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 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 "libavutil/common.h" /* for av_reverse */ 31#include "put_bits.h" 32#include "ac3.h" 33#include "audioconvert.h" 34 35typedef 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 68static int16_t costab[64]; 69static int16_t sintab[64]; 70static int16_t xcos1[128]; 71static 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 79static 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 90typedef struct IComplex { 91 short re,im; 92} IComplex; 93 94static 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. */ 130static 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 = av_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 */ 199static 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 ? */ 231static 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 241static 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 dprintf(NULL, "exp_diff=%d\n", exp_diff); 254 if (exp_diff > EXP_DIFF_THRESHOLD) 255 exp_strategy[i][ch] = EXP_NEW; 256 else 257 exp_strategy[i][ch] = EXP_REUSE; 258 } 259 if (is_lfe) 260 return; 261 262 /* now select the encoding strategy type : if exponents are often 263 recoded, we use a coarse encoding */ 264 i = 0; 265 while (i < NB_BLOCKS) { 266 j = i + 1; 267 while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE) 268 j++; 269 switch(j - i) { 270 case 1: 271 exp_strategy[i][ch] = EXP_D45; 272 break; 273 case 2: 274 case 3: 275 exp_strategy[i][ch] = EXP_D25; 276 break; 277 default: 278 exp_strategy[i][ch] = EXP_D15; 279 break; 280 } 281 i = j; 282 } 283} 284 285/* set exp[i] to min(exp[i], exp1[i]) */ 286static void exponent_min(uint8_t exp[N/2], uint8_t exp1[N/2], int n) 287{ 288 int i; 289 290 for(i=0;i<n;i++) { 291 if (exp1[i] < exp[i]) 292 exp[i] = exp1[i]; 293 } 294} 295 296/* update the exponents so that they are the ones the decoder will 297 decode. Return the number of bits used to code the exponents */ 298static int encode_exp(uint8_t encoded_exp[N/2], 299 uint8_t exp[N/2], 300 int nb_exps, 301 int exp_strategy) 302{ 303 int group_size, nb_groups, i, j, k, exp_min; 304 uint8_t exp1[N/2]; 305 306 switch(exp_strategy) { 307 case EXP_D15: 308 group_size = 1; 309 break; 310 case EXP_D25: 311 group_size = 2; 312 break; 313 default: 314 case EXP_D45: 315 group_size = 4; 316 break; 317 } 318 nb_groups = ((nb_exps + (group_size * 3) - 4) / (3 * group_size)) * 3; 319 320 /* for each group, compute the minimum exponent */ 321 exp1[0] = exp[0]; /* DC exponent is handled separately */ 322 k = 1; 323 for(i=1;i<=nb_groups;i++) { 324 exp_min = exp[k]; 325 assert(exp_min >= 0 && exp_min <= 24); 326 for(j=1;j<group_size;j++) { 327 if (exp[k+j] < exp_min) 328 exp_min = exp[k+j]; 329 } 330 exp1[i] = exp_min; 331 k += group_size; 332 } 333 334 /* constraint for DC exponent */ 335 if (exp1[0] > 15) 336 exp1[0] = 15; 337 338 /* Decrease the delta between each groups to within 2 339 * so that they can be differentially encoded */ 340 for (i=1;i<=nb_groups;i++) 341 exp1[i] = FFMIN(exp1[i], exp1[i-1] + 2); 342 for (i=nb_groups-1;i>=0;i--) 343 exp1[i] = FFMIN(exp1[i], exp1[i+1] + 2); 344 345 /* now we have the exponent values the decoder will see */ 346 encoded_exp[0] = exp1[0]; 347 k = 1; 348 for(i=1;i<=nb_groups;i++) { 349 for(j=0;j<group_size;j++) { 350 encoded_exp[k+j] = exp1[i]; 351 } 352 k += group_size; 353 } 354 355#if defined(DEBUG) 356 av_log(NULL, AV_LOG_DEBUG, "exponents: strategy=%d\n", exp_strategy); 357 for(i=0;i<=nb_groups * group_size;i++) { 358 av_log(NULL, AV_LOG_DEBUG, "%d ", encoded_exp[i]); 359 } 360 av_log(NULL, AV_LOG_DEBUG, "\n"); 361#endif 362 363 return 4 + (nb_groups / 3) * 7; 364} 365 366/* return the size in bits taken by the mantissa */ 367static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *m, int nb_coefs) 368{ 369 int bits, mant, i; 370 371 bits = 0; 372 for(i=0;i<nb_coefs;i++) { 373 mant = m[i]; 374 switch(mant) { 375 case 0: 376 /* nothing */ 377 break; 378 case 1: 379 /* 3 mantissa in 5 bits */ 380 if (s->mant1_cnt == 0) 381 bits += 5; 382 if (++s->mant1_cnt == 3) 383 s->mant1_cnt = 0; 384 break; 385 case 2: 386 /* 3 mantissa in 7 bits */ 387 if (s->mant2_cnt == 0) 388 bits += 7; 389 if (++s->mant2_cnt == 3) 390 s->mant2_cnt = 0; 391 break; 392 case 3: 393 bits += 3; 394 break; 395 case 4: 396 /* 2 mantissa in 7 bits */ 397 if (s->mant4_cnt == 0) 398 bits += 7; 399 if (++s->mant4_cnt == 2) 400 s->mant4_cnt = 0; 401 break; 402 case 14: 403 bits += 14; 404 break; 405 case 15: 406 bits += 16; 407 break; 408 default: 409 bits += mant - 1; 410 break; 411 } 412 } 413 return bits; 414} 415 416 417static void bit_alloc_masking(AC3EncodeContext *s, 418 uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2], 419 uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS], 420 int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2], 421 int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50]) 422{ 423 int blk, ch; 424 int16_t band_psd[NB_BLOCKS][AC3_MAX_CHANNELS][50]; 425 426 for(blk=0; blk<NB_BLOCKS; blk++) { 427 for(ch=0;ch<s->nb_all_channels;ch++) { 428 if(exp_strategy[blk][ch] == EXP_REUSE) { 429 memcpy(psd[blk][ch], psd[blk-1][ch], (N/2)*sizeof(int16_t)); 430 memcpy(mask[blk][ch], mask[blk-1][ch], 50*sizeof(int16_t)); 431 } else { 432 ff_ac3_bit_alloc_calc_psd(encoded_exp[blk][ch], 0, 433 s->nb_coefs[ch], 434 psd[blk][ch], band_psd[blk][ch]); 435 ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, band_psd[blk][ch], 436 0, s->nb_coefs[ch], 437 ff_ac3_fast_gain_tab[s->fast_gain_code[ch]], 438 ch == s->lfe_channel, 439 DBA_NONE, 0, NULL, NULL, NULL, 440 mask[blk][ch]); 441 } 442 } 443 } 444} 445 446static int bit_alloc(AC3EncodeContext *s, 447 int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50], 448 int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2], 449 uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2], 450 int frame_bits, int coarse_snr_offset, int fine_snr_offset) 451{ 452 int i, ch; 453 int snr_offset; 454 455 snr_offset = (((coarse_snr_offset - 15) << 4) + fine_snr_offset) << 2; 456 457 /* compute size */ 458 for(i=0;i<NB_BLOCKS;i++) { 459 s->mant1_cnt = 0; 460 s->mant2_cnt = 0; 461 s->mant4_cnt = 0; 462 for(ch=0;ch<s->nb_all_channels;ch++) { 463 ff_ac3_bit_alloc_calc_bap(mask[i][ch], psd[i][ch], 0, 464 s->nb_coefs[ch], snr_offset, 465 s->bit_alloc.floor, ff_ac3_bap_tab, 466 bap[i][ch]); 467 frame_bits += compute_mantissa_size(s, bap[i][ch], 468 s->nb_coefs[ch]); 469 } 470 } 471#if 0 472 printf("csnr=%d fsnr=%d frame_bits=%d diff=%d\n", 473 coarse_snr_offset, fine_snr_offset, frame_bits, 474 16 * s->frame_size - ((frame_bits + 7) & ~7)); 475#endif 476 return 16 * s->frame_size - frame_bits; 477} 478 479#define SNR_INC1 4 480 481static int compute_bit_allocation(AC3EncodeContext *s, 482 uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2], 483 uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2], 484 uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS], 485 int frame_bits) 486{ 487 int i, ch; 488 int coarse_snr_offset, fine_snr_offset; 489 uint8_t bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2]; 490 int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2]; 491 int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50]; 492 static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 }; 493 494 /* init default parameters */ 495 s->slow_decay_code = 2; 496 s->fast_decay_code = 1; 497 s->slow_gain_code = 1; 498 s->db_per_bit_code = 2; 499 s->floor_code = 4; 500 for(ch=0;ch<s->nb_all_channels;ch++) 501 s->fast_gain_code[ch] = 4; 502 503 /* compute real values */ 504 s->bit_alloc.sr_code = s->sr_code; 505 s->bit_alloc.sr_shift = s->sr_shift; 506 s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->sr_shift; 507 s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->sr_shift; 508 s->bit_alloc.slow_gain = ff_ac3_slow_gain_tab[s->slow_gain_code]; 509 s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code]; 510 s->bit_alloc.floor = ff_ac3_floor_tab[s->floor_code]; 511 512 /* header size */ 513 frame_bits += 65; 514 // if (s->channel_mode == 2) 515 // frame_bits += 2; 516 frame_bits += frame_bits_inc[s->channel_mode]; 517 518 /* audio