Rearrange loop structure for approx. 35-50% faster calc_transform_coeffs_cpl()
[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;
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 int64_t cpl_coord = s->cpl_coords[ch][band];
424 for (bin = band_start; bin < band_end; bin++) {
425 s->fixed_coeffs[ch][bin] = ((int64_t)s->fixed_coeffs[CPL_CH][bin] *
426 cpl_coord) >> 23;
427 }
428 if (ch == 2 && s->phase_flags[band]) {
429 for (bin = band_start; bin < band_end; bin++)
430 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
431 }
432 }
433 }
434 bin = band_end;
435 }
436 }
437
438 /**
439 * Grouped mantissas for 3-level 5-level and 11-level quantization
440 */
441 typedef struct {
442 int b1_mant[2];
443 int b2_mant[2];
444 int b4_mant;
445 int b1;
446 int b2;
447 int b4;
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 int start_freq = s->start_freq[ch_index];
457 int end_freq = s->end_freq[ch_index];
458 uint8_t *baps = s->bap[ch_index];
459 int8_t *exps = s->dexps[ch_index];
460 int *coeffs = s->fixed_coeffs[ch_index];
461 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
462 GetBitContext *gbc = &s->gbc;
463 int freq;
464
465 for(freq = start_freq; freq < end_freq; freq++){
466 int bap = baps[freq];
467 int mantissa;
468 switch(bap){
469 case 0:
470 if (dither)
471 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
472 else
473 mantissa = 0;
474 break;
475 case 1:
476 if(m->b1){
477 m->b1--;
478 mantissa = m->b1_mant[m->b1];
479 }
480 else{
481 int bits = get_bits(gbc, 5);
482 mantissa = b1_mantissas[bits][0];
483 m->b1_mant[1] = b1_mantissas[bits][1];
484 m->b1_mant[0] = b1_mantissas[bits][2];
485 m->b1 = 2;
486 }
487 break;
488 case 2:
489 if(m->b2){
490 m->b2--;
491 mantissa = m->b2_mant[m->b2];
492 }
493 else{
494 int bits = get_bits(gbc, 7);
495 mantissa = b2_mantissas[bits][0];
496 m->b2_mant[1] = b2_mantissas[bits][1];
497 m->b2_mant[0] = b2_mantissas[bits][2];
498 m->b2 = 2;
499 }
500 break;
501 case 3:
502 mantissa = b3_mantissas[get_bits(gbc, 3)];
503 break;
504 case 4:
505 if(m->b4){
506 m->b4 = 0;
507 mantissa = m->b4_mant;
508 }
509 else{
510 int bits = get_bits(gbc, 7);
511 mantissa = b4_mantissas[bits][0];
512 m->b4_mant = b4_mantissas[bits][1];
513 m->b4 = 1;
514 }
515 break;
516 case 5:
517 mantissa = b5_mantissas[get_bits(gbc, 4)];
518 break;
519 default: /* 6 to 15 */
520 mantissa = get_bits(gbc, quantization_tab[bap]);
521 /* Shift mantissa and sign-extend it. */
522 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
523 break;
524 }
525 coeffs[freq] = mantissa >> exps[freq];
526 }
527 }
528
529 /**
530 * Remove random dithering from coupling range coefficients with zero-bit
531 * mantissas for coupled channels which do not use dithering.
532 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
533 */
534 static void remove_dithering(AC3DecodeContext *s) {
535 int ch, i;
536
537 for(ch=1; ch<=s->fbw_channels; ch++) {
538 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
539 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
540 if(!s->bap[CPL_CH][i])
541 s->fixed_coeffs[ch][i] = 0;
542 }
543 }
544 }
545 }
546
547 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
548 mant_groups *m)
549 {
550 if (!s->channel_uses_aht[ch]) {
551 ac3_decode_transform_coeffs_ch(s, ch, m);
552 } else {
553 /* if AHT is used, mantissas for all blocks are encoded in the first
554 block of the frame. */
555 int bin;
556 if (!blk && CONFIG_EAC3_DECODER)
557 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
558 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
559 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
560 }
561 }
562 }
563
564 /**
565 * Decode the transform coefficients.
