&iminb,&jminb);  imins[0][1] = imint;  jmins[0][1] = jmint;  imins[1][1] = iminb;  jmins[1][1] = jminb;  /* select prediction for bottom field */  if (db<=dt)  {    dminb=db; *iminbp=iminb; *jminbp=jminb; *bselp=1;  }  else  {    dminb=dt; *iminbp=imint; *jminbp=jmint; *bselp=0;  }  *dfieldp=dmint+dminb;}/* * field picture motion estimation subroutine * * toporg: address of original top reference field * topref: address of reconstructed top reference field * botorg: address of original bottom reference field * botref: address of reconstructed bottom reference field * mb:  macroblock to be matched * i,j: location of mb (=center of search window) * sx,sy: half width/height of search window * * iminp,jminp,selp,dfieldp: location and distance of best field prediction * imin8up,jmin8up,sel8up: location of best 16x8 pred. for upper half of mb * imin8lp,jmin8lp,sel8lp: location of best 16x8 pred. for lower half of mb * d8p: distance of best 16x8 prediction * iminsp,jminsp,dsp: location and distance of best same parity field *                    prediction (needed for dual prime, only valid if *                    ipflag==0) */static void field_estimate(toporg,topref,botorg,botref,mb,i,j,sx,sy,ipflag,  iminp,jminp,imin8up,jmin8up,imin8lp,jmin8lp,dfieldp,d8p,selp,sel8up,sel8lp,  iminsp,jminsp,dsp)unsigned char *toporg, *topref, *botorg, *botref, *mb;int i,j,sx,sy;int ipflag;int *iminp, *jminp;int *imin8up, *jmin8up, *imin8lp, *jmin8lp;int *dfieldp,*d8p;int *selp, *sel8up, *sel8lp;int *iminsp, *jminsp, *dsp;{  int dt, db, imint, jmint, iminb, jminb, notop, nobot;  /* if ipflag is set, predict from field of opposite parity only */  notop = ipflag && (pict_struct==TOP_FIELD);  nobot = ipflag && (pict_struct==BOTTOM_FIELD);  /* field prediction */  /* predict current field from top field */  if (notop)    dt = 65536; /* infinity */  else    dt = fullsearch(toporg,topref,mb,width<<1,                    i,j,sx,sy>>1,16,width,height>>1,                    &imint,&jmint);  /* predict current field from bottom field */  if (nobot)    db = 65536; /* infinity */  else    db = fullsearch(botorg,botref,mb,width<<1,                    i,j,sx,sy>>1,16,width,height>>1,                    &iminb,&jminb);  /* same parity prediction (only valid if ipflag==0) */  if (pict_struct==TOP_FIELD)  {    *iminsp = imint; *jminsp = jmint; *dsp = dt;  }  else  {    *iminsp = iminb; *jminsp = jminb; *dsp = db;  }  /* select field prediction */  if (dt<=db)  {    *dfieldp = dt; *iminp = imint; *jminp = jmint; *selp = 0;  }  else  {    *dfieldp = db; *iminp = iminb; *jminp = jminb; *selp = 1;  }  /* 16x8 motion compensation */  /* predict upper half field from top field */  if (notop)    dt = 65536;  else    dt = fullsearch(toporg,topref,mb,width<<1,                    i,j,sx,sy>>1,8,width,height>>1,                    &imint,&jmint);  /* predict upper half field from bottom field */  if (nobot)    db = 65536;  else    db = fullsearch(botorg,botref,mb,width<<1,                    i,j,sx,sy>>1,8,width,height>>1,                    &iminb,&jminb);  /* select prediction for upper half field */  if (dt<=db)  {    *d8p = dt; *imin8up = imint; *jmin8up = jmint; *sel8up = 0;  }  else  {    *d8p = db; *imin8up = iminb; *jmin8up = jminb; *sel8up = 1;  }  /* predict lower half field from top field */  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);  /* predict lower half field from bottom field */  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);  /* select prediction for lower half field */  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;  /* Calculate Dual Prime distortions for 9 delta candidates   * for each of the four minimum field vectors   * Note: only for P pictures!   */  /* initialize minimum dual prime distortion to large value */  vmc = 1 << 30;  for (pref=0; pref<2; pref++)  {    for (ppred=0; ppred<2; ppred++)    {      /* convert Cartesian absolute to relative motion vector       * values (wrt current macroblock address (i,j)       */      is = iminf[pref][ppred] - (i<<1);      js = jminf[pref][ppred] - (j<<1);      if (pref!