Hello; ext Tobias Oberstein wrote: > Hello tableteers, > > I've done some initial experiments hacking my N800/OS2008 and ran into a > couple of issues: > > When using the supplied SDL library for doing timer-based frame > rendering, there seems to be > > - heavy tearing >
Tearing unfortunately happens because there is no vsync available for framebuffer driver to use. > - significant overhead due to X server > (rendering pipe is : SDL -> X -> Framebuffer) > > The overhead here is probably not as big as you expect. SDL uses shared memory extension to create and update image(s) so all it passes to X is pointer and then X copies the data to framebuffer driver. > [Note: yes, I'm aware that doing full screen blits is evil on the N800 > due to limited framebuffer -> video RAM bus bandwidth.] > > Q: Is this expected behaviour? What could I do about the tearing? What > about the Xomap overhead? > > You cannot help the tearing, you might want to try with different timer values etc. to make end result look better. If you are planning to develop a game you could take a look at : http://maemo.org/community/wiki/gamedevelopment/ You should try to minimize the amount of updated area and redraws. > == > > I've read a lot of bits on the web 'bout mplayer, vsync, omapfb etc. > and tried to assemble a minimal example of using direct framebuffer > access for gfx output. > > Q: I can't get the tearing away (only fixed at certain line positions). > What am I doing wrong? > > Nothing, you cannot get away from tearing. > Q: Also, frame rate is sluggish, though CPU load is much lower than > SDL/X. Ok, my FB example is not threaded like the SDL timer example .. > is that the reason for framerate even < 15/s? > > > Q: btw - how can I shutdown Maemo Launcher/Hildon/Matchbox/Xomap? > Whenever I do one of > > Quite likely this won't really help you with the performance issues. > /etc/init.d/maemo-launcher stop > /etc/init.d/x-server stop > > the device will automatically reboot. > > == > > I wondered if there would be any plans to make SDL run directly on > framebuffer .. if not, I'd maybe give it a try. > > I would be interested in these results too but I wouldn't expect so much performance boost from there. > Q: Where can I find the sources to the OS2008 SDL? > > I wish I knew. Anyway, there is not significant changes in our SDL, you can safely browse the upstream source at http://libsdl.org/ > Thx and cheers, > > tgo > // Tapani Pälli -- Software Engineer Open Source Software Operations _______________________________________________ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
