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Add channel layout support to the AC-3 encoder.
[FFMpeg-mirror/lagarith.git] / libavcodec / ac3enc.c
blob8714da00cfdbf1e40f73d69e964a1526ec34c3d9
1 /*
2 * The simplest AC-3 encoder
3 * Copyright (c) 2000 Fabrice Bellard
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file libavcodec/ac3enc.c
24 * The simplest AC-3 encoder.
25 */
26 //#define DEBUG
27 //#define DEBUG_BITALLOC
28 #include "libavutil/crc.h"
29 #include "avcodec.h"
30 #include "get_bits.h" // for ff_reverse
31 #include "put_bits.h"
32 #include "ac3.h"
33 #include "audioconvert.h"
34
35 typedef struct AC3EncodeContext {
36 PutBitContext pb;
37 int nb_channels;
38 int nb_all_channels;
39 int lfe_channel;
40 const uint8_t *channel_map;
41 int bit_rate;
42 unsigned int sample_rate;
43 unsigned int bitstream_id;
44 unsigned int frame_size_min; /* minimum frame size in case rounding is necessary */
45 unsigned int frame_size; /* current frame size in words */
46 unsigned int bits_written;
47 unsigned int samples_written;
48 int sr_shift;
49 unsigned int frame_size_code;
50 unsigned int sr_code; /* frequency */
51 unsigned int channel_mode;
52 int lfe;
53 unsigned int bitstream_mode;
54 short last_samples[AC3_MAX_CHANNELS][256];
55 unsigned int chbwcod[AC3_MAX_CHANNELS];
56 int nb_coefs[AC3_MAX_CHANNELS];
57
58 /* bitrate allocation control */
59 int slow_gain_code, slow_decay_code, fast_decay_code, db_per_bit_code, floor_code;
60 AC3BitAllocParameters bit_alloc;
61 int coarse_snr_offset;
62 int fast_gain_code[AC3_MAX_CHANNELS];
63 int fine_snr_offset[AC3_MAX_CHANNELS];
64 /* mantissa encoding */
65 int mant1_cnt, mant2_cnt, mant4_cnt;
66 } AC3EncodeContext;
67
68 static int16_t costab[64];
69 static int16_t sintab[64];
70 static int16_t xcos1[128];
71 static int16_t xsin1[128];
72
73 #define MDCT_NBITS 9
74 #define N (1 << MDCT_NBITS)
75
76 /* new exponents are sent if their Norm 1 exceed this number */
77 #define EXP_DIFF_THRESHOLD 1000
78
79 static inline int16_t fix15(float a)
80 {
81 int v;
82 v = (int)(a * (float)(1 << 15));
83 if (v < -32767)
84 v = -32767;
85 else if (v > 32767)
86 v = 32767;
87 return v;
88 }
89
90 typedef struct IComplex {
91 short re,im;
92 } IComplex;
93
94 static av_cold void fft_init(int ln)
95 {
96 int i, n;
97 float alpha;
98
99 n = 1 << ln;
100
101 for(i=0;i<(n/2);i++) {
102 alpha = 2 * M_PI * (float)i / (float)n;
103 costab[i] = fix15(cos(alpha));
104 sintab[i] = fix15(sin(alpha));
105 }
106 }
107
108 /* butter fly op */
109 #define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
110 {\
111 int ax, ay, bx, by;\
112 bx=pre1;\
113 by=pim1;\
114 ax=qre1;\
115 ay=qim1;\
116 pre = (bx + ax) >> 1;\
117 pim = (by + ay) >> 1;\
118 qre = (bx - ax) >> 1;\
119 qim = (by - ay) >> 1;\
120 }
121
122 #define CMUL(pre, pim, are, aim, bre, bim) \
123 {\
124 pre = (MUL16(are, bre) - MUL16(aim, bim)) >> 15;\
125 pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15;\
126 }
127
128
129 /* do a 2^n point complex fft on 2^ln points. */
130 static void fft(IComplex *z, int ln)
131 {
132 int j, l, np, np2;
133 int nblocks, nloops;
134 register IComplex *p,*q;
135 int tmp_re, tmp_im;
136
137 np = 1 << ln;
138
139 /* reverse */
140 for(j=0;j<np;j++) {
141 int k = ff_reverse[j] >> (8 - ln);
142 if (k < j)
143 FFSWAP(IComplex, z[k], z[j]);
144 }
145
146 /* pass 0 */
147
148 p=&z[0];
149 j=(np >> 1);
150 do {
151 BF(p[0].re, p[0].im, p[1].re, p[1].im,
152 p[0].re, p[0].im, p[1].re, p[1].im);
153 p+=2;
154 } while (--j != 0);
155
156 /* pass 1 */
157
158 p=&z[0];
159 j=np >> 2;
160 do {
161 BF(p[0].re, p[0].im, p[2].re, p[2].im,
162 p[0].re, p[0].im, p[2].re, p[2].im);
163 BF(p[1].re, p[1].im, p[3].re, p[3].im,
164 p[1].re, p[1].im, p[3].im, -p[3].re);
165 p+=4;
166 } while (--j != 0);
167
168 /* pass 2 .. ln-1 */
169
170 nblocks = np >> 3;
171 nloops = 1 << 2;
172 np2 = np >> 1;
173 do {
174 p = z;
175 q = z + nloops;
176 for (j = 0; j < nblocks; ++j) {
177
178 BF(p->re, p->im, q->re, q->im,
179 p->re, p->im, q->re, q->im);
180
181 p++;
182 q++;
183 for(l = nblocks; l < np2; l += nblocks) {
184 CMUL(tmp_re, tmp_im, costab[l], -sintab[l], q->re, q->im);
185 BF(p->re, p->im, q->re, q->im,
186 p->re, p->im, tmp_re, tmp_im);
187 p++;
188 q++;
189 }
190 p += nloops;
191 q += nloops;
192 }
193 nblocks = nblocks >> 1;
194 nloops = nloops << 1;
195 } while (nblocks != 0);
196 }
197
198 /* do a 512 point mdct */
199 static void mdct512(int32_t *out, int16_t *in)
200 {
201 int i, re, im, re1, im1;
202 int16_t rot[N];
203 IComplex x[N/4];
204
205 /* shift to simplify computations */
206 for(i=0;i<N/4;i++)
207 rot[i] = -in[i + 3*N/4];
208 for(i=N/4;i<N;i++)
209 rot[i] = in[i - N/4];
210
