1
2 /* -----------------------------------------------------------------------------------------------------------
3 Software 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
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 /************************ FDK PCM postprocessor module *********************
85
86 Author(s): Matthias Neusinger
87 Description: Hard limiter for clipping prevention
88
89 *******************************************************************************/
90
91 #include "limiter.h"
92
93
94 struct TDLimiter {
95 unsigned int attack;
96 FIXP_DBL attackConst, releaseConst;
97 unsigned int attackMs, releaseMs, maxAttackMs;
98 FIXP_PCM threshold;
99 unsigned int channels, maxChannels;
100 unsigned int sampleRate, maxSampleRate;
101 FIXP_DBL cor, max;
102 FIXP_DBL* maxBuf;
103 FIXP_DBL* delayBuf;
104 unsigned int maxBufIdx, delayBufIdx;
105 FIXP_DBL smoothState0;
106 FIXP_DBL minGain;
107
108 FIXP_DBL additionalGainPrev;
109 FIXP_DBL additionalGainFilterState;
110 FIXP_DBL additionalGainFilterState1;
111 };
112
113 /* create limiter */
createLimiter(unsigned int maxAttackMs,unsigned int releaseMs,INT_PCM threshold,unsigned int maxChannels,unsigned int maxSampleRate)114 TDLimiterPtr createLimiter(
115 unsigned int maxAttackMs,
116 unsigned int releaseMs,
117 INT_PCM threshold,
118 unsigned int maxChannels,
119 unsigned int maxSampleRate
120 )
121 {
122 TDLimiterPtr limiter = NULL;
123 unsigned int attack, release;
124 FIXP_DBL attackConst, releaseConst, exponent;
125 INT e_ans;
126
127 /* calc attack and release time in samples */
128 attack = (unsigned int)(maxAttackMs * maxSampleRate / 1000);
129 release = (unsigned int)(releaseMs * maxSampleRate / 1000);
130
131 /* alloc limiter struct */
132 limiter = (TDLimiterPtr)FDKcalloc(1, sizeof(struct TDLimiter));
133 if (!limiter) return NULL;
134
135 /* alloc max and delay buffers */
136 limiter->maxBuf = (FIXP_DBL*)FDKcalloc(attack + 1, sizeof(FIXP_DBL));
137 limiter->delayBuf = (FIXP_DBL*)FDKcalloc(attack * maxChannels, sizeof(FIXP_DBL));
138
139 if (!limiter->maxBuf || !limiter->delayBuf) {
140 destroyLimiter(limiter);
141 return NULL;
142 }
143
144 /* attackConst = pow(0.1, 1.0 / (attack + 1)) */
145 exponent = invFixp(attack+1);
146 attackConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);
147 attackConst = scaleValue(attackConst, e_ans);
148
149 /* releaseConst = (float)pow(0.1, 1.0 / (release + 1)) */
150 exponent = invFixp(release + 1);
151 releaseConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);
152 releaseConst = scaleValue(releaseConst, e_ans);
153
154 /* init parameters */
155 limiter->attackMs = maxAttackMs;
156 limiter->maxAttackMs = maxAttackMs;
157 limiter->releaseMs = releaseMs;
158 limiter->attack = attack;
159 limiter->attackConst = attackConst;
160 limiter->releaseConst = releaseConst;
161 limiter->threshold = (FIXP_PCM)threshold;
162 limiter->channels = maxChannels;
163 limiter->maxChannels = maxChannels;
164 limiter->sampleRate = maxSampleRate;
165 limiter->maxSampleRate = maxSampleRate;
166
167 resetLimiter(limiter);
168
169 return limiter;
170 }
171
172
173 /* reset limiter */
resetLimiter(TDLimiterPtr limiter)174 TDLIMITER_ERROR resetLimiter(TDLimiterPtr limiter)
175 {
176 if (limiter != NULL) {
177
178 limiter->maxBufIdx = 0;
179 limiter->delayBufIdx = 0;
180 limiter->max = (FIXP_DBL)0;
181 limiter->cor = FL2FXCONST_DBL(1.0f/(1<<1));
182 limiter->smoothState0 = FL2FXCONST_DBL(1.0f/(1<<1));
183 limiter->minGain = FL2FXCONST_DBL(1.0f/(1<<1));
184
185 limiter->additionalGainPrev = FL2FXCONST_DBL(1.0f/(1<<TDL_GAIN_SCALING));
