1
2 /* -----------------------------------------------------------------------------------------------------------
3 Software License for The Fraunhofer FDK AAC Codec Library for Android
4
5 � Copyright 1995 - 2012 Fraunhofer-Gesellschaft zur F�rderung der angewandten Forschung e.V.
6 All rights reserved.
7
8 1. INTRODUCTION
9 The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements
10 the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio.
11 This FDK AAC Codec software is intended to be used on a wide variety of Android devices.
12
13 AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual
14 audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by
15 independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part
16 of the MPEG specifications.
17
18 Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer)
19 may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners
20 individually for the purpose of encoding or decoding bit streams in products that are compliant with
21 the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license
22 these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec
23 software may already be covered under those patent licenses when it is used for those licensed purposes only.
24
25 Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality,
26 are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional
27 applications information and documentation.
28
29 2. COPYRIGHT LICENSE
30
31 Redistribution and use in source and binary forms, with or without modification, are permitted without
32 payment of copyright license fees provided that you satisfy the following conditions:
33
34 You must retain the complete text of this software license in redistributions of the FDK AAC Codec or
35 your modifications thereto in source code form.
36
37 You must retain the complete text of this software license in the documentation and/or other materials
38 provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form.
39 You must make available free of charge copies of the complete source code of the FDK AAC Codec and your
40 modifications thereto to recipients of copies in binary form.
41
42 The name of Fraunhofer may not be used to endorse or promote products derived from this library without
43 prior written permission.
44
45 You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec
46 software or your modifications thereto.
47
48 Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software
49 and 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
53 3. NO PATENT LICENSE
54
55 NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer,
56 ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with
57 respect to this software.
58
59 You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized
60 by appropriate patent licenses.
61
62 4. DISCLAIMER
63
64 This 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
66 of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
67 CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages,
68 including but not limited to procurement of substitute goods or services; loss of use, data, or profits,
69 or business interruption, however caused and on any theory of liability, whether in contract, strict
70 liability, or tort (including negligence), arising in any way out of the use of this software, even if
71 advised of the possibility of such damage.
72
73 5. CONTACT INFORMATION
74
75 Fraunhofer Institute for Integrated Circuits IIS
76 Attention: Audio and Multimedia Departments - FDK AAC LL
