Internal Keying

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Max Christ

  • Posts: 4
  • Joined: Thu Apr 04, 2013 3:55 pm
  • Location: Cologne, Germany

Internal Keying

PostWed Jan 14, 2015 7:28 pm

I have an ATEM Switcher and an Ultrastudio 4K and I am working on an application called BoinxTV that generates video (with alpha channel).

This is my setup for external keying. External keying is working without any problems.
Code: Select all
App -> (Thunderbolt) US4K
                     US4K (SDI OUT A) -> (SDI IN 5) ATEM
                     US4K (SDI OUT B) -> (SDI IN 6) ATEM
                                                    ATEM (SDI PROG) -> TV
However my internal keying setup is not working. And I don't understand why.
Code: Select all
ATEM (SDI PROG) -> (SDI IN A) US4K
App          -> (Thunderbolt) US4K
                              US4K (SDI OUT A) -> TV
When BoinxTV is not running I get the plain output signal from the ATEM Switcher. But as soon as I start my application and setup internal keying the only output I get is the video generated by my application with a black background.

The code I use to control the Decklink SDK is exactly the same except for the parameter to DeckLinkKeyer::Enable(bool external);. I use bmdFormat8BitARGB as pixel-format and frames are provided using DeckLinkOutput::DisplayVideoFrameSync(IDeckLinkVideoFrame *frame);.

What am I missing?
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Matt Jefferson

Blackmagic Design

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Re: Internal Keying

PostFri Jan 16, 2015 12:29 am

HI Max -
Thanks for posting the question. I sent you a private message to followup. Let me know the results. The Ultrastudio 4K does support internal and external keying as you state but most are using 10bit formats from my experience.

Also currently, the maximum resolution via the Ultrastudio 4K for keying is 1080p30.
Matt Jefferson
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Max Christ

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  • Joined: Thu Apr 04, 2013 3:55 pm
  • Location: Cologne, Germany

Re: Internal Keying

PostFri Jan 16, 2015 8:25 am

Thanks to your support I was able to find that my setup was correct. But my SDK usage was wrong.

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