*      Number of blocks belonging to a MB, when counting
 *      in vertical/horizontal direction. (Y:2 U,V:1)
 ************************************************************************
 */
int ercCollectColumnBlocks( int predBlocks[], int currRow, int currColumn, int *condition, int maxRow, int maxColumn, int step )
{
  int srcCounter = 0, threshold = ERC_BLOCK_CORRUPTED;
  
  memset( predBlocks, 0, 8*sizeof(int) );
  
  /* in this case, row > 0 and row < 17 */
  if ( condition[ (currRow-1)*maxColumn + currColumn ] > threshold ) 
  {
    predBlocks[4] = 1;
    srcCounter++;
  }
  if ( condition[ (currRow+step)*maxColumn + currColumn ] > threshold ) 
  {
    predBlocks[6] = 1;
    srcCounter++;
  }
  
  return srcCounter;
}

/*!
 ************************************************************************
 * \brief
 *      Core for the Intra blocks concealment.
 *      It is called for each color component (Y,U,V) seperately
 *      Finds the corrupted blocks and calls pixel interpolation functions 
 *      to correct them, one block at a time.
 *      Scanning is done vertically and each corrupted column is corrected
 *      bi-directionally, i.e., first block, last block, first block+1, last block -1 ...
 * \param lastColumn  
 *      Number of block columns in the frame
 * \param lastRow     
 *      Number of block rows in the frame
 * \param recfr
 *      Reconstructed frame buffer
 * \param picSizeX
 *      Width of the frame in pixels
 * \param condition
 *      The block condition (ok, lost) table
 ************************************************************************
 */
static void concealBlocks( int lastColumn, int lastRow, int comp, frame *recfr, int32 picSizeX, int *condition )
{
  int row, column, srcCounter = 0,  thr = ERC_BLOCK_CORRUPTED,
      lastCorruptedRow = -1, firstCorruptedRow = -1, currRow = 0, 
      areaHeight = 0, i = 0, smoothColumn = 0;
  int predBlocks[8], step = 1;
  
  /* in the Y component do the concealment MB-wise (not block-wise):
  this is useful if only whole MBs can be damaged or lost */
  if ( comp == 0 )
    step = 2;
  else
    step = 1;
  
  for ( column = 0; column < lastColumn; column += step ) 
  {
    for ( row = 0; row < lastRow; row += step ) 
    {
      if ( condition[row*lastColumn+column] <= thr ) 
      {
        firstCorruptedRow = row;
        /* find the last row which has corrupted blocks (in same continuous area) */
        for ( lastCorruptedRow = row+step; lastCorruptedRow < lastRow; lastCorruptedRow += step ) 
        {
          /* check blocks in the current column */
          if ( condition[ lastCorruptedRow*lastColumn + column ] > thr ) 
          {
            /* current one is already OK, so the last was the previous one */
            lastCorruptedRow -= step;
            break;
          }
        }
        if ( lastCorruptedRow >= lastRow ) 
        {
          /* correct only from above */
          lastCorruptedRow = lastRow-step;
          for ( currRow = firstCorruptedRow; currRow < lastRow; currRow += step ) 
          {
            srcCounter = ercCollect8PredBlocks( predBlocks, currRow, column, condition, lastRow, lastColumn, step, 1 );
          
            switch( comp ) 
            {
            case 0 :
              ercPixConcealIMB( recfr->yptr, currRow, column, predBlocks, picSizeX, 2 );
              break;
            case 1 :
              ercPixConcealIMB( recfr->uptr, currRow, column, predBlocks, (picSizeX>>1), 1 );
              break;
            case 2 :
              ercPixConcealIMB( recfr->vptr, currRow, column, predBlocks, (picSizeX>>1), 1 );
              break;
            }
            
            if ( comp == 0 ) 
            {
              condition[ currRow*lastColumn+column] = ERC_BLOCK_CONCEALED;
              condition[ currRow*lastColumn+column + 1] = ERC_BLOCK_CONCEALED;
              condition[ currRow*lastColumn+column + lastColumn] = ERC_BLOCK_CONCEALED;
              condition[ currRow*lastColumn+column + lastColumn + 1] = ERC_BLOCK_CONCEALED;
            }
            else 
            {
              condition[ currRow*lastColumn+column] = ERC_BLOCK_CONCEALED;
            }
            