77 Am Wolfsmantel 33
78 91058 Erlangen, Germany
79
80 www.iis.fraunhofer.de/amm
81 amm-info@iis.fraunhofer.de
82 ----------------------------------------------------------------------------------------------------------- */
83
84 /*!
85 \file
86 \brief frequency scale
87 */
88
89 #include "sbrenc_freq_sca.h"
90 #include "sbr_misc.h"
91
92 #include "genericStds.h"
93
94 /* StartFreq */
95 static INT getStartFreq(INT fs, const INT start_freq);
96
97 /* StopFreq */
98 static INT getStopFreq(INT fs, const INT stop_freq, const INT noChannels);
99
100 static INT numberOfBands(INT b_p_o, INT start, INT stop, FIXP_DBL warp_factor);
101 static void CalcBands(INT * diff, INT start , INT stop , INT num_bands);
102 static INT modifyBands(INT max_band, INT * diff, INT length);
103 static void cumSum(INT start_value, INT* diff, INT length, UCHAR *start_adress);
104
105
106
107 /*******************************************************************************
108 Functionname: FDKsbrEnc_getSbrStartFreqRAW
109 *******************************************************************************
110 Description:
111
112 Arguments:
113
114 Return:
115 *******************************************************************************/
116
117 INT
FDKsbrEnc_getSbrStartFreqRAW(INT startFreq,INT QMFbands,INT fs)118 FDKsbrEnc_getSbrStartFreqRAW (INT startFreq, INT QMFbands, INT fs)
119 {
120 INT result;
121
122 if ( startFreq < 0 || startFreq > 15) {
123 return -1;
124 }
125 /* Update startFreq struct */
126 result = getStartFreq(fs, startFreq);
127
128 result = (result*fs/QMFbands+1)>>1;
129
130 return (result);
131
132 } /* End FDKsbrEnc_getSbrStartFreqRAW */
133
134
135 /*******************************************************************************
136 Functionname: getSbrStopFreq
137 *******************************************************************************
138 Description:
139
140 Arguments:
141
142 Return:
143 *******************************************************************************/
FDKsbrEnc_getSbrStopFreqRAW(INT stopFreq,INT QMFbands,INT fs)144 INT FDKsbrEnc_getSbrStopFreqRAW (INT stopFreq, INT QMFbands, INT fs)
145 {
146 INT result;
147
148 if ( stopFreq < 0 || stopFreq > 13)
149 return -1;
150
151
152 /* Uppdate stopFreq struct */
153 result = getStopFreq( fs, stopFreq, QMFbands);
154 result = (result*fs/QMFbands+1)>>1;
155
156 return (result);
157 } /* End getSbrStopFreq */
158
159
160 /*******************************************************************************
161 Functionname: getStartFreq
162 *******************************************************************************
163 Description:
164
165 Arguments:
166
167 Return:
168 *******************************************************************************/
169 static INT
getStartFreq(INT fs,const INT start_freq)170 getStartFreq(INT fs, const INT start_freq)
171 {
172 INT k0_min;
173
174 switch(fs){
175 case 16000: k0_min = 24;
176 break;
177 case 22050: k0_min = 17;
178 break;
179 case 24000: k0_min = 16;
180 break;
181 case 32000: k0_min = 16;
182 break;
183 case 44100: k0_min = 12;
184 break;
185 case 48000: k0_min = 11;
186 break;
187 case 64000: k0_min = 10;
188 break;
189 case 88200: k0_min = 7;
190 break;
191 case 96000: k0_min = 7;
192 break;
193 default:
194 k0_min=11; /* illegal fs */
195 }
196
197
198 switch (fs) {
199
200 case 16000:
201 {
202 INT v_offset[]= {-8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7};
203 return (k0_min + v_offset[start_freq]);
204 }
205 case 22050:
206 {
