I was doing a mistake actually. For me 20fps is more than enough In my application i need to draw some graphics after the signal processing. Now I'm trying to use QT library, but unsuccessfully.
In fact i can draw in VGA display and so on, but a simple hello world with is unsing 97% of my processor .... i need to study a little bit more about QT ..... Another option that i found is minigui lib, but i didn't try yet. Felipe On Fri, Sep 25, 2009 at 7:12 PM, Eric Noulard <[email protected]>wrote: > 2009/9/23 Wolfgang Denk <[email protected]>: > > Dear Felipe Castro, > > > > In message <[email protected]> > you wrote: > >> > >> I need some suggestion about how to deal with QT library, or another and > >> xenomai real time path. > >> What I'm working on, is a real time data processing and i need to show > the > >> results in a VGA display. > >> > >> I have my data processing routine running in real time kernel with a > high > >> priority task, and now after 5ms i need to refresh all data in display. > > > > What makes you think so? A refresh every 5 milliseconds means 200 > > frames per second. No human eye is fast enough to see that. > > Even if you relax your timings by a factor of 10 (!) you get 20 frames > per > > second, which is faster than you can actually see. > > I don't know Felipe's test case but I know at least one application > which was a Star Sensor stimulator which needs higher refresh rate than > human eye, but not that high too (32..64Hz max). > The device looking at the screen was not a human in this case. > > In the human case I agree even if you still need a smooth/regular refresh > rate > if you do visualize animated 3D scene which pictures your data. > Some explanation here: > http://www.100fps.com/how_many_frames_can_humans_see.htm > > >> I don't know how to handle it to get my realtime response shown in > display > >> in a realtime too ... > > > > You don't need that, and you don't want that. Instead, you want to > > split your design into a real-time part that does the data acqui- > > sition and processing, and a non-realtime part that does the > > visualization. > > Nevertheless I agree with that, even if you need high refresh rate display > you'll certainly want to decouple display from hard RT data processing. > > >> I did some tests using a simple QT software but it appears to refresh to > >> slow. Is it possible to do ? another question is , is there another > library > >> to handle VGA display tha you suggest me ? > > > > There are many options for the GUI, but you should not attempt to > > select these for their real-time capabilities. If you need a > > RT-capable graphics environment, you can be pretty sure that your > > system is misdesigned. > > I 'm not sure to understand what you say Wolfgang, but I think > that high refresh rate display should certainly be realized using > specialized shader languages (http://en.wikipedia.org/wiki/Shader_language > ) > this must be done in user land (may be non RT) tasks taking their data > from RT ones. > > For 2D images may writing directly to some framebuffer > (http://en.wikipedia.org/wiki/Linux_framebuffer) > may be a solution. > > I did never mix Xenomai with such solution, my experience was with > "classical" linux SCHED_FIFO processes reading some serial port > at most at 32Hz with no HARD jitter requirement. > Thus I don't know the possible "interaction" off an hard RT xenomai process > with some fancy graphic driver. > > What is your precise graphic display need? > > Do you want to display animated 3D scene built from RT data? > 2D image?? > > > -- > Erk > Membre de l'April - « promouvoir et défendre le logiciel libre » - > http://www.april.org > > _______________________________________________ > Xenomai-help mailing list > [email protected] > https://mail.gna.org/listinfo/xenomai-help >
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