OS/X11 support for XO-1 hardware?

Benjamin M. Schwartz bmschwar at fas.harvard.edu
Thu Feb 26 00:46:21 EST 2009

david at lang.hm wrote:
>>  It would allow for much improved
>> video performance since you could play back a 320x240
>> video on the full screen at considerable CPU savings.
> except that you would spend those CPU savings doing the scaling up from 
> 320x240 to the higher resolution.

Argh and double argh! You're both wrong.

1. Video playback in any sane player is already routed through XV, which
uses the GPU's video overlay scaler (and YUV->RGB converter).  The result
is that playing a 320x240 video at 1200x900 full-screen already costs zero
extra CPU cycles.  No need to mess with screen resolution.

2. The Geode LX GPU can do both output scaling and video-overlay scaling,
independently, at the same time.  On the latest drivers, we should be able
to set the screen resolution to 600x450, scaled up to 1200x900, and then
play a 320x240 video, scaled up to 480x360 (which means 960x720 physical
LCD pixels), all without using any CPU power for scaling.

There are lots of good reasons to play with screen resolution.  My
favorite reason is that reducing the resolution to 800x600 would make all
graphical operations runs twice as fast, and use half as much memory,
while introducing a negligible drop in display quality (the display,
remember, is not _really_ 1200x900 in color mode; the total number of
color elements is equivalent to 800x450).


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