1 2/* ----------------------------------------------------------------------------------------------------------- 3Software License for The Fraunhofer FDK AAC Codec Library for Android 4 5� Copyright 1995 - 2013 Fraunhofer-Gesellschaft zur F�rderung der angewandten Forschung e.V. 6 All rights reserved. 7 8 1. INTRODUCTION 9The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements 10the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio. 11This FDK AAC Codec software is intended to be used on a wide variety of Android devices. 12 13AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual 14audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by 15independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part 16of the MPEG specifications. 17 18Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer) 19may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners 20individually for the purpose of encoding or decoding bit streams in products that are compliant with 21the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license 22these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec 23software may already be covered under those patent licenses when it is used for those licensed purposes only. 24 25Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality, 26are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional 27applications information and documentation. 28 292. COPYRIGHT LICENSE 30 31Redistribution and use in source and binary forms, with or without modification, are permitted without 32payment of copyright license fees provided that you satisfy the following conditions: 33 34You must retain the complete text of this software license in redistributions of the FDK AAC Codec or 35your modifications thereto in source code form. 36 37You must retain the complete text of this software license in the documentation and/or other materials 38provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form. 39You must make available free of charge copies of the complete source code of the FDK AAC Codec and your 40modifications thereto to recipients of copies in binary form. 41 42The name of Fraunhofer may not be used to endorse or promote products derived from this library without 43prior written permission. 44 45You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec 46software or your modifications thereto. 47 48Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software 49and the date of any change. For modified versions of the FDK AAC Codec, the term 50"Fraunhofer FDK AAC Codec Library for Android" must be replaced by the term 51"Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android." 52 533. NO PATENT LICENSE 54 55NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer, 56ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with 57respect to this software. 58 59You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized 60by appropriate patent licenses. 61 624. DISCLAIMER 63 64This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors 65"AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the implied warranties 66of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 67CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages, 68including but not limited to procurement of substitute goods or services; loss of use, data, or profits, 69or business interruption, however caused and on any theory of liability, whether in contract, strict 70liability, or tort (including negligence), arising in any way out of the use of this software, even if 71advised of the possibility of such damage. 