/* 亮度分量 */  FindBiDirLimits(xvec,&xstart,&xstop,nh);  FindBiDirLimits(yvec,&ystart,&ystop,nv);  BiDirPredBlock(xstart,xstop,ystart,ystop,xvec,yvec, recon_P,pred,16);  return;}
/**********************************************************************
 *
 *	函數名：FindBiDirChrPredPB
 *	函數功能：在PB模式下尋找雙向色度信息的預測值
 *	函數輸入：recon_P：重構恢復出來的P幀編碼宏塊，色度分量
 *			  dx：重構宏塊的位置（水平方位）
 *			  dy：重構宏塊的位置（豎直方位）*			  
 *			  pred：預測宏塊的數據指針
 ***********************************************************************/
void FindBiDirChrPredPB(MB_Structure *recon_P, int dx, int dy,         MB_Structure *pred){  int xstart,xstop,ystart,ystop;  FindBiDirChromaLimits(dx,&xstart,&xstop);  FindBiDirChromaLimits(dy,&ystart,&ystop);  BiDirPredBlock(xstart,xstop,ystart,ystop,dx,dy,         &recon_P->Cb[0][0], &pred->Cb[0][0],8);  BiDirPredBlock(xstart,xstop,ystart,ystop,dx,dy,         &recon_P->Cr[0][0], &pred->Cr[0][0],8);  return;}void FindBiDirLimits(int vec, int *start, int *stop, int nhv){  /* limits taken from C loop in section G5 in H.263 */  *start = mmax(0,(-vec+1)/2 - nhv*8);  *stop = mmin(7,15-(vec+1)/2 - nhv*8);  return;}  void FindBiDirChromaLimits(int vec, int *start, int *stop){  /* limits taken from C loop in section G5 in H.263 */  *start = mmax(0,(-vec+1)/2);  *stop = mmin(7,7-(vec+1)/2);  return;}void BiDirPredBlock(int xstart, int xstop, int ystart, int ystop,            int xvec, int yvec, int *recon, int *pred, int bl){  int i,j,pel;  int xint, yint;  int xh, yh;  xint = xvec>>1;  xh = xvec - 2*xint;  yint = yvec>>1;  yh = yvec - 2*yint;  if (!xh && !yh) {    for (j = ystart; j <= ystop; j++) {      for (i = xstart; i <= xstop; i++) {        pel = *(recon +(j+yint)*bl + i+xint);        *(pred + j*bl + i) = (mmin(255,mmax(0,pel)) + *(pred + j*bl + i))>>1;      }    }  }  else if (!xh && yh) {    for (j = ystart; j <= ystop; j++) {      for (i = xstart; i <= xstop; i++) {        pel = (*(recon +(j+yint)*bl + i+xint)       +                *(recon +(j+yint+yh)*bl + i+xint) + 1)>>1;        *(pred + j*bl + i) = (pel + *(pred + j*bl + i))>>1;      }    }  }  else if (xh && !yh) {    for (j = ystart; j <= ystop; j++) {      for (i = xstart; i <= xstop; i++) {        pel = (*(recon +(j+yint)*bl + i+xint)       +                *(recon +(j+yint)*bl + i+xint+xh) + 1)>>1;        *(pred + j*bl + i) = (pel + *(pred + j*bl + i))>>1;      }    }  }  else { /* xh && yh */    for (j = ystart; j <= ystop; j++) {      for (i = xstart; i <= xstop; i++) {        pel = (*(recon +(j+yint)*bl + i+xint)       +                *(recon +(j+yint+yh)*bl + i+xint) +                *(recon +(j+yint)*bl + i+xint+xh) +                *(recon +(j+yint+yh)*bl + i+xint+xh)+2)>>2;        *(pred + j*bl + i) = (pel + *(pred + j*bl + i))>>1;      }    }  }  return;}/********************************************************************** * *	Name:        DoPredChrom_P *	Description:	Does the chrominance prediction for P-frames *	 *	Input:        motionvectors for each field, *        current position in image, *        pointers to current