211 /* pre rotation */
212 for(i=0;i<N/4;i++) {
213 re = ((int)rot[2*i] - (int)rot[N-1-2*i]) >> 1;
214 im = -((int)rot[N/2+2*i] - (int)rot[N/2-1-2*i]) >> 1;
215 CMUL(x[i].re, x[i].im, re, im, -xcos1[i], xsin1[i]);
216 }
217
218 fft(x, MDCT_NBITS - 2);
219
220 /* post rotation */
221 for(i=0;i<N/4;i++) {
222 re = x[i].re;
223 im = x[i].im;
224 CMUL(re1, im1, re, im, xsin1[i], xcos1[i]);
225 out[2*i] = im1;
226 out[N/2-1-2*i] = re1;
227 }
228 }
229
230 /* XXX: use another norm ? */
231 static int calc_exp_diff(uint8_t *exp1, uint8_t *exp2, int n)
232 {
233 int sum, i;
234 sum = 0;
235 for(i=0;i<n;i++) {
236 sum += abs(exp1[i] - exp2[i]);
237 }
238 return sum;
239 }
240
241 static void compute_exp_strategy(uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
242 uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
243 int ch, int is_lfe)
244 {
245 int i, j;
246 int exp_diff;
247
248 /* estimate if the exponent variation & decide if they should be
249 reused in the next frame */
250 exp_strategy[0][ch] = EXP_NEW;
251 for(i=1;i<NB_BLOCKS;i++) {
252 exp_diff = calc_exp_diff(exp[i][ch], exp[i-1][ch], N/2);
253 #ifdef DEBUG
254 av_log(NULL, AV_LOG_DEBUG, "exp_diff=%d\n", exp_diff);
255 #endif
256 if (exp_diff > EXP_DIFF_THRESHOLD)
257 exp_strategy[i][ch] = EXP_NEW;
258 else
259 exp_strategy[i][ch] = EXP_REUSE;
260 }
261 if (is_lfe)
262 return;
263
264 /* now select the encoding strategy type : if exponents are often
265 recoded, we use a coarse encoding */
266 i = 0;
267 while (i < NB_BLOCKS) {
268 j = i + 1;
269 while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE)
270 j++;
271 switch(j - i) {
272 case 1:
273 exp_strategy[i][ch] = EXP_D45;
274 break;
275 case 2:
276 case 3:
277 exp_strategy[i][ch] = EXP_D25;
278 break;
279 default:
280 exp_strategy[i][ch] = EXP_D15;
281 break;
282 }
283 i = j;
284 }
285 }
286
287 /* set exp[i] to min(exp[i], exp1[i]) */
288 static void exponent_min(uint8_t exp[N/2], uint8_t exp1[N/2], int n)
289 {
290 int i;
291
292 for(i=0;i<n;i++) {
293 if (exp1[i] < exp[i])
294 exp[i] = exp1[i];
295 }
296 }
297
298 /* update the exponents so that they are the ones the decoder will
299 decode. Return the number of bits used to code the exponents */
300 static int encode_exp(uint8_t encoded_exp[N/2],
301 uint8_t exp[N/2],
302 int nb_exps,
303 int exp_strategy)
304 {
305 int group_size, nb_groups, i, j, k, exp_min;
306 uint8_t exp1[N/2];
307
308 switch(exp_strategy) {
309 case EXP_D15:
310 group_size = 1;
311 break;
312 case EXP_D25:
313 group_size = 2;
314 break;
315 default:
316 case EXP_D45:
317 group_size = 4;
318 break;
319 }
320 nb_groups = ((nb_exps + (group_size * 3) - 4) / (3 * group_size)) * 3;
321
322 /* for each group, compute the minimum exponent */
323 exp1[0] = exp[0]; /* DC exponent is handled separately */
324 k = 1;
325 for(i=1;i<=nb_groups;i++) {
326 exp_min = exp[k];
327 assert(exp_min >= 0 && exp_min <= 24);
328 for(j=1;j<group_size;j++) {
329 if (exp[k+j] < exp_min)
330 exp_min = exp[k+j];
331 }
332 exp1[i] = exp_min;
333 k += group_size;
334 }
335
336 /* constraint for DC exponent */
337 if (exp1[0] > 15)
338 exp1[0] = 15;
339
340 /* Decrease the delta between each groups to within 2
341 * so that they can be differentially encoded */
342 for (i=1;i<=nb_groups;i++)
343 exp1[i] = FFMIN(exp1[i], exp1[i-1] + 2);
344 for (i=nb_groups-1;i>=0;i--)
345 exp1[i] = FFMIN(exp1[i], exp1[i+1] + 2);
346
347 /* now we have the exponent values the decoder will see */
348 encoded_exp[0] = exp1[0];
349 k = 1;
350 for(i=1;i<=nb_groups;i++) {
351 for(j=0;j<group_size;j++) {
352 encoded_exp[k+j] = exp1[i];
353 }
354 k += group_size;
355 }
356
357 #if defined(DEBUG)
358 av_log(NULL, AV_LOG_DEBUG, "exponents: strategy=%d\n", exp_strategy);
359 for(i=0;i<=nb_groups * group_size;i++) {
360 av_log(NULL, AV_LOG_DEBUG, "%d ", encoded_exp[i]);
361 }
362 av_log(NULL, AV_LOG_DEBUG, "\n");
363 #endif
364
365 return 4 + (nb_groups / 3) * 7;
366 }
367
368 /* return the size in bits taken by the mantissa */
369 static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *m, int nb_coefs)
370 {
371 int bits, mant, i;
372
373 bits = 0;
374 for(i=0;i<nb_coefs;i++) {
375 mant = m[i];
376 switch(mant) {
377 case 0:
378 /* nothing */
379 break;
380 case 1:
381 /* 3 mantissa in 5 bits */
382 if (s->mant1_cnt == 0)
383 bits += 5;
384 if (++s->mant1_cnt == 3)
385 s->mant1_cnt = 0;
386 break;
387 case 2:
388 /* 3 mantissa in 7 bits */
389 if (s->mant2_cnt == 0)
390 bits += 7;
391 if (++s->mant2_cnt == 3)
392 s->mant2_cnt = 0;
393 break;
394 case 3:
395 bits += 3;
396 break;
397 case 4:
398 /* 2 mantissa in 7 bits */
399 if (s->mant4_cnt == 0)
400 bits += 7;
401 if (++s->mant4_cnt == 2)
402 s->mant4_cnt = 0;
403 break;
