[x265] [PATCH] motion: bypass the ME search if any of MVC Cost is Zero

[Steve Borho]

On 06/25, gopu at multicorewareinc.com wrote:
> # HG changeset patch
> # User Gopu Govindaswamy <gopu at multicorewareinc.com>
> # Date 1435217502 -19800
> #      Thu Jun 25 13:01:42 2015 +0530
> # Node ID 58a40cd36ed9aa5c5ab94bb8ab2cda8c36a12b05
> # Parent  b1af4c36f48a4500a4912373ebcda9a5540b5c15
> motion: bypass the ME search if any of MVC Cost is Zero
> 
> diff -r b1af4c36f48a -r 58a40cd36ed9 source/encoder/motion.cpp
> --- a/source/encoder/motion.cpp	Wed Jun 24 10:36:15 2015 -0500
> +++ b/source/encoder/motion.cpp	Thu Jun 25 13:01:42 2015 +0530
> @@ -616,6 +616,7 @@
>      MV pmv = qmvp.clipped(qmvmin, qmvmax);
>      MV bestpre = pmv;
>      int bprecost;
> +    int mvcCost = COST_MAX;
>  
>      if (ref->isLowres)
>          bprecost = ref->lowresQPelCost(fenc, blockOffset, pmv, sad);
> @@ -650,7 +651,7 @@
>                  int cost = ref->lowresQPelCost(fenc, blockOffset, m, sad) + mvcost(m);
>                  if (cost < bprecost)
>                  {
> -                    bprecost = cost;
> +                    mvcCost = bprecost = cost;

how is mvcCost different from bprecost?

>                      bestpre = m;
>                  }
>              }
> @@ -666,7 +667,7 @@
>                  int cost = subpelCompare(ref, m, sad) + mvcost(m);
>                  if (cost < bprecost)
>                  {
> -                    bprecost = cost;
> +                    mvcCost = bprecost = cost;
>                      bestpre = m;
>                  }
>              }
> @@ -676,6 +677,10 @@
>      pmv = pmv.roundToFPel();
>      MV omv = bmv;  // current search origin or starting point
>  
> +    //bypass the ME search if any of MVC Cost is Zero

space after //

> +    if (!mvcCost)
> +        goto me_early_exit;

blech

All this needs to do, in theory, is that if it finds an MVC with 0 sad
cost, then it immediately returns with sad + mvcost(mvc).

it's possible there are multiple MVC candidates with 0 sad cost, in
which case we would want to return the one with the cheapest mv cost.
but this may not be worth the trouble (especially since a different AMVP
may be selected after motion estimation returns).

>      switch (searchMethod)
>      {
>      case X265_DIA_SEARCH:
> @@ -1112,6 +1117,8 @@
>          break;
>      }
>  
> +me_early_exit:
> +
>      if (bprecost < bcost)
>      {
>          bmv = bestpre;
> _______________________________________________
> x265-devel mailing list
> x265-devel at videolan.org
> https://mailman.videolan.org/listinfo/x265-devel

-- 
Steve Borho