[SDL] Re: slooow

Mattias Blomqvist matbl748 at student.liu.se
Thu Apr 13 13:25:40 PDT 2000


Also correct. if the pixmap were actually transferred with 24 bpp. As it
is now, it is transferred in 32 bpp since the X-server doesnt support 24
bpp and therefore converts it to 32 bpp in software. Making it slower.
It's more of an academic question than a practical one anyway. It got
alot faster using 32 bpp than 24 bpp.

/Mattias

Pierre Phaneuf wrote:
> 
> Mattias.Blomqvist at nokia.com wrote:
> 
> > Yepp. But that wasnt at all what we discussed. Using 32 bits per pixel is
> > faster than using 24. Although only 24 of the bits are used for
> > colorinformation since this is the way that the X-server does. Anyway, it
> > was still much slower than expected.
> 
> Apparently, 24 bits per pixel is actually *faster*, but it makes
> computation on the pixel values more complicated and difficult. But
> transferring 24 bpp pixmaps to the video board takes 75% of the time it
> takes to transfer the same pixmap in 32 bpp. 25% is not negligible!
> 
> --
> Pierre Phaneuf
> Systems Exorcist



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