404 case 14:
405 bits += 14;
406 break;
407 case 15:
408 bits += 16;
409 break;
410 default:
411 bits += mant - 1;
412 break;
413 }
414 }
415 return bits;
416 }
417
418
419 static void bit_alloc_masking(AC3EncodeContext *s,
420 uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
421 uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
422 int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
423 int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50])
424 {
425 int blk, ch;
426 int16_t band_psd[NB_BLOCKS][AC3_MAX_CHANNELS][50];
427
428 for(blk=0; blk<NB_BLOCKS; blk++) {
429 for(ch=0;ch<s->nb_all_channels;ch++) {
430 if(exp_strategy[blk][ch] == EXP_REUSE) {
431 memcpy(psd[blk][ch], psd[blk-1][ch], (N/2)*sizeof(int16_t));
432 memcpy(mask[blk][ch], mask[blk-1][ch], 50*sizeof(int16_t));
433 } else {
434 ff_ac3_bit_alloc_calc_psd(encoded_exp[blk][ch], 0,
435 s->nb_coefs[ch],
436 psd[blk][ch], band_psd[blk][ch]);
437 ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, band_psd[blk][ch],
438 0, s->nb_coefs[ch],
439 ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
440 ch == s->lfe_channel,
441 DBA_NONE, 0, NULL, NULL, NULL,
442 mask[blk][ch]);
443 }
444 }
445 }
446 }
447
448 static int bit_alloc(AC3EncodeContext *s,
449 int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50],
450 int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
451 uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
452 int frame_bits, int coarse_snr_offset, int fine_snr_offset)
453 {
454 int i, ch;
455 int snr_offset;
456
457 snr_offset = (((coarse_snr_offset - 15) << 4) + fine_snr_offset) << 2;
458
459 /* compute size */
460 for(i=0;i<NB_BLOCKS;i++) {
461 s->mant1_cnt = 0;
462 s->mant2_cnt = 0;
463 s->mant4_cnt = 0;
464 for(ch=0;ch<s->nb_all_channels;ch++) {
465 ff_ac3_bit_alloc_calc_bap(mask[i][ch], psd[i][ch], 0,
466 s->nb_coefs[ch], snr_offset,
467 s->bit_alloc.floor, ff_ac3_bap_tab,
468 bap[i][ch]);
469 frame_bits += compute_mantissa_size(s, bap[i][ch],
470 s->nb_coefs[ch]);
471 }
472 }
473 #if 0
474 printf("csnr=%d fsnr=%d frame_bits=%d diff=%d\n",
475 coarse_snr_offset, fine_snr_offset, frame_bits,
476 16 * s->frame_size - ((frame_bits + 7) & ~7));
477 #endif
478 return 16 * s->frame_size - frame_bits;
479 }
480
481 #define SNR_INC1 4
482
483 static int compute_bit_allocation(AC3EncodeContext *s,
484 uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
485 uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
486 uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
487 int frame_bits)
488 {
489 int i, ch;
490 int coarse_snr_offset, fine_snr_offset;
491 uint8_t bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
492 int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
493 int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50];
494 static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
495
496 /* init default parameters */
497 s->slow_decay_code = 2;
498 s->fast_decay_code = 1;
499 s->slow_gain_code = 1;
500 s->db_per_bit_code = 2;
501 s->floor_code = 4;
502 for(ch=0;ch<s->nb_all_channels;ch++)
503 s->fast_gain_code[ch] = 4;
504
505 /* compute real values */
506 s->bit_alloc.sr_code = s->sr_code;
507 s->bit_alloc.sr_shift = s->sr_shift;
508 s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->sr_shift;
509 s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->sr_shift;
510 s->bit_alloc.slow_gain = ff_ac3_slow_gain_tab[s->slow_gain_code];
511 s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
512 s->bit_alloc.floor = ff_ac3_floor_tab[s->floor_code];
513
514 /* header size */
515 frame_bits += 65;
516 // if (s->channel_mode == 2)
517 // frame_bits += 2;
518 frame_bits += frame_bits_inc[s->channel_mode];
519
520 /* audio blocks */
521 for(i=0;i<NB_BLOCKS;i++) {
522 frame_bits += s->nb_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
523 if (s->channel_mode == AC3_CHMODE_STEREO) {
524 frame_bits++; /* rematstr */
525 if(i==0) frame_bits += 4;
526 }
527 frame_bits += 2 * s->nb_channels; /* chexpstr[2] * c */
528 if (s->lfe)
529 frame_bits++; /* lfeexpstr */
530 for(ch=0;ch<s->nb_channels;ch++) {
531 if (exp_strategy[i][ch] != EXP_REUSE)
532 frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
533 }
534 frame_bits++; /* baie */
535 frame_bits++; /* snr */
536 frame_bits += 2; /* delta / skip */
537 }
538 frame_bits++; /* cplinu for block 0 */
539 /* bit alloc info */
540 /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
541 /* csnroffset[6] */
542 /* (fsnoffset[4] + fgaincod[4]) * c */
543 frame_bits += 2*4 + 3 + 6 + s->nb_all_channels * (4 + 3);
544
545 /* auxdatae, crcrsv */
546 frame_bits += 2;
547
548 /* CRC */
549 frame_bits += 16;
550
551 /* calculate psd and masking curve before doing bit allocation */