and previos image, *        pointer to pred_error array, *        (int) field: 1 if field coding *         *	Side effects:	fills chrom-array in pred_error structure * *	Date: 930211	Author: Karl.Lillevold@nta.no * ***********************************************************************/void DoPredChrom_P(int x_curr, int y_curr, int dx, int dy,           PictImage *curr, PictImage *prev,            MB_Structure *pred_error){  int m,n;  int x, y, ofx, ofy, pel, lx;  int xint, yint;  int xh, yh;  lx = (mv_outside_frame ? pels/2 + (long_vectors?32:16) : pels/2);  x = x_curr>>1;  y = y_curr>>1;  xint = dx>>1;  xh = dx & 1;  yint = dy>>1;  yh = dy & 1;  if (!xh && !yh) {    for (n = 0; n < 8; n++) {      for (m = 0; m < 8; m++) {        ofx = x + xint + m;        ofy = y + yint + n;        pel=*(prev->Cr+ofx    + (ofy   )*lx);        pred_error->Cr[n][m] = (int)(*(curr->Cr + x+m + (y+n)*cpels) - pel);        pel=*(prev->Cb+ofx    + (ofy   )*lx);        pred_error->Cb[n][m] = (int)(*(curr->Cb + x+m + (y+n)*cpels) - pel);      }    }  }  else if (!xh && yh) {    for (n = 0; n < 8; n++) {      for (m = 0; m < 8; m++) {        ofx = x + xint + m;        ofy = y + yint + n;        pel=(*(prev->Cr+ofx    + (ofy   )*lx)+             *(prev->Cr+ofx    + (ofy+yh)*lx) + 1)>>1;        pred_error->Cr[n][m] =           (int)(*(curr->Cr + x+m + (y+n)*cpels) - pel);        pel=(*(prev->Cb+ofx    + (ofy   )*lx)+             *(prev->Cb+ofx    + (ofy+yh)*lx) + 1)>>1;        pred_error->Cb[n][m] =           (int)(*(curr->Cb + x+m + (y+n)*cpels) - pel);            }    }  }  else if (xh && !yh) {    for (n = 0; n < 8; n++) {      for (m = 0; m < 8; m++) {        ofx = x + xint + m;        ofy = y + yint + n;        pel=(*(prev->Cr+ofx    + (ofy   )*lx)+             *(prev->Cr+ofx+xh + (ofy   )*lx) + 1)>>1;        pred_error->Cr[n][m] =           (int)(*(curr->Cr + x+m + (y+n)*cpels) - pel);        pel=(*(prev->Cb+ofx    + (ofy   )*lx)+             *(prev->Cb+ofx+xh + (ofy   )*lx) + 1)>>1;        pred_error->Cb[n][m] =           (int)(*(curr->Cb + x+m + (y+n)*cpels) - pel);            }    }  }  else { /* xh && yh */    for (n = 0; n < 8; n++) {      for (m = 0; m < 8; m++) {        ofx = x + xint + m;        ofy = y + yint + n;        pel=(*(prev->Cr+ofx    + (ofy   )*lx)+             *(prev->Cr+ofx+xh + (ofy   )*lx)+             *(prev->Cr+ofx    + (ofy+yh)*lx)+             *(prev->Cr+ofx+xh + (ofy+yh)*lx)+             2)>>2;        pred_error->Cr[n][m] =           (int)(*(curr->Cr + x+m + (y+n)*cpels) - pel);        pel=(*(prev->Cb+ofx    + (ofy   )*lx)+             *(prev->Cb+ofx+xh + (ofy   )*lx)+             *(prev->Cb+ofx    + (ofy+yh)*lx)+             *(prev->Cb+ofx+xh + (ofy+yh)*lx)+             2)>>2;        pred_error->Cb[n][m] =           (int)(*(curr->Cb + x+m + (y+n)*cpels) - pel);            }    }  }  return;}/********************************************************************** * *	Name:        FindHalfPel *	Description:	Find the optimal half pel prediction *	 *	Input:        