1 2 /* ----------------------------------------------------------------------------------------------------------- 3 Software License for The Fraunhofer FDK AAC Codec Library for Android 4 5 Copyright 1995 - 2013 Fraunhofer-Gesellschaft zur Frderung 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 (at) 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 */ 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 */ 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 */ 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 */ 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 */ 386 unsigned int getLimiterDelay(TDLimiterPtr limiter) 387 { 388 FDK_ASSERT(limiter != NULL); 389 return limiter->attack; 390 } 391 392 /* set number of channels */ 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 */ 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 */ 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 */ 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 */ 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