186 limiter->additionalGainFilterState = FL2FXCONST_DBL(1.0f/(1<<TDL_GAIN_SCALING));
187 limiter->additionalGainFilterState1 = FL2FXCONST_DBL(1.0f/(1<<TDL_GAIN_SCALING));
188
189 FDKmemset(limiter->maxBuf, 0, (limiter->attack + 1) * sizeof(FIXP_DBL) );
190 FDKmemset(limiter->delayBuf, 0, limiter->attack * limiter->channels * sizeof(FIXP_DBL) );
191 }
192 else {
193 return TDLIMIT_INVALID_HANDLE;
194 }
195
196 return TDLIMIT_OK;
197 }
198
199
200 /* destroy limiter */
destroyLimiter(TDLimiterPtr limiter)201 TDLIMITER_ERROR destroyLimiter(TDLimiterPtr limiter)
202 {
203 if (limiter != NULL) {
204 FDKfree(limiter->maxBuf);
205 FDKfree(limiter->delayBuf);
206
207 FDKfree(limiter);
208 }
209 else {
210 return TDLIMIT_INVALID_HANDLE;
211 }
212 return TDLIMIT_OK;
213 }
214
215 /* apply limiter */
applyLimiter(TDLimiterPtr limiter,INT_PCM * samples,FIXP_DBL * pGain,const INT * gain_scale,const UINT gain_size,const UINT gain_delay,const UINT nSamples)216 TDLIMITER_ERROR applyLimiter(TDLimiterPtr limiter,
217 INT_PCM* samples,
218 FIXP_DBL* pGain,
219 const INT* gain_scale,
220 const UINT gain_size,
221 const UINT gain_delay,
222 const UINT nSamples)
223 {
224 unsigned int i, j;
225 FIXP_PCM tmp1, tmp2;
226 FIXP_DBL tmp, old, gain, additionalGain, additionalGainUnfiltered;
227 FIXP_DBL minGain = FL2FXCONST_DBL(1.0f/(1<<1));
228
229 FDK_ASSERT(gain_size == 1);
230 FDK_ASSERT(gain_delay <= nSamples);
231
232 if ( limiter == NULL ) return TDLIMIT_INVALID_HANDLE;
233
234 {
235 unsigned int channels = limiter->channels;
236 unsigned int attack = limiter->attack;
237 FIXP_DBL attackConst = limiter->attackConst;
238 FIXP_DBL releaseConst = limiter->releaseConst;
239 FIXP_DBL threshold = FX_PCM2FX_DBL(limiter->threshold)>>TDL_GAIN_SCALING;
240
241 FIXP_DBL max = limiter->max;
242 FIXP_DBL* maxBuf = limiter->maxBuf;
243 unsigned int maxBufIdx = limiter->maxBufIdx;
244 FIXP_DBL cor = limiter->cor;
245 FIXP_DBL* delayBuf = limiter->delayBuf;
246 unsigned int delayBufIdx = limiter->delayBufIdx;
247
248 FIXP_DBL smoothState0 = limiter->smoothState0;
249 FIXP_DBL additionalGainSmoothState = limiter->additionalGainFilterState;
250 FIXP_DBL additionalGainSmoothState1 = limiter->additionalGainFilterState1;
251
252 for (i = 0; i < nSamples; i++) {
253
254 if (i < gain_delay) {
255 additionalGainUnfiltered = limiter->additionalGainPrev;
256 } else {
257 additionalGainUnfiltered = pGain[0];
258 }
259
260 /* Smooth additionalGain */
261 /* [b,a] = butter(1, 0.01) */
262 static const FIXP_SGL b[] = { FL2FXCONST_SGL(0.015466*2.0), FL2FXCONST_SGL( 0.015466*2.0) };
263 static const FIXP_SGL a[] = { FL2FXCONST_SGL(1.000000), FL2FXCONST_SGL(-0.96907) };
264 /* [b,a] = butter(1, 0.001) */
265 //static const FIXP_SGL b[] = { FL2FXCONST_SGL(0.0015683*2.0), FL2FXCONST_SGL( 0.0015683*2.0) };
266 //static const FIXP_SGL a[] = { FL2FXCONST_SGL(1.0000000), FL2FXCONST_SGL(-0.99686) };
267 additionalGain = - fMult(additionalGainSmoothState, a[1]) + fMultDiv2( additionalGainUnfiltered, b[0]) + fMultDiv2(additionalGainSmoothState1, b[1]);
268 additionalGainSmoothState1 = additionalGainUnfiltered;
269 additionalGainSmoothState = additionalGain;
270
271 /* Apply the additional scaling that has no delay and no smoothing */
272 if (gain_scale[0] > 0) {
273 additionalGain <<= gain_scale[0];
274 } else {
275 additionalGain >>= gain_scale[0];
276 }
277
278 /* get maximum absolute sample value of all channels, including the additional gain. */
279 tmp1 = (FIXP_PCM)0;
280 for (j = 0; j < channels; j++) {
281 tmp2 = (FIXP_PCM)samples[i * channels + j];
