Blackmagic Key & Fill - SDI Playout

I’m using mimoLive solely for graphics insertion into a Blackmagic ATEM workflow.

  • Blackmagic UltraStudio 4K
  • Blackmagic ATEM Television Studio Pro 4K

When I activate the ATEM’s Downstream Key 1, the multiview indicates the inputs on both SDI links from the UltraStudio 4K are active, and I see the key on the Program Out.

However, the key source from mimoLive is not 100% opacity – the source video beneath the key, along with the key itself, are milky as if everything is overlaid with semi-transparent grey.

In the ATEM Software Control, I have Downstream Key 1 set to PreMultiplied as directed in mimoLive documentation. FillSource is set to UltraStudio SDI Output A, and Key Source is set to UltraStudio Output B. When I switch PreMultiplied off, the source video returns to normal, but the keyed graphic itself is still washed out as if overlaid with grey. mimoLive graphics remain milky and washed out whether DSK1 PreMultiplied is set on or off. Only the background source video seems to change by toggling the PreMultiplied Key.

I’m new to both mimoLive and Blackmagic. I don’t know where to look for a solution: mimoLive, UltraStudio 4K, ATEM Television Studio Pro 4K, ATEM Software Control, or perhaps even physical cabling and signal routing through the Smart Videohub that is the patch point for all my SDI cables.

@“Danny Grizzle” Thank you for using mimoLive. I’m sorry to hear about the grief with the key/fill. Can you please send me the mimoLive document so I can check to make sure that the grey is not created by the settings in the document?

I do not have sufficient experience with the ATEM TV Studio Pro 4K to walk you through the settings. From experience with other switchers, there is often a setting for “calibrating” the key signal. We recommend to use PreMultiplied because that should work without the calibration, but maybe the settings in the ATEM are somehow screwed up? Can you try resetting the ATEM to factory defaults?

Another bizarre observation, perhaps irrelevant: I’m feeding ATEM PGM Out to several monitors. Whenever I toggle the PreMultipled Key (using ATEM Software Control) on the mimoLive output (via UltraStudio 4K) on ATEM Downstream Key1, I get about 30 IRE boost to the LIFT on my waveform monitor. This accounts for the milky appearance on my multiview Program, which is very obviously visible on my various PROGRAM confidence monitors. All these confidence monitors are interfaced using a Blackmagic MiniConverter SDI to HDMI 6G.

Here’s the weird part: I am also sending the same ATEM PROGRAM OUT to an AtomOS Sumo19 via SDI, no MiniConverter. The Sumo19 waveform shows the same 30db IRE boost to LIFT as all the other confidence monitors as PreMultiplied Key1 in ATEM Software Control is toggled on/off. However, the AtomOS Sumo19 video image does not change at all, and remains perfect, no change in the displayed image even as it shows changes on the input with its own internal waveform, regardless of the position of the PreMultiplied Key toggle. The keyed mimoLive graphics look horrible on the Sumo19 same as all the other monitors, unchanging as the PreMultiplied Key setting is toggled.

@“Danny Grizzle” Very strange. Can you post screen shots?

Maybe the UltraStudio 4K has a hardware defect? What video format are you playing out?

Additional note: While the mimoLive test graphic is keyed over source video, the key source seems to be semi-transparent. mimoLive graphics are visible, but translucent. This seems to be a failure in the KeySource, not the KeyFill.

In fact, it makes no difference whether I assign the UltraStudio 4K Output A to ATEM Software Control Fill Source, and Ultrastudio 4K Output B to ATEM Software Control Key Source, or vice-versa. The resulting image on ATEM PROGRAM Out is identical regardless of assignment to Fill Source or Key Source in ATEM Software Control.

Just noticed in mimoLive Program Output --> Blackmagic Design:

Even though Keying Mode is set to “External” as called out in mimoLIVE docs, when I press mimoLive Start Show button, mimoLive Program Output --> Blackmagic Design displays Keying Mode: Internal.

Perhaps there is an issue between mimoLive and the Ultrastudio 4K driver?

All my software is current versions as of 20 February 2019.

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mimoLive Output Destination --> Blackmagic Design setting for Keying Mode toggles between “External” in edit mode and “Internal” when the output destination is toggled to active/online.

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ATEM Software Control
MIMO A is UltraStudio 4K OUTPUT A
MIMO B is UltraStudio 4K OUTPUT B

All mimoLive output via my UltraStudio 4K seems to be over a background of 18% grey. This accounts for the washed out image seen on my ATEM PGM OUT anytime the downstream keyer DSK1 is active.

In effect, this is a partial key over the entire 2160p UHD image area, not an exact key matte applied to the graphics only.

FYI - I’m using mimoLive demo layer “Waving Flag” for testing. Identical behavior confirmed with layers “Weather Forecast” and “Lower Third.”

Blackmagic Desktop Video Setup for UltraStudio 4K is set to 2160p23.98 for SDI, which is the same resolution as the Settings in my ATEM Television Studio Pro 4K, which should rule out scaler issues from the 2 SDI inputs for Key + Fill.

Since the ATEM Television Studio Pro 4K includes automatic scalers on each input, I’m wondering if perhaps there is a metadata issue between UltraStudio 4K SDI OUTPUT A and OUTPUT B

ATEM Multiview

Photo of the Multiview monitor from my ATEM Television Studio Pro 4K.

