media/libstagefright/codecs/aacenc/src/pre_echo_control.c

/*
 ** Copyright 2003-2010, VisualOn, Inc.
 **
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 **
 **     http://www.apache.org/licenses/LICENSE-2.0
 **
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 */
/*******************************************************************************
	File:		pre_echo_control.c

	Content:	Pre echo control functions

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

#include "basic_op.h"
#include "oper_32b.h"

#include "oper_32b.h"
#include "pre_echo_control.h"


/*****************************************************************************
*
* function name:InitPreEchoControl
* description: init pre echo control parameter
*
*****************************************************************************/
void InitPreEchoControl(Word32 *pbThresholdNm1,
                        Word16  numPb,
                        Word32 *pbThresholdQuiet)
{
  Word16 pb;

  for(pb=0; pb<numPb; pb++) {
    pbThresholdNm1[pb] = pbThresholdQuiet[pb];
  }
}

/*****************************************************************************
*
* function name:PreEchoControl
* description: update shreshold to avoid pre echo
*			   thr(n) = max(rpmin*thrq(n), min(thrq(n), rpelev*thrq1(n)))
*
*
*****************************************************************************/
void PreEchoControl(Word32 *pbThresholdNm1,
                    Word16  numPb,
                    Word32  maxAllowedIncreaseFactor,
                    Word16  minRemainingThresholdFactor,
                    Word32 *pbThreshold,
                    Word16  mdctScale,
                    Word16  mdctScalenm1)
{
  Word32 i;
  Word32 tmpThreshold1, tmpThreshold2;
  Word32 scaling;

  /* maxAllowedIncreaseFactor is hard coded to 2 */
  (void)maxAllowedIncreaseFactor;

  scaling = ((mdctScale - mdctScalenm1) << 1);

  if ( scaling > 0 ) {
    for(i = 0; i < numPb; i++) {
      tmpThreshold1 = pbThresholdNm1[i] >> (scaling-1);
      tmpThreshold2 = L_mpy_ls(pbThreshold[i], minRemainingThresholdFactor);

      /* copy thresholds to internal memory */
      pbThresholdNm1[i] = pbThreshold[i];


      if(pbThreshold[i] > tmpThreshold1) {
        pbThreshold[i] = tmpThreshold1;
      }

      if(tmpThreshold2 > pbThreshold[i]) {
        pbThreshold[i] = tmpThreshold2;
      }

    }
  }
  else {
    scaling = -scaling;
    for(i = 0; i < numPb; i++) {

      tmpThreshold1 = pbThresholdNm1[i] << 1;
      tmpThreshold2 = L_mpy_ls(pbThreshold[i], minRemainingThresholdFactor);

      /* copy thresholds to internal memory */
      pbThresholdNm1[i] = pbThreshold[i];


      if(((pbThreshold[i] >> scaling) > tmpThreshold1)) {
        pbThreshold[i] = tmpThreshold1 << scaling;
      }

      if(tmpThreshold2 > pbThreshold[i]) {
        pbThreshold[i] = tmpThreshold2;
      }

    }
  }
}