552 bit_alloc_masking(s, encoded_exp, exp_strategy, psd, mask);
553
554 /* now the big work begins : do the bit allocation. Modify the snr
555 offset until we can pack everything in the requested frame size */
556
557 coarse_snr_offset = s->coarse_snr_offset;
558 while (coarse_snr_offset >= 0 &&
559 bit_alloc(s, mask, psd, bap, frame_bits, coarse_snr_offset, 0) < 0)
560 coarse_snr_offset -= SNR_INC1;
561 if (coarse_snr_offset < 0) {
562 av_log(NULL, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
563 return -1;
564 }
565 while ((coarse_snr_offset + SNR_INC1) <= 63 &&
566 bit_alloc(s, mask, psd, bap1, frame_bits,
567 coarse_snr_offset + SNR_INC1, 0) >= 0) {
568 coarse_snr_offset += SNR_INC1;
569 memcpy(bap, bap1, sizeof(bap1));
570 }
571 while ((coarse_snr_offset + 1) <= 63 &&
572 bit_alloc(s, mask, psd, bap1, frame_bits, coarse_snr_offset + 1, 0) >= 0) {
573 coarse_snr_offset++;
574 memcpy(bap, bap1, sizeof(bap1));
575 }
576
577 fine_snr_offset = 0;
578 while ((fine_snr_offset + SNR_INC1) <= 15 &&
579 bit_alloc(s, mask, psd, bap1, frame_bits,
580 coarse_snr_offset, fine_snr_offset + SNR_INC1) >= 0) {
581 fine_snr_offset += SNR_INC1;
582 memcpy(bap, bap1, sizeof(bap1));
583 }
584 while ((fine_snr_offset + 1) <= 15 &&
585 bit_alloc(s, mask, psd, bap1, frame_bits,
586 coarse_snr_offset, fine_snr_offset + 1) >= 0) {
587 fine_snr_offset++;
588 memcpy(bap, bap1, sizeof(bap1));
589 }
590
591 s->coarse_snr_offset = coarse_snr_offset;
592 for(ch=0;ch<s->nb_all_channels;ch++)
593 s->fine_snr_offset[ch] = fine_snr_offset;
594 #if defined(DEBUG_BITALLOC)
595 {
596 int j;
597
598 for(i=0;i<6;i++) {
599 for(ch=0;ch<s->nb_all_channels;ch++) {
600 printf("Block #%d Ch%d:\n", i, ch);
601 printf("bap=");
602 for(j=0;j<s->nb_coefs[ch];j++) {
603 printf("%d ",bap[i][ch][j]);
604 }
605 printf("\n");
606 }
607 }
608 }
609 #endif
610 return 0;
611 }
612
613 static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
614 int64_t *channel_layout)
615 {
616 int ch_layout;
617
618 if (channels < 1 || channels > AC3_MAX_CHANNELS)
619 return -1;
620 if ((uint64_t)*channel_layout > 0x7FF)
621 return -1;
622 ch_layout = *channel_layout;
623 if (!ch_layout)
624 ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
625 if (avcodec_channel_layout_num_channels(ch_layout) != channels)
626 return -1;
627
628 s->lfe = !!(ch_layout & CH_LOW_FREQUENCY);
629 s->nb_all_channels = channels;
630 s->nb_channels = channels - s->lfe;
631 s->lfe_channel = s->lfe ? s->nb_channels : -1;
632 if (s->lfe)
633 ch_layout -= CH_LOW_FREQUENCY;
634
635 switch (ch_layout) {
636 case CH_LAYOUT_MONO: s->channel_mode = AC3_CHMODE_MONO; break;
637 case CH_LAYOUT_STEREO: s->channel_mode = AC3_CHMODE_STEREO; break;
638 case CH_LAYOUT_SURROUND: s->channel_mode = AC3_CHMODE_3F; break;
639 case CH_LAYOUT_2_1: s->channel_mode = AC3_CHMODE_2F1R; break;
640 case CH_LAYOUT_4POINT0: s->channel_mode = AC3_CHMODE_3F1R; break;
641 case CH_LAYOUT_QUAD:
642 case CH_LAYOUT_2_2: s->channel_mode = AC3_CHMODE_2F2R; break;
643 case CH_LAYOUT_5POINT0:
644 case CH_LAYOUT_5POINT0_BACK: s->channel_mode = AC3_CHMODE_3F2R; break;
645 default:
646 return -1;
647 }
648
649 s->channel_map = ff_ac3_enc_channel_map[s->channel_mode][s->lfe];
650 *channel_layout = ch_layout;
651 if (s->lfe)
652 *channel_layout |= CH_LOW_FREQUENCY;
653
654 return 0;
655 }
656
657 static av_cold int AC3_encode_init(AVCodecContext *avctx)
658 {
659 int freq = avctx->sample_rate;
660 int bitrate = avctx->bit_rate;
661 AC3EncodeContext *s = avctx->priv_data;
662 int i, j, ch;
663 float alpha;
664 int bw_code;
665
666 avctx->frame_size = AC3_FRAME_SIZE;
667
668 ac3_common_init();
669
670 if (set_channel_info(s, avctx->channels, &avctx->channel_layout)) {
671 av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
672 return -1;
673 }
674
675 /* frequency */
676 for(i=0;i<3;i++) {
677 for(j=0;j<3;j++)
678 if ((ff_ac3_sample_rate_tab[j] >> i) == freq)
679 goto found;
680 }
681 return -1;
682 found:
683 s->sample_rate = freq;
684 s->sr_shift = i;
685 s->sr_code = j;
686 s->bitstream_id = 8 + s->sr_shift;
687 s->bitstream_mode = 0; /* complete main audio service */
688
689 /* bitrate & frame size */
690 for(i=0;i<19;i++) {
691 if ((ff_ac3_bitrate_tab[i] >> s->sr_shift)*1000 == bitrate)
692 break;
693 }
694 if (i == 19)
695 return -1;
696 s->bit_rate = bitrate;
697 s->frame_size_code = i << 1;
698 s->frame_size_min = ff_ac3_frame_size_tab[s->frame_size_code][s->sr_code];
699 s->bits_written = 0;
700 s->samples_written = 0;
701 s->frame_size = s->frame_size_min;
702
703 /* bit allocation init */
704 if(avctx->cutoff) {
705 /* calculate bandwidth based on user-specified cutoff frequency */
