Banding in DeckLink Output

I’m noticing extreme banding in the image output through the new DeckLink interface.

This is the image in the GUI (looks good, is ProRes4444):

But here’s the image on my color calibrated reference display, which is receiving an SDI signal via DeckLink Mini Monitor 4K:

There’s lots of banding and macro blocking on her skin.

The session is set to 16 float in Si.

I don’t see any settings to control the DeckLink output in Si aside from framerate and resolution.

If I had to guess, Si is exporting an 8-bit signal to the DeckLink?

This same image looks good on my DeckLink out in Resolve.

The issue is a little more easy to see when the image is log:

On the subject of DeckLink output…

The viewer transform settings don’t seem to apply to the DeckLink image. We don’t want to see a correctly transformed image in the GUI but be showing clients a log (or worse, linear) image…

The same transform should apply equally to the DeckLink.

I thought I’d work around this by putting an Arri LUT on the OCIO LUT node. However, that node seems really slow. Playback of HD footage on a fast machine with an RTX 3090 drops to almost half.

Applying a LUT through the Si native viewer is quite fast, so the easiest thing would be to reflect that LUT in the DeckLink output, in my opinion.

You are correct, the monitor output is 8 bit only. I’ll pass the request along for higher bit depth output.
Also correct on the viewer transform not being applied. We’ll get that into the next release.

Another thing to consider with DeckLink is scaling specifically for that output. At home, I grade on a Flanders DM240, which is “just” HD. At the studio, my projector in the DI suite is 2K. And yet it’s common to want my Si sessions at the camera original resolution (4K, 6K, more…).

Resolve and Scratch both have options to essentially scale just the SDI output to match the height of the DeckLink display, typically 1080.

For colorists it’s still quite common to be grading in HD as some of the most color accurate displays are at that resolution. Flanders doesn’t even offer a 4K grading display that’s SDR, and they are the gold standard for accuracy.