 /* transform coefficients for full-bandwidth channel */
572 decode_transform_coeffs_ch(s, blk, ch, &m);
573 /* tranform coefficients for coupling channel come right after the
574 coefficients for the first coupled channel*/
575 if (s->channel_in_cpl[ch]) {
576 if (!got_cplchan) {
577 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
578 calc_transform_coeffs_cpl(s);
579 got_cplchan = 1;
580 }
581 end = s->end_freq[CPL_CH];
582 } else {
583 end = s->end_freq[ch];
584 }
585 do
586 s->fixed_coeffs[ch][end] = 0;
587 while(++end < 256);
588 }
589
590 /* zero the dithered coefficients for appropriate channels */
591 remove_dithering(s);
592 }
593
594 /**
595 * Stereo rematrixing.
596 * reference: Section 7.5.4 Rematrixing : Decoding Technique
597 */
598 static void do_rematrixing(AC3DecodeContext *s)
599 {
600 int bnd, i;
601 int end, bndend;
602 int tmp0, tmp1;
603
604 end = FFMIN(s->end_freq[1], s->end_freq[2]);
605
606 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
607 if(s->rematrixing_flags[bnd]) {
608 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
609 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
610 tmp0 = s->fixed_coeffs[1][i];
611 tmp1 = s->fixed_coeffs[2][i];
612 s->fixed_coeffs[1][i] = tmp0 + tmp1;
613 s->fixed_coeffs[2][i] = tmp0 - tmp1;
614 }
615 }
616 }
617 }
618
619 /**
620 * Inverse MDCT Transform.
621 * Convert frequency domain coefficients to time-domain audio samples.
622 * reference: Section 7.9.4 Transformation Equations
623 */
624 static inline void do_imdct(AC3DecodeContext *s, int channels)
625 {
626 int ch;
627 float add_bias = s->add_bias;
628 if(s->out_channels==1 && channels>1)
629 add_bias *= LEVEL_MINUS_3DB; // compensate for the gain in downmix
630
631 for (ch=1; ch<=channels; ch++) {
632 if (s->block_switch[ch]) {
633 int i;
634 float *x = s->tmp_output+128;
635 for(i=0; i<128; i++)
636 x[i] = s->transform_coeffs[ch][2*i];
637 ff_imdct_half(&s->imdct_256, s->tmp_output, x);
638 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
639 for(i=0; i<128; i++)
640 x[i] = s->transform_coeffs[ch][2*i+1];
641 ff_imdct_half(&s->imdct_256, s->delay[ch-1], x);
642 } else {
643 ff_imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
644 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
645 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
646 }
647 }
648 }
649
650 /**
651 * Downmix the output to mono or stereo.
652 */
653 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
654 {
655 int i, j;
656 float v0, v1;
657 if(out_ch == 2) {
658 for(i=0; i<len; i++) {
659 v0 = v1 = 0.0f;
660 for(j=0; j<in_ch; j++) {
661 v0 += samples[j][i] * matrix[j][0];
662 v1 += samples[j][i] * matrix[j][1];
663 }
664 samples[0][i] = v0;
665 samples[1][i] = v1;
666 }
667 } else if(out_ch == 1) {
668 for(i=0; i<len; i++) {
669 v0 = 0.0f;
670 for(j=0; j<in_ch; j++)
671 v0 += samples[j][i] * matrix[j][0];
672 samples[0][i] = v0;
673 }
674 }
675 }
676
677 /**
678 * Upmix delay samples from stereo to original channel layout.
679 */
680 static void ac3_upmix_delay(AC3DecodeContext *s)
681 {
682 int channel_data_size = sizeof(s->delay[0]);
683 switch(s->channel_mode) {
684 case AC3_CHMODE_DUALMONO:
685 case AC3_CHMODE_STEREO:
686 /* upmix mono to stereo */
687 memcpy(s->delay[1], s->delay[0], channel_data_size);
688 break;
689 case AC3_CHMODE_2F2R:
690 memset(s->delay[3], 0, channel_data_size);
691 case AC3_CHMODE_2F1R:
692 memset(s->delay[2], 0, channel_data_size);
693 break;
694 case AC3_CHMODE_3F2R:
695 memset(s->delay[4], 0, channel_data_size);
696 case AC3_CHMODE_3F1R:
697 memset(s->delay[3], 0, channel_data_size);
698 case AC3_CHMODE_3F:
699 memcpy(s->delay[2], s->delay[1], channel_data_size);
700 memset(s->delay[1], 0, channel_data_size);
701 break;
702 }
703 }
704
705 /**
706 * Decode band structure for coupling, spectral extension, or enhanced coupling.
