[SDL] Re: slooow

William Kendrick nbs at sonic.net
Thu Apr 13 13:14:23 PDT 2000


> 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!

For moving huge blocks this is true, I guess...

But I believe (and I'm unfortunately no expert) that the reason 32-bit is
usually considered faster than 24-bit is because of the alignment of bytes.

CPU's are MUCH better at moving 1, 2, 4, etc. bytes at a time than they
are 3, 5, etc. bytes at a time.

-bill!



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