706 int cutoff = av_clip(avctx->cutoff, 1, s->sample_rate >> 1);
707 int fbw_coeffs = cutoff * 512 / s->sample_rate;
708 bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
709 } else {
710 /* use default bandwidth setting */
711 /* XXX: should compute the bandwidth according to the frame
712 size, so that we avoid annoying high frequency artifacts */
713 bw_code = 50;
714 }
715 for(ch=0;ch<s->nb_channels;ch++) {
716 /* bandwidth for each channel */
717 s->chbwcod[ch] = bw_code;
718 s->nb_coefs[ch] = bw_code * 3 + 73;
719 }
720 if (s->lfe) {
721 s->nb_coefs[s->lfe_channel] = 7; /* fixed */
722 }
723 /* initial snr offset */
724 s->coarse_snr_offset = 40;
725
726 /* mdct init */
727 fft_init(MDCT_NBITS - 2);
728 for(i=0;i<N/4;i++) {
729 alpha = 2 * M_PI * (i + 1.0 / 8.0) / (float)N;
730 xcos1[i] = fix15(-cos(alpha));
731 xsin1[i] = fix15(-sin(alpha));
732 }
733
734 avctx->coded_frame= avcodec_alloc_frame();
735 avctx->coded_frame->key_frame= 1;
736
737 return 0;
738 }
739
740 /* output the AC-3 frame header */
741 static void output_frame_header(AC3EncodeContext *s, unsigned char *frame)
742 {
743 init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
744
745 put_bits(&s->pb, 16, 0x0b77); /* frame header */
746 put_bits(&s->pb, 16, 0); /* crc1: will be filled later */
747 put_bits(&s->pb, 2, s->sr_code);
748 put_bits(&s->pb, 6, s->frame_size_code + (s->frame_size - s->frame_size_min));
749 put_bits(&s->pb, 5, s->bitstream_id);
750 put_bits(&s->pb, 3, s->bitstream_mode);
751 put_bits(&s->pb, 3, s->channel_mode);
752 if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
753 put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */
754 if (s->channel_mode & 0x04)
755 put_bits(&s->pb, 2, 1); /* XXX -6 dB */
756 if (s->channel_mode == AC3_CHMODE_STEREO)
757 put_bits(&s->pb, 2, 0); /* surround not indicated */
758 put_bits(&s->pb, 1, s->lfe); /* LFE */
759 put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */
760 put_bits(&s->pb, 1, 0); /* no compression control word */
761 put_bits(&s->pb, 1, 0); /* no lang code */
762 put_bits(&s->pb, 1, 0); /* no audio production info */
763 put_bits(&s->pb, 1, 0); /* no copyright */
764 put_bits(&s->pb, 1, 1); /* original bitstream */
765 put_bits(&s->pb, 1, 0); /* no time code 1 */
766 put_bits(&s->pb, 1, 0); /* no time code 2 */
767 put_bits(&s->pb, 1, 0); /* no additional bit stream info */
768 }
769
770 /* symetric quantization on 'levels' levels */
771 static inline int sym_quant(int c, int e, int levels)
772 {
773 int v;
774
775 if (c >= 0) {
776 v = (levels * (c << e)) >> 24;
777 v = (v + 1) >> 1;
778 v = (levels >> 1) + v;
779 } else {
780 v = (levels * ((-c) << e)) >> 24;
781 v = (v + 1) >> 1;
782 v = (levels >> 1) - v;
783 }
784 assert (v >= 0 && v < levels);
785 return v;
786 }
787
788 /* asymetric quantization on 2^qbits levels */
789 static inline int asym_quant(int c, int e, int qbits)
790 {
791 int lshift, m, v;
792
793 lshift = e + qbits - 24;
794 if (lshift >= 0)
795 v = c << lshift;
796 else
797 v = c >> (-lshift);
798 /* rounding */
799 v = (v + 1) >> 1;
800 m = (1 << (qbits-1));
801 if (v >= m)
802 v = m - 1;
803 assert(v >= -m);
804 return v & ((1 << qbits)-1);
805 }
806
807 /* Output one audio block. There are NB_BLOCKS audio blocks in one AC-3
808 frame */
809 static void output_audio_block(AC3EncodeContext *s,
810 uint8_t exp_strategy[AC3_MAX_CHANNELS],
811 uint8_t encoded_exp[AC3_MAX_CHANNELS][N/2],
812 uint8_t bap[AC3_MAX_CHANNELS][N/2],
813 int32_t mdct_coefs[AC3_MAX_CHANNELS][N/2],
814 int8_t global_exp[AC3_MAX_CHANNELS],
815 int block_num)
816 {
817 int ch, nb_groups, group_size, i, baie, rbnd;
818 uint8_t *p;
819 uint16_t qmant[AC3_MAX_CHANNELS][N/2];
820 int exp0, exp1;
821 int mant1_cnt, mant2_cnt, mant4_cnt;
822 uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr;
823 int delta0, delta1, delta2;
824
825 for(ch=0;ch<s->nb_channels;ch++)
826 put_bits(&s->pb, 1, 0); /* 512 point MDCT */
827 for(ch=0;ch<s->nb_channels;ch++)
828 put_bits(&s->pb, 1, 1); /* no dither */
829 put_bits(&s->pb, 1, 0); /* no dynamic range */
830 if (block_num == 0) {
831 /* for block 0, even if no coupling, we must say it. This is a
832 waste of bit :-) */
833 put_bits(&s->pb, 1, 1); /* coupling strategy present */
834 put_bits(&s->pb, 1, 0); /* no coupling strategy */
835 } else {
836 put_bits(&s->pb, 1, 0); /* no new coupling strategy */
837 }
838
839 if (s->channel_mode == AC3_CHMODE_STEREO)
840 {
841 if(block_num==0)
842 {
843 /* first block must define rematrixing (rematstr) */
844 put_bits(&s->pb, 1, 1);
845
846 /* dummy rematrixing rematflg(1:4)=0 */
847 for (rbnd=0;rbnd<4;rbnd++)
848 put_bits(&s->pb, 1, 0);
849 }
850 else
851 {
852 /* no matrixing (but should be used in the future) */
