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ac3enc: reorder input channels to AC-3 channel order
[FFMpeg-mirror/lagarith.git] / libavcodec / ac3enc.c
blob4d51c2e187b1c49fd361c042d58012ad416af0bc
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
34 typedef struct AC3EncodeContext {
35 PutBitContext pb;
36 int nb_channels;
37 int nb_all_channels;
38 int lfe_channel;
39 const uint8_t *channel_map;
40 int bit_rate;
41 unsigned int sample_rate;
42 unsigned int bitstream_id;
43 unsigned int frame_size_min; /* minimum frame size in case rounding is necessary */
44 unsigned int frame_size; /* current frame size in words */
45 unsigned int bits_written;
46 unsigned int samples_written;
47 int sr_shift;
48 unsigned int frame_size_code;
49 unsigned int sr_code; /* frequency */
50 unsigned int channel_mode;
51 int lfe;
52 unsigned int bitstream_mode;
53 short last_samples[AC3_MAX_CHANNELS][256];
54 unsigned int chbwcod[AC3_MAX_CHANNELS];
55 int nb_coefs[AC3_MAX_CHANNELS];
56
57 /* bitrate allocation control */
58 int slow_gain_code, slow_decay_code, fast_decay_code, db_per_bit_code, floor_code;
59 AC3BitAllocParameters bit_alloc;
60 int coarse_snr_offset;
61 int fast_gain_code[AC3_MAX_CHANNELS];
62 int fine_snr_offset[AC3_MAX_CHANNELS];
63 /* mantissa encoding */
64 int mant1_cnt, mant2_cnt, mant4_cnt;
65 } AC3EncodeContext;
66
67 static int16_t costab[64];
68 static int16_t sintab[64];
69 static int16_t xcos1[128];
70 static int16_t xsin1[128];
71
72 #define MDCT_NBITS 9
73 #define N (1 << MDCT_NBITS)
74
75 /* new exponents are sent if their Norm 1 exceed this number */
76 #define EXP_DIFF_THRESHOLD 1000
77
78 static inline int16_t fix15(float a)
79 {
80 int v;
81 v = (int)(a * (float)(1 << 15));
82 if (v < -32767)
83 v = -32767;
84 else if (v > 32767)
85 v = 32767;
86 return v;
87 }
88
89 typedef struct IComplex {
90 short re,im;
91 } IComplex;
92
93 static av_cold void fft_init(int ln)
94 {
95 int i, n;
96 float alpha;
97
98 n = 1 << ln;
99
100 for(i=0;i<(n/2);i++) {
101 alpha = 2 * M_PI * (float)i / (float)n;
102 costab[i] = fix15(cos(alpha));
103 sintab[i] = fix15(sin(alpha));
104 }
105 }
106
107 /* butter fly op */
108 #define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
109 {\
110 int ax, ay, bx, by;\
111 bx=pre1;\
112 by=pim1;\
113 ax=qre1;\
114 ay=qim1;\
115 pre = (bx + ax) >> 1;\
116 pim = (by + ay) >> 1;\
117 qre = (bx - ax) >> 1;\
118 qim = (by - ay) >> 1;\
119 }
120
121 #define CMUL(pre, pim, are, aim, bre, bim) \
122 {\
123 pre = (MUL16(are, bre) - MUL16(aim, bim)) >> 15;\
124 pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15;\
125 }
126
127
128 /* do a 2^n point complex fft on 2^ln points. */
129 static void fft(IComplex *z, int ln)
130 {
131 int j, l, np, np2;
132 int nblocks, nloops;
133 register IComplex *p,*q;
134 int tmp_re, tmp_im;
135
136 np = 1 << ln;
137
138 /* reverse */
139 for(j=0;j<np;j++) {
140 int k = ff_reverse[j] >> (8 - ln);
141 if (k < j)
142 FFSWAP(IComplex, z[k], z[j]);
143 }
144
145 /* pass 0 */
146
147 p=&z[0];
148 j=(np >> 1);
149 do {
150 BF(p[0].re, p[0].im, p[1].re, p[1].im,
151 p[0].re, p[0].im, p[1].re, p[1].im);
152 p+=2;
153 } while (--j != 0);
154
155 /* pass 1 */
156
157 p=&z[0];
158 j=np >> 2;
159 do {
160 BF(p[0].re, p[0].im, p[2].re, p[2].im,
161 p[0].re, p[0].im, p[2].re, p[2].im);
162 BF(p[1].re, p[1].im, p[3].re, p[3].im,
163 p[1].re, p[1].im, p[3].im, -p[3].re);
164 p+=4;
165 } while (--j != 0);
166
167 /* pass 2 .. ln-1 */
168
169 nblocks = np >> 3;
170 nloops = 1 << 2;
171 np2 = np >> 1;
172 do {
173 p = z;
174 q = z + nloops;
175 for (j = 0; j < nblocks; ++j) {
176
177 BF(p->re, p->im, q->re, q->im,
178 p->re, p->im, q->re, q->im);
179
180 p++;
181 q++;
182 for(l = nblocks; l < np2; l += nblocks) {
183 CMUL(tmp_re, tmp_im, costab[l], -sintab[l], q->re, q->im);
184 BF(p->re, p->im, q->re, q->im,
185 p->re, p->im, tmp_re, tmp_im);
186 p++;
187 q++;
188 }
189 p += nloops;
190 q += nloops;
191 }
192 nblocks = nblocks >> 1;
193 nloops = nloops << 1;
194 } while (nblocks != 0);
195 }
196
197 /* do a 512 point mdct */
198 static void mdct512(int32_t *out, int16_t *in)
199 {
200 int i, re, im, re1, im1;
201 int16_t rot[N];
202 IComplex x[N/4];
203
204 /* shift to simplify computations */
205 for(i=0;i<N/4;i++)
206 rot[i] = -in[i + 3*N/4];
207 for(i=N/4;i<N;i++)
208 rot[i] = in[i - N/4];
209
210 /* pre rotation */
211 for(i=0;i<N/4;i++) {
212 re = ((int)rot[2*i] - (int)rot[N-1-2*i]) >> 1;
