motion.c

MPEG2视频编解码算法方面的源代码(包括编码和解码)

 * blk: top left pel of (16*h) block
 * h: height of block
 * lx: distance (in bytes) of vertically adjacent pels in ref,blk
 * org: top left pel of source reference picture
 * ref: top left pel of reconstructed reference picture
 * i0,j0: center of search window
 * sx,sy: half widths of search window
 * xmax,ymax: right/bottom limits of search area
 * iminp,jminp: pointers to where the result is stored
 *              result is given as half pel offset from ref(0,0)
 *              i.e. NOT relative to (i0,j0)
 */
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;

  /* full pel search, spiraling outwards */

  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;
}

/*
 * total absolute difference between two (16*h) blocks
 * including optional half pel interpolation of blk1 (hx,hy)
 * blk1,blk2: addresses of top left pels of both blocks
 * lx:        distance (in bytes) of vertically adjacent pels
 * hx,hy:     flags for horizontal and/or vertical interpolation
 * h:         height of block (usually 8 or 16)
 * distlim:   bail out if sum exceeds this value
 */
static int dist1(blk1,blk2,lx,hx,hy,h,distlim)
unsigned char *blk1,*blk2;
int lx,hx,hy,h;
int distlim;
{
  unsigned char *p1,*p1a,*p2;
  int i,j;
  int s,v;

  s = 0;
  p1 = blk1;
  p2 = blk2;

  if (!hx && !hy)
    for (j=0; j<h; j++)
    {
      if ((v = p1[0]  - p2[0])<0)  v = -v; s+= v;
      if ((v = p1[1]  - p2[1])<0)  v = -v; s+= v;
      if ((v = p1[2]  - p2[2])<0)  v = -v; s+= v;
      if ((v = p1[3]  - p2[3])<0)  v = -v; s+= v;
      if ((v = p1[4]  - p2[4])<0)  v = -v; s+= v;
      if ((v = p1[5]  - p2[5])<0)  v = -v; s+= v;
      if ((v = p1[6]  - p2[6])<0)  v = -v; s+= v;
      if ((v = p1[7]  - p2[7])<0)  v = -v; s+= v;
      if ((v = p1[8]  - p2[8])<0)  v = -v; s+= v;
      if ((v = p1[9]  - p2[9])<0)  v = -v; s+= v;
      if ((v = p1[10] - p2[10])<0) v = -v; s+= v;
      if ((v = p1[11] - p2[11])<0) v = -v; s+= v;
      if ((v = p1[12] - p2[12])<0) v = -v; s+= v;
      if ((v = p1[13] - p2[13])<0) v = -v; s+= v;
      if ((v = p1[14] - p2[14])<0) v = -v; s+= v;
      if ((v = p1[15] - p2[15])<0) v = -v; s+= v;

      if (s >= distlim)
        break;

      p1+= lx;
      p2+= lx;
    }
  else if (hx && !hy)
    for (j=0; j<h; j++)
    {
      for (i=0; i<16; i++)
      {
        v = ((unsigned int)(p1[i]+p1[i+1]+1)>>1) - p2[i];
        if (v>=0)
          s+= v;
        else
          s-= v;
      }
      p1+= lx;
      p2+= lx;
    }
  else if (!hx && hy)
  {
    p1a = p1 + lx;
    for (j=0; j<h; j++)
    {
      for (i=0; i<16; i++)
      {
        v = ((unsigned int)(p1[i]+p1a[i]+1)>>1) - p2[i];
        if (v>=0)
          s+= v;
        else
          s-= v;
      }
      p1 = p1a;
      p1a+= lx;
      p2+= lx;
    }
  }
  else /* if (hx && hy) */
  {
    p1a = p1 + lx;
    for (j=0; j<h; j++)
    {
      for (i=0; i<16; i++)
      {
        v = ((unsigned int)(p1[i]+p1[i+1]+p1a[i]+p1a[i+1]+2)>>2) - p2[i];
        if (v>=0)
          s+= v;
        else
          s-= v;
      }
      p1 = p1a;
      p1a+= lx;
      p2+= lx;
    }
  }

  return s;
}

/*
 * total squared difference between two (16*h) blocks
 * including optional half pel interpolation of blk1 (hx,hy)
 * blk1,blk2: addresses of top left pels of both blocks
 * lx:        distance (in bytes) of vertically adjacent pels
 * hx,hy:     flags for horizontal and/or vertical interpolation
 * h:         height of block (usually 8 or 16)
 */
static int dist2(blk1,blk2,lx,hx,hy,h)
unsigned char *blk1,*blk2;
int lx,hx,hy,h;
{
  unsigned char *p1,*p1a,*p2;
  int i,j;
  int s,v;

