[mythtv] OSD issue?

[Andrew Mahone]

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.

> 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.
-- 
Andrew Mahone
andrewmahone AT eml DOT cc