xref: /aosp_15_r20/external/aac/libAACenc/src/transform.cpp (revision e54365361535b070c2db7374cec45c159c7d0e7a)

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

© Copyright  1995 - 2018 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
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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
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Attention: Audio and Multimedia Departments - FDK AAC LL
Am Wolfsmantel 33
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www.iis.fraunhofer.de/amm
[email protected]
----------------------------------------------------------------------------- */

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

   Author(s):   Tobias Chalupka

   Description: FDKaacLdEnc_MdctTransform480:
                The module FDKaacLdEnc_MdctTransform will perform the MDCT.
                The MDCT supports the sine window and
                the zero padded window. The algorithm of the MDCT
                can be divided in  Windowing, PreModulation, Fft and
                PostModulation.

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

#include "transform.h"
#include "dct.h"
#include "psy_const.h"
#include "aacEnc_rom.h"
#include "FDK_tools_rom.h"

#if defined(__arm__)
#endif

INT FDKaacEnc_Transform_Real(const INT_PCM *pTimeData,
                             FIXP_DBL *RESTRICT mdctData, const INT blockType,
                             const INT windowShape, INT *prevWindowShape,
                             H_MDCT mdctPers, const INT frameLength,
                             INT *pMdctData_e, INT filterType) {
  const INT_PCM *RESTRICT timeData;

  UINT numSpec;
  UINT numMdctLines;
  UINT offset;
  int fr; /* fr: right window slope length */
  SHORT mdctData_e[8];

  timeData = pTimeData;

  if (blockType == SHORT_WINDOW) {
    numSpec = 8;
    numMdctLines = frameLength >> 3;
  } else {
    numSpec = 1;
    numMdctLines = frameLength;
  }

  offset = (windowShape == LOL_WINDOW) ? ((frameLength * 3) >> 2) : 0;
  switch (blockType) {
    case LONG_WINDOW:
    case STOP_WINDOW:
      fr = frameLength - offset;
      break;
    case START_WINDOW: /* or StopStartSequence */
    case SHORT_WINDOW:
      fr = frameLength >> 3;
      break;
    default:
      FDK_ASSERT(0);
      return -1;
  }

  mdct_block(mdctPers, timeData, frameLength, mdctData, numSpec, numMdctLines,
             FDKgetWindowSlope(fr, windowShape), fr, mdctData_e);

  if (blockType == SHORT_WINDOW) {
    if (!(mdctData_e[0] == mdctData_e[1] && mdctData_e[1] == mdctData_e[2] &&
          mdctData_e[2] == mdctData_e[3] && mdctData_e[3] == mdctData_e[4] &&
          mdctData_e[4] == mdctData_e[5] && mdctData_e[5] == mdctData_e[6] &&
          mdctData_e[6] == mdctData_e[7])) {
      return -1;
    }
  }
  *prevWindowShape = windowShape;
  *pMdctData_e = mdctData_e[0];

  return 0;
}

INT FDKaacEnc_Transform_Real_Eld(const INT_PCM *pTimeData,
                                 FIXP_DBL *RESTRICT mdctData,
                                 const INT blockType, const INT windowShape,
                                 INT *prevWindowShape, const INT frameLength,
                                 INT *mdctData_e, INT filterType,
                                 FIXP_DBL *RESTRICT overlapAddBuffer) {
  const INT_PCM *RESTRICT timeData;

  INT i;

  /* tl: transform length
     fl: left window slope length
     nl: left window slope offset
     fr: right window slope length
     nr: right window slope offset */
  const FIXP_WTB *pWindowELD = NULL;
  int N = frameLength;
  int L = frameLength;

  timeData = pTimeData;

  if (blockType != LONG_WINDOW) {
    return -1;
  }

  /*
   * MDCT scale:
   * + 1: fMultDiv2() in windowing.
   * + 1: Because of factor 1/2 in Princen-Bradley compliant windowed TDAC.
   */
  *mdctData_e = 1 + 1;

  switch (frameLength) {
    case 512:
      pWindowELD = ELDAnalysis512;
      break;
    case 480:
      pWindowELD = ELDAnalysis480;
      break;
    case 256:
      pWindowELD = ELDAnalysis256;
      *mdctData_e += 1;
      break;
    case 240:
      pWindowELD = ELDAnalysis240;
      *mdctData_e += 1;
      break;
    case 128:
      pWindowELD = ELDAnalysis128;
      *mdctData_e += 2;
      break;
    case 120:
      pWindowELD = ELDAnalysis120;
      *mdctData_e += 2;
      break;
    default:
      FDK_ASSERT(0);
      return -1;
  }

  for (i = 0; i < N / 4; i++) {
    FIXP_DBL z0, outval;

    z0 = (fMult((FIXP_PCM)timeData[L + N * 3 / 4 - 1 - i],
                pWindowELD[N / 2 - 1 - i])
          << (WTS0 - 1)) +
         (fMult((FIXP_PCM)timeData[L + N * 3 / 4 + i], pWindowELD[N / 2 + i])
          << (WTS0 - 1));

    outval = (fMultDiv2((FIXP_PCM)timeData[L + N * 3 / 4 - 1 - i],
                        pWindowELD[N + N / 2 - 1 - i]) >>
              (-WTS1));
    outval += (fMultDiv2((FIXP_PCM)timeData[L + N * 3 / 4 + i],
                         pWindowELD[N + N / 2 + i]) >>
               (-WTS1));
    outval += (fMultDiv2(overlapAddBuffer[N / 2 + i], pWindowELD[2 * N + i]) >>
               (-WTS2 - 1));

    overlapAddBuffer[N / 2 + i] = overlapAddBuffer[i];

    overlapAddBuffer[i] = z0;
    mdctData[i] = overlapAddBuffer[N / 2 + i] +
                  (fMultDiv2(overlapAddBuffer[N + N / 2 - 1 - i],
                             pWindowELD[2 * N + N / 2 + i]) >>
                   (-WTS2 - 1));

    mdctData[N - 1 - i] = outval;
    overlapAddBuffer[N + N / 2 - 1 - i] = outval;
  }

  for (i = N / 4; i < N / 2; i++) {
    FIXP_DBL z0, outval;

    z0 = fMult((FIXP_PCM)timeData[L + N * 3 / 4 - 1 - i],
               pWindowELD[N / 2 - 1 - i])
         << (WTS0 - 1);

    outval = (fMultDiv2((FIXP_PCM)timeData[L + N * 3 / 4 - 1 - i],
                        pWindowELD[N + N / 2 - 1 - i]) >>
              (-WTS1));
    outval += (fMultDiv2(overlapAddBuffer[N / 2 + i], pWindowELD[2 * N + i]) >>
               (-WTS2 - 1));

    overlapAddBuffer[N / 2 + i] =
        overlapAddBuffer[i] +
        (fMult((FIXP_PCM)timeData[L - N / 4 + i], pWindowELD[N / 2 + i])
         << (WTS0 - 1));

    overlapAddBuffer[i] = z0;
    mdctData[i] = overlapAddBuffer[N / 2 + i] +
                  (fMultDiv2(overlapAddBuffer[N + N / 2 - 1 - i],
                             pWindowELD[2 * N + N / 2 + i]) >>
                   (-WTS2 - 1));

    mdctData[N - 1 - i] = outval;
    overlapAddBuffer[N + N / 2 - 1 - i] = outval;
  }
  dct_IV(mdctData, frameLength, mdctData_e);

  *prevWindowShape = windowShape;

  return 0;
}