207 INT v_offset[]= {-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13};
208 return (k0_min + v_offset[start_freq]);
209 }
210 case 24000:
211 {
212 INT v_offset[]= {-5, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16};
213 return (k0_min + v_offset[start_freq]);
214 }
215 case 32000:
216 {
217 INT v_offset[]= {-6, -4, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16};
218 return (k0_min + v_offset[start_freq]);
219 }
220 case 44100:
221 case 48000:
222 case 64000:
223 {
224 INT v_offset[]= {-4, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20};
225 return (k0_min + v_offset[start_freq]);
226 }
227 case 88200:
228 case 96000:
229 {
230 INT v_offset[]= {-2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20, 24};
231 return (k0_min + v_offset[start_freq]);
232 }
233 default:
234 {
235 INT v_offset[]= {0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20, 24, 28, 33};
236 return (k0_min + v_offset[start_freq]);
237 }
238 }
239 } /* End getStartFreq */
240
241
242 /*******************************************************************************
243 Functionname: getStopFreq
244 *******************************************************************************
245 Description:
246
247 Arguments:
248
249 Return:
250 *******************************************************************************/
251 static INT
getStopFreq(INT fs,const INT stop_freq,const INT noChannels)252 getStopFreq(INT fs, const INT stop_freq, const INT noChannels)
253 {
254 INT result,i;
255 INT k1_min;
256 INT v_dstop[13];
257
258
259 INT *v_stop_freq = NULL;
260 INT v_stop_freq_16[14] = {48,49,50,51,52,54,55,56,57,59,60,61,63,64};
261 INT v_stop_freq_22[14] = {35,37,38,40,42,44,46,48,51,53,56,58,61,64};
262 INT v_stop_freq_24[14] = {32,34,36,38,40,42,44,46,49,52,55,58,61,64};
263 INT v_stop_freq_32[14] = {32,34,36,38,40,42,44,46,49,52,55,58,61,64};
264 INT v_stop_freq_44[14] = {23,25,27,29,32,34,37,40,43,47,51,55,59,64};
265 INT v_stop_freq_48[14] = {21,23,25,27,30,32,35,38,42,45,49,54,59,64};
266 INT v_stop_freq_64[14] = {20,22,24,26,29,31,34,37,41,45,49,54,59,64};
267 INT v_stop_freq_88[14] = {15,17,19,21,23,26,29,33,37,41,46,51,57,64};
268 INT v_stop_freq_96[14] = {13,15,17,19,21,24,27,31,35,39,44,50,57,64};
269
270 switch(fs){
271 case 16000: k1_min = 48;
272 v_stop_freq =v_stop_freq_16;
273 break;
274 case 22050: k1_min = 35;
275 v_stop_freq =v_stop_freq_22;
276 break;
277 case 24000: k1_min = 32;
278 v_stop_freq =v_stop_freq_24;
279 break;
280 case 32000: k1_min = 32;
281 v_stop_freq =v_stop_freq_32;
282 break;
283 case 44100: k1_min = 23;
284 v_stop_freq =v_stop_freq_44;
285 break;
286 case 48000: k1_min = 21;
287 v_stop_freq =v_stop_freq_48;
288 break;
289 case 64000: k1_min = 20;
290 v_stop_freq =v_stop_freq_64;
291 break;
292 case 88200: k1_min = 15;
293 v_stop_freq =v_stop_freq_88;
294 break;
295 case 96000: k1_min = 13;
296 v_stop_freq =v_stop_freq_96;
297 break;
298 default:
299 k1_min = 21; /* illegal fs */
300 }
301
302
303 /* Ensure increasing bandwidth */
304 for(i = 0; i <= 12; i++) {
305 v_dstop[i] = v_stop_freq[i+1] - v_stop_freq[i];
306 }
307
308 FDKsbrEnc_Shellsort_int(v_dstop, 13); /* Sort bandwidth changes */
309
310 result = k1_min;
311 for(i = 0; i < stop_freq; i++) {
312 result = result + v_dstop[i];
313 }
314
315 return(result);
316
317 }/* End getStopFreq */
318
319
320 /*******************************************************************************
321 Functionname: FDKsbrEnc_FindStartAndStopBand
322 *******************************************************************************
