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Testing Decklink HD Extreme Setup

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jonas echterhoff
Testing Decklink HD Extreme Setup
on Nov 12, 2008 at 6:18:22 pm

I want to add support for SDI video input using the Decklink HD Extreme to our product. I can see the device fine in any QuickTime-enabled video input software. But I'd like to test getting some actual images out of it, and I don't have any other SDI equipment. So I figured it should be possible to test this by simply connecting the card's output to it's input using a BNC cable. Then I tried using the Blackmagic Deck Control app to test it, by playing back video. I tried all sorts of different settings, and the Grab Frame commands. But all I ever see on the right side screen is black. Is there any way to actually get some images into and out of the card, using just a loop-back cable?

Any help appreciated,
jonas


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Bob Zelin
Re: Testing Decklink HD Extreme Setup
on Nov 13, 2008 at 12:08:08 am

you can try "tricks" all day long (and no, there is no loop back test). I have been in many unfortunate situations, with hardware from many companies, including AVID - where I have fully tested the system (like an AVID that had a loop back test), and when I got to the location, the SDI inputs did not work.

To test the SDI input/output, you need SDI gear - if this means dragging your entire computer to someone that you know, that owns a digi Beta VTR - then do it. There are no shortcuts, without some sort of SDI source, and SDI monitoring.

Bob Zelin




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jonas echterhoff
Re: Testing Decklink HD Extreme Setup
on Nov 13, 2008 at 9:25:47 am

Thanks for your reply. So, while I can take a "No" for an answer, can you be more specific? I have a Card which has a video-out and video-in. Is there any technical reason, why I shouldn't be able to connect the two, and then get an image into the video-in?

Thanks,
jonas



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Bob Zelin
Re: Testing Decklink HD Extreme Setup
on Nov 13, 2008 at 11:52:49 pm

I am not aware of any card manufacturer, except for AVID (with the Meridian and Adreanline products) that offer a "loop back" function. This means that to my knowlege, Blackmagic, AJA, Matrox and MOTU do not offer a "loop back" test to diagnose if your SDI input/output is working. The normal process is to put an SDI source into your system, and see if it works. If you don't own an SDI source, or have access to an SDI source, Blackmagic (and others) make very inexpensive analog to SDI and SDI to analog converters, that will allow you to take anything (like a VHS machine, DVD, or Beta VTR) converted to SDI to get into the SDI input.

But if you are saying - "I don't have any SDI sources, I don't have access to any SDI sources, I don't want to buy any converters, and I dont' want to go anywhere with my computer where there are SDI sources - I just want to test it here, and I don't have any SDI anything - how can I tell if it works" - well - you can't tell.
Not unless there is some secret that I don't know about.

Bob Zelin





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Margus Voll
Re: Testing Decklink HD Extreme Setup
on Nov 14, 2008 at 6:53:44 am

SDI secrets by Bob.

God one :)



--

Margus

http://iconstudios.eu


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jonas echterhoff
Re: Testing Decklink HD Extreme Setup
on Nov 14, 2008 at 10:27:03 am

Fair enough, thanks. I'm getting another Decklink card next week for my other machine, so I should be able to connect the two together, thus solving the issue. I still don't understand why, if I have an output and an input, I shouldn't be able to connect them to each other, thus getting a signal on the input, but, well, I'll just accept that for the time being :)

jonas



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Bob Zelin
Re: Testing Decklink HD Extreme Setup
on Nov 20, 2008 at 11:50:41 pm

you don't understand why - I will tell you why. Because for the card to output a signal, and hold it, it requires a FRAME BUFFER. Then, someone at Blackmagic (or AJA, or MOTU, or Matrox) has to write software for a loopback test - which they have not. Gee -the Blackmagic card is SO DAMN EXPENSIVE - you would figure for ALL THAT MONEY, they would continue to write more and more code for free (oh, they do, and there are free software updates all the time - just no loopback test for you !).

Baby !

Bob Zelin




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