Q:
I'm using QuickTime to draw movie frames into an offscreen
buffer, at which point I draw my own graphics over them and
blit them to the screen. I want to change my code so I instead
draw to the window's back buffer on Mac OS X rather than
to an offscreen. Can I use SetMovieGWorld to draw to the
back buffer?
A:
You can use the SetMovieGWorld function to draw to the window's
back buffer. However, in order for this to work you must
first turn off hardware acceleration for your movie. You
can turn off hardware acceleration for your movie via the
QuickTime movie toolbox SetMoviePlayHints function as shown
in listing 1:
SetMoviePlayHints(myMovie, hintsDontUseVideoOverlaySurface,
hintsDontUseVideoOverlaySurface);
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Listing 1. Using SetMoviePlayHints.
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On Mac OS X, QuickTime will avoid the back buffer if it can
(instead going through hardware acceleration) which means
that you can't then draw "on top" of the video.
This is also true on Mac OS 9.
[Jun 26 2001]
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