72 735. CONTACT INFORMATION 74 75Fraunhofer Institute for Integrated Circuits IIS 76Attention: Audio and Multimedia Departments - FDK AAC LL 77Am Wolfsmantel 33 7891058 Erlangen, Germany 79 80www.iis.fraunhofer.de/amm 81amm-info@iis.fraunhofer.de 82----------------------------------------------------------------------------------------------------------- */ 83 84/*! 85 \file 86 \brief frequency scale 87 \author Tobias Chalupka 88*/ 89 90#include "sbrenc_freq_sca.h" 91#include "sbr_misc.h" 92 93#include "genericStds.h" 94 95/* StartFreq */ 96static INT getStartFreq(INT fsCore, const INT start_freq); 97 98/* StopFreq */ 99static INT getStopFreq(INT fsCore, const INT stop_freq); 100 101static INT numberOfBands(INT b_p_o, INT start, INT stop, FIXP_DBL warp_factor); 102static void CalcBands(INT * diff, INT start , INT stop , INT num_bands); 103static INT modifyBands(INT max_band, INT * diff, INT length); 104static void cumSum(INT start_value, INT* diff, INT length, UCHAR *start_adress); 105 106 107 108/******************************************************************************* 109 Functionname: FDKsbrEnc_getSbrStartFreqRAW 110 ******************************************************************************* 111 Description: 112 113 Arguments: 114 115 Return: 116 *******************************************************************************/ 117 118INT 119FDKsbrEnc_getSbrStartFreqRAW (INT startFreq, INT fsCore) 120{ 121 INT result; 122 123 if ( startFreq < 0 || startFreq > 15) { 124 return -1; 125 } 126 /* Update startFreq struct */ 127 result = getStartFreq(fsCore, startFreq); 128 129 result = (result*(fsCore>>5)+1)>>1; /* (result*fsSBR/QMFbands+1)>>1; */ 130 131 return (result); 132 133} /* End FDKsbrEnc_getSbrStartFreqRAW */ 134 135 136/******************************************************************************* 137 Functionname: getSbrStopFreq 138 ******************************************************************************* 139 Description: 140 141 Arguments: 142 143 Return: 144 *******************************************************************************/ 145INT FDKsbrEnc_getSbrStopFreqRAW (INT stopFreq, INT fsCore) 146{ 147 INT result; 148 149 if ( stopFreq < 0 || stopFreq > 13) 150 return -1; 151 152 /* Uppdate stopFreq struct */ 153 result = getStopFreq(fsCore, stopFreq); 154 result = (result*(fsCore>>5)+1)>>1; /* (result*fsSBR/QMFbands+1)>>1; */ 155 156 return (result); 157} /* End getSbrStopFreq */ 158 159 160/******************************************************************************* 161 Functionname: getStartFreq 162 ******************************************************************************* 163 Description: 164 165 Arguments: fsCore - core sampling rate 166 167 168 Return: 169 *******************************************************************************/ 170static INT 171getStartFreq(INT fsCore, const INT start_freq) 172{ 173 INT k0_min; 174 175 switch(fsCore){ 176 case 8000: k0_min = 24; /* (3000 * nQmfChannels / fsSBR ) + 0.5 */ 177 break; 178 case 11025: k0_min = 17; /* (3000 * nQmfChannels / fsSBR ) + 0.5 */ 179 break; 180 case 12000: k0_min = 16; /* (3000 * nQmfChannels / fsSBR ) + 0.5 */ 181 break; 182 case 16000: k0_min = 16; /* (4000 * nQmfChannels / fsSBR ) + 0.5 */ 183 break; 184 case 22050: k0_min = 12; /* (4000 * nQmfChannels / fsSBR ) + 0.5 */ 185 break; 186 case 24000: k0_min = 11; /* (4000 * nQmfChannels / fsSBR ) + 0.5 */ 187 break; 188 case 32000: k0_min = 10; /* (5000 * nQmfChannels / fsSBR ) + 