707 * The band structure defines how many subbands are in each band. For each
708 * subband in the range, 1 means it is combined with the previous band, and 0
709 * means that it starts a new band.
710 *
711 * @param[in] gbc bit reader context
712 * @param[in] blk block number
713 * @param[in] eac3 flag to indicate E-AC-3
714 * @param[in] ecpl flag to indicate enhanced coupling
715 * @param[in] start_subband subband number for start of range
716 * @param[in] end_subband subband number for end of range
717 * @param[in] default_band_struct default band structure table
718 * @param[out] num_bands number of bands (optionally NULL)
719 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
720 */
721 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
722 int ecpl, int start_subband, int end_subband,
723 const uint8_t *default_band_struct,
724 int *num_bands, uint8_t *band_sizes)
725 {
726 int subbnd, bnd, n_subbands, n_bands=0;
727 uint8_t bnd_sz[22];
728 uint8_t coded_band_struct[22];
729 const uint8_t *band_struct;
730
731 n_subbands = end_subband - start_subband;
732
733 /* decode band structure from bitstream or use default */
734 if (!eac3 || get_bits1(gbc)) {
735 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
736 coded_band_struct[subbnd] = get_bits1(gbc);
737 }
738 band_struct = coded_band_struct;
739 } else if (!blk) {
740 band_struct = &default_band_struct[start_subband+1];
741 } else {
742 /* no change in band structure */
743 return;
744 }
745
746 /* calculate number of bands and band sizes based on band structure.
747 note that the first 4 subbands in enhanced coupling span only 6 bins
748 instead of 12. */
749 if (num_bands || band_sizes ) {
750 n_bands = n_subbands;
751 bnd_sz[0] = ecpl ? 6 : 12;
752 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
753 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
754 if (band_struct[subbnd-1]) {
755 n_bands--;
756 bnd_sz[bnd] += subbnd_size;
757 } else {
758 bnd_sz[++bnd] = subbnd_size;
759 }
760 }
761 }
762
763 /* set optional output params */
764 if (num_bands)
765 *num_bands = n_bands;
766 if (band_sizes)
767 memcpy(band_sizes, bnd_sz, n_bands);
768 }
769
770 /**
771 * Decode a single audio block from the AC-3 bitstream.
772 */
773 static int decode_audio_block(AC3DecodeContext *s, int blk)
774 {
775 int fbw_channels = s->fbw_channels;
776 int channel_mode = s->channel_mode;
777 int i, bnd, seg, ch;
778 int different_transforms;
779 int downmix_output;
780 int cpl_in_use;
781 GetBitContext *gbc = &s->gbc;
782 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
783
784 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
785
786 /* block switch flags */
787 different_transforms = 0;
788 if (s->block_switch_syntax) {
789 for (ch = 1; ch <= fbw_channels; ch++) {
790 s->block_switch[ch] = get_bits1(gbc);
791 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
792 different_transforms = 1;
793 }
794 }
795
796 /* dithering flags */
797 if (s->dither_flag_syntax) {
798 for (ch = 1; ch <= fbw_channels; ch++) {
799 s->dither_flag[ch] = get_bits1(gbc);
800 }
801 }
802
803 /* dynamic range */
804 i = !(s->channel_mode);
805 do {
806 if(get_bits1(gbc)) {
807 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
808 s->avctx->drc_scale)+1.0;
809 } else if(blk == 0) {
810 s->dynamic_range[i] = 1.0f;
811 }
812 } while(i--);
813
814 /* spectral extension strategy */
815 if (s->eac3 && (!blk || get_bits1(gbc))) {
816 if (get_bits1(gbc)) {
817 av_log_missing_feature(s->avctx, "Spectral extension", 1);
818 return -1;
819 }
820 /* TODO: parse spectral extension strategy info */
821 }
822
823 /* TODO: spectral extension coordinates */
824
825 /* coupling strategy */
826 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
827 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
828 if (!s->eac3)
829 s->cpl_in_use[blk] = get_bits1(gbc);
830 if (s->cpl_in_use[blk]) {
831 /* coupling in use */
832 int cpl_start_subband, cpl_end_subband;
833
834 if (channel_mode < AC3_CHMODE_STEREO) {
835 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
836 return -1;
837 }
838
839 /* check for enhanced coupling */
840 if (s->eac3 && get_bits1(gbc)) {
