motion.c

MPEG2视频编解码算法方面的源代码(包括编码和解码)

     * prediction error variance (vmc)
     *
     * blocks with small prediction error are always coded non-intra
     * even if variance is smaller (is this reasonable?)
     */
    if (vmc>var && vmc>=9*256)
      mbi->mb_type = MB_INTRA;
    else
    {
      var = vmc;
      if (mbi->motion_type==MC_FRAME)
      {
        /* forward */
        mbi->MV[0][0][0] = iminf - (i<<1);
        mbi->MV[0][0][1] = jminf - (j<<1);
        /* backward */
        mbi->MV[0][1][0] = iminr - (i<<1);
        mbi->MV[0][1][1] = jminr - (j<<1);
      }
      else
      {
        /* these are FRAME vectors */
        /* forward */
        mbi->MV[0][0][0] = imintf - (i<<1);
        mbi->MV[0][0][1] = (jmintf<<1) - (j<<1);
        mbi->MV[1][0][0] = iminbf - (i<<1);
        mbi->MV[1][0][1] = (jminbf<<1) - (j<<1);
        mbi->mv_field_sel[0][0] = tself;
        mbi->mv_field_sel[1][0] = bself;
        /* backward */
        mbi->MV[0][1][0] = imintr - (i<<1);
        mbi->MV[0][1][1] = (jmintr<<1) - (j<<1);
        mbi->MV[1][1][0] = iminbr - (i<<1);
        mbi->MV[1][1][1] = (jminbr<<1) - (j<<1);
        mbi->mv_field_sel[0][1] = tselr;
        mbi->mv_field_sel[1][1] = bselr;
      }
    }
  }

  mbi->var = var;
}

/*
 * motion estimation for field pictures
 *
 * oldorg: original frame for forward prediction (P and B frames)
 * neworg: original frame for backward prediction (B frames only)
 * oldref: reconstructed frame for forward prediction (P and B frames)
 * newref: reconstructed frame for backward prediction (B frames only)
 * cur:    current original frame (the one for which the prediction is formed)
 * curref: current reconstructed frame (to predict second field from first)
 * sxf,syf: forward search window (frame coordinates)
 * sxb,syb: backward search window (frame coordinates)
 * mbi:    pointer to macroblock info structure
 * secondfield: indicates second field of a frame (in P fields this means
 *              that reference field of opposite parity is in curref instead
 *              of oldref)
 * ipflag: indicates a P type field which is the second field of a frame
 *         in which the first field is I type (this restricts predictions
 *         to be based only on the opposite parity (=I) field)
 *
 * results:
 * mbi->
 *  mb_type: 0, MB_INTRA, MB_FORWARD, MB_BACKWARD, MB_FORWARD|MB_BACKWARD
 *  MV[][][]: motion vectors (field format)
 *  mv_field_sel: top/bottom field
 *  motion_type: MC_FIELD, MC_16X8
 *
 * uses global vars: pict_type, pict_struct
 */
static void field_ME(oldorg,neworg,oldref,newref,cur,curref,i,j,
  sxf,syf,sxb,syb,mbi,secondfield,ipflag)
unsigned char *oldorg,*neworg,*oldref,*newref,*cur,*curref;
int i,j,sxf,syf,sxb,syb;
struct mbinfo *mbi;
int secondfield,ipflag;
{
  int w2;
  unsigned char *mb, *toporg, *topref, *botorg, *botref;
  int var,vmc,v0,dmc,dmcfieldi,dmc8i;
  int imin,jmin,imin8u,jmin8u,imin8l,jmin8l,dmcfield,dmc8,sel,sel8u,sel8l;
  int iminf,jminf,imin8uf,jmin8uf,imin8lf,jmin8lf,dmcfieldf,dmc8f,self,sel8uf,sel8lf;
  int iminr,jminr,imin8ur,jmin8ur,imin8lr,jmin8lr,dmcfieldr,dmc8r,selr,sel8ur,sel8lr;
  int imins,jmins,ds,imindmv,jmindmv,vmc_dp,dmc_dp;

  w2 = width<<1;

  mb = cur + i + w2*j;
  if (pict_struct==BOTTOM_FIELD)
    mb += width;

  var = variance(mb,w2);

  if (pict_type==I_TYPE)
    mbi->mb_type = MB_INTRA;
  else if (pict_type==P_TYPE)
  {
    toporg = oldorg;
    topref = oldref;
    botorg = oldorg + width;
    botref = oldref + width;

    if (secondfield)
    {
      /* opposite parity field is in same frame */
      if (pict_struct==TOP_FIELD)
      {
        /* current is top field */
        botorg = cur + width;
        botref = curref + width;
      }
      else
      {
        /* current is bottom field */
        toporg = cur;
        topref = curref;
      }
    }

    field_estimate(toporg,topref,botorg,botref,mb,i,j,sxf,syf,ipflag,
                   &imin,&jmin,&imin8u,&jmin8u,&imin8l,&jmin8l,
                   &dmcfield,&dmc8,&sel,&sel8u,&sel8l,&imins,&jmins,&ds);

    if (M==1 && !ipflag)  /* generic condition which permits Dual Prime */
      dpfield_estimate(topref,botref,mb,i,j,imins,jmins,&imindmv,&jmindmv,
        &dmc_dp,&vmc_dp);

    /* select between dual prime, field and 16x8 prediction */
    if (M==1 && !ipflag && dmc_dp<dmc8 && dmc_dp<dmcfield)
    {
      /* Dual Prime prediction */
      mbi->motion_type = MC_DMV;
      dmc = dmc_dp;     /* L1 metric */
      vmc = vmc_dp;     /* we already calculated L2 error for Dual */

    }
    else if (dmc8<dmcfield)
    {
      /* 16x8 prediction */
      mbi->motion_type = MC_16X8;
      /* upper half block */
      vmc = dist2((sel8u?botref:topref) + (imin8u>>1) + w2*(jmin8u>>1),
                  mb,w2,imin8u&1,jmin8u&1,8);
      /* lower half block */
      vmc+= dist2((sel8l?botref:topref) + (imin8l>>1) + w2*(jmin8l>>1),
                  mb+8*w2,w2,imin8l&1,jmin8l&1,8);
    }
    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;
}

/*
 * frame picture motion estimation
 *
 * org: top left pel of source reference frame
 * ref: top left pel of reconstructed reference frame
 * mb:  macroblock to be matched
 * i,j: location of mb relative to ref (=center of search window)
 * sx,sy: half widths of search window
 * iminp,jminp,dframep: location and value of best frame prediction
 * imintp,jmintp,tselp: location of best field pred. for top field of mb
 * iminbp,jminbp,bselp: location of best field pred. for bottom field of mb
 * dfieldp: value of field prediction
 */
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,