*iminsp = iminb; *jminsp = jminb; *dsp = db;  }    /* 選擇預測場*/  if (dt<=db)  {    *dfieldp = dt; *iminp = imint; *jminp = jmint; *selp = 0;  }  else  {    *dfieldp = db; *iminp = iminb; *jminp = jminb; *selp = 1;  }  /* 16x8 運動補償 */  if (notop)    dt = 65536;  else    dt = fullsearch(toporg,topref,mb,width<<1,                    i,j,sx,sy>>1,8,width,height>>1,                    &imint,&jmint);  if (nobot)    db = 65536;  else    db = fullsearch(botorg,botref,mb,width<<1,                    i,j,sx,sy>>1,8,width,height>>1,                    &iminb,&jminb);  if (dt<=db)  {    *d8p = dt; *imin8up = imint; *jmin8up = jmint; *sel8up = 0;  }  else  {    *d8p = db; *imin8up = iminb; *jmin8up = jminb; *sel8up = 1;  }  if (notop)    dt = 65536;  else    dt = fullsearch(toporg,topref,mb+(width<<4),width<<1,                    i,j+8,sx,sy>>1,8,width,height>>1,                    &imint,&jmint);  if (nobot)    db = 65536;  else    db = fullsearch(botorg,botref,mb+(width<<4),width<<1,                    i,j+8,sx,sy>>1,8,width,height>>1,                    &iminb,&jminb);    /* 為上半部分場選擇預測場*/  if (dt<=db)  {    *d8p += dt; *imin8lp = imint; *jmin8lp = jmint; *sel8lp = 0;  }  else  {    *d8p += db; *imin8lp = iminb; *jmin8lp = jminb; *sel8lp = 1;  }}static void dpframe_estimate(ref,mb,i,j,iminf,jminf,  iminp,jminp,imindmvp, jmindmvp, dmcp, vmcp)unsigned char *ref, *mb;int i,j;int iminf[2][2], jminf[2][2];int *iminp, *jminp;int *imindmvp, *jmindmvp;int *dmcp,*vmcp;{  int pref,ppred,delta_x,delta_y;  int is,js,it,jt,ib,jb,it0,jt0,ib0,jb0;  int imins,jmins,imint,jmint,iminb,jminb,imindmv,jmindmv;  int vmc,local_dist;    vmc = 1 << 30;  for (pref=0; pref<2; pref++)  {    for (ppred=0; ppred<2; ppred++)    {      /* 將笛卡兒絕對坐標系轉化成相對運動向量的值       */      is = iminf[pref][ppred] - (i<<1);      js = jminf[pref][ppred] - (j<<1);      if (pref!=ppred)      {        /* 垂直場偏調整*/        if (ppred==0)          js++;        else          js--;        is<<=1;        js<<=1;        if (topfirst == ppred)        {          /* 第二場，比例因子為 1/3 */          is = (is>=0) ? (is+1)/3 : -((-is+1)/3);          js = (js>=0) ? (js+1)/3 : -((-js+1)/3);        }        else          continue;      }      if (topfirst)      {                it0 = ((is+(is>0))>>1);        jt0 = ((js+(js>0))>>1) - 1;                ib0 = ((3*is+(is>0))>>1);        jb0 = ((3*js+(js>0))>>1) + 1;      }      else      {        /* 用來根據底部場圖象預測上部的運動向量 */        it0 = ((3*is+(is>0))>>1);        jt0 = ((3*js+(js>0))>>1) - 1;         /* 用來根據頂部場圖象預測下部的運動向量 */        ib0 = ((is+(is>0))>>1);        jb0 = ((js+(js>0))>>1) + 1;      }            is += i<<1;      js += j<<1;      it0 += i<<1;      jt0 += j<<1;      ib0 += i<<1;      jb0 += j<<1;      if (is >= 0 && is <= (width-16)<<1 &&          js >= 0 && js <= (height-16))      {        for (delta_y=-1; delta_y<=1; delta_y++)        {          for (delta_x=-1; delta_x<=1; delta_x++)          {                        it = it0 + delta_x;            jt = jt0 + delta_y;            ib = ib0 + delta_x;            jb = jb0 + delta_y;            if (it >= 0 && it <= (width-16)<<1 &&                jt >= 0 && jt <= (height-16) &&                ib >= 0 && ib <= (width-16)<<1 &&                jb >= 0 && jb <= (height-16))            {              /* 計算預測錯誤 */              local_dist = bdist2(                ref + (is>>1) + (width<<1)*(js>>1),                ref + width + (it>>1) + (width<<1)*(jt>>1),                mb,             /* 當前宏塊位置 */                width<<1,                       is&1, js&1, it&1, jt&1,                 8);             /* 塊高 */              local_dist += bdist2(                ref + width + (is>>1) + (width<<1)*(js>>1),                ref + (ib>>1) + (width<<1)*(jb>>1),                mb + width,                     width<<1,                       is&1, js&1, ib&1, jb&1,                 8);                                         if (local_dist < vmc)              {                imins = is;                jmins = js;                imint = it;                jmint = jt;                iminb = ib;                jminb = jb;                imindmv = delta_x;                jmindmv = delta_y;                vmc = local_dist;              }            }          }  /* 結束x循環 */        } /* 結束y循環 */      }    }  }  local_dist = bdist1(    ref + (imins>>1) + (width<<1)*(jmins>>1),    ref + width + (imint>>1) + (width<<1)*(jmint>>1),    mb,    width<<1,    imins&1, jmins&1, imint&1, jmint&1,    8);  local_dist += bdist1(    ref + width + (imins>>1) + (width<<1)*(jmins>>1),    ref + (iminb>>1) + (width<<1)*(jminb>>1),    mb + width,    width<<1,    imins&1, jmins&1, iminb&1, jminb&1,    8);  *dmcp = local_dist;  *iminp = imins;  *jminp = jmins;  *imindmvp = imindmv;  *jmindmvp = jmindmv;  *vmcp = vmc;}static void dpfield_estimate(topref,botref,mb,i,j,imins,jmins,  imindmvp, jmindmvp, dmcp, vmcp)unsigned char *topref, *botref, *mb;int i,j;int imins, jmins;int *imindmvp, *jmindmvp;int *dmcp,*vmcp;{  unsigned char *sameref, *oppref;  int io0,jo0,io,jo,delta_x,delta_y,mvxs,mvys,mvxo0,mvyo0;  int imino,jmino,imindmv,jmindmv,vmc_dp,local_dist;    if (pict_struct==TOP_FIELD)  {    sameref = topref;        oppref = botref;  }  else   {    sameref = botref;    oppref = topref;  }   mvxs = imins - (i<<1);  mvys = jmins - (j<<1);   mvxo0 = (mvxs+(mvxs>0)) >> 1;  /* mvxs // 2 */  mvyo0 = (mvys+(mvys>0)) >> 1;  /* mvys // 2 */   if (pict_struct==TOP_FIELD)    mvyo0--;  else    mvyo0++;    io0 = mvxo0 + (i<<1);  jo0 = mvyo0 + (j<<1);    vmc_dp = 1 << 30;  for (delta_y = -1; delta_y <= 1; delta_y++)  {    for (delta_x = -1; delta_x <=1; delta_x++)    {            io = io0 + delta_x;      jo = jo0 + delta_y;      if (io >= 0 && io <= (width-16)<<1 &&          jo >= 0 && jo <= (height2-16)<<1)      {                local_dist = bdist2(          sameref + (imins>>1) + width2*(jmins>>1),          oppref  + (io>>1)    + width2*(jo>>1),          mb,             /* current mb location */          width2,         /* adjacent line distance */          imins&1, jmins&1, io&1, jo&1, /* half-pel flags */          16);            /* block height */        /* update delta with least distortion vector */        if (local_dist < vmc_dp)        {          imino = io;          jmino = jo;          imindmv = delta_x;          jmindmv = delta_y;          vmc_dp = local_dist;        }      }    }  /* end delta x loop */  } /* end delta y loop */  /* Compute L1 error for decision purposes */  *dmcp = bdist1(    sameref + (imins>>1) + width2*(jmins>>1),    oppref  + (imino>>1) + width2*(jmino>>1),    mb,                 width2,             imins&1, jmins&1, imino&1, jmino&1,     16);              *imindmvp = imindmv;  *jmindmvp = jmindmv;  *vmcp = vmc_dp;}/* 全搜索塊匹配
blk：塊的左上角像素坐標 
h：塊的高度 
lx：在參考塊中，垂直相鄰的像素之間的距離（以字節為單位）
org：源參考圖像的左上角像素的坐標
ref：重建參考圖像的左上角像素的坐標
i0，j0：搜索窗口的中心點
sx，sy：搜索窗口的半長和半寬
xmax，ymax：搜索區域的右邊界和下邊界
iminp，jminp：指向存儲結果的指針
*/