841 /* TODO: parse enhanced coupling strategy info */
842 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
843 return -1;
844 }
845
846 /* determine which channels are coupled */
847 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
848 s->channel_in_cpl[1] = 1;
849 s->channel_in_cpl[2] = 1;
850 } else {
851 for (ch = 1; ch <= fbw_channels; ch++)
852 s->channel_in_cpl[ch] = get_bits1(gbc);
853 }
854
855 /* phase flags in use */
856 if (channel_mode == AC3_CHMODE_STEREO)
857 s->phase_flags_in_use = get_bits1(gbc);
858
859 /* coupling frequency range */
860 /* TODO: modify coupling end freq if spectral extension is used */
861 cpl_start_subband = get_bits(gbc, 4);
862 cpl_end_subband = get_bits(gbc, 4) + 3;
863 if (cpl_start_subband >= cpl_end_subband) {
864 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
865 cpl_start_subband, cpl_end_subband);
866 return -1;
867 }
868 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
869 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
870
871 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
872 cpl_end_subband,
873 ff_eac3_default_cpl_band_struct,
874 &s->num_cpl_bands, s->cpl_band_sizes);
875 } else {
876 /* coupling not in use */
877 for (ch = 1; ch <= fbw_channels; ch++) {
878 s->channel_in_cpl[ch] = 0;
879 s->first_cpl_coords[ch] = 1;
880 }
881 s->first_cpl_leak = s->eac3;
882 s->phase_flags_in_use = 0;
883 }
884 } else if (!s->eac3) {
885 if(!blk) {
886 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
887 return -1;
888 } else {
889 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
890 }
891 }
892 cpl_in_use = s->cpl_in_use[blk];
893
894 /* coupling coordinates */
895 if (cpl_in_use) {
896 int cpl_coords_exist = 0;
897
898 for (ch = 1; ch <= fbw_channels; ch++) {
899 if (s->channel_in_cpl[ch]) {
900 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
901 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
902 s->first_cpl_coords[ch] = 0;
903 cpl_coords_exist = 1;
904 master_cpl_coord = 3 * get_bits(gbc, 2);
905 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
906 cpl_coord_exp = get_bits(gbc, 4);
907 cpl_coord_mant = get_bits(gbc, 4);
908 if (cpl_coord_exp == 15)
909 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
910 else
911 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
912 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
913 }
914 } else if (!blk) {
915 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
916 return -1;
917 }
918 } else {
919 /* channel not in coupling */
920 s->first_cpl_coords[ch] = 1;
921 }
922 }
923 /* phase flags */
924 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
925 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
926 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
927 }
928 }
929 }
930
931 /* stereo rematrixing strategy and band structure */
932 if (channel_mode == AC3_CHMODE_STEREO) {
933 if ((s->eac3 && !blk) || get_bits1(gbc)) {
934 s->num_rematrixing_bands = 4;
935 if(cpl_in_use && s->start_freq[CPL_CH] <= 61)
936 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
937 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
938 s->rematrixing_flags[bnd] = get_bits1(gbc);
939 } else if (!blk) {
940 av_log(s->avctx, AV_LOG_ERROR, "new rematrixing strategy must be present in block 0\n");
941 return -1;
942 }
943 }
944
945 /* exponent strategies for each channel */
946 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
947 if (!s->eac3)
948 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
949 if(s->exp_strategy[blk][ch] != EXP_REUSE)
950 bit_alloc_stages[ch] = 3;
951 }
952
953 /* channel bandwidth */
954 for (ch = 1; ch <= fbw_channels; ch++) {
955 s->start_freq[ch] = 0;
956 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
957 int group_size;
958 int prev = s->end_freq[ch];
959 if (s->channel_in_cpl[ch])
960 s->end_freq[ch] = s->start_freq[CPL_CH];
961 else {
962 int bandwidth_code = get_bits(gbc, 6);
963 if (bandwidth_code > 60) {
964 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
965 return -1;
966 }
967 s->end_freq[ch] = bandwidth_code * 3 + 73;
968 }
969 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
