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Genlock – not sure when I need it.
I have a DL Extreme card and had the assumption the card provides sync and decks sync to it. However I noticed that the genlock cable is an input.
Frankly I haven’t had a setup where I needed to use the genlock cable, but at the same time would like to know when to use and for what purpose.
Perhaps not using has been causing the occasional problems I have editing to tape from FCP to a BVW-D75 BetacamSP deck (I use SDI out).
I have little knowledge about using genlock so I am looking for some enlightenment beyond what’s available on howstuffworks.com
Tangier
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4 Replies
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Genlock is for integration into a live “on-line” television production environment with a switcher, many tape decks, and cameras all running in sync to house black. Say for example you wanted to put your Decklink Extreme system online and run the output to a switcher and mix it with live TV camera feeds for a live sporting event.
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Really? I’ve been told in the past that in order to record back to a BetaCamSP deck from a Decklink card, I would need a blackburst generator (e.g. Horita) which connects to the deck and the Decklink card. Is this still true?
-AJ
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Genlock is an external clock. You need it to stabilize the speed of any VTR (a beta SP or Beta digital for example). The servo for the motor will be clocked to the genlock, ensuring a perfect speed from start to finish. Genlock is also used in live situation to ensure that video switcher are switching on the same video edge as the camera, but that’s another (more complicated) issue.
With non-linear video, genlock is used to stabilize the speed of playback, ensuring you are always playing at the perfect speed. also, when transfering from the Decklink to the Beta, you need to sync the frame edges from the card, with the frame edges the Beta is expecting. this is why you need a genlock. there is a way of telling the Beta to sync to the incoming video signal (that’s the way consumer equipment works), but it is less stable.
It is more complicated that those few lines, but to make a long story short, having each piece of equipement locked to a central clock ensures that those equipement will “talk” at the same speed. there are other ways of doing it, but this one has been proven reliable for a long time.
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Try connecting the Y output of the DeckLink card to the reference input of the Beta deck, and then loop out into the Y input of the deck, and terminate. That should let the deck lock to the DeckLink.
Secondly, you can set the deck to “sync on input” in the dial menu if you are using a deck that has this feature.
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