Unable to get Synchronous Projections from 2 Projectors
  • yesyes
    junior Member
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    Joined: Mon Apr 13, 2015 7:01 pm

    Unable to get Synchronous Projections from 2 Projectors

    by yesyes » Mon Apr 20, 2015 6:41 pm


    I'm pointing 2 projectors at the same screen. At any instant, one projector sends out a wall of white light, and the other, black. At the next instant, the first one is black, and the second one throws a white rectangle. As a result, the screen should remain white continuously. But!, the screen goes black for a fraction of a second, often, and i'm unable to eliminate this issue.


    The setup
    • A MacPro 2013, or a 13" MBP Retina with an integrated Graphics Card (the issue persists, no matter which computer i use)
    • An uncompressed video at 30fps with a bitrate of under 10Mbps. My projectors are 1024x768; so my video is 2048x768. The video is essentially identical to the GIF image attached to this post. Image
    • MadMapper takes the video and cuts it into two pieces (and also corrects the perspective)
    • 2 projectors (BenQ MX525's) connected via MiniDisplayPort to DVI adapters.

    Ideally, since one projector sends out a white wall whenever the other projects nothing (or, black), the screen should remain white at all times. But there are very brief moments where the screen goes black : which means that one projector switched from White-to-Black while the other was still switching from Black-to-White.

    Any ideas how i may fix this?

    What i suspect, and what i don't
    • Is my computer too weak? » No.
    • The video is too heavy, and hence the computer is struggling. » No.
    • MadMapper is sending signals to the projectors one-after-the-other (albeit only a fraction of a second apart). » Perhaps. I don't know. But i like to believe that this isn't the case.
    • MM sends signals to both projectors simultaneously, but something in the pipeline makes it asynchronous. » Perhaps. But i don't know enough about hardware to be sure. And don't know how i'd fix such an issue. Do i need a Graphics Card which supports FrameLocking? If so, then: any suggestions?
    • The projectors get the signals at the exact same instant, but they're imperfect. » I doubt so.

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