[mythtv] OSD issue?

[Isaac Richards]

On Tuesday 10 February 2004 06:28 pm, Andrew Mahone wrote:
> On Tuesday 10 February 2004 15:51, Isaac Richards wrote:
> > Doubt it's the mmx blending code, I'd say it's more likely to be the
> > drawSurface->ClearUsed() call (used to be a full clear, but that takes a
> > lot of time at hdtv resolutions, so I changed it a bit).
>
> That was just a hunch, based on when I started seeing it...  but it did
> turn out to be wrong.

So it was ClearUsed() causing the issue?

> > Just see the ifdef'd out (half written) stuff in ttfont.cpp, then compare
> > with the C code in the function below it -- to calculate the proper alpha
> > value when blending onto the temporary surface, it's using a lookup
> > table. When I tried to use the lookup table, it was just about as slow as
> > the c version, and I couldn't come up with an easy way to calculate that
> > stuff.
>
> LUTs kill performance badly, with MMX code, especially if used between
> other operations.  Provided that the values used to index pow_lut are
> available packed, I think I can code the pow_lut function in decently fast
> MMX.

Please do =)  Same problem would affects optimizing the rest of the osd 
drawing functions..

Isaac