853 put_bits(&s->pb, 1, 0);
854 }
855 }
856
857 #if defined(DEBUG)
858 {
859 static int count = 0;
860 av_log(NULL, AV_LOG_DEBUG, "Block #%d (%d)\n", block_num, count++);
861 }
862 #endif
863 /* exponent strategy */
864 for(ch=0;ch<s->nb_channels;ch++) {
865 put_bits(&s->pb, 2, exp_strategy[ch]);
866 }
867
868 if (s->lfe) {
869 put_bits(&s->pb, 1, exp_strategy[s->lfe_channel]);
870 }
871
872 for(ch=0;ch<s->nb_channels;ch++) {
873 if (exp_strategy[ch] != EXP_REUSE)
874 put_bits(&s->pb, 6, s->chbwcod[ch]);
875 }
876
877 /* exponents */
878 for (ch = 0; ch < s->nb_all_channels; ch++) {
879 switch(exp_strategy[ch]) {
880 case EXP_REUSE:
881 continue;
882 case EXP_D15:
883 group_size = 1;
884 break;
885 case EXP_D25:
886 group_size = 2;
887 break;
888 default:
889 case EXP_D45:
890 group_size = 4;
891 break;
892 }
893 nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size);
894 p = encoded_exp[ch];
895
896 /* first exponent */
897 exp1 = *p++;
898 put_bits(&s->pb, 4, exp1);
899
900 /* next ones are delta encoded */
901 for(i=0;i<nb_groups;i++) {
902 /* merge three delta in one code */
903 exp0 = exp1;
904 exp1 = p[0];
905 p += group_size;
906 delta0 = exp1 - exp0 + 2;
907
908 exp0 = exp1;
909 exp1 = p[0];
910 p += group_size;
911 delta1 = exp1 - exp0 + 2;
912
913 exp0 = exp1;
914 exp1 = p[0];
915 p += group_size;
916 delta2 = exp1 - exp0 + 2;
917
918 put_bits(&s->pb, 7, ((delta0 * 5 + delta1) * 5) + delta2);
919 }
920
921 if (ch != s->lfe_channel)
922 put_bits(&s->pb, 2, 0); /* no gain range info */
923 }
924
925 /* bit allocation info */
926 baie = (block_num == 0);
927 put_bits(&s->pb, 1, baie);
928 if (baie) {
929 put_bits(&s->pb, 2, s->slow_decay_code);
930 put_bits(&s->pb, 2, s->fast_decay_code);
931 put_bits(&s->pb, 2, s->slow_gain_code);
932 put_bits(&s->pb, 2, s->db_per_bit_code);
933 put_bits(&s->pb, 3, s->floor_code);
934 }
935
936 /* snr offset */
937 put_bits(&s->pb, 1, baie); /* always present with bai */
938 if (baie) {
939 put_bits(&s->pb, 6, s->coarse_snr_offset);
940 for(ch=0;ch<s->nb_all_channels;ch++) {
941 put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
942 put_bits(&s->pb, 3, s->fast_gain_code[ch]);
943 }
944 }
945
946 put_bits(&s->pb, 1, 0); /* no delta bit allocation */
947 put_bits(&s->pb, 1, 0); /* no data to skip */
948
949 /* mantissa encoding : we use two passes to handle the grouping. A
950 one pass method may be faster, but it would necessitate to
951 modify the output stream. */
952
953 /* first pass: quantize */
954 mant1_cnt = mant2_cnt = mant4_cnt = 0;
955 qmant1_ptr = qmant2_ptr = qmant4_ptr = NULL;
956
957 for (ch = 0; ch < s->nb_all_channels; ch++) {
958 int b, c, e, v;
959
960 for(i=0;i<s->nb_coefs[ch];i++) {
961 c = mdct_coefs[ch][i];
962 e = encoded_exp[ch][i] - global_exp[ch];
963 b = bap[ch][i];
964 switch(b) {
965 case 0:
966 v = 0;
967 break;
968 case 1:
969 v = sym_quant(c, e, 3);
970 switch(mant1_cnt) {
971 case 0:
972 qmant1_ptr = &qmant[ch][i];
973 v = 9 * v;
974 mant1_cnt = 1;
975 break;
976 case 1:
977 *qmant1_ptr += 3 * v;
978 mant1_cnt = 2;
979 v = 128;
980 break;
981 default:
982 *qmant1_ptr += v;
983 mant1_cnt = 0;
984 v = 128;
985 break;
986 }
987 break;
988 case 2:
989 v = sym_quant(c, e, 5);
990 switch(mant2_cnt) {
991 case 0:
992 qmant2_ptr = &qmant[ch][i];
993 v = 25 * v;
994 mant2_cnt = 1;
995 break;
996 case 1:
997 *qmant2_ptr += 5 * v;
998 mant2_cnt = 2;
999 v = 128;
1000 break;
1001 default:
1002 *qmant2_ptr += v;
1003 mant2_cnt = 0;
1004 v = 128;
1005 break;
1006 }
1007 break;
1008 case 3:
1009 v = sym_quant(c, e, 7);
1010 break;
1011 case 4:
1012 v = sym_quant(c, e, 11);
1013 switch(mant4_cnt) {
1014 case 0:
1015 qmant4_ptr = &qmant[ch][i];
1016 v = 11 * v;
1017 mant4_cnt = 1;
1018 break;
1019 default:
1020 *qmant4_ptr += v;
1021 mant4_cnt = 0;
1022 v = 128;
1023 break;
1024 }
1025 break;
1026 case 5:
1027 v = sym_quant(c, e, 15);
1028 break;
1029 case 14:
1030 v = asym_quant(c, e, 14);
1031 break;
1032 case 15:
1033 v = asym_quant(c, e, 16);
1034 break;
1035 default:
1036 v = asym_quant(c, e, b - 1);
1037 break;
1038 }
1039 qmant[ch][i] = v;
1040 }
1041 }
1042
1043 /* second pass : output the values */
1044 for (ch = 0; ch < s->nb_all_channels; ch++) {
1045 int b, q;
1046
1047 for(i=0;i<s->nb_coefs[ch];i++) {
1048 q = qmant[ch][i];
1049 b = bap[ch][i];
1050 switch(b) {
1051 case 0:
1052 break;
1053 case 1:
1054 if (q != 128)
1055 put_bits(&s->pb, 5, q);
1056 break;
1057 case 2:
1058 if (q != 128)
1059 put_bits(&s->pb, 7, q);
1060 break;
1061 case 3:
1062 put_bits(&s->pb, 3, q);
1063 break;
1064 case 4:
1065 if (q != 128)
1066 put_bits(&s->pb, 7, q);
1067 break;
1068 case 14:
1069 put_bits(&s->pb, 14, q);
1070 break;
