Distorted Video From U-Matic 3/4" Into Teranex 2D

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mountaincabbage

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Distorted Video From U-Matic 3/4" Into Teranex 2D

PostSat Mar 31, 2018 2:27 pm

Hello Everyone,

I'm in a bit of a pickle here, trying to convert some U-Matic tapes to digital, but I'm getting a very distorted video in to the teranex.

First started by trying to directly capture from the U-Matic, using a decklink duo, which appeared to provide no signal (just a black screen on media express).

Then got a teranex 2D, which provided a video out, but very distorted with a black horizontal line across the video, as seen here: https://photos.app.goo.gl/mEpBlXa0YKzYjlFP2

So I had a look online and found out that one fix may be to feed in a pal signal into the U-Matic video in or reference input, but this did not seem to do anything?

I've also tried running the signal through a TBC, prior to the teranex, which did nothing.

Can someone help me please?

Thanks,
Geoff
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Peter Cave

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Re: Distorted Video From U-Matic 3/4" Into Teranex 2D

PostTue Apr 03, 2018 1:19 am

You may need to use a Black Burst generator to feed a reference signal to both the U-Matic deck and the Decklink card. You will also need a TBC for the U-Matic output to guarantee a stable signal. With analog signals, stability of the horizontal and vertical sync pulses is super important.
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JPOwens

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Re: Distorted Video From U-Matic 3/4" Into Teranex 2D

PostTue Apr 03, 2018 2:34 pm

mountaincabbage wrote: very distorted with a black horizontal line across the video, as seen


Had to turn this on its side... you took a vertical iphone snapshot of the screenvid?

Okay, the "Black bar" is displaced vertical interval as a result of unsynchronized time base correction. TBC correction of baseband depends on Advanced Sync supplied to the player unit so that the active scanlines start coherent with the TBC's memory window, which stabilizes the horizontal sync. Most time base correctors of this vintage only have a correction window of a few lines (vertical). For more than that, you need a "Frame Synchronizer" -- which -- really -- should have been the BMD Teranex, but it doesn't do that. And mostly because it can't supply Advanced Sync anyway.

Typically, a work-around for this kind of task would either involve a capture unit that can
"Sync to incoming video," capture "wild," or dub to a higher format and recapture. Those boil down to the practical choices that you would have in the same situation as a consumer VHS deck.

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Frank Wylie

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Re: Distorted Video From U-Matic 3/4" Into Teranex 2D

PostMon Apr 16, 2018 3:21 pm

Back in the "bad old days" when I worked in TV, we could improvise a stable blackburst generator by using a 2nd UMatic deck running a pre-recorded tape with a black signal in conjunction with the tape to be dubbed.

We fed the video signal out of the 2nd deck into the sync input deck of the 1st deck and then looped it through to the 3rd device to provide a reference signal.

Might be worth a shot, but of course, you'll need a 2nd deck and a tape with uninterrupted control track and video black...
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