/* -----------------------------------------------------------------------------

Software License for The Fraunhofer FDK AAC Codec Library for Android

© Copyright  1995 - 2020 Fraunhofer-Gesellschaft zur Förderung der angewandten

Forschung e.V. All rights reserved.

 1.    INTRODUCTION

The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software

that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding

scheme for digital audio. This FDK AAC Codec software is intended to be used on

a wide variety of Android devices.

AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient

general perceptual audio codecs. AAC-ELD is considered the best-performing

full-bandwidth communications codec by independent studies and is widely

deployed. AAC has been standardized by ISO and IEC as part of the MPEG

specifications.

Patent licenses for necessary patent claims for the FDK AAC Codec (including

those of Fraunhofer) may be obtained through Via Licensing

(www.vialicensing.com) or through the respective patent owners individually for

the purpose of encoding or decoding bit streams in products that are compliant

with the ISO/IEC MPEG audio standards. Please note that most manufacturers of

Android devices already license these patent claims through Via Licensing or

directly from the patent owners, and therefore FDK AAC Codec software may

already be covered under those patent licenses when it is used for those

licensed purposes only.

Commercially-licensed AAC software libraries, including floating-point versions

with enhanced sound quality, are also available from Fraunhofer. Users are

encouraged to check the Fraunhofer website for additional applications

information and documentation.

2.    COPYRIGHT LICENSE

Redistribution and use in source and binary forms, with or without modification,

are permitted without payment of copyright license fees provided that you

satisfy the following conditions:

You must retain the complete text of this software license in redistributions of

the FDK AAC Codec or your modifications thereto in source code form.

You must retain the complete text of this software license in the documentation

and/or other materials provided with redistributions of the FDK AAC Codec or

your modifications thereto in binary form. You must make available free of

charge copies of the complete source code of the FDK AAC Codec and your

modifications thereto to recipients of copies in binary form.

The name of Fraunhofer may not be used to endorse or promote products derived

from this library without prior written permission.

You may not charge copyright license fees for anyone to use, copy or distribute

the FDK AAC Codec software or your modifications thereto.

Your modified versions of the FDK AAC Codec must carry prominent notices stating

that you changed the software and the date of any change. For modified versions

of the FDK AAC Codec, the term "Fraunhofer FDK AAC Codec Library for Android"

must be replaced by the term "Third-Party Modified Version of the Fraunhofer FDK

AAC Codec Library for Android."

3.    NO PATENT LICENSE

NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without

limitation the patents of Fraunhofer, ARE GRANTED BY THIS SOFTWARE LICENSE.

Fraunhofer provides no warranty of patent non-infringement with respect to this

software.

You may use this FDK AAC Codec software or modifications thereto only for

purposes that are authorized by appropriate patent licenses.

4.    DISCLAIMER

This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright

holders and contributors "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES,

including but not limited to the implied warranties of merchantability and

fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR

CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary,

or consequential damages, including but not limited to procurement of substitute

goods or services; loss of use, data, or profits, or business interruption,

however caused and on any theory of liability, whether in contract, strict

liability, or tort (including negligence), arising in any way out of the use of

this software, even if advised of the possibility of such damage.

5.    CONTACT INFORMATION

Fraunhofer Institute for Integrated Circuits IIS

Attention: Audio and Multimedia Departments - FDK AAC LL

Am Wolfsmantel 33

91058 Erlangen, Germany

www.iis.fraunhofer.de/amm

amm-info@iis.fraunhofer.de

----------------------------------------------------------------------------- */

/**************************** PCM utility library ******************************

   Author(s):   Matthias Neusinger

   Description: Hard limiter for clipping prevention

*******************************************************************************/

#include "limiter.h"

#include "FDK_core.h"

/* library version */

#include "version.h"

/* library title */

#define TDLIMIT_LIB_TITLE "TD Limiter Lib"

/* create limiter */

TDLimiterPtr pcmLimiter_Create(unsigned int maxAttackMs, unsigned int releaseMs,

                               FIXP_DBL threshold, unsigned int maxChannels,

                               UINT maxSampleRate) {

  TDLimiterPtr limiter = NULL;

  unsigned int attack, release;

  FIXP_DBL attackConst, releaseConst, exponent;