566 */
567 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
568 {
569 int ch, end;
570 int got_cplchan = 0;
571 mant_groups m;
572
573 m.b1 = m.b2 = m.b4 = 0;
574
575 for (ch = 1; ch <= s->channels; ch++) {
576 /* transform coefficients for full-bandwidth channel */
577 decode_transform_coeffs_ch(s, blk, ch, &m);
578 /* tranform coefficients for coupling channel come right after the
579 coefficients for the first coupled channel*/
580 if (s->channel_in_cpl[ch]) {
581 if (!got_cplchan) {
582 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
583 calc_transform_coeffs_cpl(s);
584 got_cplchan = 1;
585 }
586 end = s->end_freq[CPL_CH];
587 } else {
588 end = s->end_freq[ch];
589 }
590 do
591 s->fixed_coeffs[ch][end] = 0;
592 while(++end < 256);
593 }
594
595 /* zero the dithered coefficients for appropriate channels */
596 remove_dithering(s);
597 }
598
599 /**
600 * Stereo rematrixing.
601 * reference: Section 7.5.4 Rematrixing : Decoding Technique
602 */
603 static void do_rematrixing(AC3DecodeContext *s)
604 {
605 int bnd, i;
606 int end, bndend;
607 int tmp0, tmp1;
608
609 end = FFMIN(s->end_freq[1], s->end_freq[2]);
610
611 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
612 if(s->rematrixing_flags[bnd]) {
613 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
614 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
615 tmp0 = s->fixed_coeffs[1][i];
616 tmp1 = s->fixed_coeffs[2][i];
617 s->fixed_coeffs[1][i] = tmp0 + tmp1;
618 s->fixed_coeffs[2][i] = tmp0 - tmp1;
619 }
620 }
621 }
622 }
623
624 /**
625 * Inverse MDCT Transform.
626 * Convert frequency domain coefficients to time-domain audio samples.
627 * reference: Section 7.9.4 Transformation Equations
628 */
629 static inline void do_imdct(AC3DecodeContext *s, int channels)
630 {
631 int ch;
632 float add_bias = s->add_bias;
633 if(s->out_channels==1 && channels>1)
634 add_bias *= LEVEL_MINUS_3DB; // compensate for the gain in downmix
635
636 for (ch=1; ch<=channels; ch++) {
637 if (s->block_switch[ch]) {
638 int i;
639 float *x = s->tmp_output+128;
640 for(i=0; i<128; i++)
641 x[i] = s->transform_coeffs[ch][2*i];
642 ff_imdct_half(&s->imdct_256, s->tmp_output, x);
643 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
644 for(i=0; i<128; i++)
645 x[i] = s->transform_coeffs[ch][2*i+1];
646 ff_imdct_half(&s->imdct_256, s->delay[ch-1], x);
647 } else {
648 ff_imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
649 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128);
650 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
651 }
652 }
653 }
654
655 /**
656 * Downmix the output to mono or stereo.
657 */
658 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
659 {
660 int i, j;
661 float v0, v1;
662 if(out_ch == 2) {
663 for(i=0; i<len; i++) {
664 v0 = v1 = 0.0f;
665 for(j=0; j<in_ch; j++) {
666 v0 += samples[j][i] * matrix[j][0];
667 v1 += samples[j][i] * matrix[j][1];
668 }
669 samples[0][i] = v0;
670 samples[1][i] = v1;
671 }
672 } else if(out_ch == 1) {
673 for(i=0; i<len; i++) {
674 v0 = 0.0f;
675 for(j=0; j<in_ch; j++)
676 v0 += samples[j][i] * matrix[j][0];
677 samples[0][i] = v0;
678 }
679 }
680 }
681
682 /**
683 * Upmix delay samples from stereo to original channel layout.
684 */
685 static void ac3_upmix_delay(AC3DecodeContext *s)
686 {
687 int channel_data_size = sizeof(s->delay[0]);
688 switch(s->channel_mode) {
689 case AC3_CHMODE_DUALMONO:
690 case AC3_CHMODE_STEREO:
691 /* upmix mono to stereo */
692 memcpy(s->delay[1], s->delay[0], channel_data_size);
693 break;
694 case AC3_CHMODE_2F2R:
695 memset(s->delay[3], 0, channel_data_size);
696 case AC3_CHMODE_2F1R:
697 memset(s->delay[2], 0, channel_data_size);
698 break;
699 case AC3_CHMODE_3F2R:
700 memset(s->delay[4], 0, channel_data_size);
701 case AC3_CHMODE_3F1R:
702 memset(s->delay[3], 0, channel_data_size);
703 case AC3_CHMODE_3F:
704 memcpy(s->delay[2], s->delay[1], channel_data_size);
705 memset(s->delay[1], 0, channel_data_size);
706 break;
707 }
708 }
709
710 /**
711 * Decode band structure for coupling, spectral extension, or enhanced coupling.