213 im = -((int)rot[N/2+2*i] - (int)rot[N/2-1-2*i]) >> 1;
214 CMUL(x[i].re, x[i].im, re, im, -xcos1[i], xsin1[i]);
215 }
216
217 fft(x, MDCT_NBITS - 2);
218
219 /* post rotation */
220 for(i=0;i<N/4;i++) {
221 re = x[i].re;
222 im = x[i].im;
223 CMUL(re1, im1, re, im, xsin1[i], xcos1[i]);
224 out[2*i] = im1;
225 out[N/2-1-2*i] = re1;
226 }
227 }
228
229 /* XXX: use another norm ? */
230 static int calc_exp_diff(uint8_t *exp1, uint8_t *exp2, int n)
231 {
232 int sum, i;
233 sum = 0;
234 for(i=0;i<n;i++) {
235 sum += abs(exp1[i] - exp2[i]);
236 }
237 return sum;
238 }
239
240 static void compute_exp_strategy(uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
241 uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
242 int ch, int is_lfe)
243 {
244 int i, j;
245 int exp_diff;
246
247 /* estimate if the exponent variation & decide if they should be
248 reused in the next frame */
249 exp_strategy[0][ch] = EXP_NEW;
250 for(i=1;i<NB_BLOCKS;i++) {
251 exp_diff = calc_exp_diff(exp[i][ch], exp[i-1][ch], N/2);
252 #ifdef DEBUG
253 av_log(NULL, AV_LOG_DEBUG, "exp_diff=%d\n", exp_diff);
254 #endif
255 if (exp_diff > EXP_DIFF_THRESHOLD)
256 exp_strategy[i][ch] = EXP_NEW;
257 else
258 exp_strategy[i][ch] = EXP_REUSE;
259 }
260 if (is_lfe)
261 return;
262
263 /* now select the encoding strategy type : if exponents are often
264 recoded, we use a coarse encoding */
265 i = 0;
266 while (i < NB_BLOCKS) {
267 j = i + 1;
268 while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE)
269 j++;
270 switch(j - i) {
271 case 1:
272 exp_strategy[i][ch] = EXP_D45;
273 break;
274 case 2:
275 case 3:
276 exp_strategy[i][ch] = EXP_D25;
277 break;
278 default:
279 exp_strategy[i][ch] = EXP_D15;
280 break;
281 }
282 i = j;
283 }
284 }
285
286 /* set exp[i] to min(exp[i], exp1[i]) */
287 static void exponent_min(uint8_t exp[N/2], uint8_t exp1[N/2], int n)
288 {
289 int i;
290
291 for(i=0;i<n;i++) {
292 if (exp1[i] < exp[i])
293 exp[i] = exp1[i];
294 }
295 }
296
297 /* update the exponents so that they are the ones the decoder will
298 decode. Return the number of bits used to code the exponents */
299 static int encode_exp(uint8_t encoded_exp[N/2],
300 uint8_t exp[N/2],
301 int nb_exps,
302 int exp_strategy)
303 {
304 int group_size, nb_groups, i, j, k, exp_min;
305 uint8_t exp1[N/2];
306
307 switch(exp_strategy) {
308 case EXP_D15:
309 group_size = 1;
310 break;
311 case EXP_D25:
312 group_size = 2;
313 break;
314 default:
315 case EXP_D45:
316 group_size = 4;
317 break;
318 }
319 nb_groups = ((nb_exps + (group_size * 3) - 4) / (3 * group_size)) * 3;
320
321 /* for each group, compute the minimum exponent */
322 exp1[0] = exp[0]; /* DC exponent is handled separately */
323 k = 1;
324 for(i=1;i<=nb_groups;i++) {
325 exp_min = exp[k];
326 assert(exp_min >= 0 && exp_min <= 24);
327 for(j=1;j<group_size;j++) {
328 if (exp[k+j] < exp_min)
329 exp_min = exp[k+j];
330 }
331 exp1[i] = exp_min;
332 k += group_size;
333 }
334
335 /* constraint for DC exponent */
336 if (exp1[0] > 15)
337 exp1[0] = 15;
338
339 /* Decrease the delta between each groups to within 2
340 * so that they can be differentially encoded */
341 for (i=1;i<=nb_groups;i++)
342 exp1[i] = FFMIN(exp1[i], exp1[i-1] + 2);
343 for (i=nb_groups-1;i>=0;i--)
344 exp1[i] = FFMIN(exp1[i], exp1[i+1] + 2);
345
346 /* now we have the exponent values the decoder will see */
347 encoded_exp[0] = exp1[0];
348 k = 1;
349 for(i=1;i<=nb_groups;i++) {
350 for(j=0;j<group_size;j++) {
351 encoded_exp[k+j] = exp1[i];
352 }
353 k += group_size;
354 }
355
356 #if defined(DEBUG)
357 av_log(NULL, AV_LOG_DEBUG, "exponents: strategy=%d\n", exp_strategy);
358 for(i=0;i<=nb_groups * group_size;i++) {
359 av_log(NULL, AV_LOG_DEBUG, "%d ", encoded_exp[i]);
360 }
361 av_log(NULL, AV_LOG_DEBUG, "\n");
362 #endif
363
364 return 4 + (nb_groups / 3) * 7;
365 }
366
367 /* return the size in bits taken by the mantissa */
368 static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *m, int nb_coefs)
369 {
370 int bits, mant, i;
371
372 bits = 0;
373 for(i=0;i<nb_coefs;i++) {
374 mant = m[i];
375 switch(mant) {
376 case 0:
377 /* nothing */
378 break;
379 case 1:
380 /* 3 mantissa in 5 bits */
381 if (s->mant1_cnt == 0)
382 bits += 5;
383 if (++s->mant1_cnt == 3)
384 s->mant1_cnt = 0;
385 break;
386 case 2:
387 /* 3 mantissa in 7 bits */
388 if (s->mant2_cnt == 0)
389 bits += 7;
390 if (++s->mant2_cnt == 3)
391 s->mant2_cnt = 0;
392 break;
393 case 3:
394 bits += 3;
395 break;
396 case 4:
