motion.c

avi2mpg1_src 中包含了mpeg1编码的源程序

    *iminsp = iminb; *jminsp = jminb; *dsp = db;
  }

    /* 选择预测场*/
  if (dt<=db)
  {
    *dfieldp = dt; *iminp = imint; *jminp = jmint; *selp = 0;
  }
  else
  {
    *dfieldp = db; *iminp = iminb; *jminp = jminb; *selp = 1;
  }


  /* 16x8 运动补偿 */

  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);

    /* 为上半部分场选择预测场*/
  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++)
    {
      /* 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)
      {
        /* 垂直场偏调整*/
        if (ppred==0)
          js++;
        else
          js--;

        is<<=1;
        js<<=1;
        if (topfirst == ppred)
        {
          /* 第二场，比例因子为 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
      {
        /* 用来根据底部场图象预测上部的运动向量 */
        it0 = ((3*is+(is>0))>>1);
        jt0 = ((3*js+(js>0))>>1) - 1;

         /* 用来根据顶部场图象预测下部的运动向量 */
        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))
            {
              /* 计算预测错误 */
              local_dist = bdist2(
                ref + (is>>1) + (width<<1)*(js>>1),
                ref + width + (it>>1) + (width<<1)*(jt>>1),
                mb,             /* 当前宏块位置 */
                width<<1,       
                is&1, js&1, it&1, jt&1, 
                8);             /* 块高 */
              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;
              }
            }
          }  /* 结束x循环 */
        } /* 结束y循环 */
      }
    }
  }

  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;
}

/* 全搜索块匹配
blk：块的左上角像素坐标 
h：块的高度 
lx：在参考块中，垂直相邻的像素之间的距离（以字节为单位）
org：源参考图像的左上角像素的坐标
ref：重建参考图像的左上角像素的坐标
i0，j0：搜索窗口的中心点
sx，sy：搜索窗口的半长和半宽
xmax，ymax：搜索区域的右边界和下边界
iminp，jminp：指向存储结果的指针
*/


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 )

/*
 * 求两个块之间绝对差值
 * blk1,blk2：为两个块左上角像素坐标
 *lx：垂直相邻的像素之间的距离（以字节为单位）
 *hx，hy：水平和垂直插值的标志
 *h：块的高度（通常为8或16）
 *distlim：极值，如果结果超过该值则放弃之。
 */
static int dist1(blk1,blk2,lx,hx,hy,h,distlim)