712 * The band structure defines how many subbands are in each band. For each
713 * subband in the range, 1 means it is combined with the previous band, and 0
714 * means that it starts a new band.
715 *
716 * @param[in] gbc bit reader context
717 * @param[in] blk block number
718 * @param[in] eac3 flag to indicate E-AC-3
719 * @param[in] ecpl flag to indicate enhanced coupling
720 * @param[in] start_subband subband number for start of range
721 * @param[in] end_subband subband number for end of range
722 * @param[in] default_band_struct default band structure table
723 * @param[out] num_bands number of bands (optionally NULL)
724 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
725 */
726 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
727 int ecpl, int start_subband, int end_subband,
728 const uint8_t *default_band_struct,
729 int *num_bands, uint8_t *band_sizes)
730 {
731 int subbnd, bnd, n_subbands, n_bands=0;
732 uint8_t bnd_sz[22];
733 uint8_t coded_band_struct[22];
734 const uint8_t *band_struct;
735
736 n_subbands = end_subband - start_subband;
737
738 /* decode band structure from bitstream or use default */
739 if (!eac3 || get_bits1(gbc)) {
740 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
741 coded_band_struct[subbnd] = get_bits1(gbc);
742 }
743 band_struct = coded_band_struct;
744 } else if (!blk) {
745 band_struct = &default_band_struct[start_subband+1];
746 } else {
747 /* no change in band structure */
748 return;
749 }
750
751 /* calculate number of bands and band sizes based on band structure.
752 note that the first 4 subbands in enhanced coupling span only 6 bins
753 instead of 12. */
754 if (num_bands || band_sizes ) {
755 n_bands = n_subbands;
756 bnd_sz[0] = ecpl ? 6 : 12;
757 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
758 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
759 if (band_struct[subbnd-1]) {
760 n_bands--;
761 bnd_sz[bnd] += subbnd_size;
762 } else {
763 bnd_sz[++bnd] = subbnd_size;
764 }
765 }
766 }
767
768 /* set optional output params */
769 if (num_bands)
770 *num_bands = n_bands;
771 if (band_sizes)
772 memcpy(band_sizes, bnd_sz, n_bands);
773 }
774
775 /**
776 * Decode a single audio block from the AC-3 bitstream.
777 */
778 static int decode_audio_block(AC3DecodeContext *s, int blk)
779 {
780 int fbw_channels = s->fbw_channels;
781 int channel_mode = s->channel_mode;
782 int i, bnd, seg, ch;
783 int different_transforms;
784 int downmix_output;
785 int cpl_in_use;
786 GetBitContext *gbc = &s->gbc;
787 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
788
789 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
790
791 /* block switch flags */
792 different_transforms = 0;
793 if (s->block_switch_syntax) {
794 for (ch = 1; ch <= fbw_channels; ch++) {
795 s->block_switch[ch] = get_bits1(gbc);
796 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
797 different_transforms = 1;
798 }
799 }
800
801 /* dithering flags */
802 if (s->dither_flag_syntax) {
803 for (ch = 1; ch <= fbw_channels; ch++) {
804 s->dither_flag[ch] = get_bits1(gbc);
805 }
806 }
807
808 /* dynamic range */
809 i = !(s->channel_mode);
810 do {
811 if(get_bits1(gbc)) {
812 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
813 s->avctx->drc_scale)+1.0;
814 } else if(blk == 0) {
815 s->dynamic_range[i] = 1.0f;
816 }
817 } while(i--);
818
819 /* spectral extension strategy */
820 if (s->eac3 && (!blk || get_bits1(gbc))) {
821 if (get_bits1(gbc)) {
822 av_log_missing_feature(s->avctx, "Spectral extension", 1);
823 return -1;
824 }
825 /* TODO: parse spectral extension strategy info */
826 }
827
828 /* TODO: spectral extension coordinates */
829
830 /* coupling strategy */
831 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
832 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
833 if (!s->eac3)
834 s->cpl_in_use[blk] = get_bits1(gbc);
835 if (s->cpl_in_use[blk]) {
836 /* coupling in use */
837 int cpl_start_subband, cpl_end_subband;
838
839 if (channel_mode < AC3_CHMODE_STEREO) {
840 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
841 return -1;
842 }
843
844 /* check for enhanced coupling */
845 if (s->eac3 && get_bits1(gbc)) {