blocks */ 519 for(i=0;i<NB_BLOCKS;i++) { 520 frame_bits += s->nb_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */ 521 if (s->channel_mode == AC3_CHMODE_STEREO) { 522 frame_bits++; /* rematstr */ 523 if(i==0) frame_bits += 4; 524 } 525 frame_bits += 2 * s->nb_channels; /* chexpstr[2] * c */ 526 if (s->lfe) 527 frame_bits++; /* lfeexpstr */ 528 for(ch=0;ch<s->nb_channels;ch++) { 529 if (exp_strategy[i][ch] != EXP_REUSE) 530 frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */ 531 } 532 frame_bits++; /* baie */ 533 frame_bits++; /* snr */ 534 frame_bits += 2; /* delta / skip */ 535 } 536 frame_bits++; /* cplinu for block 0 */ 537 /* bit alloc info */ 538 /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */ 539 /* csnroffset[6] */ 540 /* (fsnoffset[4] + fgaincod[4]) * c */ 541 frame_bits += 2*4 + 3 + 6 + s->nb_all_channels * (4 + 3); 542 543 /* auxdatae, crcrsv */ 544 frame_bits += 2; 545 546 /* CRC */ 547 frame_bits += 16; 548 549 /* calculate psd and masking curve before doing bit allocation */ 550 bit_alloc_masking(s, encoded_exp, exp_strategy, psd, mask); 551 552 /* now the big work begins : do the bit allocation. Modify the snr 553 offset until we can pack everything in the requested frame size */ 554 555 coarse_snr_offset = s->coarse_snr_offset; 556 while (coarse_snr_offset >= 0 && 557 bit_alloc(s, mask, psd, bap, frame_bits, coarse_snr_offset, 0) < 0) 558 coarse_snr_offset -= SNR_INC1; 559 if (coarse_snr_offset < 0) { 560 av_log(NULL, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n"); 561 return -1; 562 } 563 while ((coarse_snr_offset + SNR_INC1) <= 63 && 564 bit_alloc(s, mask, psd, bap1, frame_bits, 565 coarse_snr_offset + SNR_INC1, 0) >= 0) { 566 coarse_snr_offset += SNR_INC1; 567 memcpy(bap, bap1, sizeof(bap1)); 568 } 569 while ((coarse_snr_offset + 1) <= 63 && 570 bit_alloc(s, mask, psd, bap1, frame_bits, coarse_snr_offset + 1, 0) >= 0) { 571 coarse_snr_offset++; 572 memcpy(bap, bap1, sizeof(bap1)); 573 } 574 575 fine_snr_offset = 0; 576 while ((fine_snr_offset + SNR_INC1) <= 15 && 577 bit_alloc(s, mask, psd, bap1, frame_bits, 578 coarse_snr_offset, fine_snr_offset + SNR_INC1) >= 0) { 579 fine_snr_offset += SNR_INC1; 580 memcpy(bap, bap1, sizeof(bap1)); 581 } 582 while ((fine_snr_offset + 1) <= 15 && 583 bit_alloc(s, mask, psd, bap1, frame_bits, 584 coarse_snr_offset, fine_snr_offset + 1) >= 0) { 585 fine_snr_offset++; 586 memcpy(bap, bap1, sizeof(bap1)); 587 } 588 589 s->coarse_snr_offset = coarse_snr_offset; 590 for(ch=0;ch<s->nb_all_channels;ch++) 591 s->fine_snr_offset[ch] = fine_snr_offset; 592#if defined(DEBUG_BITALLOC) 593 { 594 int j; 595 596 for(i=0;i<6;i++) { 597 for(ch=0;ch<s->nb_all_channels;ch++) { 598 printf("Block #%d Ch%d:\n", i, ch); 599 printf("bap="); 600 for(j=0;j<s->nb_coefs[ch];j++) { 601 printf("%d ",bap[i][ch][j]); 602 } 603 printf("\n"); 604 } 605 } 606 } 607#endif 608 return 0; 609} 610 611static av_cold int set_channel_info(AC3EncodeContext *s, int channels, 612 int64_t *channel_layout) 613{ 614 int ch_layout; 615 616 if (channels < 1 || channels > AC3_MAX_CHANNELS) 617 return -1; 618 if ((uint64_t)*channel_layout > 0x7FF) 619 return -1; 620 ch_layout = *channel_layout; 621 if (!ch_layout) 622 ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL); 623 if (avcodec_channel_layout_num_channels(ch_layout) != channels) 624 return -1; 625 626 s->lfe = !!(ch_layout & CH_LOW_FREQUENCY); 627 s->nb_all_channels = channels; 628 s->nb_channels = channels - s->lfe; 629 s->lfe_channel = s->lfe ? s->nb_channels : -1; 630 if (s->lfe) 631 ch_layout -= CH_LOW_FREQUENCY; 632 633 switch (ch_layout) { 634 case CH_LAYOUT_MONO: s->channel_mode = AC3_CHMODE_MONO; break; 635 case CH_LAYOUT_STEREO: s->channel_mode = AC3_CHMODE_STEREO; break; 636 case CH_LAYOUT_SURROUND: s->channel_mode = AC3_CHMODE_3F; break; 637 case CH_LAYOUT_2_1: s->channel_mode = AC3_CHMODE_2F1R; break; 638 case CH_LAYOUT_4POINT0: s->channel_mode = AC3_CHMODE_3F1R; break; 639 case CH_LAYOUT_QUAD: 640 case CH_LAYOUT_2_2: s->channel_mode = AC3_CHMODE_2F2R; break; 641 case CH_LAYOUT_5POINT0: 642 case CH_LAYOUT_5POINT0_BACK: s->channel_mode = AC3_CHMODE_3F2R; break; 643 default: 644 return -1; 645 } 646 647 s->channel_map = ff_ac3_enc_channel_map[s->channel_mode][s->lfe]; 648 *channel_layout = ch_layout; 649 if (s->lfe) 650 *channel_layout |= CH_LOW_FREQUENCY; 651 652 return 0; 653} 654 655static av_cold int AC3_encode_init(AVCodecContext *avctx) 656{ 657 int freq = avctx->sample_rate; 658 int bitrate = avctx->bit_rate; 659 AC3EncodeContext *s = avctx->priv_data; 660 int i, j, ch; 661 float alpha; 662 int bw_code; 663 664 avctx->frame_size = AC3_FRAME_SIZE; 665 666 ac3_common_init(); 667 668 if (!avctx->channel_layout) { 669 av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The " 670 "encoder will guess the layout, but it " 671 "might be incorrect.\n"); 672 } 673 if (set_channel_info(s, avctx->channels, &avctx->channel_layout)) { 674 av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n"); 675 return -1; 676 } 677 678 /* frequency */ 679 for(i=0;i<3;i++) { 680 for(j=0;j<3;j++) 681 if ((ff_ac3_sample_rate_tab[j] >> i) == freq) 682 goto found; 683 } 684 return -1; 685 found: 686 s->sample_rate = freq; 687 s->sr_shift = i; 688 s->sr_code = j; 689 s->bitstream_id = 8 + s->sr_shift; 690 s->bitstream_mode = 0; /* complete main audio service */ 691 692 /* bitrate & frame size */ 693 for(i=0;i<19;i++) { 694 if ((ff_ac3_bitrate_tab[i] >> s->sr_shift)*1000 == bitrate) 695 break; 696 } 697 if (i == 19) 698 return -1; 699 s->bit_rate = bitrate; 700 s->frame_size_code = i << 1; 701 s->frame_size_min = ff_ac3_frame_size_tab[s->frame_size_code][s->sr_code]; 702 s->bits_written = 0; 703 s->samples_written = 0; 704 s->frame_size = s->frame_size_min; 705 706 /* bit allocation init */ 707 if(avctx->cutoff) { 708 /* calculate bandwidth based on user-specified cutoff frequency */ 709 int cutoff = av_clip(avctx->cutoff, 1, s->sample_rate >> 1); 710 int fbw_coeffs = cutoff * 512 / s->sample_rate; 711 bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60); 712 } else { 713 /* use default bandwidth setting */ 714 /* XXX: should compute the bandwidth according to the frame 715 size, so that we avoid annoying high frequency artifacts */ 716 bw_code = 50; 717 } 718 for(ch=0;ch<s->nb_channels;ch++) { 719 /* bandwidth for each channel */ 720 s->chbwcod[ch] = bw_code; 721 s->nb_coefs[ch] = bw_code * 3 + 73; 722 } 723 if (s->lfe) { 724 s->nb_coefs[s->lfe_channel] = 7; /* fixed */ 725 } 726 /* initial snr offset */ 727 s->coarse_snr_offset = 40; 728 729 /* mdct init */ 730 fft_init(MDCT_NBITS - 2); 731 for(i=0;i<N/4;i++) { 732 alpha = 2 * M_PI * (i + 1.0 / 8.0) / (float)N; 733 xcos1[i] = fix15(-cos(alpha)); 734 xsin1[i] = fix15(-sin(alpha)); 735 } 736 737 avctx->coded_frame= avcodec_alloc_frame(); 738 avctx->coded_frame->key_frame= 1; 739 740 return 0; 741} 742 743/* output the AC-3 frame header */ 744static void output_frame_header(AC3EncodeContext *s, unsigned char *frame) 745{ 746 init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE); 747 748 put_bits(&s->pb, 16, 0x0b77); /* frame header */ 749 put_bits(&s->pb, 16, 0); /* crc1: will be filled later */ 750 put_bits(&s->pb, 2, s->sr_code); 751 put_bits(&s->pb, 6, s->frame_size_code + (s->frame_size - s->frame_size_min)); 752 put_bits(&s->pb, 5, s->bitstream_id); 753 put_bits(&s->pb, 3, s->bitstream_mode); 754 put_bits(&s->pb, 3, s->channel_mode); 755 if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO) 756 put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */ 757 if (s->channel_mode & 0x04) 758 put_bits(&s->pb, 2, 1); /* XXX -6 dB */ 759 if (s->channel_mode == AC3_CHMODE_STEREO) 760 put_bits(&s->pb, 2, 0); /* surround not indicated */ 761 put_bits(&s->pb, 1, s->lfe); /* LFE */ 762 put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */ 763 put_bits(&s->pb, 1, 0); /* no compression control word */ 764 put_bits(&s->pb, 1, 0); /* no lang code */ 765 put_bits(&s->pb, 1, 0); /* no audio production info */ 766 put_bits(&s->pb, 1, 0); /* no copyright */ 767 put_bits(&s->pb, 1, 1); /* original bitstream */ 768 put_bits(&s->pb, 1, 0); /* no time code 1 */ 769 put_bits(&s->pb, 1, 0); /* no time code 2 */ 770 