static int fullsearch(org,ref,blk,lx,i0,j0,sx,sy,h,xmax,ymax,iminp,jminp)unsigned char *org,*ref,*blk;int lx,i0,j0,sx,sy,h,xmax,ymax;int *iminp,*jminp;{  int i,j,imin,jmin,ilow,ihigh,jlow,jhigh;  int d,dmin;  int k,l,sxy;

  ilow = i0 - sx;  ihigh = i0 + sx;  if (ilow<0)    ilow = 0;  if (ihigh>xmax-16)    ihigh = xmax-16;  jlow = j0 - sy;  jhigh = j0 + sy;  if (jlow<0)    jlow = 0;  if (jhigh>ymax-h)    jhigh = ymax-h;  /* 全搜索，螺旋向外 */  imin = i0;  jmin = j0;  dmin = dist1(org+imin+lx*jmin,blk,lx,0,0,h,65536);
  sxy = (sx>sy) ? sx : sy;  for (l=1; l<=sxy; l++)  {    i = i0 - l;    j = j0 - l;    for (k=0; k<8*l; k++)    {      if (i>=ilow && i<=ihigh && j>=jlow && j<=jhigh)      {        d = dist1(org+i+lx*j,blk,lx,0,0,h,dmin);
        if (d<dmin)        {          dmin = d;          imin = i;          jmin = j;        }      }      if      (k<2*l) i++;      else if (k<4*l) j++;      else if (k<6*l) i--;      else            j--;    }  }
  /* half pel */
  dmin = 65536;  imin <<= 1;  jmin <<= 1;  ilow = imin - (imin>0);  ihigh = imin + (imin<((xmax-16)<<1));  jlow = jmin - (jmin>0);  jhigh = jmin + (jmin<((ymax-h)<<1));  for (j=jlow; j<=jhigh; j++)    for (i=ilow; i<=ihigh; i++)    {      d = dist1(ref+(i>>1)+lx*(j>>1),blk,lx,i&1,j&1,h,dmin);      if (d<dmin)      {        dmin = d;        imin = i;        jmin = j;
      }    }
  *iminp = imin;  *jminp = jmin;  return dmin;}

#pragma warning( disable : 4799 )

/*
 * 求兩個塊之間絕對差值
 * blk1,blk2：為兩個塊左上角像素坐標
 *lx：垂直相鄰的像素之間的距離（以字節為單位）
 *hx，hy：水平和垂直插值的標志
 *h：塊的高度（通常為8或16）
 *distlim：極值，如果結果超過該值則放棄之。
 */
static int dist1(blk1,blk2,lx,hx,hy,h,distlim)