HDMI black level

Using the 4K Extreme to output live graphics using HDMI, I noticed that black is not completely black. I assume colors are in the 16-235 range. Is there a way to modify the black level so black is really black? If not in the settings, perhaps using the SDK?

I assume colors are in the 16-235 range. Is there a way to modify the black level so black is really black? If not in the settings, perhaps using the SDK?

You could check if your throughput is set up for "Full Range" or "Linear Video"... that might be easier than weeding through the SDK.

jPo

Where can I find this throughput setting? Doesn't seem to be anything like it in the control panel.

Please clarify what you mean by "live graphics." Do you have access to the media in the Resolve browser?

jPo

In this instance we use our own custom render engine to render graphics at 50fps, which we then output to screens in a studio. So for example a background loop on a plasma screen, or led screen. Normally we'd go via BNC, but since led controllers usually only have a DVI input, we use the HDMI output of the 4K Extreme to have as little delay as possible.

This works fine, except when outputting black it's slightly grey.

So essentially you are using the BlackMagic card as a playback device to feed a practical set piece... do I have that right? I have been assuming you were using Resolve as a Software interface. If that were true...

Examine your Media Browser Clip settings to confirm how the graphics are being sent to the timeline -- Video 64-960 or full scale 0-1023. This may be the reason the black levels are being pushed up.

find your graphic file, right click to bring up -

Clip Attributes...
Levels... will be "Auto"... you probably want "Data"... not Video.

In Project Settings, Video Monitoring also offers a Video/Data Level toggle.

However, different software applications might not be able to differentiate between these scaling options. The Decklink card does offer a 4:4:4 RGB option for its output and I assume the HDMI output would follow the SDI output. I don't think its an analog "Setup" issue, where 7.5 IRE would be introduced as a pedestal offset.

So, what software are you using as a display interface?

jPo

We send data to the decklink ourselves, not using software like Adobe. So we render a scene in our software, then send frames to the decklink for output using the sdk.

But as a reference it may be a good idea to try and use Adobe for output, to see if it gives the same black issue and whether it can be resolved from there using the settings you mentioned. If we can get black to be black that way, we should be able too, and if not, it may be driver related.