323 Description:
324
325 Arguments:
326
327 Return:
328 *******************************************************************************/
329 INT
FDKsbrEnc_FindStartAndStopBand(const INT samplingFreq,const INT noChannels,const INT startFreq,const INT stopFreq,const SR_MODE sampleRateMode,INT * k0,INT * k2)330 FDKsbrEnc_FindStartAndStopBand(const INT samplingFreq,
331 const INT noChannels,
332 const INT startFreq,
333 const INT stopFreq,
334 const SR_MODE sampleRateMode,
335 INT *k0,
336 INT *k2)
337 {
338
339 /* Update startFreq struct */
340 *k0 = getStartFreq(samplingFreq, startFreq);
341
342 /* Test if start freq is outside corecoder range */
343 if( ( sampleRateMode == 1 ) &&
344 ( samplingFreq*noChannels <
345 2**k0 * samplingFreq) ) {
346 return (1); /* raise the cross-over frequency and/or lower the number
347 of target bands per octave (or lower the sampling frequency) */
348 }
349
350 /*Update stopFreq struct */
351 if ( stopFreq < 14 ) {
352 *k2 = getStopFreq(samplingFreq, stopFreq, noChannels);
353 } else if( stopFreq == 14 ) {
354 *k2 = 2 * *k0;
355 } else {
356 *k2 = 3 * *k0;
357 }
358
359 /* limit to Nyqvist */
360 if (*k2 > noChannels) {
361 *k2 = noChannels;
362 }
363
364
365
366 /* Test for invalid k0 k2 combinations */
367 if ( (samplingFreq == 44100) && ( (*k2 - *k0) > MAX_FREQ_COEFFS_FS44100 ) )
368 return (1); /* Number of bands exceeds valid range of MAX_FREQ_COEFFS for fs=44.1kHz */
369
370 if ( (samplingFreq >= 48000) && ( (*k2 - *k0) > MAX_FREQ_COEFFS_FS48000 ) )
371 return (1); /* Number of bands exceeds valid range of MAX_FREQ_COEFFS for fs>=48kHz */
372
373 if ((*k2 - *k0) > MAX_FREQ_COEFFS)
374 return (1);/*Number of bands exceeds valid range of MAX_FREQ_COEFFS */
375
376 if ((*k2 - *k0) < 0)
377 return (1);/* Number of bands is negative */
378
379
380 return(0);
381 }
382
383 /*******************************************************************************
384 Functionname: FDKsbrEnc_UpdateFreqScale
385 *******************************************************************************
386 Description:
387
388 Arguments:
389
390 Return:
391 *******************************************************************************/
392 INT
FDKsbrEnc_UpdateFreqScale(UCHAR * v_k_master,INT * h_num_bands,const INT k0,const INT k2,const INT freqScale,const INT alterScale)393 FDKsbrEnc_UpdateFreqScale(UCHAR *v_k_master, INT *h_num_bands,
394 const INT k0, const INT k2,
395 const INT freqScale,
396 const INT alterScale)
397
398 {
399
400 INT b_p_o = 0; /* bands_per_octave */
401 FIXP_DBL warp = FL2FXCONST_DBL(0.0f);
402 INT dk = 0;
403
404 /* Internal variables */
405 INT k1 = 0, i;
406 INT num_bands0;
407 INT num_bands1;
408 INT diff_tot[MAX_OCTAVE + MAX_SECOND_REGION];
409 INT *diff0 = diff_tot;
410 INT *diff1 = diff_tot+MAX_OCTAVE;
411 INT k2_achived;
412 INT k2_diff;
413 INT incr = 0;
414
415 /* Init */
416 if (freqScale==1) b_p_o = 12;
417 if (freqScale==2) b_p_o = 10;
418 if (freqScale==3) b_p_o = 8;
419
420
421 if(freqScale > 0) /*Bark*/
422 {
423 if(alterScale==0)
424 warp = FL2FXCONST_DBL(0.5f); /* 1.0/(1.0*2.0) */
425 else
426 warp = FL2FXCONST_DBL(1.0f/2.6f); /* 1.0/(1.3*2.0); */
427
428
429 if(4*k2 >= 9*k0) /*two or more regions*/
430 {
431 k1=2*k0;
432
433 num_bands0=numberOfBands(b_p_o, k0, k1, FL2FXCONST_DBL(0.5f));
434 num_bands1=numberOfBands(b_p_o, k1, k2, warp);
435
436 CalcBands(diff0, k0, k1, num_bands0);/*CalcBands1 => diff0 */
437 FDKsbrEnc_Shellsort_int( diff0, num_bands0);/*SortBands sort diff0 */
