mb_access.c

H.264编码解码器源码(c语言).zip

/*!
 *************************************************************************************
 * \file mb_access.c
 *
 * \brief
 *    Functions for macroblock neighborhoods
 *
 *  \author
 *      Main contributors (see contributors.h for copyright, address and affiliation details)
 *      - Karsten S黨ring          <[e-mail]>
 *************************************************************************************
 */

#include "global.h"

/*!
 ************************************************************************
 * \brief
 *    returns 1 if the macroblock at the given address is available
 ************************************************************************
 */
int mb_is_available(int mbAddr, int currMbAddr)
{
  if ((mbAddr < 0) || (mbAddr > ((int)img->PicSizeInMbs - 1)))
    return 0;

  // the following line checks both: slice number and if the mb has been decoded
  if (img->mb_data[mbAddr].slice_nr != img->mb_data[currMbAddr].slice_nr)
    return 0;
  
  return 1;
}


/*!
 ************************************************************************
 * \brief
 *    Checks the availability of neighboring macroblocks of
 *    the current macroblock for prediction and context determination;
 ************************************************************************
 */
void CheckAvailabilityOfNeighbors()
{
  const int mb_nr = img->current_mb_nr;
  Macroblock *currMB = &img->mb_data[mb_nr];

  // mark all neighbors as unavailable
  currMB->mb_available_up   = NULL;
  currMB->mb_available_left = NULL;

  if (img->MbaffFrameFlag)
  {
    currMB->mbAddrA = 2 * (mb_nr/2 - 1);
    currMB->mbAddrB = 2 * (mb_nr/2 - img->PicWidthInMbs);
    currMB->mbAddrC = 2 * (mb_nr/2 - img->PicWidthInMbs + 1);
    currMB->mbAddrD = 2 * (mb_nr/2 - img->PicWidthInMbs - 1);
    
    currMB->mbAvailA = mb_is_available(currMB->mbAddrA, mb_nr) && ((mb_nr/2 % img->PicWidthInMbs)!=0);
    currMB->mbAvailB = mb_is_available(currMB->mbAddrB, mb_nr);
    currMB->mbAvailC = mb_is_available(currMB->mbAddrC, mb_nr) && (((mb_nr/2 +1) % img->PicWidthInMbs)!=0);
    currMB->mbAvailD = mb_is_available(currMB->mbAddrD, mb_nr) && ((mb_nr/2 % img->PicWidthInMbs)!=0);
  }
  else
  {
    currMB->mbAddrA = mb_nr - 1;
    currMB->mbAddrB = mb_nr - img->PicWidthInMbs;
    currMB->mbAddrC = mb_nr - img->PicWidthInMbs + 1;
    currMB->mbAddrD = mb_nr - img->PicWidthInMbs - 1;

    currMB->mbAvailA = mb_is_available(currMB->mbAddrA, mb_nr) && ((mb_nr % img->PicWidthInMbs)!=0);
    currMB->mbAvailB = mb_is_available(currMB->mbAddrB, mb_nr);
    currMB->mbAvailC = mb_is_available(currMB->mbAddrC, mb_nr) && (((mb_nr+1) % img->PicWidthInMbs)!=0);
    currMB->mbAvailD = mb_is_available(currMB->mbAddrD, mb_nr) && ((mb_nr % img->PicWidthInMbs)!=0);
  }

  if (currMB->mbAvailA) currMB->mb_available_left = &(img->mb_data[mb_nr-1]);
  if (currMB->mbAvailB) currMB->mb_available_up = &(img->mb_data[mb_nr-img->PicWidthInMbs]);
}


/*!
 ************************************************************************
 * \brief
 *    returns the x and y macroblock coordinates for a given MbAddress
 ************************************************************************
 */
void get_mb_block_pos (int mb_addr, int *x, int*y)
{

  if (img->MbaffFrameFlag)
  {
    *x = ((mb_addr/2) % img->PicWidthInMbs);
    *y = ( ((mb_addr/2) / img->PicWidthInMbs)  * 2 + (mb_addr%2));
  }
  else
  {
    *x = (mb_addr % img->PicWidthInMbs);
    *y = (mb_addr / img->PicWidthInMbs);
  }
}


