ac3dec_exponents.cpp

这是在PCA下的基于IPP库示例代码例子,在网上下了IPP的库之后,设置相关参数就可以编译该代码.

/* ////////////////////////// ac3dec_exponents.cpp ////////////////////////// */
/*
//
//              INTeL CORPORATION PROPRIETARY INFORMATION
//  This software is supplied under the terms of a license  agreement or
//  nondisclosure agreement with Intel Corporation and may not be copied
//  or disclosed except in  accordance  with the terms of that agreement.
//        Copyright (c) 2003-2005 Intel Corporation. All Rights Reserved.
//
*/

#include "umc_ac3_decoder.h"
#include "ac3dec_tables.h"

int UMC::AC3Decoder::DecodeExponents(int nblk)
{
  int i;
  Ipp32u cbErrors = 0;

  for (i = 0; i < bsi.nfchans; i++) {
    cbErrors +=
      expUnpackCh(CH_FBW, audblk[nblk]->chexpstr[i], audblk[nblk]->nchgrps[i],
                  audblk[nblk]->exps[i][0], &audblk[nblk]->exps[i][1],
                  &audblk[nblk]->fbw_exp[i][0]);
  }

  if (audblk[nblk]->cplinu) {
    cbErrors +=
      expUnpackCh(CH_CPL, audblk[nblk]->cplexpstr, audblk[nblk]->ncplgrps,
                  (Ipp16u)(audblk[nblk]->cplabsexp << 1),
                  &audblk[nblk]->cplexps[0],
                  &audblk[nblk]->cpl_exp[audblk[nblk]->cplstrtmant]);
  }

  if (bsi.lfeon) {
    cbErrors +=
      expUnpackCh(CH_LFE, audblk[nblk]->lfeexpstr, 2, audblk[nblk]->lfeexps[0],
                  &audblk[nblk]->lfeexps[1], &audblk[nblk]->lfe_exp[0]);
  }

  return cbErrors;      /* return # unpacking errors */
}

int UMC::AC3Decoder::expUnpackCh(Ipp16u TypeCh, Ipp16u ExpStr, Ipp16u nGrps,
                                 Ipp16u Exp0, Ipp16u *source, Ipp16u *dest)
{
  Ipp16u i, j;
  Ipp16s exp_acc;
  Ipp32u cbErrors = 0;  /* error counter */
  short pkexp = 0;

  if (ExpStr == EXP_REUSE)
    return cbErrors;

/*
 * Handle the initial absolute exponent
 */
  exp_acc = Exp0;
  j = 0;

/*
 * In the case of a fbw channel then the initial absolute values is also an
 * exponent
 */
  if (TypeCh != CH_CPL) {
    dest[j++] = exp_acc;
  }

/*
 * Loop through the groups and fill the dest array appropriately
 */
  for (i = 0; i < nGrps; i++) {
    if (source[i] > 124)        // FIXME set an error flag and mute the frame
    {
      ++cbErrors;
      continue; // do not update current exponent
    }

    pkexp = source[i];
    pkexp = UNGRP5[pkexp];

    exp_acc = (((pkexp >> 12) & 0x000f) - 2) + exp_acc;

    switch (ExpStr) {
    case EXP_D45:
      dest[j++] = exp_acc;
      dest[j++] = exp_acc;
    case EXP_D25:
      dest[j++] = exp_acc;
    case EXP_D15:
      dest[j++] = exp_acc;
    }

    exp_acc = (((pkexp >> 8) & 0x000f) - 2) + exp_acc;

    switch (ExpStr) {
    case EXP_D45:
      dest[j++] = exp_acc;
      dest[j++] = exp_acc;
    case EXP_D25:
      dest[j++] = exp_acc;
    case EXP_D15:
      dest[j++] = exp_acc;
    }

    exp_acc = (((pkexp >> 4) & 0x000f) - 2) + exp_acc;

    switch (ExpStr) {
    case EXP_D45:
      dest[j++] = exp_acc;
      dest[j++] = exp_acc;
    case EXP_D25:
      dest[j++] = exp_acc;
    case EXP_D15:
      dest[j++] = exp_acc;
    }
  }

  return cbErrors;      /* return # exponent unpacking errors */
}