[mythtv] OSD issue?

Isaac Richards ijr at po.cwru.edu
Tue Feb 10 15:51:12 EST 2004


On Monday 09 February 2004 05:18 pm, Andrew Mahone wrote:
> Has anybody else seen color "ghosts" of the pause/position and show info
> OSD elements in the CC text when the other OSD elements are not active?
> I've been seeing this in more recent CVS builds, my hunch is that the
> MMX OSD code is responsible, when I get a chance I'll try to back out
> just those changes and see if it fixes it.

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).

> I also noticed in the CVS log that blending could not be done with
> enough precision in MMX while staying faster than C code.  What was the
> operation that was causing trouble?  If it was mulplication, I may have
> a trick from the range scaler that would help.

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.

Isaac


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