motion.c

MPEG2视频编解码程序

    }
    else
    {
      /* field prediction */
      mbi->motion_type = MC_FIELD;
      vmc = dist2((sel?botref:topref) + (imin>>1) + w2*(jmin>>1),
                  mb,w2,imin&1,jmin&1,16);
    }

    /* select between intra and non-intra coding */
    if (vmc>var && vmc>=9*256)
      mbi->mb_type = MB_INTRA;
    else
    {
      /* zero MV field prediction from same parity ref. field
       * (not allowed if ipflag is set)
       */
      if (!ipflag)
        v0 = dist2(((pict_struct==BOTTOM_FIELD)?botref:topref) + i + w2*j,
                   mb,w2,0,0,16);
      if (ipflag || (4*v0>5*vmc && v0>=9*256))
      {
        var = vmc;
        mbi->mb_type = MB_FORWARD;
        if (mbi->motion_type==MC_FIELD)
        {
          mbi->MV[0][0][0] = imin - (i<<1);
          mbi->MV[0][0][1] = jmin - (j<<1);
          mbi->mv_field_sel[0][0] = sel;
        }
        else if (mbi->motion_type==MC_DMV)
        {
          /* same parity vector */
          mbi->MV[0][0][0] = imins - (i<<1);
          mbi->MV[0][0][1] = jmins - (j<<1);

          /* opposite parity vector */
          mbi->dmvector[0] = imindmv;
          mbi->dmvector[1] = jmindmv;
        }
        else
        {
          mbi->MV[0][0][0] = imin8u - (i<<1);
          mbi->MV[0][0][1] = jmin8u - (j<<1);
          mbi->MV[1][0][0] = imin8l - (i<<1);
          mbi->MV[1][0][1] = jmin8l - ((j+8)<<1);
          mbi->mv_field_sel[0][0] = sel8u;
          mbi->mv_field_sel[1][0] = sel8l;
        }
      }
      else
      {
        /* No MC */
        var = v0;
        mbi->mb_type = 0;
        mbi->motion_type = MC_FIELD;
        mbi->MV[0][0][0] = 0;
        mbi->MV[0][0][1] = 0;
        mbi->mv_field_sel[0][0] = (pict_struct==BOTTOM_FIELD);
      }
    }
  }
  else /* if (pict_type==B_TYPE) */
  {
    /* forward prediction */
    field_estimate(oldorg,oldref,oldorg+width,oldref+width,mb,
                   i,j,sxf,syf,0,
                   &iminf,&jminf,&imin8uf,&jmin8uf,&imin8lf,&jmin8lf,
                   &dmcfieldf,&dmc8f,&self,&sel8uf,&sel8lf,&imins,&jmins,&ds);

    /* backward prediction */
    field_estimate(neworg,newref,neworg+width,newref+width,mb,
                   i,j,sxb,syb,0,
                   &iminr,&jminr,&imin8ur,&jmin8ur,&imin8lr,&jmin8lr,
                   &dmcfieldr,&dmc8r,&selr,&sel8ur,&sel8lr,&imins,&jmins,&ds);

    /* calculate distances for bidirectional prediction */
    /* field */
    dmcfieldi = bdist1(oldref + (self?width:0) + (iminf>>1) + w2*(jminf>>1),
                       newref + (selr?width:0) + (iminr>>1) + w2*(jminr>>1),
                       mb,w2,iminf&1,jminf&1,iminr&1,jminr&1,16);

    /* 16x8 upper half block */
    dmc8i = bdist1(oldref + (sel8uf?width:0) + (imin8uf>>1) + w2*(jmin8uf>>1),
                   newref + (sel8ur?width:0) + (imin8ur>>1) + w2*(jmin8ur>>1),
                   mb,w2,imin8uf&1,jmin8uf&1,imin8ur&1,jmin8ur&1,8);

    /* 16x8 lower half block */
    dmc8i+= bdist1(oldref + (sel8lf?width:0) + (imin8lf>>1) + w2*(jmin8lf>>1),
                   newref + (sel8lr?width:0) + (imin8lr>>1) + w2*(jmin8lr>>1),
                   mb+8*w2,w2,imin8lf&1,jmin8lf&1,imin8lr&1,jmin8lr&1,8);