397 /* 2 mantissa in 7 bits */
398 if (s->mant4_cnt == 0)
399 bits += 7;
400 if (++s->mant4_cnt == 2)
401 s->mant4_cnt = 0;
402 break;
403 case 14:
404 bits += 14;
405 break;
406 case 15:
407 bits += 16;
408 break;
409 default:
410 bits += mant - 1;
411 break;
412 }
413 }
414 return bits;
415 }
416
417
418 static void bit_alloc_masking(AC3EncodeContext *s,
419 uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
420 uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
421 int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
422 int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50])
423 {
424 int blk, ch;
425 int16_t band_psd[NB_BLOCKS][AC3_MAX_CHANNELS][50];
426
427 for(blk=0; blk<NB_BLOCKS; blk++) {
428 for(ch=0;ch<s->nb_all_channels;ch++) {
429 if(exp_strategy[blk][ch] == EXP_REUSE) {
430 memcpy(psd[blk][ch], psd[blk-1][ch], (N/2)*sizeof(int16_t));
431 memcpy(mask[blk][ch], mask[blk-1][ch], 50*sizeof(int16_t));
432 } else {
433 ff_ac3_bit_alloc_calc_psd(encoded_exp[blk][ch], 0,
434 s->nb_coefs[ch],
435 psd[blk][ch], band_psd[blk][ch]);
436 ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, band_psd[blk][ch],
437 0, s->nb_coefs[ch],
438 ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
439 ch == s->lfe_channel,
440 DBA_NONE, 0, NULL, NULL, NULL,
441 mask[blk][ch]);
442 }
443 }
444 }
445 }
446
447 static int bit_alloc(AC3EncodeContext *s,
448 int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50],
449 int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
450 uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
451 int frame_bits, int coarse_snr_offset, int fine_snr_offset)
452 {
453 int i, ch;
454 int snr_offset;
455
456 snr_offset = (((coarse_snr_offset - 15) << 4) + fine_snr_offset) << 2;
457
458 /* compute size */
459 for(i=0;i<NB_BLOCKS;i++) {
460 s->mant1_cnt = 0;
461 s->mant2_cnt = 0;
462 s->mant4_cnt = 0;
463 for(ch=0;ch<s->nb_all_channels;ch++) {
464 ff_ac3_bit_alloc_calc_bap(mask[i][ch], psd[i][ch], 0,
465 s->nb_coefs[ch], snr_offset,
466 s->bit_alloc.floor, ff_ac3_bap_tab,
467 bap[i][ch]);
468 frame_bits += compute_mantissa_size(s, bap[i][ch],
469 s->nb_coefs[ch]);
470 }
471 }
472 #if 0
473 printf("csnr=%d fsnr=%d frame_bits=%d diff=%d\n",
474 coarse_snr_offset, fine_snr_offset, frame_bits,
475 16 * s->frame_size - ((frame_bits + 7) & ~7));
476 #endif
477 return 16 * s->frame_size - frame_bits;
478 }
479
480 #define SNR_INC1 4
481
482 static int compute_bit_allocation(AC3EncodeContext *s,
483 uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
484 uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
485 uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
486 int frame_bits)
487 {
488 int i, ch;
489 int coarse_snr_offset, fine_snr_offset;
490 uint8_t bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
491 int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
492 int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50];
493 static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
494
495 /* init default parameters */
496 s->slow_decay_code = 2;
497 s->fast_decay_code = 1;
498 s->slow_gain_code = 1;
499 s->db_per_bit_code = 2;
500 s->floor_code = 4;
501 for(ch=0;ch<s->nb_all_channels;ch++)
502 s->fast_gain_code[ch] = 4;
503
504 /* compute real values */
505 s->bit_alloc.sr_code = s->sr_code;
506 s->bit_alloc.sr_shift = s->sr_shift;
507 s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->sr_shift;
508 s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->sr_shift;
509 s->bit_alloc.slow_gain = ff_ac3_slow_gain_tab[s->slow_gain_code];
510 s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
511 s->bit_alloc.floor = ff_ac3_floor_tab[s->floor_code];
512
513 /* header size */
514 frame_bits += 65;
515 // if (s->channel_mode == 2)
516 // frame_bits += 2;
517 frame_bits += frame_bits_inc[s->channel_mode];
518
519 /* audio blocks */
520 for(i=0;i<NB_BLOCKS;i++) {
521 frame_bits += s->nb_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
522 if (s->channel_mode == AC3_CHMODE_STEREO) {
523 frame_bits++; /* rematstr */
524 if(i==0) frame_bits += 4;
525 }
526 frame_bits += 2 * s->nb_channels; /* chexpstr[2] * c */
527 if (s->lfe)
528 frame_bits++; /* lfeexpstr */
529 for(ch=0;ch<s->nb_channels;ch++) {
530 if (exp_strategy[i][ch] != EXP_REUSE)
531 frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
532 }
533 frame_bits++; /* baie */
534 frame_bits++; /* snr */
535 frame_bits += 2; /* delta / skip */
536 }
