Scaled key signal

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Jonas Geduldig

  • Posts: 13
  • Joined: Tue Jun 17, 2014 7:04 pm

Scaled key signal

PostTue Aug 22, 2017 7:17 pm

I'm having an issue with the key signal's luminance being scaled.

I have driver version 10.9.3 on Windows 7 with the 4K Extreme and the Duo 2. I'm using Live Key to display a TGA file with a full key as 720p 59.94.

When I look at the key output from the Duo 2 in a scope the luminance range is 0 to 100%. However, the key output from the 4K Extreme appears to be scaled. Viewed in a scope the black level is greater than 0% (looks like 7.5 IRE), and the full key is less than 100%. The scaling is what I would expect for NTSC.

Is there a setting that the 4K Extreme requires (that the Duo 2 does not require) to get the full luminance scale? Shouldn't it be automatically scaled correctly for the HD setting I'm using?
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Tim Philip

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  • Joined: Thu Feb 09, 2017 4:47 am

Re: Scaled key signal

PostThu Aug 24, 2017 11:57 am

I have the same problem with the external key on both 4K Extreme and 4K Pro cards using 10.8.3 driver.

The luminance has a maximum of about 92% and minumum of about 7%. White is 92% and black is 7%, whereas they should be 100% and 0%.

I have check the values in the memory I am passing in the alpha byte of the videoframe and they have the correct values of 0x00 and 0xFF.

The keyer level is set to 255. Everything else I have checked is fine. The problem is the key output.

I recently put these into production and this is causing all sorts of keying problems - IS THERE A SOLUTION?
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Tim Philip

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  • Joined: Thu Feb 09, 2017 4:47 am

Re: Scaled key signal

PostThu Aug 24, 2017 11:58 am

BTW further to my last post I am using 1080i50 SDI output.
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Tim Philip

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Re: Scaled key signal

PostThu Aug 24, 2017 12:46 pm

Driver version 10.9.5a4 solves the external key level problem with 4K Extreme on Linux at 1080i50.

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