846 /* TODO: parse enhanced coupling strategy info */
847 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
848 return -1;
849 }
850
851 /* determine which channels are coupled */
852 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
853 s->channel_in_cpl[1] = 1;
854 s->channel_in_cpl[2] = 1;
855 } else {
856 for (ch = 1; ch <= fbw_channels; ch++)
857 s->channel_in_cpl[ch] = get_bits1(gbc);
858 }
859
860 /* phase flags in use */
861 if (channel_mode == AC3_CHMODE_STEREO)
862 s->phase_flags_in_use = get_bits1(gbc);
863
864 /* coupling frequency range */
865 /* TODO: modify coupling end freq if spectral extension is used */
866 cpl_start_subband = get_bits(gbc, 4);
867 cpl_end_subband = get_bits(gbc, 4) + 3;
868 if (cpl_start_subband >= cpl_end_subband) {
869 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
870 cpl_start_subband, cpl_end_subband);
871 return -1;
872 }
873 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
874 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
875
876 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
877 cpl_end_subband,
878 ff_eac3_default_cpl_band_struct,
879 &s->num_cpl_bands, s->cpl_band_sizes);
880 } else {
881 /* coupling not in use */
882 for (ch = 1; ch <= fbw_channels; ch++) {
883 s->channel_in_cpl[ch] = 0;
884 s->first_cpl_coords[ch] = 1;
885 }
886 s->first_cpl_leak = s->eac3;
887 s->phase_flags_in_use = 0;
888 }
889 } else if (!s->eac3) {
890 if(!blk) {
891 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
892 return -1;
893 } else {
894 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
895 }
896 }
897 cpl_in_use = s->cpl_in_use[blk];
898
899 /* coupling coordinates */
900 if (cpl_in_use) {
901 int cpl_coords_exist = 0;
902
903 for (ch = 1; ch <= fbw_channels; ch++) {
904 if (s->channel_in_cpl[ch]) {
905 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
906 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
907 s->first_cpl_coords[ch] = 0;
908 cpl_coords_exist = 1;
909 master_cpl_coord = 3 * get_bits(gbc, 2);
910 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
911 cpl_coord_exp = get_bits(gbc, 4);
912 cpl_coord_mant = get_bits(gbc, 4);
913 if (cpl_coord_exp == 15)
914 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
915 else
916 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
917 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
918 }
919 } else if (!blk) {
920 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
921 return -1;
922 }
923 } else {
924 /* channel not in coupling */
925 s->first_cpl_coords[ch] = 1;
926 }
927 }
928 /* phase flags */
929 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
930 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
931 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
932 }
933 }
934 }
935
936 /* stereo rematrixing strategy and band structure */
937 if (channel_mode == AC3_CHMODE_STEREO) {
938 if ((s->eac3 && !blk) || get_bits1(gbc)) {
939 s->num_rematrixing_bands = 4;
940 if(cpl_in_use && s->start_freq[CPL_CH] <= 61)
941 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
942 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
943 s->rematrixing_flags[bnd] = get_bits1(gbc);
944 } else if (!blk) {
945 av_log(s->avctx, AV_LOG_ERROR, "new rematrixing strategy must be present in block 0\n");
946 return -1;
947 }
948 }
949
950 /* exponent strategies for each channel */
951 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
952 if (!s->eac3)
953 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
954 if(s->exp_strategy[blk][ch] != EXP_REUSE)
955 bit_alloc_stages[ch] = 3;
956 }
957
958 /* channel bandwidth */
959 for (ch = 1; ch <= fbw_channels; ch++) {
960 s->start_freq[ch] = 0;
961 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
962 int group_size;
963 int prev = s->end_freq[ch];
964 if (s->channel_in_cpl[ch])
965 s->end_freq[ch] = s->start_freq[CPL_CH];
966 else {
967 int bandwidth_code = get_bits(gbc, 6);
968 if (bandwidth_code > 60) {
969 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
970 return -1;
971 }
972 s->end_freq[ch] = bandwidth_code * 3 + 73;
973 }
974 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