970 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
971 if(blk > 0 && s->end_freq[ch] != prev)
972 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
973 }
974 }
975 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
976 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
977 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
978 }
979
980 /* decode exponents for each channel */
981 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
982 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
983 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
984 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
985 s->num_exp_groups[ch], s->dexps[ch][0],
986 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
987 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
988 return -1;
989 }
990 if(ch != CPL_CH && ch != s->lfe_ch)
991 skip_bits(gbc, 2); /* skip gainrng */
992 }
993 }
994
995 /* bit allocation information */
996 if (s->bit_allocation_syntax) {
997 if (get_bits1(gbc)) {
998 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
999 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1000 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1001 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1002 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1003 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1004 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1005 } else if (!blk) {
1006 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1007 return -1;
1008 }
1009 }
1010
1011 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1012 if(!s->eac3 || !blk){
1013 if(s->snr_offset_strategy && get_bits1(gbc)) {
1014 int snr = 0;
1015 int csnr;
1016 csnr = (get_bits(gbc, 6) - 15) << 4;
1017 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1018 /* snr offset */
1019 if (ch == i || s->snr_offset_strategy == 2)
1020 snr = (csnr + get_bits(gbc, 4)) << 2;
1021 /* run at least last bit allocation stage if snr offset changes */
1022 if(blk && s->snr_offset[ch] != snr) {
1023 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1024 }
1025 s->snr_offset[ch] = snr;
1026
1027 /* fast gain (normal AC-3 only) */
1028 if (!s->eac3) {
1029 int prev = s->fast_gain[ch];
1030 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1031 /* run last 2 bit allocation stages if fast gain changes */
1032 if(blk && prev != s->fast_gain[ch])
1033 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1034 }
1035 }
1036 } else if (!s->eac3 && !blk) {
1037 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1038 return -1;
1039 }
1040 }
1041
1042 /* fast gain (E-AC-3 only) */
1043 if (s->fast_gain_syntax && get_bits1(gbc)) {
1044 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1045 int prev = s->fast_gain[ch];
1046 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1047 /* run last 2 bit allocation stages if fast gain changes */
1048 if(blk && prev != s->fast_gain[ch])
1049 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1050 }
1051 } else if (s->eac3 && !blk) {
1052 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1053 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1054 }
1055
1056 /* E-AC-3 to AC-3 converter SNR offset */
1057 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1058 skip_bits(gbc, 10); // skip converter snr offset
1059 }
1060
1061 /* coupling leak information */
1062 if (cpl_in_use) {
1063 if (s->first_cpl_leak || get_bits1(gbc)) {
1064 int fl = get_bits(gbc, 3);
1065 int sl = get_bits(gbc, 3);
1066 /* run last 2 bit allocation stages for coupling channel if
1067 coupling leak changes */
1068 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1069 sl != s->bit_alloc_params.cpl_slow_leak)) {
1070 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1071 }
1072 s->bit_alloc_params.cpl_fast_leak = fl;
1073 s->bit_alloc_params.cpl_slow_leak = sl;
1074 } else if (!s->eac3 && !blk) {
1075 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1076 return -1;
1077 }
1078 s->first_cpl_leak = 0;
1079 }
1080
1081 /* delta bit allocation information */
1082 if (s->dba_syntax && get_bits1(gbc)) {
1083 /* delta bit allocation exists (strategy) */