position, vector, array with current data *        pointer to previous interpolated luminance, * *	Returns: * *	Date: 930126        Author: Karl.Lillevold@nta.no *            950208    Mod: Karl.Lillevold@nta.no * ***********************************************************************/void FindHalfPel(int x, int y, MotionVector *fr, unsigned char *prev,          int *curr, int bs, int comp){  int i, m, n;  int half_pel;  int start_x, start_y, stop_x, stop_y, new_x, new_y, lx;  int min_pos;  int AE, AE_min;  Point search[9];  start_x = -1;  stop_x = 1;  start_y = -1;  stop_y = 1;  new_x = x + fr->x;  new_y = y + fr->y;  new_x += ((comp&1)<<3);  new_y += ((comp&2)<<2);  lx = (mv_outside_frame ? pels + (long_vectors?64:32) : pels);  /* Make sure that no addressing is outside the frame */  if (!mv_outside_frame) {    if ((new_x) <= 0)       start_x = 0;    if ((new_y) <= 0)       start_y = 0;    if ((new_x) >= (pels-bs))       stop_x = 0;    if ((new_y) >= (lines-bs))       stop_y = 0;  }  search[0].x = 0;        search[0].y = 0;  search[1].x = start_x;        search[1].y = start_y; /*   1 2 3   */  search[2].x = 0;        search[2].y = start_y; /*   4 0 5   */  search[3].x = stop_x;        search[3].y = start_y; /*   6 7 8   */  search[4].x = start_x;        search[4].y = 0;  search[5].x = stop_x;        search[5].y = 0;  search[6].x = start_x;        search[6].y = stop_y;  search[7].x = 0;        search[7].y = stop_y;  search[8].x = stop_x;        search[8].y = stop_y;  AE_min = INT_MAX;  min_pos = 0;  for (i = 0; i < 9; i++) {    AE = 0;    for (n = 0; n < bs; n++) {      for (m = 0; m < bs; m++) {        /* Find absolute error */        half_pel = *(prev + 2*new_x + 2*m + search[i].x +             (2*new_y + 2*n + search[i].y)*lx*2);        AE += abs(half_pel - *(curr + m + n*16));      }    }    /*     * if (i == 0 && fr->x == 0 && fr->y == 0 && bs == 16)      * AE -= PREF_NULL_VEC;     */    if (AE < AE_min) {      AE_min = AE;      min_pos = i;    }  }  /* Store optimal values */  fr->min_error = AE_min;  fr->x_half = search[min_pos].x;  fr->y_half = search[min_pos].y;          return;}/**********************************************************************
 *
 *	函數名：FindPred
 *	函數功能：尋找運測編碼塊
 *	函數輸入：x：編碼塊的水平位置
 *			  y：編碼塊的豎直位置
 *			  fr：運動向量
 *			  prev：前一幀數據
 *			  pred：預測宏塊的數據指針
 ***********************************************************************/void FindPred(int x, int y, MotionVector *fr, unsigned char *prev,               int *pred, int bs, int comp){  int m, n;  int new_x, new_y;  int lx;  lx = (mv_outside_frame ? pels + (long_vectors?64:32) : pels);  new_x = x + fr->x;  new_y = y + fr->y;  new_x += ((comp&1)<<3);  new_y += ((comp&2)<<2);  /* Fill pred. data */  for (n = 0; n < bs; n++) {    for (m = 0; m < bs; m++) {      /* Find interpolated pixel-value */      *(pred + m + n*16) = *(prev + (new_x + m)*2 + fr->x_half +             ((new_y + n)*2 + fr->y_half)*lx*2);    }	  }  return;}/**********************************************************************
 *