  INT e_ans;

  /* calc attack and release time in samples */

  attack = (unsigned int)(maxAttackMs * maxSampleRate / 1000);

  release = (unsigned int)(releaseMs * maxSampleRate / 1000);

  /* alloc limiter struct */

  limiter = (TDLimiterPtr)FDKcalloc(1, sizeof(struct TDLimiter));

  if (!limiter) return NULL;

  /* alloc max and delay buffers */

  limiter->maxBuf = (FIXP_DBL*)FDKcalloc(attack + 1, sizeof(FIXP_DBL));

  limiter->delayBuf =

      (FIXP_DBL*)FDKcalloc(attack * maxChannels, sizeof(FIXP_DBL));

  if (!limiter->maxBuf || !limiter->delayBuf) {

    pcmLimiter_Destroy(limiter);

    return NULL;

  }

  /* attackConst = pow(0.1, 1.0 / (attack + 1)) */

  exponent = invFixp(attack + 1);

  attackConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);

  attackConst = scaleValue(attackConst, e_ans);

  /* releaseConst  = (float)pow(0.1, 1.0 / (release + 1)) */

  exponent = invFixp(release + 1);

  releaseConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);

  releaseConst = scaleValue(releaseConst, e_ans);

  /* init parameters */

  limiter->attackMs = maxAttackMs;

  limiter->maxAttackMs = maxAttackMs;

  limiter->releaseMs = releaseMs;

  limiter->attack = attack;

  limiter->attackConst = attackConst;

  limiter->releaseConst = releaseConst;

  limiter->threshold = threshold;

  limiter->channels = maxChannels;

  limiter->maxChannels = maxChannels;

  limiter->sampleRate = maxSampleRate;

  limiter->maxSampleRate = maxSampleRate;

  pcmLimiter_Reset(limiter);

  return limiter;

}

/* apply limiter */

TDLIMITER_ERROR pcmLimiter_Apply(TDLimiterPtr limiter, PCM_LIM* samplesIn,

                                 INT_PCM* samplesOut, FIXP_DBL* pGainPerSample,

                                 const INT scaling, const UINT nSamples) {

  unsigned int i, j;

  FIXP_DBL tmp2;

  FIXP_DBL tmp, old, gain, additionalGain = 0;

  FIXP_DBL minGain = FL2FXCONST_DBL(1.0f / (1 << 1));

  UINT additionalGainAvailable = 1;

  if (limiter == NULL) return TDLIMIT_INVALID_HANDLE;

  {

    unsigned int channels = limiter->channels;

    unsigned int attack = limiter->attack;

    FIXP_DBL attackConst = limiter->attackConst;

    FIXP_DBL releaseConst = limiter->releaseConst;

    FIXP_DBL threshold = limiter->threshold >> scaling;

    FIXP_DBL max = limiter->max;

    FIXP_DBL* maxBuf = limiter->maxBuf;

    unsigned int maxBufIdx = limiter->maxBufIdx;

    FIXP_DBL cor = limiter->cor;

    FIXP_DBL* delayBuf = limiter->delayBuf;

    unsigned int delayBufIdx = limiter->delayBufIdx;

    FIXP_DBL smoothState0 = limiter->smoothState0;

    if (limiter->scaling != scaling) {

      scaleValuesSaturate(delayBuf, attack * channels,

                          limiter->scaling - scaling);

      scaleValuesSaturate(maxBuf, attack + 1, limiter->scaling - scaling);

      max = scaleValueSaturate(max, limiter->scaling - scaling);

      limiter->scaling = scaling;

    }

    if (pGainPerSample == NULL) {

      additionalGainAvailable = 0;

    }

    for (i = 0; i < nSamples; i++) {

      /* get maximum absolute sample value of all channels, including the

       * additional gain. */

      tmp = (FIXP_DBL)0;

      for (j = 0; j < channels; j++) {

        tmp2 = PCM_LIM2FIXP_DBL(samplesIn[j]);

        tmp2 =

            (tmp2 == (FIXP_DBL)MINVAL_DBL) ? (FIXP_DBL)MAXVAL_DBL : fAbs(tmp2);

        tmp = fMax(tmp, tmp2);