put_bits(&s->pb, 1, 0); /* no additional bit stream info */ 771} 772 773/* symetric quantization on 'levels' levels */ 774static inline int sym_quant(int c, int e, int levels) 775{ 776 int v; 777 778 if (c >= 0) { 779 v = (levels * (c << e)) >> 24; 780 v = (v + 1) >> 1; 781 v = (levels >> 1) + v; 782 } else { 783 v = (levels * ((-c) << e)) >> 24; 784 v = (v + 1) >> 1; 785 v = (levels >> 1) - v; 786 } 787 assert (v >= 0 && v < levels); 788 return v; 789} 790 791/* asymetric quantization on 2^qbits levels */ 792static inline int asym_quant(int c, int e, int qbits) 793{ 794 int lshift, m, v; 795 796 lshift = e + qbits - 24; 797 if (lshift >= 0) 798 v = c << lshift; 799 else 800 v = c >> (-lshift); 801 /* rounding */ 802 v = (v + 1) >> 1; 803 m = (1 << (qbits-1)); 804 if (v >= m) 805 v = m - 1; 806 assert(v >= -m); 807 return v & ((1 << qbits)-1); 808} 809 810/* Output one audio block. There are NB_BLOCKS audio blocks in one AC-3 811 frame */ 812static void output_audio_block(AC3EncodeContext *s, 813 uint8_t exp_strategy[AC3_MAX_CHANNELS], 814 uint8_t encoded_exp[AC3_MAX_CHANNELS][N/2], 815 uint8_t bap[AC3_MAX_CHANNELS][N/2], 816 int32_t mdct_coefs[AC3_MAX_CHANNELS][N/2], 817 int8_t global_exp[AC3_MAX_CHANNELS], 818 int block_num) 819{ 820 int ch, nb_groups, group_size, i, baie, rbnd; 821 uint8_t *p; 822 uint16_t qmant[AC3_MAX_CHANNELS][N/2]; 823 int exp0, exp1; 824 int mant1_cnt, mant2_cnt, mant4_cnt; 825 uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; 826 int delta0, delta1, delta2; 827 828 for(ch=0;ch<s->nb_channels;ch++) 829 put_bits(&s->pb, 1, 0); /* 512 point MDCT */ 830 for(ch=0;ch<s->nb_channels;ch++) 831 put_bits(&s->pb, 1, 1); /* no dither */ 832 put_bits(&s->pb, 1, 0); /* no dynamic range */ 833 if (block_num == 0) { 834 /* for block 0, even if no coupling, we must say it. This is a 835 waste of bit :-) */ 836 put_bits(&s->pb, 1, 1); /* coupling strategy present */ 837 put_bits(&s->pb, 1, 0); /* no coupling strategy */ 838 } else { 839 put_bits(&s->pb, 1, 0); /* no new coupling strategy */ 840 } 841 842 if (s->channel_mode == AC3_CHMODE_STEREO) 843 { 844 if(block_num==0) 845 { 846 /* first block must define rematrixing (rematstr) */ 847 put_bits(&s->pb, 1, 1); 848 849 /* dummy rematrixing rematflg(1:4)=0 */ 850 for (rbnd=0;rbnd<4;rbnd++) 851 put_bits(&s->pb, 1, 0); 852 } 853 else 854 { 855 /* no matrixing (but should be used in the future) */ 856 put_bits(&s->pb, 1, 0); 857 } 858 } 859 860#if defined(DEBUG) 861 { 862 static int count = 0; 863 av_log(NULL, AV_LOG_DEBUG, "Block #%d (%d)\n", block_num, count++); 864 } 865#endif 866 /* exponent strategy */ 867 for(ch=0;ch<s->nb_channels;ch++) { 868 put_bits(&s->pb, 2, exp_strategy[ch]); 869 } 870 871 if (s->lfe) { 872 put_bits(&s->pb, 1, exp_strategy[s->lfe_channel]); 873 } 874 875 for(ch=0;ch<s->nb_channels;ch++) { 876 if (exp_strategy[ch] != EXP_REUSE) 877 put_bits(&s->pb, 6, s->chbwcod[ch]); 878 } 879 880 /* exponents */ 881 for (ch = 0; ch < s->nb_all_channels; ch++) { 882 switch(exp_strategy[ch]) { 883 case EXP_REUSE: 884 continue; 885 case EXP_D15: 886 group_size = 1; 887 break; 888 case EXP_D25: 889 group_size = 2; 890 break; 891 default: 892 case EXP_D45: 893 group_size = 4; 894 break; 895 } 896 nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size); 897 p = encoded_exp[ch]; 898 899 /* first exponent */ 900 exp1 = *p++; 901 put_bits(&s->pb, 4, exp1); 902 903 /* next ones are delta encoded */ 904 for(i=0;i<nb_groups;i++) { 905 /* merge three delta in one code */ 906 exp0 = exp1; 907 exp1 = p[0]; 908 p += group_size; 909 delta0 = exp1 - exp0 + 2; 910 911 exp0 = exp1; 912 exp1 = p[0]; 913 p += group_size; 914 delta1 = exp1 - exp0 + 2; 915 916 exp0 = exp1; 917 exp1 = p[0]; 918 p += group_size; 919 delta2 = exp1 - exp0 + 2; 920 921 put_bits(&s->pb, 7, ((delta0 * 5 + delta1) * 5) + delta2); 922 } 923 924 if (ch != s->lfe_channel) 925 put_bits(&s->pb, 2, 0); /* no gain range info */ 926 } 927 928 /* bit allocation info */ 929 baie = (block_num == 0); 930 put_bits(&s->pb, 1, baie); 931 if (baie) { 932 put_bits(&s->pb, 2, s->slow_decay_code); 933 put_bits(&s->pb, 