  s = 0;
  p1 = blk1;
  p2 = blk2;
  if (!hx && !hy)
    for (j=0; j<h; j++)
    {
      for (i=0; i<16; i++)
      {
        v = p1[i] - p2[i];
        s+= v*v;
      }
      p1+= lx;
      p2+= lx;
    }
  else if (hx && !hy)
    for (j=0; j<h; j++)
    {
      for (i=0; i<16; i++)
      {
        v = ((unsigned int)(p1[i]+p1[i+1]+1)>>1) - p2[i];
        s+= v*v;
      }
      p1+= lx;
      p2+= lx;
    }
  else if (!hx && hy)
  {
    p1a = p1 + lx;
    for (j=0; j<h; j++)
    {
      for (i=0; i<16; i++)
      {
        v = ((unsigned int)(p1[i]+p1a[i]+1)>>1) - p2[i];
        s+= v*v;
      }
      p1 = p1a;
      p1a+= lx;
      p2+= lx;
    }
  }
  else /* if (hx && hy) */
  {
    p1a = p1 + lx;
    for (j=0; j<h; j++)
    {
      for (i=0; i<16; i++)
      {
        v = ((unsigned int)(p1[i]+p1[i+1]+p1a[i]+p1a[i+1]+2)>>2) - p2[i];
        s+= v*v;
      }
      p1 = p1a;
      p1a+= lx;
      p2+= lx;
    }
  }

  return s;
}

/*
 * absolute difference error between a (16*h) block and a bidirectional
 * prediction
 *
 * p2: address of top left pel of block
 * pf,hxf,hyf: address and half pel flags of forward ref. block
 * pb,hxb,hyb: address and half pel flags of backward ref. block
 * h: height of block
 * lx: distance (in bytes) of vertically adjacent pels in p2,pf,pb
 */
static int bdist1(pf,pb,p2,lx,hxf,hyf,hxb,hyb,h)
unsigned char *pf,*pb,*p2;
int lx,hxf,hyf,hxb,hyb,h;
{
  unsigned char *pfa,*pfb,*pfc,*pba,*pbb,*pbc;
  int i,j;
  int s,v;

  pfa = pf + hxf;
  pfb = pf + lx*hyf;
  pfc = pfb + hxf;

  pba = pb + hxb;
  pbb = pb + lx*hyb;
  pbc = pbb + hxb;

  s = 0;

  for (j=0; j<h; j++)
  {
    for (i=0; i<16; i++)
    {
      v = ((((unsigned int)(*pf++ + *pfa++ + *pfb++ + *pfc++ + 2)>>2) +
            ((unsigned int)(*pb++ + *pba++ + *pbb++ + *pbc++ + 2)>>2) + 1)>>1)
           - *p2++;
      if (v>=0)
        s+= v;
      else
        s-= v;
    }
    p2+= lx-16;
    pf+= lx-16;
    pfa+= lx-16;
    pfb+= lx-16;
    pfc+= lx-16;
    pb+= lx-16;
    pba+= lx-16;
    pbb+= lx-16;
    pbc+= lx-16;
  }

  return s;
}

/*
 * squared error between a (16*h) block and a bidirectional
 * prediction
 *
 * p2: address of top left pel of block
 * pf,hxf,hyf: address and half pel flags of forward ref. block
 * pb,hxb,hyb: address and half pel flags of backward ref. block
 * h: height of block
 * lx: distance (in bytes) of vertically adjacent pels in p2,pf,pb
 */
static int bdist2(pf,pb,p2,lx,hxf,hyf,hxb,hyb,h)
unsigned char *pf,*pb,*p2;
int lx,hxf,hyf,hxb,hyb,h;
{
  unsigned char *pfa,*pfb,*pfc,*pba,*pbb,*pbc;
  int i,j;
  int s,v;

  pfa = pf + hxf;
  pfb = pf + lx*hyf;
  pfc = pfb + hxf;

  pba = pb + hxb;
  pbb = pb + lx*hyb;
  pbc = pbb + hxb;

  s = 0;

  for (j=0; j<h; j++)
  {
    for (i=0; i<16; i++)
    {
      v = ((((unsigned int)(*pf++ + *pfa++ + *pfb++ + *pfc++ + 2)>>2) +
            ((unsigned int)(*pb++ + *pba++ + *pbb++ + *pbc++ + 2)>>2) + 1)>>1)
          - *p2++;
      s+=v*v;
    }
    p2+= lx-16;
    pf+= lx-16;
    pfa+= lx-16;
    pfb+= lx-16;
    pfc+= lx-16;
    pb+= lx-16;
    pba+= lx-16;
    pbb+= lx-16;
    pbc+= lx-16;
  }

  return s;
}

/*
 * variance of a (16*16) block, multiplied by 256
 * p:  address of top left pel of block
 * lx: distance (in bytes) of vertically adjacent pels
 */
static int variance(p,lx)
unsigned char *p;
int lx;
{
  int i,j;
  unsigned int v,s,s2;

  s = s2 = 0;

  for (j=0; j<16; j++)
  {
    for (i=0; i<16; i++)
    {
      v = *p++;
      s+= v;
      s2+= v*v;
    }
    p+= lx-16;
  }
  return s2 - (s*s)/256;
}