Le 16/07/2012 19:31, Theo Burt a écrit : > Hi, me and a friend of mine do a lot of live audio-video performance, > professionally, all using pd/gem as an environment. We both use > Macbook Pros (different models), and for the last couple of years > we've been having a serious problem which we now suspect is something > to do with GEM/PD, rather than, for example, the graphics cards or > drivers. > > The problem occurs when running at higher frame rates - it is highly > preferable for us to run at 60 frames per second, because (1) it syncs > with the refresh rates of most projectors and seems to produce much > smoother/more regular movement, and (2) often we are using very > precise, high frequency flashing, for optical effects, that we need to > be able to sync exactly with screen refreshes. We are generally > running the gem window in a second screen (such as a monitor or > projector), but it happens when running on one screen too. > > As soon as we run at 60 frames per second (or near it), glitching > starts to occur frequently in the audio, and the audio goes out of > sync with GEM. While the glitching is occurring, processes in PD and > GEM jerk along, pausing frequently. To resolve it (temporarily), the > audio has to be reset in PD (by reselecting the audio device). The > glitching then goes away and everything runs smoothly, but it returns > spontaneously after a short time. The glitching is also exacerbated by > moving windows around on the screen. It might be worth noting that the > same patch running on the very same machine in Windows XP (using > bootcamp) does not have this problem. > > We have different GPUs, mine is a Nvidia 9600m GT, and his was an ATI > of some sort. We are using very simple, geometric graphics, and are > not approaching the processing limits of the GPUs at all (if I do push > the graphics card very hard, I notice that frames are skipped rather > than glitching occurring). I also note that it happens equally when > there is low CPU activity, so it's not related to that. > > My friend has just purchased a new Macbook Pro, yesterday with a 60% > more powerful Nvidia GPU, and unfortunately the glitching is still > occurring. It occurs in OS X Lion, and also was happening in Snow > Leopard. We've tried disabling power management on the GPU, and this > doesn't help either. > > I've looked through the gem code in an attempt to try and understand > what is happening, but I am afraid it is beyond me! > > Does anyone have any idea at all what the problem could be? It would > make such a huge difference to us if we could resolve it. Thanks very > much for any help in advance (and for developing GEM in the first place) > > All the best, Theo > > _______________________________________________ > GEM-dev mailing list > [email protected] > http://lists.puredata.info/listinfo/gem-dev
Hello, Can you provide a small exemple patch with this trouble ? When you use Gem and sound, it is a good practice to separate these two process on different cores to avoid glitch. You have 2 solutions to achieve this : - use [pd~] (see the help patch) - use 2 instances of Pd, one for Gem, the other for the sound, and send data between these two instances with [netsend]/[netreceive] (the system should manage these two instances on different cores). ++ Jack _______________________________________________ GEM-dev mailing list [email protected] http://lists.puredata.info/listinfo/gem-dev