975 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
976 if(blk > 0 && s->end_freq[ch] != prev)
977 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
978 }
979 }
980 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
981 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
982 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
983 }
984
985 /* decode exponents for each channel */
986 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
987 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
988 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
989 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
990 s->num_exp_groups[ch], s->dexps[ch][0],
991 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
992 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
993 return -1;
994 }
995 if(ch != CPL_CH && ch != s->lfe_ch)
996 skip_bits(gbc, 2); /* skip gainrng */
997 }
998 }
999
1000 /* bit allocation information */
1001 if (s->bit_allocation_syntax) {
1002 if (get_bits1(gbc)) {
1003 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1004 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1005 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1006 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1007 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1008 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1009 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1010 } else if (!blk) {
1011 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1012 return -1;
1013 }
1014 }
1015
1016 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1017 if(!s->eac3 || !blk){
1018 if(s->snr_offset_strategy && get_bits1(gbc)) {
1019 int snr = 0;
1020 int csnr;
1021 csnr = (get_bits(gbc, 6) - 15) << 4;
1022 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1023 /* snr offset */
1024 if (ch == i || s->snr_offset_strategy == 2)
1025 snr = (csnr + get_bits(gbc, 4)) << 2;
1026 /* run at least last bit allocation stage if snr offset changes */
1027 if(blk && s->snr_offset[ch] != snr) {
1028 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1029 }
1030 s->snr_offset[ch] = snr;
1031
1032 /* fast gain (normal AC-3 only) */
1033 if (!s->eac3) {
1034 int prev = s->fast_gain[ch];
1035 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1036 /* run last 2 bit allocation stages if fast gain changes */
1037 if(blk && prev != s->fast_gain[ch])
1038 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1039 }
1040 }
1041 } else if (!s->eac3 && !blk) {
1042 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1043 return -1;
1044 }
1045 }
1046
1047 /* fast gain (E-AC-3 only) */
1048 if (s->fast_gain_syntax && get_bits1(gbc)) {
1049 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1050 int prev = s->fast_gain[ch];
1051 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1052 /* run last 2 bit allocation stages if fast gain changes */
1053 if(blk && prev != s->fast_gain[ch])
1054 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1055 }
1056 } else if (s->eac3 && !blk) {
1057 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1058 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1059 }
1060
1061 /* E-AC-3 to AC-3 converter SNR offset */
1062 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1063 skip_bits(gbc, 10); // skip converter snr offset
1064 }
1065
1066 /* coupling leak information */
1067 if (cpl_in_use) {
1068 if (s->first_cpl_leak || get_bits1(gbc)) {
1069 int fl = get_bits(gbc, 3);
1070 int sl = get_bits(gbc, 3);
1071 /* run last 2 bit allocation stages for coupling channel if
1072 coupling leak changes */
1073 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1074 sl != s->bit_alloc_params.cpl_slow_leak)) {
1075 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1076 }
1077 s->bit_alloc_params.cpl_fast_leak = fl;
1078 s->bit_alloc_params.cpl_slow_leak = sl;
1079 } else if (!s->eac3 && !blk) {
1080 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1081 return -1;
1082 }
1083 s->first_cpl_leak = 0;
1084 }
1085
1086 /* delta bit allocation information */
1087 if (s->dba_syntax && get_bits1(gbc)) {
1088 /* delta bit allocation exists (strategy) */