282 if (tmp2 == (FIXP_PCM)SAMPLE_MIN) /* protect fAbs from -1.0 value */
283 tmp2 = (FIXP_PCM)(SAMPLE_MIN+1);
284 tmp1 = fMax(tmp1, fAbs(tmp2));
285 }
286 tmp = SATURATE_LEFT_SHIFT(fMultDiv2(tmp1, additionalGain), 1, DFRACT_BITS);
287
288 /* set threshold as lower border to save calculations in running maximum algorithm */
289 tmp = fMax(tmp, threshold);
290
291 /* running maximum */
292 old = maxBuf[maxBufIdx];
293 maxBuf[maxBufIdx] = tmp;
294
295 if (tmp >= max) {
296 /* new sample is greater than old maximum, so it is the new maximum */
297 max = tmp;
298 }
299 else if (old < max) {
300 /* maximum does not change, as the sample, which has left the window was
301 not the maximum */
302 }
303 else {
304 /* the old maximum has left the window, we have to search the complete
305 buffer for the new max */
306 max = maxBuf[0];
307 for (j = 1; j <= attack; j++) {
308 if (maxBuf[j] > max) max = maxBuf[j];
309 }
310 }
311 maxBufIdx++;
312 if (maxBufIdx >= attack+1) maxBufIdx = 0;
313
314 /* calc gain */
315 /* gain is downscaled by one, so that gain = 1.0 can be represented */
316 if (max > threshold) {
317 gain = fDivNorm(threshold, max)>>1;
318 }
319 else {
320 gain = FL2FXCONST_DBL(1.0f/(1<<1));
321 }
322
323 /* gain smoothing, method: TDL_EXPONENTIAL */
324 /* first order IIR filter with attack correction to avoid overshoots */
325
326 /* correct the 'aiming' value of the exponential attack to avoid the remaining overshoot */
327 if (gain < smoothState0) {
328 cor = fMin(cor, fMultDiv2((gain - fMultDiv2(FL2FXCONST_SGL(0.1f*(1<<1)),smoothState0)), FL2FXCONST_SGL(1.11111111f/(1<<1)))<<2);
329 }
330 else {
331 cor = gain;
332 }
333
334 /* smoothing filter */
335 if (cor < smoothState0) {
336 smoothState0 = fMult(attackConst,(smoothState0 - cor)) + cor; /* attack */
337 smoothState0 = fMax(smoothState0, gain); /* avoid overshooting target */
338 }
339 else {
340 /* sign inversion twice to round towards +infinity,
341 so that gain can converge to 1.0 again,
342 for bit-identical output when limiter is not active */
343 smoothState0 = -fMult(releaseConst,-(smoothState0 - cor)) + cor; /* release */
344 }
345
346 gain = smoothState0;
347
348 /* lookahead delay, apply gain */
349 for (j = 0; j < channels; j++) {
350
351 tmp = delayBuf[delayBufIdx * channels + j];
352 delayBuf[delayBufIdx * channels + j] = fMult((FIXP_PCM)samples[i * channels + j], additionalGain);
353
354 /* Apply gain to delayed signal */
355 if (gain < FL2FXCONST_DBL(1.0f/(1<<1)))
356 tmp = fMult(tmp,gain<<1);
357
358 samples[i * channels + j] = FX_DBL2FX_PCM((FIXP_DBL)SATURATE_LEFT_SHIFT(tmp,TDL_GAIN_SCALING,DFRACT_BITS));
359 }
360 delayBufIdx++;
361 if (delayBufIdx >= attack) delayBufIdx = 0;
362
363 /* save minimum gain factor */
364 if (gain < minGain) minGain = gain;
365 }
366
367
368 limiter->max = max;
369 limiter->maxBufIdx = maxBufIdx;
370 limiter->cor = cor;
371 limiter->delayBufIdx = delayBufIdx;
372
373 limiter->smoothState0 = smoothState0;
374 limiter->additionalGainFilterState = additionalGainSmoothState;
375 limiter->additionalGainFilterState1 = additionalGainSmoothState1;
376
377 limiter->minGain = minGain;
378
379 limiter->additionalGainPrev = pGain[0];
380
381 return TDLIMIT_OK;
382 }
383 }
384
385 /* get delay in samples */
getLimiterDelay(TDLimiterPtr limiter)386 unsigned int getLimiterDelay(TDLimiterPtr limiter)
387 {
388 FDK_ASSERT(limiter != NULL);
389 return limiter->attack;
390 }
391
392 /* set number of channels */
setLimiterNChannels(TDLimiterPtr limiter,unsigned int nChannels)393 TDLIMITER_ERROR setLimiterNChannels(TDLimiterPtr limiter, unsigned int nChannels)