438
439 if (diff0[0] == 0) /* too wide FB bands for target tuning */
440 {
441 return (1);/* raise the cross-over frequency and/or lower the number
442 of target bands per octave (or lower the sampling frequency */
443 }
444
445 cumSum(k0, diff0, num_bands0, v_k_master); /* cumsum */
446
447 CalcBands(diff1, k1, k2, num_bands1); /* CalcBands2 => diff1 */
448 FDKsbrEnc_Shellsort_int( diff1, num_bands1); /* SortBands sort diff1 */
449 if(diff0[num_bands0-1] > diff1[0]) /* max(1) > min(2) */
450 {
451 if(modifyBands(diff0[num_bands0-1],diff1, num_bands1))
452 return(1);
453 }
454
455 /* Add 2'nd region */
456 cumSum(k1, diff1, num_bands1, &v_k_master[num_bands0]);
457 *h_num_bands=num_bands0+num_bands1; /* Output nr of bands */
458
459 }
460 else /* one region */
461 {
462 k1=k2;
463
464 num_bands0=numberOfBands(b_p_o, k0, k1, FL2FXCONST_DBL(0.5f));
465 CalcBands(diff0, k0, k1, num_bands0);/* CalcBands1 => diff0 */
466 FDKsbrEnc_Shellsort_int( diff0, num_bands0); /* SortBands sort diff0 */
467
468 if (diff0[0] == 0) /* too wide FB bands for target tuning */
469 {
470 return (1); /* raise the cross-over frequency and/or lower the number
471 of target bands per octave (or lower the sampling frequency */
472 }
473
474 cumSum(k0, diff0, num_bands0, v_k_master);/* cumsum */
475 *h_num_bands=num_bands0; /* Output nr of bands */
476
477 }
478 }
479 else /* Linear mode */
480 {
481 if (alterScale==0) {
482 dk = 1;
483 num_bands0 = 2 * ((k2 - k0)/2); /* FLOOR to get to few number of bands*/
484 } else {
485 dk = 2;
486 num_bands0 = 2 * (((k2 - k0)/dk +1)/2); /* ROUND to get closest fit */
487 }
488
489 k2_achived = k0 + num_bands0*dk;
490 k2_diff = k2 - k2_achived;
491
492 for(i=0;i<num_bands0;i++)
493 diff_tot[i] = dk;
494
495 /* If linear scale wasn't achived */
496 /* and we got wide SBR are */
497 if (k2_diff < 0) {
498 incr = 1;
499 i = 0;
500 }
501
502 /* If linear scale wasn't achived */
503 /* and we got small SBR are */
504 if (k2_diff > 0) {
505 incr = -1;
506 i = num_bands0-1;
507 }
508
509 /* Adjust diff vector to get sepc. SBR range */
510 while (k2_diff != 0) {
511 diff_tot[i] = diff_tot[i] - incr;
512 i = i + incr;
513 k2_diff = k2_diff + incr;
514 }
515
516 cumSum(k0, diff_tot, num_bands0, v_k_master);/* cumsum */
517 *h_num_bands=num_bands0; /* Output nr of bands */
518
519 }
520
521 if (*h_num_bands < 1)
522 return(1); /*To small sbr area */
523
524 return (0);
525 }/* End FDKsbrEnc_UpdateFreqScale */
526
527 static INT
numberOfBands(INT b_p_o,INT start,INT stop,FIXP_DBL warp_factor)528 numberOfBands(INT b_p_o, INT start, INT stop, FIXP_DBL warp_factor)
529 {
530 INT result=0;
531 /* result = 2* (INT) ( (double)b_p_o * (double)(FDKlog((double)stop/(double)start)/FDKlog((double)2)) * (double)FX_DBL2FL(warp_factor) + 0.5); */
532 result = ( ( b_p_o * fMult( (CalcLdInt(stop) - CalcLdInt(start)), warp_factor) + (FL2FX_DBL(0.5f)>>LD_DATA_SHIFT)
533 ) >> ((DFRACT_BITS-1)-LD_DATA_SHIFT) ) << 1; /* do not optimize anymore (rounding!!) */
534
535 return(result);
536 }
537
538
539 static void
CalcBands(INT * diff,INT start,INT stop,INT num_bands)540 CalcBands(INT * diff, INT start , INT stop , INT num_bands)
541 {
542 INT i, qb, qe, qtmp;
543 INT previous;
544 INT current;
545 FIXP_DBL base, exp, tmp;
546
547 previous=start;
548 for(i=1; i<= num_bands; i++)
549 {
550 base = fDivNorm((FIXP_DBL)stop, (FIXP_DBL)start, &qb);
551 exp = fDivNorm((FIXP_DBL)i, (FIXP_DBL)num_bands, &qe);
552 tmp = fPow(base, qb, exp, qe, &qtmp);
553 tmp = fMult(tmp, (FIXP_DBL)(start<<24));