537 frame_bits++; /* cplinu for block 0 */
538 /* bit alloc info */
539 /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
540 /* csnroffset[6] */
541 /* (fsnoffset[4] + fgaincod[4]) * c */
542 frame_bits += 2*4 + 3 + 6 + s->nb_all_channels * (4 + 3);
543
544 /* auxdatae, crcrsv */
545 frame_bits += 2;
546
547 /* CRC */
548 frame_bits += 16;
549
550 /* calculate psd and masking curve before doing bit allocation */
551 bit_alloc_masking(s, encoded_exp, exp_strategy, psd, mask);
552
553 /* now the big work begins : do the bit allocation. Modify the snr
554 offset until we can pack everything in the requested frame size */
555
556 coarse_snr_offset = s->coarse_snr_offset;
557 while (coarse_snr_offset >= 0 &&
558 bit_alloc(s, mask, psd, bap, frame_bits, coarse_snr_offset, 0) < 0)
559 coarse_snr_offset -= SNR_INC1;
560 if (coarse_snr_offset < 0) {
561 av_log(NULL, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
562 return -1;
563 }
564 while ((coarse_snr_offset + SNR_INC1) <= 63 &&
565 bit_alloc(s, mask, psd, bap1, frame_bits,
566 coarse_snr_offset + SNR_INC1, 0) >= 0) {
567 coarse_snr_offset += SNR_INC1;
568 memcpy(bap, bap1, sizeof(bap1));
569 }
570 while ((coarse_snr_offset + 1) <= 63 &&
571 bit_alloc(s, mask, psd, bap1, frame_bits, coarse_snr_offset + 1, 0) >= 0) {
572 coarse_snr_offset++;
573 memcpy(bap, bap1, sizeof(bap1));
574 }
575
576 fine_snr_offset = 0;
577 while ((fine_snr_offset + SNR_INC1) <= 15 &&
578 bit_alloc(s, mask, psd, bap1, frame_bits,
579 coarse_snr_offset, fine_snr_offset + SNR_INC1) >= 0) {
580 fine_snr_offset += SNR_INC1;
581 memcpy(bap, bap1, sizeof(bap1));
582 }
583 while ((fine_snr_offset + 1) <= 15 &&
584 bit_alloc(s, mask, psd, bap1, frame_bits,
585 coarse_snr_offset, fine_snr_offset + 1) >= 0) {
586 fine_snr_offset++;
587 memcpy(bap, bap1, sizeof(bap1));
588 }
589
590 s->coarse_snr_offset = coarse_snr_offset;
591 for(ch=0;ch<s->nb_all_channels;ch++)
592 s->fine_snr_offset[ch] = fine_snr_offset;
593 #if defined(DEBUG_BITALLOC)
594 {
595 int j;
596
597 for(i=0;i<6;i++) {
598 for(ch=0;ch<s->nb_all_channels;ch++) {
599 printf("Block #%d Ch%d:\n", i, ch);
600 printf("bap=");
601 for(j=0;j<s->nb_coefs[ch];j++) {
602 printf("%d ",bap[i][ch][j]);
603 }
604 printf("\n");
605 }
606 }
607 }
608 #endif
609 return 0;
610 }
611
612 static av_cold int AC3_encode_init(AVCodecContext *avctx)
613 {
614 int freq = avctx->sample_rate;
615 int bitrate = avctx->bit_rate;
616 int channels = avctx->channels;
617 AC3EncodeContext *s = avctx->priv_data;
618 int i, j, ch;
619 float alpha;
620 int bw_code;
621 static const uint8_t channel_mode_defs[6] = {
622 0x01, /* C */
623 0x02, /* L R */
624 0x03, /* L C R */
625 0x06, /* L R SL SR */
626 0x07, /* L C R SL SR */
627 0x07, /* L C R SL SR (+LFE) */
628 };
629
630 avctx->frame_size = AC3_FRAME_SIZE;
631
632 ac3_common_init();
633
634 /* number of channels */
635 if (channels < 1 || channels > 6)
636 return -1;
637 s->channel_mode = channel_mode_defs[channels - 1];
638 s->lfe = (channels == 6) ? 1 : 0;
639 s->nb_all_channels = channels;
640 s->nb_channels = channels > 5 ? 5 : channels;
641 s->lfe_channel = s->lfe ? 5 : -1;
642 s->channel_map = ff_ac3_enc_channel_map[s->channel_mode][s->lfe];
643
644 /* frequency */
645 for(i=0;i<3;i++) {
646 for(j=0;j<3;j++)
647 if ((ff_ac3_sample_rate_tab[j] >> i) == freq)
648 goto found;
649 }
650 return -1;
651 found:
652 s->sample_rate = freq;
653 s->sr_shift = i;
654 s->sr_code = j;
655 s->bitstream_id = 8 + s->sr_shift;
656 s->bitstream_mode = 0; /* complete main audio service */
657
658 /* bitrate & frame size */
659 for(i=0;i<19;i++) {
660 if ((ff_ac3_bitrate_tab[i] >> s->sr_shift)*1000 == bitrate)
661 break;
662 }
663 if (i == 19)
664 return -1;
665 s->bit_rate = bitrate;
666 s->frame_size_code = i << 1;
667 s->frame_size_min = ff_ac3_frame_size_tab[s->frame_size_code][s->sr_code];
668 s->bits_written = 0;
669 s->samples_written = 0;
670 s->frame_size = s->frame_size_min;
671
672 /* bit allocation init */
673 if(avctx->cutoff) {
674 /* calculate bandwidth based on user-specified cutoff frequency */
675 int cutoff = av_clip(avctx->cutoff, 1, s->sample_rate >> 1);
676 int fbw_coeffs = cutoff * 512 / s->sample_rate;
677 bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
678 } else {
679 /* use default bandwidth setting */
680 /* XXX: should compute the bandwidth according to the frame
681 size, so that we avoid annoying high frequency artifacts */
682 bw_code = 50;