=ppred)      {        /* vertical field shift adjustment */        if (ppred==0)          js++;        else          js--;        /* mvxs and mvys scaling*/        is<<=1;        js<<=1;        if (topfirst == ppred)        {          /* second field: scale by 1/3 */          is = (is>=0) ? (is+1)/3 : -((-is+1)/3);          js = (js>=0) ? (js+1)/3 : -((-js+1)/3);        }        else          continue;      }      /* vector for prediction from field of opposite 'parity' */      if (topfirst)      {        /* vector for prediction of top field from bottom field */        it0 = ((is+(is>0))>>1);        jt0 = ((js+(js>0))>>1) - 1;        /* vector for prediction of bottom field from top field */        ib0 = ((3*is+(is>0))>>1);        jb0 = ((3*js+(js>0))>>1) + 1;      }      else      {        /* vector for prediction of top field from bottom field */        it0 = ((3*is+(is>0))>>1);        jt0 = ((3*js+(js>0))>>1) - 1;        /* vector for prediction of bottom field from top field */        ib0 = ((is+(is>0))>>1);        jb0 = ((js+(js>0))>>1) + 1;      }      /* convert back to absolute half-pel field picture coordinates */      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++)          {            /* opposite field coordinates */            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))            {              /* compute prediction error */              local_dist = bdist2(                ref + (is>>1) + (width<<1)*(js>>1),                ref + width + (it>>1) + (width<<1)*(jt>>1),                mb,             /* current mb location */                width<<1,       /* adjacent line distance */                is&1, js&1, it&1, jt&1, /* half-pel flags */                8);             /* block height */              local_dist += bdist2(                ref + width + (is>>1) + (width<<1)*(js>>1),                ref + (ib>>1) + (width<<1)*(jb>>1),                mb + width,     /* current mb location */                width<<1,       /* adjacent line distance */                is&1, js&1, ib&1, jb&1, /* half-pel flags */                8);             /* block height */              /* update delta with least distortion vector */              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;              }            }          }  /* end delta x loop */        } /* end delta y loop */      }    }  }  /* Compute L1 error for decision purposes */  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;  /* Calculate Dual Prime distortions for 9 delta candidates */  /* Note: only for P pictures! */  /* Assign opposite and same reference pointer */  if (pict_struct==TOP_FIELD)  {    sameref = topref;        oppref = botref;  }  else   {    sameref = botref;    oppref = topref;  }  /* convert Cartesian absolute to relative motion vector   * values (wrt current macroblock address (i,j)   */  mvxs = imins - (i<<1);  mvys = jmins - (j<<1);  /* vector for prediction from field of opposite 'parity' */  mvxo0 = (mvxs+(mvxs>0)) >> 1;  /* mvxs // 2 */  mvyo0 = (mvys+(mvys>0)) >> 1;  /* mvys // 2 */  /* vertical field shift correction */  if (pict_struct==TOP_FIELD)    mvyo0--;  else    mvyo0++;  /* convert back to absolute coordinates */  io0 = mvxo0 + (i<<1);  jo0 = mvyo0 + (j<<1);  /* initialize minimum dual prime distortion to large value */  vmc_dp = 1 << 30;  for (delta_y = -1; delta_y <= 1; delta_y++)  {    for (delta_x = -1; delta_x <=1; delta_x++)    {      /* opposite field coordinates */      io = io0 + delta_x;      jo = jo0 + delta_y;      if (io >= 0 && io <= (width-16)<<1 &&          jo >= 0 && jo <= (height2-16)<<1)      {        /* compute prediction error */        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,             /* current mb location */    width2,         /* adjacent line distance */    imins&1, jmins&1, imino&1, jmino&1, /* half-pel flags */    16);            /* block height */  *imindmvp = imindmv;  *jmindmvp = jmindmv;  *vmcp = vmc_dp;}/* * full search block matching *