1089 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1090 s->dba_mode[ch] = get_bits(gbc, 2);
1091 if (s->dba_mode[ch] == DBA_RESERVED) {
1092 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1093 return -1;
1094 }
1095 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1096 }
1097 /* channel delta offset, len and bit allocation */
1098 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1099 if (s->dba_mode[ch] == DBA_NEW) {
1100 s->dba_nsegs[ch] = get_bits(gbc, 3);
1101 for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) {
1102 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1103 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1104 s->dba_values[ch][seg] = get_bits(gbc, 3);
1105 }
1106 /* run last 2 bit allocation stages if new dba values */
1107 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1108 }
1109 }
1110 } else if(blk == 0) {
1111 for(ch=0; ch<=s->channels; ch++) {
1112 s->dba_mode[ch] = DBA_NONE;
1113 }
1114 }
1115
1116 /* Bit allocation */
1117 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1118 if(bit_alloc_stages[ch] > 2) {
1119 /* Exponent mapping into PSD and PSD integration */
1120 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1121 s->start_freq[ch], s->end_freq[ch],
1122 s->psd[ch], s->band_psd[ch]);
1123 }
1124 if(bit_alloc_stages[ch] > 1) {
1125 /* Compute excitation function, Compute masking curve, and
1126 Apply delta bit allocation */
1127 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1128 s->start_freq[ch], s->end_freq[ch],
1129 s->fast_gain[ch], (ch == s->lfe_ch),
1130 s->dba_mode[ch], s->dba_nsegs[ch],
1131 s->dba_offsets[ch], s->dba_lengths[ch],
1132 s->dba_values[ch], s->mask[ch])) {
1133 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1134 return -1;
1135 }
1136 }
1137 if(bit_alloc_stages[ch] > 0) {
1138 /* Compute bit allocation */
1139 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1140 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1141 ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1142 s->start_freq[ch], s->end_freq[ch],
1143 s->snr_offset[ch],
1144 s->bit_alloc_params.floor,
1145 bap_tab, s->bap[ch]);
1146 }
1147 }
1148
1149 /* unused dummy data */
1150 if (s->skip_syntax && get_bits1(gbc)) {
1151 int skipl = get_bits(gbc, 9);
1152 while(skipl--)
1153 skip_bits(gbc, 8);
1154 }
1155
1156 /* unpack the transform coefficients
1157 this also uncouples channels if coupling is in use. */
1158 decode_transform_coeffs(s, blk);
1159
1160 /* TODO: generate enhanced coupling coordinates and uncouple */
1161
1162 /* TODO: apply spectral extension */
1163
1164 /* recover coefficients if rematrixing is in use */
1165 if(s->channel_mode == AC3_CHMODE_STEREO)
1166 do_rematrixing(s);
1167
1168 /* apply scaling to coefficients (headroom, dynrng) */
1169 for(ch=1; ch<=s->channels; ch++) {
1170 float gain = s->mul_bias / 4194304.0f;
1171 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1172 gain *= s->dynamic_range[ch-1];
1173 } else {
1174 gain *= s->dynamic_range[0];
1175 }
1176 s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1177 }
1178
1179 /* downmix and MDCT. order depends on whether block switching is used for
1180 any channel in this block. this is because coefficients for the long
1181 and short transforms cannot be mixed. */
1182 downmix_output = s->channels != s->out_channels &&
1183 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1184 s->fbw_channels == s->out_channels);
1185 if(different_transforms) {
1186 /* the delay samples have already been downmixed, so we upmix the delay
1187 samples in order to reconstruct all channels before downmixing. */
1188 if(s->downmixed) {
1189 s->downmixed = 0;
1190 ac3_upmix_delay(s);
1191 }
1192
1193 do_imdct(s, s->channels);
1194
1195 if(downmix_output) {
1196 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1197 }
1198 } else {
1199 if(downmix_output) {
1200 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1201 }
1202
1203 if(downmix_output && !s->downmixed) {
1204 s->downmixed = 1;
1205 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1206 }
1207
1208 do_imdct(s, s->out_channels);
1209 }
1210
1211 return 0;
1212 }
1213
1214 /**
1215 * Decode a single AC-3 frame.
