Thread: iPhone and iPod Touch SDK is amazing... Wow.
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fms is offline fms
2008-03-07 , 19:51
Posts: 1,418 | Thanked: 1,541 times | Joined on Feb 2008
#63
Originally Posted by fanoush View Post
internal 640x480 SRAM is used for additional video plane (why not when we have it) but this does not bring big benefits now as it also needs to be transferred to external chip (together with rest of normal 800x480 framebuffer in SDRAM).
This does not sound like much of a problem, more like an optimization. You can only transfer parts of the screen that you change and thus save memory bandwidth.

- as for 3D - maybe the video plane in SRAM would be a benefit but maybe not, I don't know if the (currently unused) 3D chip can draw to it or must draw to SDRAM and what is performance of both solutions (if both are possible). Maybe it doesn't matter much and this is not the main problem, see below
Taking into account that both PowerVR and the framebuffer are integrated into the same OMAP2 chip, the PowerVR should be usable to render directly into that framebuffer. You can then tell the hardware to transfer that framebuffer to the display.

- current video system is pretty complex even now so it is not surprise that nobody at Nokia pushed hard for making 3D acceleration working.
As far as I could tell from your information, it just adds an extra step before things show up at the display. Funnily, at least some (if not all) iPods use the same mechanism. It is not very complex, just a bit cumbersome.