/*!
 ************************************************************************
 * \brief
 *    returns the x and y sample coordinates for a given MbAddress
 ************************************************************************
 */
void get_mb_pos (int mb_addr, int *x, int*y)
{
  get_mb_block_pos(mb_addr, x, y);
  
  (*x) *= MB_BLOCK_SIZE;
  (*y) *= MB_BLOCK_SIZE;
}


/*!
 ************************************************************************
 * \brief
 *    get neighbouring positions for non-aff coding
 * \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 getNonAffNeighbour(int curr_mb_nr, int xN, int yN, int luma, PixelPos *pix)
{
  Macroblock *currMb = &img->mb_data[curr_mb_nr];
  int maxWH;

  if (luma)
    maxWH = 16;
  else
    maxWH = 8;

  if ((xN<0)&&(yN<0))
  {
    pix->mb_addr   = currMb->mbAddrD;
    pix->available = currMb->mbAvailD;
  }
  else
  if ((xN<0)&&((yN>=0)&&(yN<maxWH)))
  {
    pix->mb_addr  = currMb->mbAddrA;
    pix->available = currMb->mbAvailA;
  }
  else
  if (((xN>=0)&&(xN<maxWH))&&(yN<0))
  {
    pix->mb_addr  = currMb->mbAddrB;
    pix->available = currMb->mbAvailB;
  }
  else
  if (((xN>=0)&&(xN<maxWH))&&((yN>=0)&&(yN<maxWH)))
  {
    pix->mb_addr  = curr_mb_nr;
    pix->available = 1;
  }
  else
  if ((xN>=maxWH)&&(yN<0))
  {
    pix->mb_addr  = currMb->mbAddrC;
    pix->available = currMb->mbAvailC;
  }
  else 
  {
    pix->available = 0;
  }
  if (pix->available)
  {
    pix->x = (xN + maxWH) % maxWH;
    pix->y = (yN + 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 for aff coding
 * \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 getAffNeighbour(int curr_mb_nr, int xN, int yN, int luma, PixelPos *pix)
{
  Macroblock *currMb = &img->mb_data[curr_mb_nr];
  int maxWH;
  int yM = -1;

  if (luma)
    maxWH = 16;
  else
    maxWH = 8;

  // initialize to "not available"
  pix->available = 0;

  if(yN > (maxWH - 1))
  {
    return;
  }
  if ((xN > (maxWH -1)) && ((yN >= 0)&&(yN < (maxWH ))))
  {
    return;
  }

  if (xN < 0)
  {
    if (yN < 0)
    {
      if(!currMb->mb_field)
      {
        // frame
        if (curr_mb_nr%2 == 0)
        {
          // top
          pix->mb_addr  = currMb->mbAddrD  + 1;
          pix->available = currMb->mbAvailD;
           yM      = yN;
        }
        else
        {
          // bottom
          pix->mb_addr  = currMb->mbAddrA;
          pix->available = currMb->mbAvailA;
          if (currMb->mbAvailA)
          {
            if(!img->mb_data[currMb->mbAddrA].mb_field)
            {
               yM = yN;
            }
            else
            {
              (pix->mb_addr)++;
               yM = (yN + maxWH) >> 1;
            }
          }
        }
      }
      else
      {
        // field
        if(curr_mb_nr % 2 == 0)
        {
          // top
          pix->mb_addr  = currMb->mbAddrD;
          pix->available = currMb->mbAvailD;
          if (currMb->mbAvailD)
          {
            if(!img->mb_data[currMb->mbAddrD].mb_field)
            {
              (pix->mb_addr)++;
               yM = 2 * yN;
            }
            else
            {
               yM = yN;
            }
          }
        }
        else
        {
          // bottom
          pix->mb_addr  = currMb->mbAddrD+1;
          pix->available = currMb->mbAvailD;
           yM      = yN;
        }
      }
    }
    else
    { // xN < 0 && yN >= 0
      if ((yN >= 0) && (yN <maxWH))
      {
        if (!currMb->mb_field)
        {
          // frame
          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)
              {
                 yM = yN;
              }
              else
              {
                if (yN %2 == 0)
                {
                   yM = yN>> 1;
                }
                else
                {