1084 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1085 s->dba_mode[ch] = get_bits(gbc, 2);
1086 if (s->dba_mode[ch] == DBA_RESERVED) {
1087 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1088 return -1;
1089 }
1090 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1091 }
1092 /* channel delta offset, len and bit allocation */
1093 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1094 if (s->dba_mode[ch] == DBA_NEW) {
1095 s->dba_nsegs[ch] = get_bits(gbc, 3);
1096 for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1097 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1098 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1099 s->dba_values[ch][seg] = get_bits(gbc, 3);
1100 }
1101 /* run last 2 bit allocation stages if new dba values */
1102 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1103 }
1104 }
1105 } else if(blk == 0) {
1106 for(ch=0; ch<=s->channels; ch++) {
1107 s->dba_mode[ch] = DBA_NONE;
1108 }
1109 }
1110
1111 /* Bit allocation */
1112 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1113 if(bit_alloc_stages[ch] > 2) {
1114 /* Exponent mapping into PSD and PSD integration */
1115 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1116 s->start_freq[ch], s->end_freq[ch],
1117 s->psd[ch], s->band_psd[ch]);
1118 }
1119 if(bit_alloc_stages[ch] > 1) {
1120 /* Compute excitation function, Compute masking curve, and
1121 Apply delta bit allocation */
1122 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1123 s->start_freq[ch], s->end_freq[ch],
1124 s->fast_gain[ch], (ch == s->lfe_ch),
1125 s->dba_mode[ch], s->dba_nsegs[ch],
1126 s->dba_offsets[ch], s->dba_lengths[ch],
1127 s->dba_values[ch], s->mask[ch])) {
1128 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1129 return -1;
1130 }
1131 }
1132 if(bit_alloc_stages[ch] > 0) {
1133 /* Compute bit allocation */
1134 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1135 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1136 ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1137 s->start_freq[ch], s->end_freq[ch],
1138 s->snr_offset[ch],
1139 s->bit_alloc_params.floor,
1140 bap_tab, s->bap[ch]);
1141 }
1142 }
1143
1144 /* unused dummy data */
1145 if (s->skip_syntax && get_bits1(gbc)) {
1146 int skipl = get_bits(gbc, 9);
1147 while(skipl--)
1148 skip_bits(gbc, 8);
1149 }
1150
1151 /* unpack the transform coefficients
1152 this also uncouples channels if coupling is in use. */
1153 decode_transform_coeffs(s, blk);
1154
1155 /* TODO: generate enhanced coupling coordinates and uncouple */
1156
1157 /* TODO: apply spectral extension */
1158
1159 /* recover coefficients if rematrixing is in use */
1160 if(s->channel_mode == AC3_CHMODE_STEREO)
1161 do_rematrixing(s);
1162
1163 /* apply scaling to coefficients (headroom, dynrng) */
1164 for(ch=1; ch<=s->channels; ch++) {
1165 float gain = s->mul_bias / 4194304.0f;
1166 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1167 gain *= s->dynamic_range[ch-1];
1168 } else {
1169 gain *= s->dynamic_range[0];
1170 }
1171 s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1172 }
1173
1174 /* downmix and MDCT. order depends on whether block switching is used for
1175 any channel in this block. this is because coefficients for the long
1176 and short transforms cannot be mixed. */
1177 downmix_output = s->channels != s->out_channels &&
1178 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1179 s->fbw_channels == s->out_channels);
1180 if(different_transforms) {
1181 /* the delay samples have already been downmixed, so we upmix the delay
1182 samples in order to reconstruct all channels before downmixing. */
1183 if(s->downmixed) {
1184 s->downmixed = 0;
1185 ac3_upmix_delay(s);
1186 }
1187
1188 do_imdct(s, s->channels);
1189
1190 if(downmix_output) {
1191 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1192 }
1193 } else {
1194 if(downmix_output) {
1195 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1196 }
1197
1198 if(downmix_output && !s->downmixed) {
1199 s->downmixed = 1;
1200 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1201 }
1202
1203 do_imdct(s, s->out_channels);
1204 }
1205
1206 return 0;
1207 }
1208
1209 /**
1210 * Decode a single AC-3 frame.
