fdk-aac/libAACenc/src/chaosmeasure.cpp

/* -----------------------------------------------------------------------------
Software License for The Fraunhofer FDK AAC Codec Library for Android

© Copyright  1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
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 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
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already be covered under those patent licenses when it is used for those
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Commercially-licensed AAC software libraries, including floating-point versions
with enhanced sound quality, are also available from Fraunhofer. Users are
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2.    COPYRIGHT LICENSE

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

/**************************** AAC encoder library ******************************

   Author(s):   M. Werner

   Description: Chaos measure calculation

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

#include "chaosmeasure.h"

/*****************************************************************************
    functionname: FDKaacEnc_FDKaacEnc_CalculateChaosMeasurePeakFast
    description:  Eberlein method of chaos measure calculation by high-pass
                  filtering amplitude spectrum
                  A special case of FDKaacEnc_CalculateChaosMeasureTonalGeneric
-- highly optimized
*****************************************************************************/
static void FDKaacEnc_FDKaacEnc_CalculateChaosMeasurePeakFast(
    FIXP_DBL *RESTRICT paMDCTDataNM0, INT numberOfLines,
    FIXP_DBL *RESTRICT chaosMeasure) {
  INT i, j;

  /* calculate chaos measure by "peak filter" */
  /* make even and odd pass through data */
  FIXP_DBL left_0_div2,
      center_0; /* left, center tap of filter, even numbered */
  FIXP_DBL left_1_div2, center_1; /* left, center tap of filter, odd numbered */

  left_0_div2 = (FIXP_DBL)(((LONG)paMDCTDataNM0[0] ^
                            ((LONG)paMDCTDataNM0[0] >> (DFRACT_BITS - 1))) >>
                           1);
  left_1_div2 = (FIXP_DBL)(((LONG)paMDCTDataNM0[1] ^
                            ((LONG)paMDCTDataNM0[1] >> (DFRACT_BITS - 1))) >>
                           1);
  center_0 = (FIXP_DBL)((LONG)paMDCTDataNM0[2] ^
                        ((LONG)paMDCTDataNM0[2] >> (DFRACT_BITS - 1)));
  center_1 = (FIXP_DBL)((LONG)paMDCTDataNM0[3] ^
                        ((LONG)paMDCTDataNM0[3] >> (DFRACT_BITS - 1)));

  for (j = 2; j < numberOfLines - 2; j += 2) {
    FIXP_DBL right_0 =
        (FIXP_DBL)((LONG)paMDCTDataNM0[j + 2] ^
                   ((LONG)paMDCTDataNM0[j + 2] >> (DFRACT_BITS - 1)));
    FIXP_DBL tmp_0 = left_0_div2 + (right_0 >> 1);
    FIXP_DBL right_1 =
        (FIXP_DBL)((LONG)paMDCTDataNM0[j + 3] ^
                   ((LONG)paMDCTDataNM0[j + 3] >> (DFRACT_BITS - 1)));
    FIXP_DBL tmp_1 = left_1_div2 + (right_1 >> 1);

    if (tmp_0 < center_0) {
      INT leadingBits = CntLeadingZeros(center_0) - 1;
      tmp_0 = schur_div(tmp_0 << leadingBits, center_0 << leadingBits, 8);
      tmp_0 = fMult(tmp_0, tmp_0);
    } else {
      tmp_0 = (FIXP_DBL)MAXVAL_DBL;
    }
    chaosMeasure[j + 0] = tmp_0;
    left_0_div2 = center_0 >> 1;
    center_0 = right_0;

    if (tmp_1 < center_1) {
      INT leadingBits = CntLeadingZeros(center_1) - 1;
      tmp_1 = schur_div(tmp_1 << leadingBits, center_1 << leadingBits, 8);
      tmp_1 = fMult(tmp_1, tmp_1);
    } else {
      tmp_1 = (FIXP_DBL)MAXVAL_DBL;
    }

    left_1_div2 = center_1 >> 1;
    center_1 = right_1;
    chaosMeasure[j + 1] = tmp_1;
  }

  /* provide chaos measure for first few lines */
  chaosMeasure[0] = chaosMeasure[2];
  chaosMeasure[1] = chaosMeasure[2];

  /* provide chaos measure for last few lines */
  for (i = (numberOfLines - 3); i < numberOfLines; i++)
    chaosMeasure[i] = FL2FXCONST_DBL(0.5);
}

/*****************************************************************************
    functionname: FDKaacEnc_CalculateChaosMeasure
    description:  calculates a chaosmeasure for every line, different methods
                  are available. 0 means tonal, 1 means noiselike
    returns:
    input:        MDCT data, number of lines
    output:       chaosMeasure
*****************************************************************************/
void FDKaacEnc_CalculateChaosMeasure(FIXP_DBL *paMDCTDataNM0, INT numberOfLines,
                                     FIXP_DBL *chaosMeasure)

{
  FDKaacEnc_FDKaacEnc_CalculateChaosMeasurePeakFast(
      paMDCTDataNM0, numberOfLines, chaosMeasure);
}