1071 case 15:
1072 put_bits(&s->pb, 16, q);
1073 break;
1074 default:
1075 put_bits(&s->pb, b - 1, q);
1076 break;
1077 }
1078 }
1079 }
1080 }
1081
1082 #define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1083
1084 static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1085 {
1086 unsigned int c;
1087
1088 c = 0;
1089 while (a) {
1090 if (a & 1)
1091 c ^= b;
1092 a = a >> 1;
1093 b = b << 1;
1094 if (b & (1 << 16))
1095 b ^= poly;
1096 }
1097 return c;
1098 }
1099
1100 static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1101 {
1102 unsigned int r;
1103 r = 1;
1104 while (n) {
1105 if (n & 1)
1106 r = mul_poly(r, a, poly);
1107 a = mul_poly(a, a, poly);
1108 n >>= 1;
1109 }
1110 return r;
1111 }
1112
1113
1114 /* compute log2(max(abs(tab[]))) */
1115 static int log2_tab(int16_t *tab, int n)
1116 {
1117 int i, v;
1118
1119 v = 0;
1120 for(i=0;i<n;i++) {
1121 v |= abs(tab[i]);
1122 }
1123 return av_log2(v);
1124 }
1125
1126 static void lshift_tab(int16_t *tab, int n, int lshift)
1127 {
1128 int i;
1129
1130 if (lshift > 0) {
1131 for(i=0;i<n;i++) {
1132 tab[i] <<= lshift;
1133 }
1134 } else if (lshift < 0) {
1135 lshift = -lshift;
1136 for(i=0;i<n;i++) {
1137 tab[i] >>= lshift;
1138 }
1139 }
1140 }
1141
1142 /* fill the end of the frame and compute the two crcs */
1143 static int output_frame_end(AC3EncodeContext *s)
1144 {
1145 int frame_size, frame_size_58, n, crc1, crc2, crc_inv;
1146 uint8_t *frame;
1147
1148 frame_size = s->frame_size; /* frame size in words */
1149 /* align to 8 bits */
1150 flush_put_bits(&s->pb);
1151 /* add zero bytes to reach the frame size */
1152 frame = s->pb.buf;
1153 n = 2 * s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1154 assert(n >= 0);
1155 if(n>0)
1156 memset(put_bits_ptr(&s->pb), 0, n);
1157
1158 /* Now we must compute both crcs : this is not so easy for crc1
1159 because it is at the beginning of the data... */
1160 frame_size_58 = (frame_size >> 1) + (frame_size >> 3);
1161 crc1 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
1162 frame + 4, 2 * frame_size_58 - 4));
1163 /* XXX: could precompute crc_inv */
1164 crc_inv = pow_poly((CRC16_POLY >> 1), (16 * frame_size_58) - 16, CRC16_POLY);
1165 crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
1166 AV_WB16(frame+2,crc1);
1167
1168 crc2 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
1169 frame + 2 * frame_size_58,
1170 (frame_size - frame_size_58) * 2 - 2));
1171 AV_WB16(frame+2*frame_size-2,crc2);
1172
1173 // printf("n=%d frame_size=%d\n", n, frame_size);
1174 return frame_size * 2;
1175 }
1176
1177 static int AC3_encode_frame(AVCodecContext *avctx,
1178 unsigned char *frame, int buf_size, void *data)
1179 {
1180 AC3EncodeContext *s = avctx->priv_data;
1181 int16_t *samples = data;
1182 int i, j, k, v, ch;
1183 int16_t input_samples[N];
1184 int32_t mdct_coef[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1185 uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1186 uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS];
1187 uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1188 uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1189 int8_t exp_samples[NB_BLOCKS][AC3_MAX_CHANNELS];
1190 int frame_bits;
1191
1192 frame_bits = 0;
1193 for(ch=0;ch<s->nb_all_channels;ch++) {
1194 int ich = s->channel_map[ch];
1195 /* fixed mdct to the six sub blocks & exponent computation */
1196 for(i=0;i<NB_BLOCKS;i++) {
1197 int16_t *sptr;
1198 int sinc;
1199
1200 /* compute input samples */
1201 memcpy(input_samples, s->last_samples[ich], N/2 * sizeof(int16_t));
1202 sinc = s->nb_all_channels;
1203 sptr = samples + (sinc * (N/2) * i) + ich;
1204 for(j=0;j<N/2;j++) {
1205 v = *sptr;
1206 input_samples[j + N/2] = v;
1207 s->last_samples[ich][j] = v;
1208 sptr += sinc;
1209 }
1210
1211 /* apply the MDCT window */
1212 for(j=0;j<N/2;j++) {
1213 input_samples[j] = MUL16(input_samples[j],
1214 ff_ac3_window[j]) >> 15;
1215 input_samples[N-j-1] = MUL16(input_samples[N-j-1],
1216 ff_ac3_window[j]) >> 15;
1217 }
1218
1219 /* Normalize the samples to use the maximum available
1220 precision */
1221 v = 14 - log2_tab(input_samples, N);
1222 if (v < 0)
1223 v = 0;
1224 exp_samples[i][ch] = v - 9;
1225 lshift_tab(input_samples, N, v);
1226
1227 /* do the MDCT */
1228 mdct512(mdct_coef[i][ch], input_samples);
1229
1230 /* compute "exponents". We take into account the
1231 normalization there */
1232 for(j=0;j<N/2;j++) {
1233 int e;
1234 v = abs(mdct_coef[i][ch][j]);
1235 if (v == 0)
1236 e = 24;
1237 else {
1238 e = 23 - av_log2(v) + exp_samples[i][ch];
1239 if (e >= 24) {
1240 e = 24;
1241 mdct_coef[i][ch][j] = 0;
1242 }
1243 }
1244 exp[i][ch][j] = e;
1245 }
1246 }
1247