1211 */
1212 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1213 AVPacket *avpkt)
1214 {
1215 const uint8_t *buf = avpkt->data;
1216 int buf_size = avpkt->size;
1217 AC3DecodeContext *s = avctx->priv_data;
1218 int16_t *out_samples = (int16_t *)data;
1219 int blk, ch, err;
1220 const uint8_t *channel_map;
1221 const float *output[AC3_MAX_CHANNELS];
1222
1223 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1224 if (s->input_buffer) {
1225 /* copy input buffer to decoder context to avoid reading past the end
1226 of the buffer, which can be caused by a damaged input stream. */
1227 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1228 init_get_bits(&s->gbc, s->input_buffer, buf_size * 8);
1229 } else {
1230 init_get_bits(&s->gbc, buf, buf_size * 8);
1231 }
1232
1233 /* parse the syncinfo */
1234 *data_size = 0;
1235 err = parse_frame_header(s);
1236
1237 /* check that reported frame size fits in input buffer */
1238 if(s->frame_size > buf_size) {
1239 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1240 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1241 }
1242
1243 /* check for crc mismatch */
1244 if(err != AAC_AC3_PARSE_ERROR_FRAME_SIZE && avctx->error_recognition >= FF_ER_CAREFUL) {
1245 if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1246 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1247 err = AAC_AC3_PARSE_ERROR_CRC;
1248 }
1249 }
1250
1251 if(err && err != AAC_AC3_PARSE_ERROR_CRC) {
1252 switch(err) {
1253 case AAC_AC3_PARSE_ERROR_SYNC:
1254 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1255 return -1;
1256 case AAC_AC3_PARSE_ERROR_BSID:
1257 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1258 break;
1259 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1260 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1261 break;
1262 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1263 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1264 break;
1265 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1266 /* skip frame if CRC is ok. otherwise use error concealment. */
1267 /* TODO: add support for substreams and dependent frames */
1268 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1269 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1270 return s->frame_size;
1271 } else {
1272 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1273 }
1274 break;
1275 default:
1276 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1277 break;
1278 }
1279 }
1280
1281 /* if frame is ok, set audio parameters */
1282 if (!err) {
1283 avctx->sample_rate = s->sample_rate;
1284 avctx->bit_rate = s->bit_rate;
1285
1286 /* channel config */
1287 s->out_channels = s->channels;
1288 s->output_mode = s->channel_mode;
1289 if(s->lfe_on)
1290 s->output_mode |= AC3_OUTPUT_LFEON;
1291 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1292 avctx->request_channels < s->channels) {
1293 s->out_channels = avctx->request_channels;
1294 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1295 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1296 }
1297 avctx->channels = s->out_channels;
1298 avctx->channel_layout = s->channel_layout;
1299
1300 /* set downmixing coefficients if needed */
1301 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1302 s->fbw_channels == s->out_channels)) {
1303 set_downmix_coeffs(s);
1304 }
1305 } else if (!s->out_channels) {
1306 s->out_channels = avctx->channels;
1307 if(s->out_channels < s->channels)
1308 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1309 }
1310
1311 /* decode the audio blocks */
1312 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1313 for (ch = 0; ch < s->out_channels; ch++)
1314 output[ch] = s->output[channel_map[ch]];
1315 for (blk = 0; blk < s->num_blocks; blk++) {
1316 if (!err && decode_audio_block(s, blk)) {
1317 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1318 err = 1;
1319 }
1320 s->dsp.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1321 out_samples += 256 * s->out_channels;
1322 }
1323 *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1324 return s->frame_size;
1325 }
1326
1327 /**
1328 * Uninitialize the AC-3 decoder.
1329 */
1330 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1331 {
1332 AC3DecodeContext *s = avctx->priv_data;
1333 ff_mdct_end(&s->imdct_512);
1334 ff_mdct_end(&s->imdct_256);
1335
1336 av_freep(&s->input_buffer);
1337
1338 return 0;
1339 }
1340
1341 AVCodec ac3_decoder = {
1342 .name = "ac3",
1343 .type = CODEC_TYPE_AUDIO,
1344 .id = CODEC_ID_AC3,
1345 .priv_data_size = sizeof (AC3DecodeContext),
1346 .init = ac3_decode_init,
1347 .close = ac3_decode_end,
1348 .decode = ac3_decode_frame,
1349 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1350 };
1351
1352 #if CONFIG_EAC3_DECODER
1353 AVCodec eac3_decoder = {
1354 .name = "eac3",
1355 .type = CODEC_TYPE_AUDIO,
1356 .id = CODEC_ID_EAC3,
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/52B (AC-3, E-AC-3)"),
1362 };
1363 #endif