 *	函數名：FindPredOBMC
 *	函數功能：計算用于重疊塊匹配運動補償的預測塊
 *	函數輸入：x：編碼塊的水平位置
 *			  y：編碼塊的豎直位置
 *			  MV：運動向量
 *			  prev：前一幀數據
 *			  pred：預測宏塊的數據指針
 ***********************************************************************/
void FindPredOBMC(int x, int y, MotionVector *MV[6][MBR+1][MBC+2],           unsigned char *prev, int *pred, int comp, int PB){  int m, n;  int pc,pt,pb,pr,pl;  int nxc,nxt,nxb,nxr,nxl;  int nyc,nyt,nyb,nyr,nyl;  int xit,xib,xir,xil;  int yit,yib,yir,yil;  int vect,vecb,vecr,vecl;  int c8,t8,l8,r8;  int ti8,li8,ri8;  int xmb, ymb, lx;  MotionVector *fc,*ft,*fb,*fr,*fl;  int Mc[8][8] = {    {4,5,5,5,5,5,5,4},    {5,5,5,5,5,5,5,5},    {5,5,6,6,6,6,5,5},    {5,5,6,6,6,6,5,5},    {5,5,6,6,6,6,5,5},    {5,5,6,6,6,6,5,5},    {5,5,5,5,5,5,5,5},    {4,5,5,5,5,5,5,4},  };  int Mt[8][8] = {    {2,2,2,2,2,2,2,2},    {1,1,2,2,2,2,1,1},    {1,1,1,1,1,1,1,1},    {1,1,1,1,1,1,1,1},    {0,0,0,0,0,0,0,0},    {0,0,0,0,0,0,0,0},    {0,0,0,0,0,0,0,0},    {0,0,0,0,0,0,0,0},  };  int Mb[8][8] = {    {0,0,0,0,0,0,0,0},    {0,0,0,0,0,0,0,0},    {0,0,0,0,0,0,0,0},    {0,0,0,0,0,0,0,0},    {1,1,1,1,1,1,1,1},    {1,1,1,1,1,1,1,1},    {1,1,2,2,2,2,1,1},    {2,2,2,2,2,2,2,2},  };  int Mr[8][8] = {    {0,0,0,0,1,1,1,2},    {0,0,0,0,1,1,2,2},    {0,0,0,0,1,1,2,2},    {0,0,0,0,1,1,2,2},    {0,0,0,0,1,1,2,2},    {0,0,0,0,1,1,2,2},    {0,0,0,0,1,1,2,2},    {0,0,0,0,1,1,1,2},  };  int Ml[8][8] = {    {2,1,1,1,0,0,0,0},    {2,2,1,1,0,0,0,0},    {2,2,1,1,0,0,0,0},    {2,2,1,1,0,0,0,0},    {2,2,1,1,0,0,0,0},    {2,2,1,1,0,0,0,0},    {2,2,1,1,0,0,0,0},    {2,1,1,1,0,0,0,0},  };  xmb = x/MB_SIZE+1;  ymb = y/MB_SIZE+1;  lx = (mv_outside_frame ? pels + (long_vectors?64:32) : pels);  c8  = (MV[0][ymb][xmb]->Mode == MODE_INTER4V ? 1 : 0);  t8  = (MV[0][ymb-1][xmb]->Mode == MODE_INTER4V ? 1 : 0);  ti8 = (MV[0][ymb-1][xmb]->Mode == MODE_INTRA ? 1 : 0);  ti8 = (MV[0][ymb-1][xmb]->Mode == MODE_INTRA_Q ? 1 : ti8);  l8  = (MV[0][ymb][xmb-1]->Mode == MODE_INTER4V ? 1 : 0);  li8 = (MV[0][ymb][xmb-1]->Mode == MODE_INTRA ? 1 : 0);  li8 = (MV[0][ymb][xmb-1]->Mode == MODE_INTRA_Q ? 1 : li8);    r8  = (MV[0][ymb][xmb+1]->Mode == MODE_INTER4V ? 1 : 0);  ri8 = (MV[0][ymb][xmb+1]->Mode == MODE_INTRA ? 1 : 0);  ri8 = (MV[0][ymb][xmb+1]->Mode == MODE_INTRA_Q ? 1 : ri8);  if (PB) {    ti8 = li8 = ri8 = 0;  }  switch (comp+1) {  case 1:    vect = (ti8 ? (c8 ? 1 : 0) : (t8 ? 3 : 0));     yit  = (ti8 ? ymb : ymb - 1);     xit = xmb;    vecb = (c8 ? 3 : 0) ; yib = ymb; xib = xmb;    vecl = (li8 ? (c8 ? 1 : 0) : (l8 ? 2 : 0));     yil = ymb;     xil = (li8 ? xmb : xmb-1);    vecr = (c8 ? 2 : 0) ; yir = ymb; xir = xmb;    /* edge handling */    if (ymb == 1) {      yit = ymb;      vect = (c8 ? 1 : 0);    }    if (xmb == 1) {      xil = xmb;      vecl = (c8 ? 1 : 0);    }    break;    case 2:    vect = (ti8 ? (c8 ? 2 : 0) : (t8 ? 4 : 0));     yit = (ti8 ? ymb : ymb-1);     xit = xmb;    vecb = (c8 ? 4 : 0) ; yib = ymb; xib = xmb;    vecl = (c8 ? 1 : 0) ; yil = ymb; xil = xmb;    vecr = (ri8 ? (c8 ? 2 : 0) : (r8 ? 1 : 0));     yir = ymb;