1248 compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_channel);
1249
1250 /* compute the exponents as the decoder will see them. The
1251 EXP_REUSE case must be handled carefully : we select the
1252 min of the exponents */
1253 i = 0;
1254 while (i < NB_BLOCKS) {
1255 j = i + 1;
1256 while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE) {
1257 exponent_min(exp[i][ch], exp[j][ch], s->nb_coefs[ch]);
1258 j++;
1259 }
1260 frame_bits += encode_exp(encoded_exp[i][ch],
1261 exp[i][ch], s->nb_coefs[ch],
1262 exp_strategy[i][ch]);
1263 /* copy encoded exponents for reuse case */
1264 for(k=i+1;k<j;k++) {
1265 memcpy(encoded_exp[k][ch], encoded_exp[i][ch],
1266 s->nb_coefs[ch] * sizeof(uint8_t));
1267 }
1268 i = j;
1269 }
1270 }
1271
1272 /* adjust for fractional frame sizes */
1273 while(s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
1274 s->bits_written -= s->bit_rate;
1275 s->samples_written -= s->sample_rate;
1276 }
1277 s->frame_size = s->frame_size_min + (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
1278 s->bits_written += s->frame_size * 16;
1279 s->samples_written += AC3_FRAME_SIZE;
1280
1281 compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits);
1282 /* everything is known... let's output the frame */
1283 output_frame_header(s, frame);
1284
1285 for(i=0;i<NB_BLOCKS;i++) {
1286 output_audio_block(s, exp_strategy[i], encoded_exp[i],
1287 bap[i], mdct_coef[i], exp_samples[i], i);
1288 }
1289 return output_frame_end(s);
1290 }
1291
1292 static av_cold int AC3_encode_close(AVCodecContext *avctx)
1293 {
1294 av_freep(&avctx->coded_frame);
1295 return 0;
1296 }
1297
1298 #if 0
1299 /*************************************************************************/
1300 /* TEST */
1301
1302 #undef random
1303 #define FN (N/4)
1304
1305 void fft_test(void)
1306 {
1307 IComplex in[FN], in1[FN];
1308 int k, n, i;
1309 float sum_re, sum_im, a;
1310
1311 /* FFT test */
1312
1313 for(i=0;i<FN;i++) {
1314 in[i].re = random() % 65535 - 32767;
1315 in[i].im = random() % 65535 - 32767;
1316 in1[i] = in[i];
1317 }
1318 fft(in, 7);
1319
1320 /* do it by hand */
1321 for(k=0;k<FN;k++) {
1322 sum_re = 0;
1323 sum_im = 0;
1324 for(n=0;n<FN;n++) {
1325 a = -2 * M_PI * (n * k) / FN;
1326 sum_re += in1[n].re * cos(a) - in1[n].im * sin(a);
1327 sum_im += in1[n].re * sin(a) + in1[n].im * cos(a);
1328 }
1329 printf("%3d: %6d,%6d %6.0f,%6.0f\n",
1330 k, in[k].re, in[k].im, sum_re / FN, sum_im / FN);
1331 }
1332 }
1333
1334 void mdct_test(void)
1335 {
1336 int16_t input[N];
1337 int32_t output[N/2];
1338 float input1[N];
1339 float output1[N/2];
1340 float s, a, err, e, emax;
1341 int i, k, n;
1342
1343 for(i=0;i<N;i++) {
1344 input[i] = (random() % 65535 - 32767) * 9 / 10;
1345 input1[i] = input[i];
1346 }
1347
1348 mdct512(output, input);
1349
1350 /* do it by hand */
1351 for(k=0;k<N/2;k++) {
1352 s = 0;
1353 for(n=0;n<N;n++) {
1354 a = (2*M_PI*(2*n+1+N/2)*(2*k+1) / (4 * N));
1355 s += input1[n] * cos(a);
1356 }
1357 output1[k] = -2 * s / N;
1358 }
1359
1360 err = 0;
1361 emax = 0;
1362 for(i=0;i<N/2;i++) {
1363 printf("%3d: %7d %7.0f\n", i, output[i], output1[i]);
1364 e = output[i] - output1[i];
1365 if (e > emax)
1366 emax = e;
1367 err += e * e;
1368 }
1369 printf("err2=%f emax=%f\n", err / (N/2), emax);
1370 }
1371
1372 void test_ac3(void)
1373 {
1374 AC3EncodeContext ctx;
1375 unsigned char frame[AC3_MAX_CODED_FRAME_SIZE];
1376 short samples[AC3_FRAME_SIZE];
1377 int ret, i;
1378
1379 AC3_encode_init(&ctx, 44100, 64000, 1);
1380
1381 fft_test();
1382 mdct_test();
1383
1384 for(i=0;i<AC3_FRAME_SIZE;i++)
1385 samples[i] = (int)(sin(2*M_PI*i*1000.0/44100) * 10000);
1386 ret = AC3_encode_frame(&ctx, frame, samples);
1387 printf("ret=%d\n", ret);
1388 }
1389 #endif
1390
1391 AVCodec ac3_encoder = {
1392 "ac3",
1393 CODEC_TYPE_AUDIO,
1394 CODEC_ID_AC3,
1395 sizeof(AC3EncodeContext),
1396 AC3_encode_init,
1397 AC3_encode_frame,
1398 AC3_encode_close,
1399 NULL,
1400 .sample_fmts = (enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
1401 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1402 .channel_layouts = (int64_t[]){
1403 CH_LAYOUT_MONO,
1404 CH_LAYOUT_STEREO,
1405 CH_LAYOUT_2_1,
1406 CH_LAYOUT_SURROUND,
1407 CH_LAYOUT_2_2,
1408 CH_LAYOUT_QUAD,
1409 CH_LAYOUT_4POINT0,
1410 CH_LAYOUT_5POINT0,
1411 CH_LAYOUT_5POINT0_BACK,
1412 (CH_LAYOUT_MONO | CH_LOW_FREQUENCY),
1413 (CH_LAYOUT_STEREO | CH_LOW_FREQUENCY),
1414 (CH_LAYOUT_2_1 | CH_LOW_FREQUENCY),
1415 (CH_LAYOUT_SURROUND | CH_LOW_FREQUENCY),
1416 (CH_LAYOUT_2_2 | CH_LOW_FREQUENCY),
1417 (CH_LAYOUT_QUAD | CH_LOW_FREQUENCY),
1418 (CH_LAYOUT_4POINT0 | CH_LOW_FREQUENCY),
1419 CH_LAYOUT_5POINT1,
1420 CH_LAYOUT_5POINT1_BACK,
1421 0 },
1422 };
ffmpeg Lagarith lossless decoder