683 }
684 for(ch=0;ch<s->nb_channels;ch++) {
685 /* bandwidth for each channel */
686 s->chbwcod[ch] = bw_code;
687 s->nb_coefs[ch] = bw_code * 3 + 73;
688 }
689 if (s->lfe) {
690 s->nb_coefs[s->lfe_channel] = 7; /* fixed */
691 }
692 /* initial snr offset */
693 s->coarse_snr_offset = 40;
694
695 /* mdct init */
696 fft_init(MDCT_NBITS - 2);
697 for(i=0;i<N/4;i++) {
698 alpha = 2 * M_PI * (i + 1.0 / 8.0) / (float)N;
699 xcos1[i] = fix15(-cos(alpha));
700 xsin1[i] = fix15(-sin(alpha));
701 }
702
703 avctx->coded_frame= avcodec_alloc_frame();
704 avctx->coded_frame->key_frame= 1;
705
706 return 0;
707 }
708
709 /* output the AC-3 frame header */
710 static void output_frame_header(AC3EncodeContext *s, unsigned char *frame)
711 {
712 init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
713
714 put_bits(&s->pb, 16, 0x0b77); /* frame header */
715 put_bits(&s->pb, 16, 0); /* crc1: will be filled later */
716 put_bits(&s->pb, 2, s->sr_code);
717 put_bits(&s->pb, 6, s->frame_size_code + (s->frame_size - s->frame_size_min));
718 put_bits(&s->pb, 5, s->bitstream_id);
719 put_bits(&s->pb, 3, s->bitstream_mode);
720 put_bits(&s->pb, 3, s->channel_mode);
721 if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
722 put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */
723 if (s->channel_mode & 0x04)
724 put_bits(&s->pb, 2, 1); /* XXX -6 dB */
725 if (s->channel_mode == AC3_CHMODE_STEREO)
726 put_bits(&s->pb, 2, 0); /* surround not indicated */
727 put_bits(&s->pb, 1, s->lfe); /* LFE */
728 put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */
729 put_bits(&s->pb, 1, 0); /* no compression control word */
730 put_bits(&s->pb, 1, 0); /* no lang code */
731 put_bits(&s->pb, 1, 0); /* no audio production info */
732 put_bits(&s->pb, 1, 0); /* no copyright */
733 put_bits(&s->pb, 1, 1); /* original bitstream */
734 put_bits(&s->pb, 1, 0); /* no time code 1 */
735 put_bits(&s->pb, 1, 0); /* no time code 2 */
736 put_bits(&s->pb, 1, 0); /* no additional bit stream info */
737 }
738
739 /* symetric quantization on 'levels' levels */
740 static inline int sym_quant(int c, int e, int levels)
741 {
742 int v;
743
744 if (c >= 0) {
745 v = (levels * (c << e)) >> 24;
746 v = (v + 1) >> 1;
747 v = (levels >> 1) + v;
748 } else {
749 v = (levels * ((-c) << e)) >> 24;
750 v = (v + 1) >> 1;
751 v = (levels >> 1) - v;
752 }
753 assert (v >= 0 && v < levels);
754 return v;
755 }
756
757 /* asymetric quantization on 2^qbits levels */
758 static inline int asym_quant(int c, int e, int qbits)
759 {
760 int lshift, m, v;
761
762 lshift = e + qbits - 24;
763 if (lshift >= 0)
764 v = c << lshift;
765 else
766 v = c >> (-lshift);
767 /* rounding */
768 v = (v + 1) >> 1;
769 m = (1 << (qbits-1));
770 if (v >= m)
771 v = m - 1;
772 assert(v >= -m);
773 return v & ((1 << qbits)-1);
774 }
775
776 /* Output one audio block. There are NB_BLOCKS audio blocks in one AC-3
777 frame */
778 static void output_audio_block(AC3EncodeContext *s,
779 uint8_t exp_strategy[AC3_MAX_CHANNELS],
780 uint8_t encoded_exp[AC3_MAX_CHANNELS][N/2],
781 uint8_t bap[AC3_MAX_CHANNELS][N/2],
782 int32_t mdct_coefs[AC3_MAX_CHANNELS][N/2],
783 int8_t global_exp[AC3_MAX_CHANNELS],
784 int block_num)
785 {
786 int ch, nb_groups, group_size, i, baie, rbnd;
787 uint8_t *p;
788 uint16_t qmant[AC3_MAX_CHANNELS][N/2];
789 int exp0, exp1;
790 int mant1_cnt, mant2_cnt, mant4_cnt;
791 uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr;
792 int delta0, delta1, delta2;
793
794 for(ch=0;ch<s->nb_channels;ch++)
795 put_bits(&s->pb, 1, 0); /* 512 point MDCT */
796 for(ch=0;ch<s->nb_channels;ch++)
797 put_bits(&s->pb, 1, 1); /* no dither */
798 put_bits(&s->pb, 1, 0); /* no dynamic range */
799 if (block_num == 0) {
800 /* for block 0, even if no coupling, we must say it. This is a
801 waste of bit :-) */
802 put_bits(&s->pb, 1, 1); /* coupling strategy present */
803 put_bits(&s->pb, 1, 0); /* no coupling strategy */
804 } else {
805 put_bits(&s->pb, 1, 0); /* no new coupling strategy */
806 }
807
808 if (s->channel_mode == AC3_CHMODE_STEREO)
809 {
810 if(block_num==0)
811 {
812 /* first block must define rematrixing (rematstr) */
813 put_bits(&s->pb, 1, 1);
814
815 /* dummy rematrixing rematflg(1:4)=0 */
816 for (rbnd=0;rbnd<4;rbnd++)
817 put_bits(&s->pb, 1, 0);
818 }
819 else
820 {
821 /* no matrixing (but should be used in the future) */
822 put_bits(&s->pb, 1, 0);
823 }
824 }
825
826 #if defined(DEBUG)
827 {
828 static int count = 0;