I probably should have posted this photo earlier because it shows that the UltraStudio 4K outputs from mimoLive are identical for both OUTPUT A and OUTPUT B.

Neither one looks right. There is no black & white mask for the key, and there is no correct solid color for the fill.

I have already retraced my physical cables and routing inside the Smart Videohub 12G 40x40. I might need to do that again.

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Full screen capture of mimoLive. The program output looks good here, good flag on solid black background.

Somehow, this is falling apart between mimoLive and the ATEM because the fill and key are not being delivered through OUTPUTS A and B of the UltraStudio 4K.

It all comes down to the Keying Mode not holding set to “External” as shown in the previous screen caps where I drew yellow arrows. The moment I switch mimoLive Program Output on the Blackmagic Design to toggle the output destination online, mimoLive switches the Keying Mode to “internal” and the key fails because both inputs to the ATEM are identical.

@“Danny Grizzle” I vaguely remember from playing around with the Ultrastudio 4K that you could set the device to „dual link“ SDI in which case it would split the 2160p signal and transmit half of it over A and the other half over B. This was done in the BMD Desktop Video Setup app. It would explain why you can’t switch to external keying. I‘ll try to check in the next couple of days.

@“Oliver (Boinx)” Yes, Blackmagic Desktop Video Setup --> UltraStudio 4K --> Video Output --> SDI Output --> SDI Connector --> Dual Link

See screen shot for UltraSudio 4K configuration active during this entire support request.

Thanks for your help! I’ve spent weeks building this studio and everyone is breathing down my neck!

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@“Danny Grizzle” I think it needs to be set to „Single Link“. Have you tried that?

@“Oliver (Boinx)” Tested set to Single Link. Rebooted computer afterwards, confirmed setting remained on Single Link afterwards. Launched mimoLive and keyed “Waving Flag.”

No difference:

ATEM Program Out still shows 30db IRE Lift boost when downstream key is active
ATEM Multiview displays idemtical images on UltraStudio SDI OUT A and B (no distinct key / fill)

mimoLive’s Blackmagic Program Output behavior unchanged:

“Keying Mode: External” when inactive
“Keying Mode: Internal” when active


While the Thunderbolt link between the Macintosh and UltraStudio 4K is a single link, we definitely must have a dual link on the SDI A and B outputs of the UltraStudio 4K.

@“Oliver (Boinx)” I called Blackmagic tech support on the chance this is a hardware issue. We connected an SDI monitor directly to the UltraStudio 4K Output B and confirmed that no key matte exists – the image coming off Output B exactly matches what is displayed in the ATEM multiview photo shown in this thread.

My configuration, FYI:

mimoLive 4.7
Blackmagic Desktop Video Setup 10.11.4 (UltraStudio 4K driver)
macOS Mojave 10.14.3

All these versions are latest as of today, 22 February 2019.

Since we’re not getting clean key and fill signals out of the UltraStudio 4K outputs, I think we’ve narrowed the problem to either the UltraStudio 4K or a bug in the mimoLive Blackmagic Design Output Destination module.

Clearly, the inability of mimoLive to maintain settings on the Blackmagic Design Output Destination to External Keying Mode is the leading clue.

Blackmagic suggested I inquire what version of Desktop Video Setup was used for compatibility testing. They said it might be possible to downgrade the UltraStudio 4K driver to a version compatible with mimoLive.

The issue with this is going to be previous versions of Blackmagic Desktop Video Setup have not been qualified for macOS Mojave.

Although Blackmagic does not qualify third party software such as mimoLive, the tech support rep indicated they would probably be willing to supply an UltraStudio 4K on loan to Boinx for testing.

@“Danny Grizzle” I’m sorry about the ongoing difficulties. I just went to a customer who has an Ultrastudio 4K to do some testing but they are only set up for 1080p. Can you confirm that your setup works when using 1080p like the one I was testing today?

In 4K I could only check the small display integrated in the US4K and it did not look right in the way you describe but I did not have external monitors or a switcher to check the 4K signal.

We will do some testing on that over the next couple of days, trying to replicate your environment as closely as possible.

Could you please send me your computer profile in a private message? (Go to “About this Mac” -> “System Report” -> “Save…” and send me the file that is generated.)

@“Danny Grizzle” A quick followup: You say you “must have a dual link on the SDI A and B outputs of the UltraStudio 4K”. As far as I understand it, that means there can not be a key/fill signal as both SDI ports are being used to send one combined signal when “Dual Link” is enabled. So, what is the reason for you to have to use dual link?

@“Danny Grizzle” We can confirm that there is a bug in mimoLive that let it display the used Keying Mode in the user interface incorrectly: It always will display “Internally” regardless what you setup in advanced. However, mimoLive is actually using your selected Keying Mode so that the Blackmagic Design hardware should work as expected. This display bug will be fixed in the next release. Sorry for the confusion!

@“Oliver (Boinx)” Dropbox link for computer profile requested.

FYI - this MacBook Pro is dedicated to running mimoLive, not used for anything else.

Danny Grizzle mimoLive MacBook Pro system profile

@“Oliver (Boinx)” re: Dual Link vs. Single Link

I’ve tried it both ways, set to Dual Link and to Single Link.

Dual Link makes sense to me because there are two Outs on the UltraStudio 4K and two input channels used on the ATEM. That seems to be dual link – one for fill, one for key.

Again, I’ve seen no difference in outcome either way.

Thanks for your attention and assistance!