      }

      if (additionalGainAvailable) {

        additionalGain = pGainPerSample[i];

        tmp = fMult(tmp, additionalGain);

      }

      /* set threshold as lower border to save calculations in running maximum

       * algorithm */

      tmp = fMax(tmp, threshold);

      /* running maximum */

      old = maxBuf[maxBufIdx];

      maxBuf[maxBufIdx] = tmp;

      if (tmp >= max) {

        /* new sample is greater than old maximum, so it is the new maximum */

        max = tmp;

      } else if (old < max) {

        /* maximum does not change, as the sample, which has left the window was

           not the maximum */

      } else {

        /* the old maximum has left the window, we have to search the complete

           buffer for the new max */

        max = maxBuf[0];

        for (j = 1; j <= attack; j++) {

          max = fMax(max, maxBuf[j]);

        }

      }

      maxBufIdx++;

      if (maxBufIdx >= attack + 1) maxBufIdx = 0;

      /* calc gain */

      /* gain is downscaled by one, so that gain = 1.0 can be represented */

      if (max > threshold) {

        gain = fDivNorm(threshold, max) >> 1;

      } else {

        gain = FL2FXCONST_DBL(1.0f / (1 << 1));

      }

      /* gain smoothing, method: TDL_EXPONENTIAL */

      /* first order IIR filter with attack correction to avoid overshoots */

      /* correct the 'aiming' value of the exponential attack to avoid the

       * remaining overshoot */

      if (gain < smoothState0) {

        cor = fMin(cor,

                   fMultDiv2((gain - fMultDiv2(FL2FXCONST_SGL(0.1f * (1 << 1)),

                                               smoothState0)),

                             FL2FXCONST_SGL(1.11111111f / (1 << 1)))

                       << 2);

      } else {

        cor = gain;

      }

      /* smoothing filter */

      if (cor < smoothState0) {

        smoothState0 =

            fMult(attackConst, (smoothState0 - cor)) + cor; /* attack */

        smoothState0 = fMax(smoothState0, gain); /* avoid overshooting target */

      } else {

        /* sign inversion twice to round towards +infinity,

           so that gain can converge to 1.0 again,

           for bit-identical output when limiter is not active */

        smoothState0 =

            -fMult(releaseConst, -(smoothState0 - cor)) + cor; /* release */

      }

      gain = smoothState0;

      FIXP_DBL* p_delayBuf = &delayBuf[delayBufIdx * channels + 0];

      if (gain < FL2FXCONST_DBL(1.0f / (1 << 1))) {

        gain <<= 1;

        /* lookahead delay, apply gain */

        for (j = 0; j < channels; j++) {

          tmp = p_delayBuf[j];

          if (additionalGainAvailable) {

            p_delayBuf[j] = fMult((FIXP_PCM_LIM)samplesIn[j], additionalGain);

          } else {

            p_delayBuf[j] = PCM_LIM2FIXP_DBL(samplesIn[j]);

          }

          /* Apply gain to delayed signal */

          tmp = fMultDiv2(tmp, gain);

#if (SAMPLE_BITS == DFRACT_BITS)

          samplesOut[j] = (INT_PCM)FX_DBL2FX_PCM(

              (FIXP_DBL)SATURATE_LEFT_SHIFT(tmp, scaling + 1, DFRACT_BITS));

#else

          samplesOut[j] = (INT_PCM)FX_DBL2FX_PCM((FIXP_DBL)SATURATE_LEFT_SHIFT(

              tmp + ((FIXP_DBL)0x8000 >> (scaling + 1)), scaling + 1,

              DFRACT_BITS));

#endif

        }

        gain >>= 1;

      } else {

        /* lookahead delay, apply gain=1.0f */

        for (j = 0; j < channels; j++) {

          tmp = p_delayBuf[j];

          if (additionalGainAvailable) {

            p_delayBuf[j] = fMult((FIXP_PCM_LIM)samplesIn[j], additionalGain);

          } else {

            p_delayBuf[j] = PCM_LIM2FIXP_DBL(samplesIn[j]);

          }

#if (SAMPLE_BITS == DFRACT_BITS)

          samplesOut[j] = (INT_PCM)FX_DBL2FX_PCM(

              (FIXP_DBL)SATURATE_LEFT_SHIFT(tmp, scaling, DFRACT_BITS));