0.5 */ 189 break; 190 case 44100: k0_min = 7; /* (5000 * nQmfChannels / fsSBR ) + 0.5 */ 191 break; 192 case 48000: k0_min = 7; /* (5000 * nQmfChannels / fsSBR ) + 0.5 */ 193 break; 194 case 96000: k0_min = 3; /* (5000 * nQmfChannels / fsSBR ) + 0.5 */ 195 break; 196 default: 197 k0_min=11; /* illegal fs */ 198 } 199 200 201 switch (fsCore) { 202 203 case 8000: 204 { 205 INT v_offset[]= {-8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7}; 206 return (k0_min + v_offset[start_freq]); 207 } 208 case 11025: 209 { 210 INT v_offset[]= {-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13}; 211 return (k0_min + v_offset[start_freq]); 212 } 213 case 12000: 214 { 215 INT v_offset[]= {-5, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16}; 216 return (k0_min + v_offset[start_freq]); 217 } 218 case 16000: 219 { 220 INT v_offset[]= {-6, -4, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16}; 221 return (k0_min + v_offset[start_freq]); 222 } 223 case 22050: 224 case 24000: 225 case 32000: 226 { 227 INT v_offset[]= {-4, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20}; 228 return (k0_min + v_offset[start_freq]); 229 } 230 case 44100: 231 case 48000: 232 case 96000: 233 { 234 INT v_offset[]= {-2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20, 24}; 235 return (k0_min + v_offset[start_freq]); 236 } 237 default: 238 { 239 INT v_offset[]= {0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20, 24, 28, 33}; 240 return (k0_min + v_offset[start_freq]); 241 } 242 } 243} /* End getStartFreq */ 244 245 246/******************************************************************************* 247 Functionname: getStopFreq 248 ******************************************************************************* 249 Description: 250 251 Arguments: 252 253 Return: 254 *******************************************************************************/ 255 static INT 256getStopFreq(INT fsCore, const INT stop_freq) 257{ 258 INT result,i; 259 INT k1_min; 260 INT v_dstop[13]; 261 262 INT *v_stop_freq = NULL; 263 INT v_stop_freq_16[14] = {48,49,50,51,52,54,55,56,57,59,60,61,63,64}; 264 INT v_stop_freq_22[14] = {35,37,38,40,42,44,46,48,51,53,56,58,61,64}; 265 INT v_stop_freq_24[14] = {32,34,36,38,40,42,44,46,49,52,55,58,61,64}; 266 INT v_stop_freq_32[14] = {32,34,36,38,40,42,44,46,49,52,55,58,61,64}; 267 INT v_stop_freq_44[14] = {23,25,27,29,32,34,37,40,43,47,51,55,59,64}; 268 INT v_stop_freq_48[14] = {21,23,25,27,30,32,35,38,42,45,49,54,59,64}; 269 INT v_stop_freq_64[14] = {20,22,24,26,29,31,34,37,41,45,49,54,59,64}; 270 INT v_stop_freq_88[14] = {15,17,19,21,23,26,29,33,37,41,46,51,57,64}; 271 INT v_stop_freq_96[14] = {13,15,17,19,21,24,27,31,35,39,44,50,57,64}; 272 INT v_stop_freq_192[14] = {7, 8,10,12,14,16,19,23,27,32,38,46,54,64}; 273 274 switch(fsCore){ 275 case 8000: k1_min = 48; 276 v_stop_freq =v_stop_freq_16; 277 break; 278 case 11025: k1_min = 35; 279 v_stop_freq =v_stop_freq_22; 280 break; 281 case 12000: k1_min = 32; 282 v_stop_freq =v_stop_freq_24; 283 break; 284 case 16000: k1_min = 32; 285 v_stop_freq =v_stop_freq_32; 286 break; 287 case 22050: k1_min = 23; 288 v_stop_freq =v_stop_freq_44; 289 break; 290 case 24000: k1_min = 21; 291 v_stop_freq =v_stop_freq_48; 292 break; 293 case 32000: k1_min = 20; 294 v_stop_freq =v_stop_freq_64; 295 break; 296 case 44100: k1_min = 15; 297 v_stop_freq =v_stop_freq_88; 298 break; 299 case 48000: k1_min = 13; 300 v_stop_freq =v_stop_freq_96; 301 break; 302 case 96000: k1_min = 7; 303 v_stop_freq =v_stop_freq_192; 304 break; 305 default: 306 k1_min = 21; /* illegal fs */ 307 } 308 309 /* if no valid core samplingrate is used this loop produces 310 a segfault, because v_stop_freq is not initialized */ 311 /* Ensure increasing bandwidth */ 312 for(i = 0; i <= 12; i++) { 313 v_dstop[i] = v_stop_freq[i+1] - v_stop_freq[i]; 314 } 315 316 FDKsbrEnc_Shellsort_int(v_dstop, 13); /* Sort bandwidth changes */ 317 318 result = k1_min; 319 for(i = 0; i < stop_freq; i++) { 320 result = result + v_dstop[i]; 321 } 322 323 return(result); 324 325}/* End getStopFreq */ 326 327 328/******************************************************************************* 329 Functionname: FDKsbrEnc_FindStartAndStopBand 330 ******************************************************************************* 331 Description: 332 333 Arguments: srSbr SBR sampling freqency 334 srCore AAC core sampling freqency 335 noChannels Number of QMF channels 336 startFreq SBR start frequency in QMF bands 337 stopFreq SBR start frequency in QMF bands 338 339 *k0 Output parameter 340 *k2 Output parameter 341 342 Return: Error code (0 is OK) 343 *******************************************************************************/ 344INT 345FDKsbrEnc_FindStartAndStopBand( 346 const INT srSbr, 347 const INT srCore, 348 const INT noChannels, 349 const INT startFreq, 350 const INT stopFreq, 351 INT *k0, 352 INT *k2 353 ) 354{ 355 356 /* Update startFreq struct */ 357 *k0 = getStartFreq(srCore, startFreq); 358 359 /* Test if start freq is outside corecoder range */ 360 if( srSbr*noChannels < *k0 * srCore ) { 361 return (1); /* raise the cross-over frequency and/or lower the number 362 of target bands per octave (or lower the sampling frequency) */ 363 } 364 365 /*Update stopFreq struct */ 366 if ( stopFreq < 14 ) { 367 *k2 = getStopFreq(srCore, stopFreq); 368 } else if( stopFreq == 14 ) { 369 *k2 = 2 * *k0; 370 } else { 371 *k2 = 3 * *k0; 372 } 373 374 /* limit to Nyqvist */ 375 if (*k2 > noChannels) { 376 *k2 = noChannels; 377 } 378 379 380 381 /* Test for invalid k0 k2 combinations */ 382 if ( (srCore == 22050) && ( (*k2 - *k0) > MAX_FREQ_COEFFS_FS44100 ) ) 383 return (1); /* Number of bands exceeds valid range of MAX_FREQ_COEFFS for fs=44.1kHz */ 384 385 if ( (srCore >= 24000) && ( (*k2 - *k0) > MAX_FREQ_COEFFS_FS48000 ) ) 386 return (1); /* Number of bands exceeds valid range of MAX_FREQ_COEFFS for fs>=48kHz */ 387 388 if ((*k2 - *k0) > MAX_FREQ_COEFFS) 389 return (1);/*Number of bands exceeds valid range of MAX_FREQ_COEFFS */ 390 391 if ((*k2 - *k0) < 0) 392 return (1);/* Number of bands is negative */ 393 394 395 return(0); 396} 397 398/******************************************************************************* 399 Functionname: FDKsbrEnc_UpdateFreqScale 400 ******************************************************************************* 401 Description: 402 403 Arguments: 404 405 Return: 406 *******************************************************************************/ 407INT 408FDKsbrEnc_UpdateFreqScale( 409 UCHAR *v_k_master, 410 INT *h_num_bands, 411 const INT k0, 412 const INT k2, 413 const INT freqScale, 414 const INT alterScale 415 ) 416 417{ 418 419 INT b_p_o = 0; /* bands_per_octave */ 420 FIXP_DBL warp = FL2FXCONST_DBL(0.0f); 421 INT dk = 0; 422 423 /* Internal variables */ 424 INT k1 = 0, i; 425 INT num_bands0; 426 INT num_bands1; 427 INT diff_tot[MAX_OCTAVE + MAX_SECOND_REGION]; 428 INT *diff0 = diff_tot; 429 INT *diff1 = diff_tot+MAX_OCTAVE; 430 INT k2_achived; 431 INT k2_diff; 432 INT incr = 0; 433 434 /* Init */ 435 if (freqScale==1) b_p_o = 12; 436 if (freqScale==2) b_p_o = 10; 437 if (freqScale==3) b_p_o = 8; 438 439 440 if(freqScale > 0) /*Bark*/ 441 { 442 if(alterScale==0) 443 warp = FL2FXCONST_DBL(0.5f); /* 1.0/(1.0*2.0) */ 444 else 445 warp = FL2FXCONST_DBL(1.0f/2.6f); /* 1.0/(1.3*2.0); */ 446 447 448 if(4*k2 >= 9*k0) /*two or more regions (how many times the basis band is copied)*/ 449 { 450 k1=2*k0; 451 452 num_bands0=numberOfBands(b_p_o, k0, k1, FL2FXCONST_DBL(0.5f)); 453 num_bands1=numberOfBands(b_p_o, k1, k2, warp); 454 455 CalcBands(diff0, k0, k1, num_bands0);/*CalcBands1 => diff0 */ 456 FDKsbrEnc_Shellsort_int( diff0, num_bands0);/*SortBands sort diff0 */ 457 458 if (diff0[0] == 0) /* too wide FB bands for target tuning */ 459 { 460 return (1);/* raise the cross-over frequency and/or lower the number 461 of target bands per octave (or lower the sampling frequency */ 462 } 463 464 cumSum(k0, diff0, num_bands0, v_k_master); /* cumsum */ 465 466 CalcBands(diff1, k1, k2, num_bands1); /* CalcBands2 => diff1 */ 467 FDKsbrEnc_Shellsort_int( diff1, num_bands1); /* SortBands sort diff1 */ 468 if(diff0[num_bands0-1] > diff1[0]) /* max(1) > min(2) */ 469 { 470 if(modifyBands(diff0[num_bands0-1],diff1, num_bands1)) 471 return(1); 472 } 473 474 /* Add 2'nd region */ 475 cumSum(k1, diff1, num_bands1, &v_k_master[num_bands0]); 476 *h_num_bands=num_bands0+num_bands1; /* Output nr of bands */ 477 478 } 479 else /* one region */ 480 { 481 k1=k2; 482 483 num_bands0=numberOfBands(b_p_o, k0, k1, FL2FXCONST_DBL(0.5f)); 484 CalcBands(diff0, k0, k1, num_bands0);/* CalcBands1 => diff0 */ 485 FDKsbrEnc_Shellsort_int( diff0, num_bands0); /* SortBands sort diff0 */ 486 487 if (diff0[0] == 0) /* too wide FB bands for target tuning */ 488 { 489 return (1); /* raise the cross-over frequency and/or lower the number 490 of target bands per octave (or lower the sampling frequency */ 491 } 492 493 cumSum(k0, diff0, num_bands0, v_k_master);/* cumsum */ 494 *h_num_bands=num_bands0; /* Output nr of bands */ 495 496 } 497 } 498 else /* Linear mode */ 499 { 500 if (alterScale==0) { 501 dk = 1; 502 num_bands0 = 2 * ((k2 - k0)/2); /* FLOOR to get to few number of bands*/ 503 } else { 504 dk = 2; 505 num_bands0 = 2 * (((k2 - k0)/dk +1)/2); /* ROUND to get closest fit */ 506 } 507 508 k2_achived = k0 + num_bands0*dk; 509 k2_diff = k2 - k2_achived; 510 511 for(i=0;i<num_bands0;i++) 512 diff_tot[i] = dk; 513 514 /* If linear scale wasn't achived */ 515 /* and we got wide SBR are */ 516 if (k2_diff < 0) { 517 incr = 1; 518 i = 0; 519 } 520 521 /* If linear scale wasn't achived */ 522 /* and we got small SBR are */ 523 if (k2_diff > 0) { 524 incr = -1; 525 i = num_bands0-1; 526 } 527 528 /* Adjust diff vector to get sepc. SBR range */ 529 while (k2_diff != 0) { 530 diff_tot[i] = diff_tot[i] - incr; 531 i = i + incr; 532 k2_diff = k2_diff + incr; 533 } 534 535 cumSum(k0, diff_tot, num_bands0, v_k_master);/* cumsum */ 536 *h_num_bands=num_bands0; /* Output nr of bands */ 537 538 } 539 540 if (*h_num_bands < 1) 541 return(1); /*To small sbr area */ 542 543 return (0); 544}/* End FDKsbrEnc_UpdateFreqScale */ 545 546static INT 547numberOfBands(INT b_p_o, INT start, INT stop, FIXP_DBL warp_factor) 548{ 549 INT result=0; 550 /* result = 2* (INT) ( (double)b_p_o * (double)(FDKlog((double)stop/(double)start)/FDKlog((double)2)) * (double)FX_DBL2FL(warp_factor) + 0.5); */ 551 result = ( ( b_p_o * fMult( (CalcLdInt(stop) - CalcLdInt(start)), warp_factor) + (FL2FX_DBL(0.5f)>>LD_DATA_SHIFT) 552 ) >> ((DFRACT_BITS-1)-LD_DATA_SHIFT) ) << 1; /* do not optimize anymore (rounding!!) */ 553 