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Using Genlock with Decklink HD-SDI capture card...

Question regarding using genlock with the HD-SDI capture card....

We are currently feeding our Axon HD-SDI from an Aux output of the Grass Valley Kayak switcher. Without genlock, the signal is unusable as it has jitters and lock ups. When I hook up genlock (Tri-Level Sync), I get a beautiful signal. However, after some time, it seems like the Axon is no longer syncing to the genlock and I have to reboot. At the top of the day (after sitting overnight), the signal is unusable and I have to reboot. After the reboot, I can take the capture card with about a 5-8 frame delay (I can accept that). However, after a couple of hours, it will be 15-20 frames behind or more. By the end of the day, if I don't reboot the server between, I'm back to the unusable signal (approximately 8-9 hours later).

Our genlock/video system is never shut down and tri-level is constantly running. We don't shut down the Axon either as there are cues that are triggered when we are away. Is there anything I can look at/check or does anyone have any ideas what might be causing the drifts?

J
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    I'm going to venture a guess that it's the nature of the capture card. Unless HES has worked with the card capture manufacturer or found a way to bypass the cache on their own, you will see a drift over time. Capture cards are not concerned with going "as fast as possible", but are trying to get everything frame accurate. The cache will get filled up with bad frames and thus push back your video stream. Resetting the server clears this cache and thus you are back to not having a bad delay. I could be wrong, but I believe this is how it works with most capture cards.

    Cheers,
    -
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  • 0
    I'm going to venture a guess that it's the nature of the capture card. Unless HES has worked with the card capture manufacturer or found a way to bypass the cache on their own, you will see a drift over time. Capture cards are not concerned with going "as fast as possible", but are trying to get everything frame accurate. The cache will get filled up with bad frames and thus push back your video stream. Resetting the server clears this cache and thus you are back to not having a bad delay. I could be wrong, but I believe this is how it works with most capture cards.

    Cheers,
    -
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