#else

          samplesOut[j] = (INT_PCM)FX_DBL2FX_PCM((FIXP_DBL)SATURATE_LEFT_SHIFT(

              (tmp >> 1) + ((FIXP_DBL)0x8000 >> (scaling + 1)), scaling + 1,

              DFRACT_BITS));

#endif

        }

      }

      delayBufIdx++;

      if (delayBufIdx >= attack) {

        delayBufIdx = 0;

      }

      /* save minimum gain factor */

      if (gain < minGain) {

        minGain = gain;

      }

      /* advance sample pointer by <channel> samples */

      samplesIn += channels;

      samplesOut += channels;

    }

    limiter->max = max;

    limiter->maxBufIdx = maxBufIdx;

    limiter->cor = cor;

    limiter->delayBufIdx = delayBufIdx;

    limiter->smoothState0 = smoothState0;

    limiter->minGain = minGain;

    return TDLIMIT_OK;

  }

}

/* set limiter threshold */

TDLIMITER_ERROR pcmLimiter_SetThreshold(TDLimiterPtr limiter,

                                        FIXP_DBL threshold) {

  if (limiter == NULL) return TDLIMIT_INVALID_HANDLE;

  limiter->threshold = threshold;

  return TDLIMIT_OK;

}

/* reset limiter */

TDLIMITER_ERROR pcmLimiter_Reset(TDLimiterPtr limiter) {

  if (limiter != NULL) {

    limiter->maxBufIdx = 0;

    limiter->delayBufIdx = 0;

    limiter->max = (FIXP_DBL)0;

    limiter->cor = FL2FXCONST_DBL(1.0f / (1 << 1));

    limiter->smoothState0 = FL2FXCONST_DBL(1.0f / (1 << 1));

    limiter->minGain = FL2FXCONST_DBL(1.0f / (1 << 1));

    limiter->scaling = 0;

    FDKmemset(limiter->maxBuf, 0, (limiter->attack + 1) * sizeof(FIXP_DBL));

    FDKmemset(limiter->delayBuf, 0,

              limiter->attack * limiter->channels * sizeof(FIXP_DBL));

  } else {

    return TDLIMIT_INVALID_HANDLE;

  }

  return TDLIMIT_OK;

}

/* destroy limiter */

TDLIMITER_ERROR pcmLimiter_Destroy(TDLimiterPtr limiter) {

  if (limiter != NULL) {

    FDKfree(limiter->maxBuf);

    FDKfree(limiter->delayBuf);

    FDKfree(limiter);

  } else {

    return TDLIMIT_INVALID_HANDLE;

  }

  return TDLIMIT_OK;

}

/* get delay in samples */

unsigned int pcmLimiter_GetDelay(TDLimiterPtr limiter) {

  FDK_ASSERT(limiter != NULL);

  return limiter->attack;

}

/* get maximum gain reduction of last processed block */

INT pcmLimiter_GetMaxGainReduction(TDLimiterPtr limiter) {

  /* maximum gain reduction in dB = -20 * log10(limiter->minGain)

     = -20 * log2(limiter->minGain)/log2(10) = -6.0206*log2(limiter->minGain) */

  int e_ans;

  FIXP_DBL loggain, maxGainReduction;

  FDK_ASSERT(limiter != NULL);

  loggain = fLog2(limiter->minGain, 1, &e_ans);

  maxGainReduction = fMult(loggain, FL2FXCONST_DBL(-6.0206f / (1 << 3)));

  return fixp_roundToInt(maxGainReduction, (e_ans + 3));

}

/* set number of channels */

TDLIMITER_ERROR pcmLimiter_SetNChannels(TDLimiterPtr limiter,

                                        unsigned int nChannels) {

  if (limiter == NULL) return TDLIMIT_INVALID_HANDLE;

  if (nChannels > limiter->maxChannels) return TDLIMIT_INVALID_PARAMETER;

  limiter->channels = nChannels;

  // pcmLimiter_Reset(limiter);

  return TDLIMIT_OK;

}

/* set sampling rate */

TDLIMITER_ERROR pcmLimiter_SetSampleRate(TDLimiterPtr limiter,

                                         UINT sampleRate) {

  unsigned int attack, release;

