[XviD-devel] SAD cache

[skal]

On Tue, 2003-03-11 at 11:58, Radek Czyz wrote:
> Hi,
> skal wrote,
> 
> >         so far I've seen, it's 10-20% hits for 'regular' fast moving
> >         scenes. For slow moving ones (where the diamond/square search
> >         does not wander too far), it raises up to 20-30%. Conversely,
> >          for 'hard' scenes, it drops to 5%.
> 
> Ooooops, there must be a bug - a big one ;_; .
> 
	Don't rush! These figures are for the SAD-cache in full action,
	using a dull search function that would look like:


void Eval_Dir(SAD_CACHE * const C, int x, int y, int Dir, int * const New_Dir)
  {
    if (Sad_Is_Tested(C, x,y)) return;
    uint32_t Sad = sad16(C->Src, C->Ref+x+y*C->stride, C->stride);
    if (Sad<C->Best_Sad) {
      Cache_Sad(C, x,y,Sad);
      *New_Dir = (*New_Dir & 0xff) | Dir;
    }
  }

int MV_Search(SAD_CACHE * const C, const VECTOR v)
{
  int Dir = 0;
  const uint32_t Best_Sad = C->Best_Sad;
  Dir = 0x0;
  while(1) {
    int x = C->Best_MV.x;
    int y = C->Best_MV.y;
    if (x<C->xMax && !(Dir&0x02)) Eval_Dir(C, x+1,y,  0x100, &Dir);
    if (x>C->xmin && !(Dir&0x01)) Eval_Dir(C, x-1,y,  0x200, &Dir);
    if (y<C->yMax && !(Dir&0x08)) Eval_Dir(C, x,  y+1,0x400, &Dir);
    if (y>C->ymin && !(Dir&0x04)) Eval_Dir(C, x,  y-1,0x800, &Dir);

    if (Dir&0xf00)	// check corners now, if new dir was found
    {
      x = C->Best_MV.x;
      y = C->Best_MV.y;
      if (Dir&0x300) {  
        Eval_Dir(C, x, y+1,0x400, &Dir);
        Eval_Dir(C, x, y-1,0x800, &Dir);
      }
      else {
        Eval_Dir(C, x+1, y,0x100, &Dir);
   	Eval_Dir(C, x-1, y,0x200, &Dir);
      }
      Dir >>= 8;
    }
    else break;
  }
  return (C->Best_Sad<Best_Sad); // success?
}

	The ones in xvid are more refined than this :)


	bye,
			Skal