Blackmagic Forum

I notice that the "use 4:4:4" options in both the Desktop Video Setup utility and in Resolve refer specifically to SDI. Indeed the flag in the SDK is called bmdDeckLinkConfig444SDIVideoOutput.

However some cards, such as the Mini Monitor 4K, say in the spec that they support 4:4:4 for HDMI. Setting 4:4:4 in Resolve appears to have no effect on the HDMI output, but if in my own software I change the pixel format to bmdFormat10BitRGBXLE, and set the bmdDeckLinkConfig444SDIVideoOutput flag, the output does change. I can't be certain that the output is really changing to RGB, as I have nothing which can analyse an HDMI signal.

How is Resolve behaving differently to my software, changing SDI only?

Sorry, I was wrong. Resolve does switch to RGB 4:4:4 as well. It just doesn't do so until you scrub in the timeline, forcing an output refresh. So it would appear that on cards supporting 4:4:4 HDMI, it simply follows the setting of the SDI output. Is this correct?

A secondary question then. Is there any way of setting the HDMI InfoFrame metadata to specify colorimetry and range of the signal. Some monitors appear to interpret HDMI RGB data as Rec.601, but others think it's Rec.709.

This thread has been moved to the Resolve forum for some reason. It really is not Resolve related. I originally mentioned Resolve behaviour for comparison, but as I mention above, that turned out to be incorrect.

So it really is a Software Development topic, unrelated to Resolve.

Hi Nick,

I can confirm for devices which support RGB over HDMI, that this is enabled based on the 4:4:4 flag (and subject to EDID negotiation).

API support for colour space metadata is planned to be incorporated into a future release, to complement the existing HDR metadata support.

Sincerely,

-nick