mb_access.c

H.264标准代码(用于视频编码)

                }
              }
            }
          }
          else
          {
            // bottom
            pix->mb_addr  = currMb->mbAddrA;
            pix->available = currMb->mbAvailA;
            if (currMb->mbAvailA)
            {
              if(!img->mb_data[currMb->mbAddrA].mb_field)
              {
                (pix->mb_addr)++;
                 yM = yN;
              }
              else
              {
                if (yN %2 == 0)
                {
                   yM = (yN + maxWH) >> 1;
                }
                else
                {
                  (pix->mb_addr)++;
                   yM = (yN + maxWH) >> 1;
                }
              }
            }
          }
        }
        else
        {
          // field
          if (curr_mb_nr % 2 == 0)
          {
            // top
            pix->mb_addr  = currMb->mbAddrA;
            pix->available = currMb->mbAvailA;
            if (currMb->mbAvailA)
            {
              if(!img->mb_data[currMb->mbAddrA].mb_field)
              {
                if (yN < (maxWH / 2))
                {
                   yM = yN << 1;
                }
                else
                {
                  (pix->mb_addr)++;
                   yM = (yN << 1 ) - maxWH;
                }
              }
              else
              {
                 yM = yN;
              }
            }
          }
          else
          {
            // bottom
            pix->mb_addr  = currMb->mbAddrA;
            pix->available = currMb->mbAvailA;
            if (currMb->mbAvailA)
            {
              if(!img->mb_data[currMb->mbAddrA].mb_field)
              {
                if (yN < (maxWH / 2))
                {
                   yM = (yN << 1) + 1;
                }
                else
                {
                  (pix->mb_addr)++;
                   yM = (yN << 1 ) + 1 - maxWH;
                }
              }
              else
              {
                 (pix->mb_addr)++;
                 yM = yN;
              }
            }
          }
        }
      }
    }
  }
  else
  {
    // xN >= 0
    if ((xN >= 0)&&(xN <maxWH))
    {
      if (yN<0)
      {
        if (!currMb->mb_field)
        {
          //frame
          if (curr_mb_nr % 2 == 0)
          {
            //top
            pix->mb_addr  = currMb->mbAddrB + 1;
            pix->available = currMb->mbAvailB;
             yM      = yN;
          }
          else
          {
            // bottom
            pix->mb_addr  = curr_mb_nr - 1;
            pix->available = 1;
             yM      = yN;
          }
        }
        else
        {
          // field
          if (curr_mb_nr % 2 == 0)
          {
            // top
            pix->mb_addr  = currMb->mbAddrB;
            pix->available = currMb->mbAvailB;
            if (currMb->mbAvailB)
            {
              if(!img->mb_data[currMb->mbAddrB].mb_field)
              {
                (pix->mb_addr)++;
                 yM = 2* yN;
              }
              else
              {
                 yM = yN;
              }
            }
          }
          else
          {
            // bottom
            pix->mb_addr  = currMb->mbAddrB + 1;
            pix->available = currMb->mbAvailB;
             yM      = yN;
          }
        }
      }
      else
      {
        // yN >=0
        if ((yN >= 0) && (yN <maxWH))
        {
          pix->mb_addr  = curr_mb_nr;
          pix->available = 1;
           yM      = yN;
        }
      }
    }
    else
    {
      // xN >= maxWH
      if(yN < 0)
      {
        if (!currMb->mb_field)
        {
          // frame
          if (curr_mb_nr % 2 == 0)
          {
            // top
            pix->mb_addr  = currMb->mbAddrC + 1;
            pix->available = currMb->mbAvailC;
             yM      = yN;
          }
          else
          {
            // bottom
            pix->available = 0;
          }
        }
        else
        {
          // field
          if (curr_mb_nr % 2 == 0)
          {
            // top
            pix->mb_addr  = currMb->mbAddrC;
            pix->available = currMb->mbAvailC;
            if (currMb->mbAvailC)
            {
              if(!img->mb_data[currMb->mbAddrC].mb_field)
              {
                (pix->mb_addr)++;
                 yM = 2* yN;
              }
              else
              {
                 yM = yN;
              }
            }
          }
          else
          {
            // bottom
            pix->mb_addr  = currMb->mbAddrC + 1;
            pix->available = currMb->mbAvailC;
             yM      = yN;
          }
        }
      }
    }
  }
  if (pix->available)
  {
    pix->x = (xN + maxWH) % maxWH;
    pix->y = (yM + maxWH) % maxWH;
    get_mb_pos(pix->mb_addr, &(pix->pos_x), &(pix->pos_y));
    if (luma)
    {
      pix->pos_x += pix->x;
      pix->pos_y += pix->y;
    }
    else
    {
      pix->pos_x = (pix->pos_x/2) + pix->x;
      pix->pos_y = (pix->pos_y/2) + pix->y;
    }
  }
}


/*!
 ************************************************************************
 * \brief
 *    get neighbouring positions. MB AFF is automatically used from img structure
 * \param curr_mb_nr
 *   current macroblock number (decoding order)
 * \param xN
 *    input x position
 * \param yN
 *    input y position
 * \param luma
 *    1 if luma coding, 0 for chroma
 * \param pix
 *    returns position informations
 ************************************************************************
 */
void getNeighbour(int curr_mb_nr, int xN, int yN, int luma, PixelPos *pix)
{
  if (img->MbaffFrameFlag)
    getAffNeighbour(curr_mb_nr, xN, yN, luma, pix);
  else
    getNonAffNeighbour(curr_mb_nr, xN, yN, luma, pix);
}


/*!
 ************************************************************************
 * \brief
 *    get neighbouring  get neighbouring 4x4 luma block
 * \param curr_mb_nr
 *   current macroblock number (decoding order)
 * \param block_x
 *    input x block position
 * \param block_y
 *    input y block position
 * \param rel_x
 *    relative x position of neighbor
 * \param rel_y
 *    relative y position of neighbor
 * \param pix
 *    returns position informations
 ************************************************************************
 */
void getLuma4x4Neighbour (int curr_mb_nr, int block_x, int block_y, int rel_x, int rel_y, PixelPos *pix)
{
  int x = 4* block_x + rel_x;
  int y = 4* block_y + rel_y;

  getNeighbour(curr_mb_nr, x, y, 1, pix);

  if (pix->available)
  {
    pix->x /= 4;
    pix->y /= 4;
    pix->pos_x /= 4;
    pix->pos_y /= 4;
  }
}


/*!
 ************************************************************************
 * \brief
 *    get neighbouring 4x4 chroma block
 * \param curr_mb_nr
 *   current macroblock number (decoding order)
 * \param block_x
 *    input x block position
 * \param block_y
 *    input y block position
 * \param rel_x
 *    relative x position of neighbor
 * \param rel_y
 *    relative y position of neighbor
 * \param pix
 *    returns position informations
 ************************************************************************
 */
void getChroma4x4Neighbour (int curr_mb_nr, int block_x, int block_y, int rel_x, int rel_y, PixelPos *pix)
{
  int x = 4* block_x + rel_x;
  int y = 4* block_y + rel_y;

  getNeighbour(curr_mb_nr, x, y, 0, pix);

  if (pix->available)
  {
    pix->x /= 4;
    pix->y /= 4;
    pix->pos_x /= 4;
    pix->pos_y /= 4;
  }
}