829 av_log(NULL, AV_LOG_DEBUG, "Block #%d (%d)\n", block_num, count++);
830 }
831 #endif
832 /* exponent strategy */
833 for(ch=0;ch<s->nb_channels;ch++) {
834 put_bits(&s->pb, 2, exp_strategy[ch]);
835 }
836
837 if (s->lfe) {
838 put_bits(&s->pb, 1, exp_strategy[s->lfe_channel]);
839 }
840
841 for(ch=0;ch<s->nb_channels;ch++) {
842 if (exp_strategy[ch] != EXP_REUSE)
843 put_bits(&s->pb, 6, s->chbwcod[ch]);
844 }
845
846 /* exponents */
847 for (ch = 0; ch < s->nb_all_channels; ch++) {
848 switch(exp_strategy[ch]) {
849 case EXP_REUSE:
850 continue;
851 case EXP_D15:
852 group_size = 1;
853 break;
854 case EXP_D25:
855 group_size = 2;
856 break;
857 default:
858 case EXP_D45:
859 group_size = 4;
860 break;
861 }
862 nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size);
863 p = encoded_exp[ch];
864
865 /* first exponent */
866 exp1 = *p++;
867 put_bits(&s->pb, 4, exp1);
868
869 /* next ones are delta encoded */
870 for(i=0;i<nb_groups;i++) {
871 /* merge three delta in one code */
872 exp0 = exp1;
873 exp1 = p[0];
874 p += group_size;
875 delta0 = exp1 - exp0 + 2;
876
877 exp0 = exp1;
878 exp1 = p[0];
879 p += group_size;
880 delta1 = exp1 - exp0 + 2;
881
882 exp0 = exp1;
883 exp1 = p[0];
884 p += group_size;
885 delta2 = exp1 - exp0 + 2;
886
887 put_bits(&s->pb, 7, ((delta0 * 5 + delta1) * 5) + delta2);
888 }
889
890 if (ch != s->lfe_channel)
891 put_bits(&s->pb, 2, 0); /* no gain range info */
892 }
893
894 /* bit allocation info */
895 baie = (block_num == 0);
896 put_bits(&s->pb, 1, baie);
897 if (baie) {
898 put_bits(&s->pb, 2, s->slow_decay_code);
899 put_bits(&s->pb, 2, s->fast_decay_code);
900 put_bits(&s->pb, 2, s->slow_gain_code);
901 put_bits(&s->pb, 2, s->db_per_bit_code);
902 put_bits(&s->pb, 3, s->floor_code);
903 }
904
905 /* snr offset */
906 put_bits(&s->pb, 1, baie); /* always present with bai */
907 if (baie) {
908 put_bits(&s->pb, 6, s->coarse_snr_offset);
909 for(ch=0;ch<s->nb_all_channels;ch++) {
910 put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
911 put_bits(&s->pb, 3, s->fast_gain_code[ch]);
912 }
913 }
914
915 put_bits(&s->pb, 1, 0); /* no delta bit allocation */
916 put_bits(&s->pb, 1, 0); /* no data to skip */
917
918 /* mantissa encoding : we use two passes to handle the grouping. A
919 one pass method may be faster, but it would necessitate to
920 modify the output stream. */
921
922 /* first pass: quantize */
923 mant1_cnt = mant2_cnt = mant4_cnt = 0;
924 qmant1_ptr = qmant2_ptr = qmant4_ptr = NULL;
925
926 for (ch = 0; ch < s->nb_all_channels; ch++) {
927 int b, c, e, v;
928
929 for(i=0;i<s->nb_coefs[ch];i++) {
930 c = mdct_coefs[ch][i];
931 e = encoded_exp[ch][i] - global_exp[ch];
932 b = bap[ch][i];
933 switch(b) {
934 case 0:
935 v = 0;
936 break;
937 case 1:
938 v = sym_quant(c, e, 3);
939 switch(mant1_cnt) {
940 case 0:
941 qmant1_ptr = &qmant[ch][i];
942 v = 9 * v;
943 mant1_cnt = 1;
944 break;
945 case 1:
946 *qmant1_ptr += 3 * v;
947 mant1_cnt = 2;
948 v = 128;
949 break;
950 default:
951 *qmant1_ptr += v;
952 mant1_cnt = 0;
953 v = 128;
954 break;
955 }
956 break;
957 case 2:
958 v = sym_quant(c, e, 5);
959 switch(mant2_cnt) {
960 case 0:
961 qmant2_ptr = &qmant[ch][i];
962 v = 25 * v;
963 mant2_cnt = 1;
964 break;
965 case 1:
966 *qmant2_ptr += 5 * v;
967 mant2_cnt = 2;
968 v = 128;
969 break;
970 default:
971 *qmant2_ptr += v;
972 mant2_cnt = 0;
973 v = 128;
974 break;
975 }
976 break;
977 case 3:
978 v = sym_quant(c, e, 7);
979 break;
980 case 4:
981 v = sym_quant(c, e, 11);
982 switch(mant4_cnt) {
983 case 0:
984 qmant4_ptr = &qmant[ch][i];
985 v = 11 * v;
986 mant4_cnt = 1;
987 break;
988 default:
989 *qmant4_ptr += v;
990 mant4_cnt = 0;
991 v = 128;
992 break;
993 }
994 break;
995 case 5:
996 v = sym_quant(c, e, 15);
997 break;
998 case 14:
999 v = asym_quant(c, e, 14);
1000 break;
1001 case 15:
1002 v = asym_quant(c, e, 16);
1003 break;
1004 default:
1005 v = asym_quant(c, e, b - 1);
1006 break;
1007 }
1008 qmant[ch][i] = v;
1009 }
1010 }
1011
1012 /* second pass : output the values */
1013 for (ch = 0; ch < s->nb_all_channels; ch++) {
1014 int b, q;
1015
1016 for(i=0;i<s->nb_coefs[ch];i++) {
1017 q = qmant[ch][i];
1018 b = bap[ch][i];
1019 switch(b) {
1020 case 0:
1021 break;
1022 case 1:
1023 if (q != 128)
1024 put_bits(&s->pb, 5, q);
1025 break;
1026 case 2:
1027 if (q != 128)
1028 put_bits(&s->pb, 7, q);
1029 break;
1030 case 3:
1031 put_bits(&s->pb, 3, q);
1032 break;
1033 case 4:
