[GEM-dev] GEM HD

IOhannes m zmoelnig zmoelnig at iem.at
Thu Apr 28 09:23:51 CEST 2005


chris clepper wrote:
> On Mar 1, 2005, at 11:27 AM, vade wrote:
> 
>>
>>
>> BTW, we had 2 1080i DVCPro HD Streams running to 2 rects with barely a
>> frame dropped, with 3D transforms and all. Very.. very impressive..
> 
> 
> You know I just figured out that the pixel packing for DVCPRO-HD is
> reversed from what we use in GEM.  That causes a Quicktime routine to
> kick in which eats about 40% of my CPU here.  It's only a change to two
> lines of code to get the proper format, but it would require all of the
> pix_objects to be rewritten!
> 
> So looks like I may have guessed wrong back in Fall of 2002 when picking
> pixel formats.  Oh damn.  This could be something CoreVideo would sort out.

in theory(!) we should be able to handle this (or most of it) by just
fixing some preprocessor defines in the GemPixUtil.h and recompile the
whole thing.
this of course implies, that people used those defines.

thinking while i'm writing i notice, that the major problems might be in
the altivec code. correct ? (i guess there is no way to use those
shift-constants,... in a general but still optimized way within SIMD)

mfg..asdr
IOhannes

> 
> cgc
> 
> 
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