    /* select prediction type of minimum distance */
    if (dmcfieldi<dmc8i && dmcfieldi<dmcfieldf && dmcfieldi<dmc8f
        && dmcfieldi<dmcfieldr && dmcfieldi<dmc8r)
    {
      /* field, interpolated */
      mbi->mb_type = MB_FORWARD|MB_BACKWARD;
      mbi->motion_type = MC_FIELD;
      vmc = bdist2(oldref + (self?width:0) + (iminf>>1) + w2*(jminf>>1),
                   newref + (selr?width:0) + (iminr>>1) + w2*(jminr>>1),
                   mb,w2,iminf&1,jminf&1,iminr&1,jminr&1,16);
    }
    else if (dmc8i<dmcfieldf && dmc8i<dmc8f
             && dmc8i<dmcfieldr && dmc8i<dmc8r)
    {
      /* 16x8, interpolated */
      mbi->mb_type = MB_FORWARD|MB_BACKWARD;
      mbi->motion_type = MC_16X8;

      /* upper half block */
      vmc = bdist2(oldref + (sel8uf?width:0) + (imin8uf>>1) + w2*(jmin8uf>>1),
                   newref + (sel8ur?width:0) + (imin8ur>>1) + w2*(jmin8ur>>1),
                   mb,w2,imin8uf&1,jmin8uf&1,imin8ur&1,jmin8ur&1,8);

      /* lower half block */
      vmc+= bdist2(oldref + (sel8lf?width:0) + (imin8lf>>1) + w2*(jmin8lf>>1),
                   newref + (sel8lr?width:0) + (imin8lr>>1) + w2*(jmin8lr>>1),
                   mb+8*w2,w2,imin8lf&1,jmin8lf&1,imin8lr&1,jmin8lr&1,8);
    }
    else if (dmcfieldf<dmc8f && dmcfieldf<dmcfieldr && dmcfieldf<dmc8r)
    {
      /* field, forward */
      mbi->mb_type = MB_FORWARD;
      mbi->motion_type = MC_FIELD;
      vmc = dist2(oldref + (self?width:0) + (iminf>>1) + w2*(jminf>>1),
                  mb,w2,iminf&1,jminf&1,16);
    }
    else if (dmc8f<dmcfieldr && dmc8f<dmc8r)
    {
      /* 16x8, forward */
      mbi->mb_type = MB_FORWARD;
      mbi->motion_type = MC_16X8;

      /* upper half block */
      vmc = dist2(oldref + (sel8uf?width:0) + (imin8uf>>1) + w2*(jmin8uf>>1),
                  mb,w2,imin8uf&1,jmin8uf&1,8);

      /* lower half block */
      vmc+= dist2(oldref + (sel8lf?width:0) + (imin8lf>>1) + w2*(jmin8lf>>1),
                  mb+8*w2,w2,imin8lf&1,jmin8lf&1,8);
    }
    else if (dmcfieldr<dmc8r)
    {
      /* field, backward */
      mbi->mb_type = MB_BACKWARD;
      mbi->motion_type = MC_FIELD;
      vmc = dist2(newref + (selr?width:0) + (iminr>>1) + w2*(jminr>>1),
                  mb,w2,iminr&1,jminr&1,16);
    }
    else
    {
      /* 16x8, backward */
      mbi->mb_type = MB_BACKWARD;
      mbi->motion_type = MC_16X8;

      /* upper half block */
      vmc = dist2(newref + (sel8ur?width:0) + (imin8ur>>1) + w2*(jmin8ur>>1),
                  mb,w2,imin8ur&1,jmin8ur&1,8);

      /* lower half block */
      vmc+= dist2(newref + (sel8lr?width:0) + (imin8lr>>1) + w2*(jmin8lr>>1),
                  mb+8*w2,w2,imin8lr&1,jmin8lr&1,8);
    }