1034 if (q != 128)
1035 put_bits(&s->pb, 7, q);
1036 break;
1037 case 14:
1038 put_bits(&s->pb, 14, q);
1039 break;
1040 case 15:
1041 put_bits(&s->pb, 16, q);
1042 break;
1043 default:
1044 put_bits(&s->pb, b - 1, q);
1045 break;
1046 }
1047 }
1048 }
1049 }
1050
1051 #define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1052
1053 static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1054 {
1055 unsigned int c;
1056
1057 c = 0;
1058 while (a) {
1059 if (a & 1)
1060 c ^= b;
1061 a = a >> 1;
1062 b = b << 1;
1063 if (b & (1 << 16))
1064 b ^= poly;
1065 }
1066 return c;
1067 }
1068
1069 static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1070 {
1071 unsigned int r;
1072 r = 1;
1073 while (n) {
1074 if (n & 1)
1075 r = mul_poly(r, a, poly);
1076 a = mul_poly(a, a, poly);
1077 n >>= 1;
1078 }
1079 return r;
1080 }
1081
1082
1083 /* compute log2(max(abs(tab[]))) */
1084 static int log2_tab(int16_t *tab, int n)
1085 {
1086 int i, v;
1087
1088 v = 0;
1089 for(i=0;i<n;i++) {
1090 v |= abs(tab[i]);
1091 }
1092 return av_log2(v);
1093 }
1094
1095 static void lshift_tab(int16_t *tab, int n, int lshift)
1096 {
1097 int i;
1098
1099 if (lshift > 0) {
1100 for(i=0;i<n;i++) {
1101 tab[i] <<= lshift;
1102 }
1103 } else if (lshift < 0) {
1104 lshift = -lshift;
1105 for(i=0;i<n;i++) {
1106 tab[i] >>= lshift;
1107 }
1108 }
1109 }
1110
1111 /* fill the end of the frame and compute the two crcs */
1112 static int output_frame_end(AC3EncodeContext *s)
1113 {
1114 int frame_size, frame_size_58, n, crc1, crc2, crc_inv;
1115 uint8_t *frame;
1116
1117 frame_size = s->frame_size; /* frame size in words */
1118 /* align to 8 bits */
1119 flush_put_bits(&s->pb);
1120 /* add zero bytes to reach the frame size */
1121 frame = s->pb.buf;
1122 n = 2 * s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1123 assert(n >= 0);
1124 if(n>0)
1125 memset(put_bits_ptr(&s->pb), 0, n);
1126
1127 /* Now we must compute both crcs : this is not so easy for crc1
1128 because it is at the beginning of the data... */
1129 frame_size_58 = (frame_size >> 1) + (frame_size >> 3);
1130 crc1 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
1131 frame + 4, 2 * frame_size_58 - 4));
1132 /* XXX: could precompute crc_inv */
1133 crc_inv = pow_poly((CRC16_POLY >> 1), (16 * frame_size_58) - 16, CRC16_POLY);
1134 crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
1135 AV_WB16(frame+2,crc1);
1136
1137 crc2 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
1138 frame + 2 * frame_size_58,
1139 (frame_size - frame_size_58) * 2 - 2));
1140 AV_WB16(frame+2*frame_size-2,crc2);
1141
1142 // printf("n=%d frame_size=%d\n", n, frame_size);
1143 return frame_size * 2;
1144 }
1145
1146 static int AC3_encode_frame(AVCodecContext *avctx,
1147 unsigned char *frame, int buf_size, void *data)
1148 {
1149 AC3EncodeContext *s = avctx->priv_data;
1150 int16_t *samples = data;
1151 int i, j, k, v, ch;
1152 int16_t input_samples[N];
1153 int32_t mdct_coef[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1154 uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1155 uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS];
1156 uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1157 uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
1158 int8_t exp_samples[NB_BLOCKS][AC3_MAX_CHANNELS];
1159 int frame_bits;
1160
1161 frame_bits = 0;
1162 for(ch=0;ch<s->nb_all_channels;ch++) {
1163 int ich = s->channel_map[ch];
1164 /* fixed mdct to the six sub blocks & exponent computation */
1165 for(i=0;i<NB_BLOCKS;i++) {
1166 int16_t *sptr;
1167 int sinc;
1168
1169 /* compute input samples */
1170 memcpy(input_samples, s->last_samples[ich], N/2 * sizeof(int16_t));
1171 sinc = s->nb_all_channels;
1172 sptr = samples + (sinc * (N/2) * i) + ich;
1173 for(j=0;j<N/2;j++) {
1174 v = *sptr;
1175 input_samples[j + N/2] = v;
1176 s->last_samples[ich][j] = v;
1177 sptr += sinc;
1178 }
1179
1180 /* apply the MDCT window */
1181 for(j=0;j<N/2;j++) {
1182 input_samples[j] = MUL16(input_samples[j],
1183 ff_ac3_window[j]) >> 15;
1184 input_samples[N-j-1] = MUL16(input_samples[N-j-1],
1185 ff_ac3_window[j]) >> 15;
1186 }
1187
1188 /* Normalize the samples to use the maximum available
1189 precision */
1190 v = 14 - log2_tab(input_samples, N);
1191 if (v < 0)
1192 v = 0;
1193 exp_samples[i][ch] = v - 9;
1194 lshift_tab(input_samples, N, v);
1195
1196 /* do the MDCT */
1197 mdct512(mdct_coef[i][ch], input_samples);
1198
1199 /* compute "exponents". We take into account the