2, s->fast_decay_code); 934 put_bits(&s->pb, 2, s->slow_gain_code); 935 put_bits(&s->pb, 2, s->db_per_bit_code); 936 put_bits(&s->pb, 3, s->floor_code); 937 } 938 939 /* snr offset */ 940 put_bits(&s->pb, 1, baie); /* always present with bai */ 941 if (baie) { 942 put_bits(&s->pb, 6, s->coarse_snr_offset); 943 for(ch=0;ch<s->nb_all_channels;ch++) { 944 put_bits(&s->pb, 4, s->fine_snr_offset[ch]); 945 put_bits(&s->pb, 3, s->fast_gain_code[ch]); 946 } 947 } 948 949 put_bits(&s->pb, 1, 0); /* no delta bit allocation */ 950 put_bits(&s->pb, 1, 0); /* no data to skip */ 951 952 /* mantissa encoding : we use two passes to handle the grouping. A 953 one pass method may be faster, but it would necessitate to 954 modify the output stream. */ 955 956 /* first pass: quantize */ 957 mant1_cnt = mant2_cnt = mant4_cnt = 0; 958 qmant1_ptr = qmant2_ptr = qmant4_ptr = NULL; 959 960 for (ch = 0; ch < s->nb_all_channels; ch++) { 961 int b, c, e, v; 962 963 for(i=0;i<s->nb_coefs[ch];i++) { 964 c = mdct_coefs[ch][i]; 965 e = encoded_exp[ch][i] - global_exp[ch]; 966 b = bap[ch][i]; 967 switch(b) { 968 case 0: 969 v = 0; 970 break; 971 case 1: 972 v = sym_quant(c, e, 3); 973 switch(mant1_cnt) { 974 case 0: 975 qmant1_ptr = &qmant[ch][i]; 976 v = 9 * v; 977 mant1_cnt = 1; 978 break; 979 case 1: 980 *qmant1_ptr += 3 * v; 981 mant1_cnt = 2; 982 v = 128; 983 break; 984 default: 985 *qmant1_ptr += v; 986 mant1_cnt = 0; 987 v = 128; 988 break; 989 } 990 break; 991 case 2: 992 v = sym_quant(c, e, 5); 993 switch(mant2_cnt) { 994 case 0: 995 qmant2_ptr = &qmant[ch][i]; 996 v = 25 * v; 997 mant2_cnt = 1; 998 break; 999 case 1: 1000 *qmant2_ptr += 5 * v; 1001 mant2_cnt = 2; 1002 v = 128; 1003 break; 1004 default: 1005 *qmant2_ptr += v; 1006 mant2_cnt = 0; 1007 v = 128; 1008 break; 1009 } 1010 break; 1011 case 3: 1012 v = sym_quant(c, e, 7); 1013 break; 1014 case 4: 1015 v = sym_quant(c, e, 11); 1016 switch(mant4_cnt) { 1017 case 0: 1018 qmant4_ptr = &qmant[ch][i]; 1019 v = 11 * v; 1020 mant4_cnt = 1; 1021 break; 1022 default: 1023 *qmant4_ptr += v; 1024 mant4_cnt = 0; 1025 v = 128; 1026 break; 1027 } 1028 break; 1029 case 5: 1030 v = sym_quant(c, e, 15); 1031 break; 1032 case 14: 1033 v = asym_quant(c, e, 14); 1034 break; 1035 case 15: 1036 v = asym_quant(c, e, 16); 1037 break; 1038 default: 1039 v = asym_quant(c, e, b - 1); 1040 break; 1041 } 1042 qmant[ch][i] = v; 1043 } 1044 } 1045 1046 /* second pass : output the values */ 1047 for (ch = 0; ch < s->nb_all_channels; ch++) { 1048 int b, q; 1049 1050 for(i=0;i<s->nb_coefs[ch];i++) { 1051 q = qmant[ch][i]; 1052 b = bap[ch][i]; 1053 switch(b) { 1054 case 0: 1055 break; 1056 case 1: 1057 if (q != 128) 1058 put_bits(&s->pb, 5, q); 1059 break; 1060 case 2: 1061 if (q != 128) 1062 put_bits(&s->pb, 7, q); 1063 break; 1064 case 3: 1065 put_bits(&s->pb, 3, q); 1066 break; 1067 case 4: 1068 if (q != 128) 1069 put_bits(&s->pb, 7, q); 1070 break; 1071 case 14: 1072 put_bits(&s->pb, 14, q); 1073 break; 1074 case 15: 1075 put_bits(&s->pb, 16, q); 1076 break; 1077 default: 1078 put_bits(&s->pb, b - 1, q); 1079 break; 1080 } 1081 } 1082 } 1083} 1084 1085#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16)) 1086 1087static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly) 1088{ 1089 unsigned int c; 1090 1091 c = 0; 1092 while (a) { 1093 if (a & 1) 1094 c ^= b; 1095 a = a >> 1; 1096 b = b << 1; 1097 if (b & (1 << 16)) 1098 b ^= poly; 1099 } 1100 return c; 1101} 1102 1103static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly) 1104{ 1105 unsigned int r; 1106 r = 1; 1107 while (n) { 1108 if (n & 1) 1109 r = mul_poly(r, a, poly); 1110 a = mul_poly(a, a, poly); 1111 n >>= 1; 1112 } 1113 return r; 1114} 1115 1116 1117/* compute log2(max(abs(tab[]))) */ 1118static int log2_tab(int16_t *tab, int n) 1119{ 1120 int i, v; 1121 1122 v = 0; 1123 for(i=0;i<n;i++) { 1124 v |= abs(tab[i]); 1125 } 1126 return av_log2(v); 1127} 1128 1129static void lshift_tab(int16_t *tab, int n, int lshift) 1130{ 1131 int i; 1132 1133 if (lshift > 0) { 1134 for(i=0;i<n;i++) { 1135 tab[i] <<= lshift; 1136 } 1137 } else if (lshift < 0) { 1138 lshift = -lshift; 1139 for(i=0;i<n;i++) { 1140 tab[i] >>= lshift; 1141 } 1142 } 1143} 1144 1145/* fill the end of the frame and compute the two crcs */ 1146static int output_frame_end(AC3EncodeContext *s) 1147{ 1148 int frame_size, frame_size_58, n, crc1, crc2, crc_inv; 1149 uint8_t *frame; 1150 1151 frame_size = s->frame_size; /* frame size in words */ 1152 /* align to 8 bits */ 1153 flush_put_bits(&s->pb); 1154 /* add zero bytes to reach the frame size */ 1155 frame = s->pb.buf; 1156 n = 2 * s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2; 1157 assert(n >= 0); 1158 if(n>0) 1159 memset(put_bits_ptr(&s->pb), 0, n); 1160 1161 /* Now we must compute both crcs : this is not so easy for crc1 1162 because it is at the beginning of the data... */ 1163 frame_size_58 = (frame_size >> 1) + (frame_size >> 3); 1164 crc1 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, 1165 frame + 4, 2 * frame_size_58 - 4)); 1166 /* XXX: could precompute crc_inv */ 1167 crc_inv = pow_poly((CRC16_POLY >> 1), (16 * frame_size_58) - 16, CRC16_POLY); 1168 crc1 = mul_poly(crc_inv, crc1, CRC16_POLY); 1169 AV_WB16(frame+2,crc1); 1170 1171 crc2 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, 1172 frame + 2 * frame_size_58, 1173 (frame_size - frame_size_58) * 2 - 2)); 1174 AV_WB16(frame+2*frame_size-2,crc2); 1175 1176 // printf("n=%d frame_size=%d\n", n, frame_size); 1177 return frame_size * 2; 1178} 1179 1180static int AC3_encode_frame(AVCodecContext *avctx, 1181 unsigned char *frame, int buf_size, void *data) 1182{ 1183 AC3EncodeContext *s = avctx->priv_data; 1184 int16_t *samples = data; 1185 int i, j, k, v, ch; 1186 int16_t input_samples[N]; 1187 int32_t mdct_coef[NB_BLOCKS][AC3_MAX_CHANNELS][N/2]; 1188 uint8_t exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2]; 1189 uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS]; 1190 uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2]; 1191 uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2]; 1192 int8_t exp_samples[NB_BLOCKS][AC3_MAX_CHANNELS]; 1193 int frame_bits; 1194 1195 frame_bits = 0; 1196 for(ch=0;ch<s->nb_all_channels;ch++) { 1197 int ich = s->channel_map[ch]; 1198 /* fixed mdct to the six sub blocks & exponent computation */ 1199 for(i=0;i<NB_BLOCKS;i++) { 1200 int16_t *sptr; 1201 int sinc; 1202 1203 /* compute input samples */ 1204 memcpy(input_samples, s->last_samples[ich], N/2 * sizeof(int16_t)); 1205 sinc = s->nb_all_channels; 1206 sptr = samples + (sinc * (N/2) * i) + ich; 1207 for(j=0;j<N/2;j++) { 1208 v = *sptr; 1209 input_samples[j + N/2] = v; 1210 s->last_samples[ich][j] = v; 1211 sptr += sinc; 1212 } 1213 1214 /* apply the MDCT window */ 1215 for(j=0;j<N/2;j++) { 1216 input_samples[j] = MUL16(input_samples[j], 1217 ff_ac3_window[j]) >> 15; 1218 input_samples[N-j-1] = MUL16(input_samples[N-j-1], 1219 ff_ac3_window[j]) >> 15; 1220 } 1221 1222 /* Normalize the samples to use the maximum available 1223 precision */ 1224 v = 14 - log2_tab(input_samples, N); 1225 if (v < 0) 1226 v = 0; 1227 exp_samples[i][ch] = v - 9; 1228 lshift_tab(input_samples, N, v); 1229 1230 /* do the MDCT */ 1231 mdct512(mdct_coef[i][ch], input_samples); 1232 1233 /* compute "exponents". We take into account the 1234 normalization there */ 1235 for(j=0;j<N/2;j++) { 1236 int e; 1237 v = abs(mdct_coef[i][ch][j]); 1238 if (v == 0) 1239 e = 24; 1240 else { 1241 e = 23 - av_log2(v) + exp_samples[i][ch]; 1242 if (e >= 24) { 1243 e = 24; 1244 mdct_coef[i][ch][j] = 0; 1245 } 1246 } 1247 exp[i][ch][j] = e; 1248 } 1249 } 1250 1251 compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_channel); 1252 1253 /* compute the exponents as the decoder will see them. The 1254 EXP_REUSE case must be handled carefully : we select the 1255 min of the exponents */ 1256 i = 0; 1257 while (i < NB_BLOCKS) { 1258 j = i + 1; 1259 while (j < NB_BLOCKS && exp_strategy[j][ch] == EXP_REUSE) { 1260 exponent_min(exp[i][ch], exp[j][ch], s->nb_coefs[ch]); 1261 j++; 1262 } 1263 frame_bits += encode_exp(encoded_exp[i][ch], 1264 exp[i][ch], s->nb_coefs[ch], 1265 exp_strategy[i][ch]); 1266 /* copy encoded exponents for reuse case */ 1267 