[PD] GEM problem with [alpha] on MacOS

IOhannes zmölnig zmoelnig at iem.at
Fri Feb 25 11:27:36 CET 2011


On 02/25/2011 03:15 AM, Matteo Sisti Sette wrote:
> On 02/25/2011 02:41 AM, chris clepper wrote:
> 
>>     Just out of curiosity, who is responsible for determining the color
>>     space used by default?
>>
>> Myself and Jamie Tittle.  The speed difference between YUV and RGBA is
>> massive since all video is the former natively.
> 
> :D Hahahha
> 
> I meant which object. I mean, if it is pix_video who "decides" which
> color space to use (as opposed to the OS or somebody else outside GEM)
> then I guess the same color space could be used by default in all
> platforms.

the source is responsible for choosing the default colorspace, in your
case [pix_video]

> 
> Or is there a particular reason to prefer rgba by default on linux?

there are several:
- legacy
- unlike on OSX, there is no direct support for YUV-textures in openGL
on linux & w32; which means that the conversion has to be done on the
CPU at some stage anyhow
- pix-fx plugins (FreeFrame, frei0r) usually expect 32bit pixels, which
makes the YUV-speedup void if you want to use these.

> I think all unnecessary differences among platform should be avoided
> even in default values (otherwise one is obliged to set everything
> explicitely)...

in many cases (e.g. when not using alpha) you won't (or rather: should
not) notice a difference.

using [pix_rgba] with pixes that are already in RGBA space, should have
virtually no (well, only a very small) overhead.

i suggest making things explicit whenever you need them

gfmasdr
IOhannes

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