554 return(result); 555} 556 557 558static void 559CalcBands(INT * diff, INT start , INT stop , INT num_bands) 560{ 561 INT i, qb, qe, qtmp; 562 INT previous; 563 INT current; 564 FIXP_DBL base, exp, tmp; 565 566 previous=start; 567 for(i=1; i<= num_bands; i++) 568 { 569 base = fDivNorm((FIXP_DBL)stop, (FIXP_DBL)start, &qb); 570 exp = fDivNorm((FIXP_DBL)i, (FIXP_DBL)num_bands, &qe); 571 tmp = fPow(base, qb, exp, qe, &qtmp); 572 tmp = fMult(tmp, (FIXP_DBL)(start<<24)); 573 current = (INT)scaleValue(tmp, qtmp-23); 574 current = (current+1) >> 1; /* rounding*/ 575 diff[i-1] = current-previous; 576 previous = current; 577 } 578 579}/* End CalcBands */ 580 581 582static void 583cumSum(INT start_value, INT* diff, INT length, UCHAR *start_adress) 584{ 585 INT i; 586 start_adress[0]=start_value; 587 for(i=1;i<=length;i++) 588 start_adress[i]=start_adress[i-1]+diff[i-1]; 589} /* End cumSum */ 590 591 592static INT 593modifyBands(INT max_band_previous, INT * diff, INT length) 594{ 595 INT change=max_band_previous-diff[0]; 596 597 /* Limit the change so that the last band cannot get narrower than the first one */ 598 if ( change > (diff[length-1] - diff[0]) / 2 ) 599 change = (diff[length-1] - diff[0]) / 2; 600 601 diff[0] += change; 602 diff[length-1] -= change; 603 FDKsbrEnc_Shellsort_int(diff, length); 604 605 return(0); 606}/* End modifyBands */ 607 608 609/******************************************************************************* 610 Functionname: FDKsbrEnc_UpdateHiRes 611 ******************************************************************************* 612 Description: 613 614 615 Arguments: 616 617 Return: 618 *******************************************************************************/ 619INT 620FDKsbrEnc_UpdateHiRes( 621 UCHAR *h_hires, 622 INT *num_hires, 623 UCHAR *v_k_master, 624 INT num_master, 625 INT *xover_band 626 ) 627{ 628 INT i; 629 INT max1,max2; 630 631 if( (v_k_master[*xover_band] > 32 ) || /* v_k_master[*xover_band] > noQMFChannels(dualRate)/divider */ 632 ( *xover_band > num_master ) ) { 633 /* xover_band error, too big for this startFreq. Will be clipped */ 634 635 /* Calculate maximum value for xover_band */ 636 max1=0; 637 max2=num_master; 638 while( (v_k_master[max1+1] < 32 ) && /* noQMFChannels(dualRate)/divider */ 639 ( (max1+1) < max2) ) 640 { 641 max1++; 642 } 643 644 *xover_band=max1; 645 } 646 647 *num_hires = num_master - *xover_band; 648 for(i = *xover_band; i <= num_master; i++) 649 { 650 h_hires[i - *xover_band] = v_k_master[i]; 651 } 652 653 return (0); 654}/* End FDKsbrEnc_UpdateHiRes */ 655 656 657/******************************************************************************* 658 Functionname: FDKsbrEnc_UpdateLoRes 659 ******************************************************************************* 660 Description: 661 662 Arguments: 663 664 Return: 665 *******************************************************************************/ 666void 667FDKsbrEnc_UpdateLoRes(UCHAR * h_lores, INT *num_lores, UCHAR * h_hires, INT num_hires) 668{ 669 INT i; 670 671 if(num_hires%2 == 0) /* if even number of hires bands */ 672 { 673 *num_lores=num_hires/2; 674 /* Use every second lores=hires[0,2,4...] */ 675 for(i=0;i<=*num_lores;i++) 676 h_lores[i]=h_hires[i*2]; 677 678 } 679 else /* odd number of hires which means xover is odd */ 680 { 681 *num_lores=(num_hires+1)/2; 682 683 /* Use lores=hires[0,1,3,5 ...] */ 684 h_lores[0]=h_hires[0]; 685 for(i=1;i<=*num_lores;i++) 686 { 687 h_lores[i]=h_hires[i*2-1]; 688 } 689 } 690 691}/* End FDKsbrEnc_UpdateLoRes */ 692