for(k=i+1;k<j;k++) { 1268 memcpy(encoded_exp[k][ch], encoded_exp[i][ch], 1269 s->nb_coefs[ch] * sizeof(uint8_t)); 1270 } 1271 i = j; 1272 } 1273 } 1274 1275 /* adjust for fractional frame sizes */ 1276 while(s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) { 1277 s->bits_written -= s->bit_rate; 1278 s->samples_written -= s->sample_rate; 1279 } 1280 s->frame_size = s->frame_size_min + (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate); 1281 s->bits_written += s->frame_size * 16; 1282 s->samples_written += AC3_FRAME_SIZE; 1283 1284 compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits); 1285 /* everything is known... let's output the frame */ 1286 output_frame_header(s, frame); 1287 1288 for(i=0;i<NB_BLOCKS;i++) { 1289 output_audio_block(s, exp_strategy[i], encoded_exp[i], 1290 bap[i], mdct_coef[i], exp_samples[i], i); 1291 } 1292 return output_frame_end(s); 1293} 1294 1295static av_cold int AC3_encode_close(AVCodecContext *avctx) 1296{ 1297 av_freep(&avctx->coded_frame); 1298 return 0; 1299} 1300 1301#if 0 1302/*************************************************************************/ 1303/* TEST */ 1304 1305#undef random 1306#define FN (N/4) 1307 1308void fft_test(void) 1309{ 1310 IComplex in[FN], in1[FN]; 1311 int k, n, i; 1312 float sum_re, sum_im, a; 1313 1314 /* FFT test */ 1315 1316 for(i=0;i<FN;i++) { 1317 in[i].re = random() % 65535 - 32767; 1318 in[i].im = random() % 65535 - 32767; 1319 in1[i] = in[i]; 1320 } 1321 fft(in, 7); 1322 1323 /* do it by hand */ 1324 for(k=0;k<FN;k++) { 1325 sum_re = 0; 1326 sum_im = 0; 1327 for(n=0;n<FN;n++) { 1328 a = -2 * M_PI * (n * k) / FN; 1329 sum_re += in1[n].re * cos(a) - in1[n].im * sin(a); 1330 sum_im += in1[n].re * sin(a) + in1[n].im * cos(a); 1331 } 1332 printf("%3d: %6d,%6d %6.0f,%6.0f\n", 1333 k, in[k].re, in[k].im, sum_re / FN, sum_im / FN); 1334 } 1335} 1336 1337void mdct_test(void) 1338{ 1339 int16_t input[N]; 1340 int32_t output[N/2]; 1341 float input1[N]; 1342 float output1[N/2]; 1343 float s, a, err, e, emax; 1344 int i, k, n; 1345 1346 for(i=0;i<N;i++) { 1347 input[i] = (random() % 65535 - 32767) * 9 / 10; 1348 input1[i] = input[i]; 1349 } 1350 1351 mdct512(output, input); 1352 1353 /* do it by hand */ 1354 for(k=0;k<N/2;k++) { 1355 s = 0; 1356 for(n=0;n<N;n++) { 1357 a = (2*M_PI*(2*n+1+N/2)*(2*k+1) / (4 * N)); 1358 s += input1[n] * cos(a); 1359 } 1360 output1[k] = -2 * s / N; 1361 } 1362 1363 err = 0; 1364 emax = 0; 1365 for(i=0;i<N/2;i++) { 1366 printf("%3d: %7d %7.0f\n", i, output[i], output1[i]); 1367 e = output[i] - output1[i]; 1368 if (e > emax) 1369 emax = e; 1370 err += e * e; 1371 } 1372 printf("err2=%f emax=%f\n", err / (N/2), emax); 1373} 1374 1375void test_ac3(void) 1376{ 1377 AC3EncodeContext ctx; 1378 unsigned char frame[AC3_MAX_CODED_FRAME_SIZE]; 1379 short samples[AC3_FRAME_SIZE]; 1380 int ret, i; 1381 1382 AC3_encode_init(&ctx, 44100, 64000, 1); 1383 1384 fft_test(); 1385 mdct_test(); 1386 1387 for(i=0;i<AC3_FRAME_SIZE;i++) 1388 samples[i] = (int)(sin(2*M_PI*i*1000.0/44100) * 10000); 1389 ret = AC3_encode_frame(&ctx, frame, samples); 1390 printf("ret=%d\n", ret); 1391} 1392#endif 1393 1394AVCodec ac3_encoder = { 1395 "ac3", 1396 AVMEDIA_TYPE_AUDIO, 1397 CODEC_ID_AC3, 1398 sizeof(AC3EncodeContext), 1399 AC3_encode_init, 1400 AC3_encode_frame, 1401 AC3_encode_close, 1402 NULL, 1403 .sample_fmts = (const enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE}, 1404 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), 1405 .channel_layouts = (const int64_t[]){ 1406 CH_LAYOUT_MONO, 1407 CH_LAYOUT_STEREO, 1408 CH_LAYOUT_2_1, 1409 CH_LAYOUT_SURROUND, 1410 CH_LAYOUT_2_2, 1411 CH_LAYOUT_QUAD, 1412 CH_LAYOUT_4POINT0, 1413 CH_LAYOUT_5POINT0, 1414 CH_LAYOUT_5POINT0_BACK, 1415 (CH_LAYOUT_MONO | CH_LOW_FREQUENCY), 1416 (CH_LAYOUT_STEREO | CH_LOW_FREQUENCY), 1417 (CH_LAYOUT_2_1 | CH_LOW_FREQUENCY), 1418 (CH_LAYOUT_SURROUND | CH_LOW_FREQUENCY), 1419 (CH_LAYOUT_2_2 | CH_LOW_FREQUENCY), 1420 (CH_LAYOUT_QUAD | CH_LOW_FREQUENCY), 1421 (CH_LAYOUT_4POINT0 | CH_LOW_FREQUENCY), 1422 CH_LAYOUT_5POINT1, 1423 CH_LAYOUT_5POINT1_BACK, 1424 0 }, 1425}; 1426