          }
          row = lastRow;
        } 
        else if ( firstCorruptedRow == 0 ) 
        {
          /* correct only from below */
          for ( currRow = lastCorruptedRow; currRow >= 0; currRow -= step ) 
          {
            srcCounter = ercCollect8PredBlocks( predBlocks, currRow, column, condition, lastRow, lastColumn, step, 1 );
            
            switch( comp ) 
            {
            case 0 :
              ercPixConcealIMB( recfr->yptr, currRow, column, predBlocks, picSizeX, 2 );
              break;
            case 1 :
              ercPixConcealIMB( recfr->uptr, currRow, column, predBlocks, (picSizeX>>1), 1 );
              break;
            case 2 :
              ercPixConcealIMB( recfr->vptr, currRow, column, predBlocks, (picSizeX>>1), 1 );
              break;
            }
            
            if ( comp == 0 ) 
            {
              condition[ currRow*lastColumn+column] = ERC_BLOCK_CONCEALED;
              condition[ currRow*lastColumn+column + 1] = ERC_BLOCK_CONCEALED;
              condition[ currRow*lastColumn+column + lastColumn] = ERC_BLOCK_CONCEALED;
              condition[ currRow*lastColumn+column + lastColumn + 1] = ERC_BLOCK_CONCEALED;
            }
            else 
            {
              condition[ currRow*lastColumn+column] = ERC_BLOCK_CONCEALED;
            }
            
          }
          
          row = lastCorruptedRow+step;
        }
        else 
        {
          /* correct bi-directionally */
          
          row = lastCorruptedRow+step;
          areaHeight = lastCorruptedRow-firstCorruptedRow+step;
          
          /* 
          *  Conceal the corrupted area switching between the up and the bottom rows 
          */
          for ( i = 0; i < areaHeight; i += step ) 
          {
            if ( i % 2 ) 
            {
              currRow = lastCorruptedRow;
              lastCorruptedRow -= step;
            }
            else 
            {
              currRow = firstCorruptedRow;
              firstCorruptedRow += step;
            }
            
            if (smoothColumn > 0) 
            {
              srcCounter = ercCollectColumnBlocks( predBlocks, currRow, column, condition, lastRow, lastColumn, step );
            }
            else 
            {
              srcCounter = ercCollect8PredBlocks( predBlocks, currRow, column, condition, lastRow, lastColumn, step, 1 );
            }
            
            switch( comp ) 
            {
            case 0 :
              ercPixConcealIMB( recfr->yptr, currRow, column, predBlocks, picSizeX, 2 );
              break;
              
            case 1 :
              ercPixConcealIMB( recfr->uptr, currRow, column, predBlocks, (picSizeX>>1), 1 );
              break;
              
            case 2 :
              ercPixConcealIMB( recfr->vptr, currRow, column, predBlocks, (picSizeX>>1), 1 );
              break;
            }
            
            if ( comp == 0 ) 
            {
              condition[ currRow*lastColumn+column] = ERC_BLOCK_CONCEALED;
              condition[ currRow*lastColumn+column + 1] = ERC_BLOCK_CONCEALED;
              condition[ currRow*lastColumn+column + lastColumn] = ERC_BLOCK_CONCEALED;
              condition[ currRow*lastColumn+column + lastColumn + 1] = ERC_BLOCK_CONCEALED;
            }
            else 
            {
              condition[ currRow*lastColumn+column ] = ERC_BLOCK_CONCEALED;
            }
          }
        }

        lastCorruptedRow = -1;
        firstCorruptedRow = -1;

      }
    }
  }
}

/*!
 ************************************************************************
 * \brief
 *      Does the actual pixel based interpolation for block[]
 *      using weighted average
 * \param src[] 
 *      pointers to neighboring source blocks
 * \param block     
 *      destination block
 * \param blockSize
 *      16 for Y, 8 for U/V components
 * \param frameWidth
 *      Width of the frame in pixels
 ************************************************************************
 */
static void pixMeanInterpolateBlock( byte *src[], byte *block, int blockSize, int frameWidth )
{
  int row, column, k, tmp, srcCounter = 0, weight = 0, bmax = blockSize - 1;
  
  k = 0;
  for ( row = 0; row < blockSize; row++ ) 
  {
    for ( column = 0; column < blockSize; column++ ) 
    {
      tmp = 0;
      srcCounter = 0;
      /* above */
      if ( src[4] != NULL )   
      {
        weight = blockSize-row;
        tmp += weight * (*(src[4]+bmax*frameWidth+column));
        srcCounter += weight;
      }
      /* left */
      if ( src[5] != NULL )   
      {
        weight = blockSize-column;
        tmp += weight * (*(src[5]+row*frameWidth+bmax));
        srcCounter += weight;
      }
      /* below */
      if ( src[6] != NULL )   
      {
        weight = row+1;
        tmp += weight * (*(src[6]+column));
        srcCounter += weight;
      }
      /* right */
      if ( src[7] != NULL )   
      {
        weight = column+1;
        tmp += weight * (*(src[7]+row*frameWidth));
        srcCounter += weight;
      }

      if ( srcCounter > 0 )
        block[ k + column ] = (byte)(tmp/srcCounter);
      else 
        block[ k + column ] = 127;
    }
    k += frameWidth;
  }
  
}