554 current = (INT)scaleValue(tmp, qtmp-23);
555 current = (current+1) >> 1; /* rounding*/
556 diff[i-1] = current-previous;
557 previous = current;
558 }
559
560 }/* End CalcBands */
561
562
563 static void
cumSum(INT start_value,INT * diff,INT length,UCHAR * start_adress)564 cumSum(INT start_value, INT* diff, INT length, UCHAR *start_adress)
565 {
566 INT i;
567 start_adress[0]=start_value;
568 for(i=1;i<=length;i++)
569 start_adress[i]=start_adress[i-1]+diff[i-1];
570 } /* End cumSum */
571
572
573 static INT
modifyBands(INT max_band_previous,INT * diff,INT length)574 modifyBands(INT max_band_previous, INT * diff, INT length)
575 {
576 INT change=max_band_previous-diff[0];
577
578 /* Limit the change so that the last band cannot get narrower than the first one */
579 if ( change > (diff[length-1] - diff[0]) / 2 )
580 change = (diff[length-1] - diff[0]) / 2;
581
582 diff[0] += change;
583 diff[length-1] -= change;
584 FDKsbrEnc_Shellsort_int(diff, length);
585
586 return(0);
587 }/* End modifyBands */
588
589
590 /*******************************************************************************
591 Functionname: FDKsbrEnc_UpdateHiRes
592 *******************************************************************************
593 Description:
594
595 Arguments:
596
597 Return:
598 *******************************************************************************/
599 INT
FDKsbrEnc_UpdateHiRes(UCHAR * h_hires,INT * num_hires,UCHAR * v_k_master,INT num_master,INT * xover_band,SR_MODE drOrSr,INT noQMFChannels)600 FDKsbrEnc_UpdateHiRes(UCHAR *h_hires, INT *num_hires,UCHAR * v_k_master,
601 INT num_master , INT *xover_band, SR_MODE drOrSr,
602 INT noQMFChannels)
603 {
604 INT i;
605 INT divider;
606 INT max1,max2;
607
608 /* Check if we use a Dual rate => diver=2 else 1 */
609 divider = (drOrSr == DUAL_RATE) ? 2 : 1;
610
611 if( (v_k_master[*xover_band] > (noQMFChannels/divider) ) ||
612 ( *xover_band > num_master ) ) {
613 /* xover_band error, too big for this startFreq. Will be clipped */
614
615 /* Calculate maximum value for xover_band */
616 max1=0;
617 max2=num_master;
618 while( (v_k_master[max1+1] < (noQMFChannels/divider)) &&
619 ( (max1+1) < max2) )
620 {
621 max1++;
622 }
623
624 *xover_band=max1;
625 }
626
627 *num_hires = num_master - *xover_band;
628 for(i = *xover_band; i <= num_master; i++)
629 {
630 h_hires[i - *xover_band] = v_k_master[i];
631 }
632
633 return (0);
634 }/* End FDKsbrEnc_UpdateHiRes */
635
636
637 /*******************************************************************************
638 Functionname: FDKsbrEnc_UpdateLoRes
639 *******************************************************************************
640 Description:
641
642 Arguments:
643
644 Return:
645 *******************************************************************************/
646 void
FDKsbrEnc_UpdateLoRes(UCHAR * h_lores,INT * num_lores,UCHAR * h_hires,INT num_hires)647 FDKsbrEnc_UpdateLoRes(UCHAR * h_lores, INT *num_lores, UCHAR * h_hires, INT num_hires)
648 {
649 INT i;
650
651 if(num_hires%2 == 0) /* if even number of hires bands */
652 {
653 *num_lores=num_hires/2;
654 /* Use every second lores=hires[0,2,4...] */
655 for(i=0;i<=*num_lores;i++)
656 h_lores[i]=h_hires[i*2];
657
658 }
659 else /* odd number of hires which means xover is odd */
660 {
661 *num_lores=(num_hires+1)/2;
662
663 /* Use lores=hires[0,1,3,5 ...] */
664 h_lores[0]=h_hires[0];
665 for(i=1;i<=*num_lores;i++)
666 {
667 h_lores[i]=h_hires[i*2-1];
668 }
669 }
670
671 }/* End FDKsbrEnc_UpdateLoRes */
672