  FIXP_DBL attackConst, releaseConst, exponent;

  INT e_ans;

  if (limiter == NULL) return TDLIMIT_INVALID_HANDLE;

  if (sampleRate > limiter->maxSampleRate) return TDLIMIT_INVALID_PARAMETER;

  /* update attack and release time in samples */

  attack = (unsigned int)(limiter->attackMs * sampleRate / 1000);

  release = (unsigned int)(limiter->releaseMs * sampleRate / 1000);

  /* attackConst = pow(0.1, 1.0 / (attack + 1)) */

  exponent = invFixp(attack + 1);

  attackConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);

  attackConst = scaleValue(attackConst, e_ans);

  /* releaseConst  = (float)pow(0.1, 1.0 / (release + 1)) */

  exponent = invFixp(release + 1);

  releaseConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);

  releaseConst = scaleValue(releaseConst, e_ans);

  limiter->attack = attack;

  limiter->attackConst = attackConst;

  limiter->releaseConst = releaseConst;

  limiter->sampleRate = sampleRate;

  /* reset */

  // pcmLimiter_Reset(limiter);

  return TDLIMIT_OK;

}

/* set attack time */

TDLIMITER_ERROR pcmLimiter_SetAttack(TDLimiterPtr limiter,

                                     unsigned int attackMs) {

  unsigned int attack;

  FIXP_DBL attackConst, exponent;

  INT e_ans;

  if (limiter == NULL) return TDLIMIT_INVALID_HANDLE;

  if (attackMs > limiter->maxAttackMs) return TDLIMIT_INVALID_PARAMETER;

  /* calculate attack time in samples */

  attack = (unsigned int)(attackMs * limiter->sampleRate / 1000);

  /* attackConst = pow(0.1, 1.0 / (attack + 1)) */

  exponent = invFixp(attack + 1);

  attackConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);

  attackConst = scaleValue(attackConst, e_ans);

  limiter->attack = attack;

  limiter->attackConst = attackConst;

  limiter->attackMs = attackMs;

  return TDLIMIT_OK;

}

/* set release time */

TDLIMITER_ERROR pcmLimiter_SetRelease(TDLimiterPtr limiter,

                                      unsigned int releaseMs) {

  unsigned int release;

  FIXP_DBL releaseConst, exponent;

  INT e_ans;

  if (limiter == NULL) return TDLIMIT_INVALID_HANDLE;

  /* calculate  release time in samples */

  release = (unsigned int)(releaseMs * limiter->sampleRate / 1000);

  /* releaseConst  = (float)pow(0.1, 1.0 / (release + 1)) */

  exponent = invFixp(release + 1);

  releaseConst = fPow(FL2FXCONST_DBL(0.1f), 0, exponent, 0, &e_ans);

  releaseConst = scaleValue(releaseConst, e_ans);

  limiter->releaseConst = releaseConst;

  limiter->releaseMs = releaseMs;

  return TDLIMIT_OK;

}

/* Get library info for this module. */

TDLIMITER_ERROR pcmLimiter_GetLibInfo(LIB_INFO* info) {

  int i;

  if (info == NULL) {

    return TDLIMIT_INVALID_PARAMETER;

  }

  /* Search for next free tab */

  for (i = 0; i < FDK_MODULE_LAST; i++) {

    if (info[i].module_id == FDK_NONE) break;

  }

  if (i == FDK_MODULE_LAST) {

    return TDLIMIT_UNKNOWN;

  }

  /* Add the library info */

  info[i].module_id = FDK_TDLIMIT;

  info[i].version =

      LIB_VERSION(PCMUTIL_LIB_VL0, PCMUTIL_LIB_VL1, PCMUTIL_LIB_VL2);

  LIB_VERSION_STRING(info + i);

  info[i].build_date = PCMUTIL_LIB_BUILD_DATE;

  info[i].build_time = PCMUTIL_LIB_BUILD_TIME;

  info[i].title = TDLIMIT_LIB_TITLE;

  /* Set flags */

  info[i].flags = CAPF_LIMITER;

  /* Add lib info for FDK tools (if not yet done). */

  FDK_toolsGetLibInfo(info);

  return TDLIMIT_OK;

}