DeckLink 8K Pro - Signal with 2 different resolutions

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CedricLarvoire

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DeckLink 8K Pro - Signal with 2 different resolutions

PostTue Jun 18, 2019 2:13 pm

Hi every one!

and I hope I'm not asking too dumb of a question, I have searched through the manuals but haven't figured out how to do this yet. I am building a small grading setup at a friend's post-prod company. We have DaVinci running on a PC and a Decklink 8K Pro card. I would like to send from DaVinci Resolve one signal to my grading monitor (a FSI in HD resolution so I need a HD signal) and one signal to the client's monitor that is a 4K TV (that is HDMI only so the signal is going through a Teranex Mini to convert).

But I have not figured out how to send signals of 2 different resolution.
- In DaVinci Resolve > Preference > Video and Audio I/O, I have selected the first video stream as my output: DeckLink 8K Pro (1). and in Project Settings > Master Settings, I can choose my video format
- in parallel, in Desktop Video Setup, I have assigned the video stream DeckLink 8K Pro (1) to the connectors 1 to 4 (SDI 1 to 4 In or Out)

I do get my video signal on all SDI ports, but they are always of the resolution set in Resolve. So my question is how to I get to choose to send and HD signal to let's say SDI 1, and 4K to SDI 2 that will go to the Teranex and eventually to the 4K monitor. Am I understand the workflow wrong?

Thanks a lot!
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Jack Fairley

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Re: DeckLink 8K Pro - Signal with 2 different resolutions

PostTue Jun 18, 2019 6:21 pm

The settings in Resolve override the defaults set in Desktop Video. I would try setting the Resolve monitoring format to your desired UHD signal, and setting SDI configuration to single link. I believe on cards with multiple SDI output channels, one of them will be set to HD.
Threadripper 1950X 3.7GHz
64GB DDR4-2666
2x GTX 1080 Ti
DeckLink 4K Extreme 12G
Resolve Studio 16.1
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CedricLarvoire

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Re: DeckLink 8K Pro - Signal with 2 different resolutions

PostWed Jun 19, 2019 11:16 pm

Cool, thanks for the answer I'm gonna try that asap and keep you updated :)
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CedricLarvoire

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Re: DeckLink 8K Pro - Signal with 2 different resolutions

PostFri Jun 21, 2019 11:35 am

Hello again, so I have tried to set my video playback to UHD.

One SDI cable goes into my HD FSI, one SDI cable goes through Teranex Mini then to UHD TV. and I've tried to switch those cables in every possible combination, I still don't get any HD signal to the FSI. The DeckLink 8K pro is sending 4x UHD signals it seems.

Would you have any other idea? Apart from outputing only UHD signals and running one through something like an AJA 4k to HD box? that would seem really unnecessary, there must be a lot of people having such a configuration, right? :)
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Jack Fairley

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Re: DeckLink 8K Pro - Signal with 2 different resolutions

PostFri Jun 21, 2019 7:27 pm

I believe on the 12G Extreme and old 4K Pro cards this "just worked".
I don't have the 8K Pro card, so I don't know for sure if what you want can be done with no conversions. Do you have a downscale option available in the Desktop Video settings?
Threadripper 1950X 3.7GHz
64GB DDR4-2666
2x GTX 1080 Ti
DeckLink 4K Extreme 12G
Resolve Studio 16.1
Windows 10 Pro 1803
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CedricLarvoire

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Re: DeckLink 8K Pro - Signal with 2 different resolutions

PostMon Jun 24, 2019 10:22 am

So after talking directly with BlackMagic, they confirmed what I started to fear : the DeckLink 8K pro doesn't do down-conversion. It will only output one resolution from DaVinci. It's a bit tough to find information on this, but I should have gone for a DeckLink 4K Extreme, which does the down conversion.

They said they would file a request for a possible software update that might be able to add that feature to the Decklink 8K, but of course that might take time.

Would you have any recommendation of a cheap-ish and good downconverter? I know there's one from Aja but it's a bit expensive. and it can't affect the quality of the signal as it's feeding into the FSI monitor.

Thanks a lot!
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Dave Del Vecchio

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Re: DeckLink 8K Pro - Signal with 2 different resolutions

PostWed Jun 26, 2019 2:00 am

Unfortunately, there aren't a ton of affordable 4K capable SDI video scalers/downconverters that I am aware of.

It doesn't look like the AJA 4K2HD can handle 6G SDI or 12G SDI input signals (only dual link or quad link 3G SDI), so you would probably need something like a Teranex Express to convert a single link 4K SDI signal. Decimator has announced a 12G SDI capable scaler (a 4K version of their MD-HX unit), but it's not actually shipping yet.

Note that the Teranex Mini SDI to HDMI 12G and Mini Converter SDI to HDMI 6G are both capable of down-converting 4K signals, but only to an HDMI output (they don't offer downconverted SDI outputs). Still, this might be an option if your monitor has an HDMI input. If you need SDI output, I suppose you could also take the HDMI output of the Mini Converter into an HDMI to SDI Micro Converter, but this starts to be a lot of parts and cables.

Honestly the simplest option may be to ditch the DeckLink 8K Pro card, and get a DeckLink 4K Extreme or DeckLink 4K Pro (if you can find one still available). These cards both support 4K on one SDI output and HD downconversion on the second SDI output.
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Jack Fairley

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Re: DeckLink 8K Pro - Signal with 2 different resolutions

PostWed Jun 26, 2019 6:10 pm

As Dave says, 4K scaling is still not cheap or convenient. I would probably just replace the card.
Threadripper 1950X 3.7GHz
64GB DDR4-2666
2x GTX 1080 Ti
DeckLink 4K Extreme 12G
Resolve Studio 16.1
Windows 10 Pro 1803

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