Blackmagic UltraStudio 4k Mini 10 Bit HLG Output

Aphorism wrote on 1/12/2021, 12:42 AM

Hi! Vegas 18.0 10 Bit HLG question:

I have an issue that I'm trying to work through - I have an UltraStudio Mini 4k on a thunderbolt connection.

If I choose it as a preview device, both audio and video will pass, until I check the use 10-bit option.

The preview stops in both the mini-monitor on the device and the display.

I know that the same display will handle 10-bit HDR from Vegas using the 'Windows Graphics Device' option.

I shoot in HEVC HLG and would like to be able to grade in it as well. The UltraStudio 4k Mini has an HDMI 2.0b port, so it should theoretically be able to support this mode.

Any thoughts or assistance is appreciated.

Thanks!

Comments

fr0sty wrote on 1/12/2021, 1:50 AM

Unfortunately, while VEGAS does support rendering in HLG, there currently is no way to preview in HLG, as only windows HDR output is supported, and windows does not yet support HLG. VEGAS devs are aware of this limitation and have told me that they are working on fixing it, but I cannot give any timetable as to when it will be available. While the card may be sending your TV a 10 bit signal, it may not be a HDR signal, so your TV may not know to flag itself into 10 bit mode. I'll bring this up to the team, I also create HDR content and would love to be able to overcome this limitation.

In the mean time, HLG does convert over to HDR10 nicely (and without quality loss, since HDR is technically superior to HLG), that's what I've been doing... though I usually shoot log and then convert to HDR from there. When you load HLG footage into a HDR VEGAS project, there's a place to specify its color space when you right click on your media and go to "properties". There's an HLG option (called "Rec2020 HLG 1000 nits) in there to auto-convert the footage to HDR.

Aphorism wrote on 1/23/2021, 1:27 PM

fr0sty,

I followed your recommendations and moved forward but I've run into two issues that maybe you've encountered:

- The HDR fullscreen display is ok, but the preview window on a separate computer monitor looks grey-ish almost as though it's in a V-log style mode still.

- The grading controls respond in a strange way, giving different behavior depending on whether the project is set for HLG/HDR and what the view transform settings are.

I've been using the ACEScc color space for the project, as it seems to deliver the only accurate results, compared to the larger ACES2065-1.

Thoughts?

fr0sty wrote on 1/23/2021, 10:39 PM

- The HDR fullscreen display is ok, but the preview window on a separate computer monitor looks grey-ish almost as though it's in a V-log style mode still.

This is normal. Chances are, the other monitor is not HDR compatible, and that is what HDR video looks like when displayed on non-HDR screens. HDR uses a different color space and also has colors/shades that extend beyond what would be pure white or pure black in SDR (technically, the correct way to state it would be that there are more colors and shades between pure black and pure white).

- The grading controls respond in a strange way, giving different behavior depending on whether the project is set for HLG/HDR and what the view transform settings are.

This also is normal. HDR uses 10 bit video, so instead of just having 256 levels of black/white or any color, you get 1024, so there's a lot more range to work with. Also, if you have the incorrect color space set, you will get undesirable results, so make sure that is all set correctly. If your camera is capable of VLOG, you will want to record in that mode instead of HLG, as you'll get better results that way when grading to HDR, just make sure that you right click on your video clips, go to properties, then look under color space and set it to "vlog/vgamut". You can set the color space of multiple clips at once, you don't have to do it one at a time.

Aphorism wrote on 6/19/2021, 7:11 PM

fr0sty,

Thanks for the advice. I'm enamored of the 10 Bit 72 Mbps on the GH5 onward, so if there's not a V-LOG that fits that bitrate and the HEVC codec, I'll probably stick to the HLG mode.

Any advice on render settings for HDR/HLG for YouTube/Vimeo? I get a ton of different results depending on the project properties. Is it possible to grade in HDR/10 Bit/32 Bit Color Project Depth with a Rec 709 view transform and export conventional 709 footage?

Are LUTS like the Leeming LUT a good idea in this space?

Musicvid wrote on 6/19/2021, 11:02 PM

Shoot 709, not HLG, and you will have a lot more time for the important things in your life.

fr0sty wrote on 6/21/2021, 3:19 PM

For HDR, best image quality will come from VLOG. I always render to the HEVC HDR preset, and leave the project settings stock to what hdr mode enables, but this is using an hdr monitor.

For rec709 monitors and output, if shooting vlog, use a LUT, it's the easiest. Panasonic has some nice ones on their site.