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Jerky video playback after long running time



  • I've always noticed this & perhaps it's a QT issue, but when running Isadora for long periods of time (over an hour) the video playback often plays at a quite low frame rate.
    This is most obvious when the patch is "dormant" for quite some time in an installation, waiting to be triggered. I'm using compressed clips that are optimised for fast start.
    any ideas on how to keep the playback "alive"?
    thanks



  • This sounds like it could be related to a memory leak or something along those lines. Mark would have to weigh in though.


  • Tech Staff

    I think this is the QT memory leak issue.

    For instillation work it's quite a tricky thing to do; apart from run an apple script to restart the machine halfway through the day there is not much you can do. I have two Mac Mini running 7 days a week 365 days a year playing video back on a loop using Isadora and they can slow down after 6/7 hours.


  • Dear Nic,

    I apologize for taking so long to chime in on this topic.
    I don't believe there to be any memory leaks in Isadora aside from one that is beyond my control in QuickTime. But that leak should cause problems after days of use -- not hours -- unless you are changing movies every second or something like that.
    Please send me the patch in question so I can see what you're doing. Also, please tell me exactly what version of Isadora you're using.
    Best Wishes,
    Mark


  • Hi Mark,
    no problem, it's taken me til Christmas to get back to you!
    I don't have any specific patches though I've noticed this on simple setups with a movie player & projector pair: speed = 0, playback position takes it's input from OSC (sent by Eyecon and then smoothed). in retrospect I think the low frame rate playback creeps in over days rather than hours and so must be due to the Quicktime issue you've highlighted. Could you suggest any workaround? Would a timed quit and restart of the patch/Isadora help if it was automated at say 12am each day?
    thanks,
    Nic



  • Dear Nic,

    Well, the memory leak thing should only happen when _changing_ movies, not when you play a single movie and change the speed. But you can use AppleScript to something that will shut down and restart Isadora. I don't have a sample handy right now, but this related thread might get you going:
    http://troikatronix.com/troikatronixforum/discussion/319/auto-reopen-on-crash/
    Best Wishes,
    Mark

  • Tech Staff

    Hi Nic,

    I am pretty sure after a few days of running a video a machine will go slow. Does it not start/stop each night?
    Basically the RAM just needs flushing out and restarting is the easiest way to do it.
    My machines in the museum (as above) turn off and start up each day - as long as there is not a power cut! ;)
    They run fine 99% of the time.

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