394 {
395 if ( limiter == NULL ) return TDLIMIT_INVALID_HANDLE;
396
397 if (nChannels > limiter->maxChannels) return TDLIMIT_INVALID_PARAMETER;
398
399 limiter->channels = nChannels;
400 //resetLimiter(limiter);
401
402 return TDLIMIT_OK;
403 }
404
405 /* set sampling rate */
setLimiterSampleRate(TDLimiterPtr limiter,unsigned int sampleRate)406 TDLIMITER_ERROR setLimiterSampleRate(TDLimiterPtr limiter, unsigned int sampleRate)
407 {
408 unsigned int attack, release;
409 FIXP_DBL attackConst, releaseConst, exponent;
410 INT e_ans;
411
412 if ( limiter == NULL ) return TDLIMIT_INVALID_HANDLE;
413
414 if (sampleRate > limiter->maxSampleRate) return TDLIMIT_INVALID_PARAMETER;
415
416 /* update attack and release time in samples */
417 attack = (unsigned int)(limiter->attackMs * sampleRate / 1000);
418 release = (unsigned int)(limiter->releaseMs * sampleRate / 1000);
419
420 /* attackConst = pow(0.1, 1.0 / (attack + 1)) */
421 exponent = invFixp(attack+1);
422 attackConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);
423 attackConst = scaleValue(attackConst, e_ans);
424
425 /* releaseConst = (float)pow(0.1, 1.0 / (release + 1)) */
426 exponent = invFixp(release + 1);
427 releaseConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);
428 releaseConst = scaleValue(releaseConst, e_ans);
429
430 limiter->attack = attack;
431 limiter->attackConst = attackConst;
432 limiter->releaseConst = releaseConst;
433 limiter->sampleRate = sampleRate;
434
435 /* reset */
436 //resetLimiter(limiter);
437
438 return TDLIMIT_OK;
439 }
440
441 /* set attack time */
setLimiterAttack(TDLimiterPtr limiter,unsigned int attackMs)442 TDLIMITER_ERROR setLimiterAttack(TDLimiterPtr limiter, unsigned int attackMs)
443 {
444 unsigned int attack;
445 FIXP_DBL attackConst, exponent;
446 INT e_ans;
447
448 if ( limiter == NULL ) return TDLIMIT_INVALID_HANDLE;
449
450 if (attackMs > limiter->maxAttackMs) return TDLIMIT_INVALID_PARAMETER;
451
452 /* calculate attack time in samples */
453 attack = (unsigned int)(attackMs * limiter->sampleRate / 1000);
454
455 /* attackConst = pow(0.1, 1.0 / (attack + 1)) */
456 exponent = invFixp(attack+1);
457 attackConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);
458 attackConst = scaleValue(attackConst, e_ans);
459
460 limiter->attack = attack;
461 limiter->attackConst = attackConst;
462 limiter->attackMs = attackMs;
463
464 return TDLIMIT_OK;
465 }
466
467 /* set release time */
setLimiterRelease(TDLimiterPtr limiter,unsigned int releaseMs)468 TDLIMITER_ERROR setLimiterRelease(TDLimiterPtr limiter, unsigned int releaseMs)
469 {
470 unsigned int release;
471 FIXP_DBL releaseConst, exponent;
472 INT e_ans;
473
474 if ( limiter == NULL ) return TDLIMIT_INVALID_HANDLE;
475
476 /* calculate release time in samples */
477 release = (unsigned int)(releaseMs * limiter->sampleRate / 1000);
478
479 /* releaseConst = (float)pow(0.1, 1.0 / (release + 1)) */
480 exponent = invFixp(release + 1);
481 releaseConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);
482 releaseConst = scaleValue(releaseConst, e_ans);
483
484 limiter->releaseConst = releaseConst;
485 limiter->releaseMs = releaseMs;
486
487 return TDLIMIT_OK;
488 }
489
490 /* set limiter threshold */
setLimiterThreshold(TDLimiterPtr limiter,INT_PCM threshold)491 TDLIMITER_ERROR setLimiterThreshold(TDLimiterPtr limiter, INT_PCM threshold)
492 {
493 if ( limiter == NULL ) return TDLIMIT_INVALID_HANDLE;
494
495 limiter->threshold = (FIXP_PCM)threshold;
496
497 return TDLIMIT_OK;
498 }
499