1200 normalization there */
1201 for(j=0;j<N/2;j++) {
1202 int e;
1203 v = abs(mdct_coef[i][ch][j]);
1204 if (v == 0)
1205 e = 24;
1206 else {
1207 e = 23 - av_log2(v) + exp_samples[i][ch];
1208 if (e >= 24) {
1209 e = 24;
1210 mdct_coef[i][ch][j] = 0;
1211 }
1212 }
1213 exp[i][ch][j] = e;
1214 }
1215 }
1216
1217 compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_channel);
1218
1219 /* compute the exponents as the decoder will see them. The
1220 EXP_REUSE case must be handled carefully : we select the
1221 min of the exponents */
1222 i = 0;
1223 while (i < NB_BLOCKS) {
1224 j = i + 1;
1225 while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE) {
1226 exponent_min(exp[i][ch], exp[j][ch], s->nb_coefs[ch]);
1227 j++;
1228 }
1229 frame_bits += encode_exp(encoded_exp[i][ch],
1230 exp[i][ch], s->nb_coefs[ch],
1231 exp_strategy[i][ch]);
1232 /* copy encoded exponents for reuse case */
1233 for(k=i+1;k<j;k++) {
1234 memcpy(encoded_exp[k][ch], encoded_exp[i][ch],
1235 s->nb_coefs[ch] * sizeof(uint8_t));
1236 }
1237 i = j;
1238 }
1239 }
1240
1241 /* adjust for fractional frame sizes */
1242 while(s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
1243 s->bits_written -= s->bit_rate;
1244 s->samples_written -= s->sample_rate;
1245 }
1246 s->frame_size = s->frame_size_min + (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
1247 s->bits_written += s->frame_size * 16;
1248 s->samples_written += AC3_FRAME_SIZE;
1249
1250 compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits);
1251 /* everything is known... let's output the frame */
1252 output_frame_header(s, frame);
1253
1254 for(i=0;i<NB_BLOCKS;i++) {
1255 output_audio_block(s, exp_strategy[i], encoded_exp[i],
1256 bap[i], mdct_coef[i], exp_samples[i], i);
1257 }
1258 return output_frame_end(s);
1259 }
1260
1261 static av_cold int AC3_encode_close(AVCodecContext *avctx)
1262 {
1263 av_freep(&avctx->coded_frame);
1264 return 0;
1265 }
1266
1267 #if 0
1268 /*************************************************************************/
1269 /* TEST */
1270
1271 #undef random
1272 #define FN (N/4)
1273
1274 void fft_test(void)
1275 {
1276 IComplex in[FN], in1[FN];
1277 int k, n, i;
1278 float sum_re, sum_im, a;
1279
1280 /* FFT test */
1281
1282 for(i=0;i<FN;i++) {
1283 in[i].re = random() % 65535 - 32767;
1284 in[i].im = random() % 65535 - 32767;
1285 in1[i] = in[i];
1286 }
1287 fft(in, 7);
1288
1289 /* do it by hand */
1290 for(k=0;k<FN;k++) {
1291 sum_re = 0;
1292 sum_im = 0;
1293 for(n=0;n<FN;n++) {
1294 a = -2 * M_PI * (n * k) / FN;
1295 sum_re += in1[n].re * cos(a) - in1[n].im * sin(a);
1296 sum_im += in1[n].re * sin(a) + in1[n].im * cos(a);
1297 }
1298 printf("%3d: %6d,%6d %6.0f,%6.0f\n",
1299 k, in[k].re, in[k].im, sum_re / FN, sum_im / FN);
1300 }
1301 }
1302
1303 void mdct_test(void)
1304 {
1305 int16_t input[N];
1306 int32_t output[N/2];
1307 float input1[N];
1308 float output1[N/2];
1309 float s, a, err, e, emax;
1310 int i, k, n;
1311
1312 for(i=0;i<N;i++) {
1313 input[i] = (random() % 65535 - 32767) * 9 / 10;
1314 input1[i] = input[i];
1315 }
1316
1317 mdct512(output, input);
1318
1319 /* do it by hand */
1320 for(k=0;k<N/2;k++) {
1321 s = 0;
1322 for(n=0;n<N;n++) {
1323 a = (2*M_PI*(2*n+1+N/2)*(2*k+1) / (4 * N));
1324 s += input1[n] * cos(a);
1325 }
1326 output1[k] = -2 * s / N;
1327 }
1328
1329 err = 0;
1330 emax = 0;
1331 for(i=0;i<N/2;i++) {
1332 printf("%3d: %7d %7.0f\n", i, output[i], output1[i]);
1333 e = output[i] - output1[i];
1334 if (e > emax)
1335 emax = e;
1336 err += e * e;
1337 }
1338 printf("err2=%f emax=%f\n", err / (N/2), emax);
1339 }
1340
1341 void test_ac3(void)
1342 {
1343 AC3EncodeContext ctx;
1344 unsigned char frame[AC3_MAX_CODED_FRAME_SIZE];
1345 short samples[AC3_FRAME_SIZE];
1346 int ret, i;
1347
1348 AC3_encode_init(&ctx, 44100, 64000, 1);
1349
1350 fft_test();
1351 mdct_test();
1352
1353 for(i=0;i<AC3_FRAME_SIZE;i++)
1354 samples[i] = (int)(sin(2*M_PI*i*1000.0/44100) * 10000);
1355 ret = AC3_encode_frame(&ctx, frame, samples);
1356 printf("ret=%d\n", ret);
1357 }
1358 #endif
1359
1360 AVCodec ac3_encoder = {
1361 "ac3",
1362 CODEC_TYPE_AUDIO,
1363 CODEC_ID_AC3,
1364 sizeof(AC3EncodeContext),
1365 AC3_encode_init,
1366 AC3_encode_frame,
1367 AC3_encode_close,
1368 NULL,
1369 .sample_fmts = (enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
1370 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1371 };
ffmpeg Lagarith lossless decoder