mb_access.c

H.264基于baseline解码器的C++实现源码

/*!
 *************************************************************************************
 * \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"
#include "mbuffer.h"
#include "mb_access.h"

extern StorablePicture *dec_picture;
static int *CurPos;
/*!
 ************************************************************************
 * \brief
 *    returns 1 if the macroblock at the given address is available
 ************************************************************************
 */
int mb_is_available(int mbAddr, Macroblock *currMB)
{
  if ((mbAddr < 0) || (mbAddr > ((int)dec_picture->PicSizeInMbs - 1)))
    return 0;

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

  return 1;
}


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

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

  if (dec_picture->MbaffFrameFlag)
  {
    int cur_mb_pair = mb_nr >> 1;
    currMB->mbAddrA = 2 * (cur_mb_pair - 1);
    currMB->mbAddrB = 2 * (cur_mb_pair - dec_picture->PicWidthInMbs);
    currMB->mbAddrC = 2 * (cur_mb_pair - dec_picture->PicWidthInMbs + 1);
    currMB->mbAddrD = 2 * (cur_mb_pair - dec_picture->PicWidthInMbs - 1);

    currMB->mbAvailA = mb_is_available(currMB->mbAddrA, currMB) && ((PicPos[ cur_mb_pair     ][0])!=0);
    currMB->mbAvailB = mb_is_available(currMB->mbAddrB, currMB);
    currMB->mbAvailC = mb_is_available(currMB->mbAddrC, currMB) && ((PicPos[ cur_mb_pair + 1 ][0])!=0);
    currMB->mbAvailD = mb_is_available(currMB->mbAddrD, currMB) && ((PicPos[ cur_mb_pair     ][0])!=0);
  }
  else
  {
    currMB->mbAddrA = mb_nr - 1;
    currMB->mbAddrB = mb_nr - dec_picture->PicWidthInMbs;
    currMB->mbAddrC = mb_nr - dec_picture->PicWidthInMbs + 1;
    currMB->mbAddrD = mb_nr - dec_picture->PicWidthInMbs - 1;

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


/*!
 ************************************************************************
 * \brief
 *    returns the x and y macroblock coordinates for a given MbAddress
 ************************************************************************
 */
void get_mb_block_pos_normal (int mb_addr, int *x, int*y)
{
  *x = PicPos[ mb_addr ][0];
  *y = PicPos[ mb_addr ][1];
}

/*!
 ************************************************************************
 * \brief
 *    returns the x and y macroblock coordinates for a given MbAddress
 *    for mbaff type slices
 ************************************************************************
 */
void get_mb_block_pos_mbaff (int mb_addr, int *x, int*y)
{
  *x =  PicPos[mb_addr>>1][0];
  *y = (PicPos[mb_addr>>1][1] << 1) + (mb_addr & 0x01);
}

/*!
 ************************************************************************
 * \brief
 *    returns the x and y sample coordinates for a given MbAddress
 ************************************************************************
 */
void get_mb_pos (int mb_addr, int mb_size[2], int *x, int*y)
{
  get_mb_block_pos(mb_addr, x, y);

  (*x) *= mb_size[0];
  (*y) *= mb_size[1];
}


/*!
 ************************************************************************
 * \brief
 *    get neighboring positions for non-aff coding
 * \param currMb
 *   current macroblock
 * \param xN
 *    input x position
 * \param yN
 *    input y position
 * \param mb_size
 *    Macroblock size in pixel (according to luma or chroma MB access)
 * \param pix
 *    returns position informations
 ************************************************************************
 */
void getNonAffNeighbour(Macroblock *currMb, int xN, int yN, int mb_size[2], PixelPos *pix)
{
  int maxW = mb_size[0], maxH = mb_size[1];

  if ((xN < 0))
  {
    if (yN < 0)
    {
      pix->mb_addr   = currMb->mbAddrD;
      pix->available = currMb->mbAvailD;
    }
    else if (yN < maxH)
    {
      pix->mb_addr  = currMb->mbAddrA;
      pix->available = currMb->mbAvailA;
    }
    else
      pix->available = FALSE;
  }
  else if (xN < maxW)
  {
    if (yN<0)
    {
      pix->mb_addr   = currMb->mbAddrB;
      pix->available = currMb->mbAvailB;
    }
    else if (yN < maxH)
    {
      pix->mb_addr   = currMb->mbAddrX;
      pix->available = TRUE;
    }
    else
    {
      pix->available = FALSE;
    }
  }
  else if ((xN >= maxW) && (yN < 0))
  {
    pix->mb_addr   = currMb->mbAddrC;
    pix->available = currMb->mbAvailC;
  }
  else
  {
    pix->available = FALSE;
  }

  if (pix->available || img->DeblockCall)
  {
    CurPos = PicPos[ pix->mb_addr ];

    pix->x = xN & (maxW - 1);
    pix->y = yN & (maxH - 1);
    pix->pos_x = CurPos[0] * maxW + pix->x;
    pix->pos_y = CurPos[1] * maxH + pix->y;
  }
}

/*!
 ************************************************************************
 * \brief
 *    get neighboring positions for aff coding
 * \param currMB
 *   current macroblock
 * \param xN
 *    input x position
 * \param yN
 *    input y position
 * \param mb_size
 *    Macroblock size in pixel (according to luma or chroma MB access)
 * \param pix
 *    returns position informations
 ************************************************************************
 */
void getAffNeighbour(Macroblock *currMB, int xN, int yN, int mb_size[2], PixelPos *pix)
{
  int maxW, maxH;
  int yM = -1;

  maxW = mb_size[0];
  maxH = mb_size[1];

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

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

  if (xN < 0)
  {
    if (yN < 0)
    {
      if(!currMB->mb_field)
      {
        // frame
        if ((currMB->mbAddrX & 0x01) == 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 + maxH) >> 1;
            }
          }
        }
      }
      else
      {
        // field
        if ((currMB->mbAddrX & 0x01) == 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;