    /* select between intra and non-intra coding */
    if (vmc>var && vmc>=9*256)
      mbi->mb_type = MB_INTRA;
    else
    {
      var = vmc;
      if (mbi->motion_type==MC_FIELD)
      {
        /* forward */
        mbi->MV[0][0][0] = iminf - (i<<1);
        mbi->MV[0][0][1] = jminf - (j<<1);
        mbi->mv_field_sel[0][0] = self;
        /* backward */
        mbi->MV[0][1][0] = iminr - (i<<1);
        mbi->MV[0][1][1] = jminr - (j<<1);
        mbi->mv_field_sel[0][1] = selr;
      }
      else /* MC_16X8 */
      {
        /* forward */
        mbi->MV[0][0][0] = imin8uf - (i<<1);
        mbi->MV[0][0][1] = jmin8uf - (j<<1);
        mbi->mv_field_sel[0][0] = sel8uf;
        mbi->MV[1][0][0] = imin8lf - (i<<1);
        mbi->MV[1][0][1] = jmin8lf - ((j+8)<<1);
        mbi->mv_field_sel[1][0] = sel8lf;
        /* backward */
        mbi->MV[0][1][0] = imin8ur - (i<<1);
        mbi->MV[0][1][1] = jmin8ur - (j<<1);
        mbi->mv_field_sel[0][1] = sel8ur;
        mbi->MV[1][1][0] = imin8lr - (i<<1);
        mbi->MV[1][1][1] = jmin8lr - ((j+8)<<1);
        mbi->mv_field_sel[1][1] = sel8lr;
      }
    }
  }

  mbi->var = var;
}

/*
 * 帧图像运动估计
 *
 
 */
static void frame_estimate(org,ref,mb,i,j,sx,sy,
  iminp,jminp,imintp,jmintp,iminbp,jminbp,dframep,dfieldp,tselp,bselp,
  imins,jmins)
unsigned char *org,*ref,*mb;
int i,j,sx,sy;
int *iminp,*jminp;
int *imintp,*jmintp,*iminbp,*jminbp;
int *dframep,*dfieldp;
int *tselp,*bselp;
int imins[2][2],jmins[2][2];
{
  int dt,db,dmint,dminb;
  int imint,iminb,jmint,jminb;

  /* frame prediction */
  *dframep = fullsearch(org,ref,mb,width,i,j,sx,sy,16,width,height,
                        iminp,jminp);

  /* predict top field from top field */
  dt = fullsearch(org,ref,mb,width<<1,i,j>>1,sx,sy>>1,8,width,height>>1,
                  &imint,&jmint);

  /* predict top field from bottom field */
  db = fullsearch(org+width,ref+width,mb,width<<1,i,j>>1,sx,sy>>1,8,width,height>>1,
                  &iminb,&jminb);

  imins[0][0] = imint;
  jmins[0][0] = jmint;
  imins[1][0] = iminb;
  jmins[1][0] = jminb;

  /* select prediction for top field */
  if (dt<=db)
  {
    dmint=dt; *imintp=imint; *jmintp=jmint; *tselp=0;
  }
  else
  {
    dmint=db; *imintp=iminb; *jmintp=jminb; *tselp=1;
  }

  /* predict bottom field from top field */
  dt = fullsearch(org,ref,mb+width,width<<1,i,j>>1,sx,sy>>1,8,width,height>>1,
                  &imint,&jmint);

  /* predict bottom field from bottom field */
  db = fullsearch(org+width,ref+width,mb+width,width<<1,i,j>>1,sx,sy>>1,8,width,height>>1,
                  &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;
}

/*
 * 场图片运动预测程序
 *
 * toporg：原始上半部分场地址
 *topref：重建的上半部分场地址
 *botorg：原始下半部分参考场地址
 *botref：重建的下半部分参考场的地址
 *mb：待匹配的宏块
 *i，j：宏块的位置（即搜索窗口的中心）
 *iminp，jminp，selp，dfieldp：最佳预测场的位置和距离
 *imin8up，jmin8up，sel8up：上半部分宏块的最佳预测的位置
 *imin8lp，jmin8lp，sel8lp：下半部分宏块的最佳预测的位置
 *d8p：最佳16×8的预测块的距离
 *iminsp，jminsp，dsp：最佳同奇偶性预测场的位置和距离
 */

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++)
    {
      /* 将笛卡儿绝对坐标系转化成相对运动向量的值
       */
      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;