1216 */
1217 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1218 AVPacket *avpkt)
1219 {
1220 const uint8_t *buf = avpkt->data;
1221 int buf_size = avpkt->size;
1222 AC3DecodeContext *s = avctx->priv_data;
1223 int16_t *out_samples = (int16_t *)data;
1224 int blk, ch, err;
1225 const uint8_t *channel_map;
1226 const float *output[AC3_MAX_CHANNELS];
1227
1228 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1229 if (s->input_buffer) {
1230 /* copy input buffer to decoder context to avoid reading past the end
1231 of the buffer, which can be caused by a damaged input stream. */
1232 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1233 init_get_bits(&s->gbc, s->input_buffer, buf_size * 8);
1234 } else {
1235 init_get_bits(&s->gbc, buf, buf_size * 8);
1236 }
1237
1238 /* parse the syncinfo */
1239 *data_size = 0;
1240 err = parse_frame_header(s);
1241
1242 /* check that reported frame size fits in input buffer */
1243 if(s->frame_size > buf_size) {
1244 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1245 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1246 }
1247
1248 /* check for crc mismatch */
1249 if(err != AAC_AC3_PARSE_ERROR_FRAME_SIZE && avctx->error_recognition >= FF_ER_CAREFUL) {
1250 if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1251 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1252 err = AAC_AC3_PARSE_ERROR_CRC;
1253 }
1254 }
1255
1256 if(err && err != AAC_AC3_PARSE_ERROR_CRC) {
1257 switch(err) {
1258 case AAC_AC3_PARSE_ERROR_SYNC:
1259 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1260 return -1;
1261 case AAC_AC3_PARSE_ERROR_BSID:
1262 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1263 break;
1264 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1265 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1266 break;
1267 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1268 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1269 break;
1270 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1271 /* skip frame if CRC is ok. otherwise use error concealment. */
1272 /* TODO: add support for substreams and dependent frames */
1273 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1274 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1275 return s->frame_size;
1276 } else {
1277 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1278 }
1279 break;
1280 default:
1281 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1282 break;
1283 }
1284 }
1285
1286 /* if frame is ok, set audio parameters */
1287 if (!err) {
1288 avctx->sample_rate = s->sample_rate;
1289 avctx->bit_rate = s->bit_rate;
1290
1291 /* channel config */
1292 s->out_channels = s->channels;
1293 s->output_mode = s->channel_mode;
1294 if(s->lfe_on)
1295 s->output_mode |= AC3_OUTPUT_LFEON;
1296 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1297 avctx->request_channels < s->channels) {
1298 s->out_channels = avctx->request_channels;
1299 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1300 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1301 }
1302 avctx->channels = s->out_channels;
1303 avctx->channel_layout = s->channel_layout;
1304
1305 /* set downmixing coefficients if needed */
1306 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1307 s->fbw_channels == s->out_channels)) {
1308 set_downmix_coeffs(s);
1309 }
1310 } else if (!s->out_channels) {
1311 s->out_channels = avctx->channels;
1312 if(s->out_channels < s->channels)
1313 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1314 }
1315
1316 /* decode the audio blocks */
1317 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1318 for (ch = 0; ch < s->out_channels; ch++)
1319 output[ch] = s->output[channel_map[ch]];
1320 for (blk = 0; blk < s->num_blocks; blk++) {
1321 if (!err && decode_audio_block(s, blk)) {
1322 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1323 err = 1;
1324 }
1325 s->dsp.float_to_int16_interleave(out_samples, output, 256, s->out_channels);
1326 out_samples += 256 * s->out_channels;
1327 }
1328 *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t);
1329 return s->frame_size;
1330 }
1331
1332 /**
1333 * Uninitialize the AC-3 decoder.
1334 */
1335 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1336 {
1337 AC3DecodeContext *s = avctx->priv_data;
1338 ff_mdct_end(&s->imdct_512);
1339 ff_mdct_end(&s->imdct_256);
1340
1341 av_freep(&s->input_buffer);
1342
1343 return 0;
1344 }
1345
1346 AVCodec ac3_decoder = {
1347 .name = "ac3",
1348 .type = CODEC_TYPE_AUDIO,
1349 .id = CODEC_ID_AC3,
1350 .priv_data_size = sizeof (AC3DecodeContext),
1351 .init = ac3_decode_init,
1352 .close = ac3_decode_end,
1353 .decode = ac3_decode_frame,
1354 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1355 };
1356
1357 #if CONFIG_EAC3_DECODER
1358 AVCodec eac3_decoder = {
1359 .name = "eac3",
1360 .type = CODEC_TYPE_AUDIO,
1361 .id = CODEC_ID_EAC3,
1362 .priv_data_size = sizeof (AC3DecodeContext),
1363 .init = ac3_decode_init,
1364 .close = ac3_decode_end,
1365 .decode = ac3_decode_frame,
1366 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1367 };
1368 #endif