How does the level measurement work with Dolby Atmos (Renderer/SuperVision)?

I have searched the forum, but it seems that no one has asked this question yet. (But maybe everyone knows but me.) I would like to understand how the Atmos renderer and SuperVison built into Nundeo measures volume/level. Are there any fixed standards there? Normally with Dolby Atmos, loudness and volume are measured based on a 5.1 downmix. (DEE and DME do it this way, for example.) But how does this work with Nuendo?

I also ask because we noticed some oddities when leveling in. Apparently the renderer has a limiter built in to prevent the signal from going off scale. I can still keep up with that far.
But, for example, exactly how and when the signal is cut off is not entirely clear to me. Sometimes I can’t understand why a certain level value is displayed for a channel in SuperVison or Halo Vision, for example. Because this value often has nothing to do with the final result (for example in the Dolby Reference Player).

We have collected some results, which I can’t publish right now, because I don’t have the time.
But I will be glad to publish them if needed.

I am looking forward to new findings. :+1:

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I’m very interested in this also. This post by Mark Ayres suggests the internal renderer take it’s loudness from the 5.1.4 downmix? Trim and Downmix Editor (Dolby Atmos) Bug?

Either way, this is certainly the biggest topic that needs clarification for me. Also, while I’m here - I think it would be nice if after the ADM has been rendered, Nuendo could display a ‘loudness summary’ report? Or at least the loudness readings not to reset after export… Just for final piece of mind that loudness is within spec…

Bruce

Yes, the loudness measurement is taken from an internal 5.1 down mix (not 5.1.4; I have corrected my original post).

There is a specific internal loudness re-render bus in the Renderer for this purpose. From the manual:

Using the 5.1 loudness re-render for loudness measurement

Use the 5.1 loudness re-render for loudness measurement during postproduction. Ensure that content meets delivery specifications by returning content to your chosen DAW, using the your chosen method and loudness measurement plug-in. The loudness measurement display in the Renderer is also fed from this loudness re-render bus.

This means that if you change your downmix settings in the renderer (for instance set the surround mix to 0dB rather than -3dB) your measured loudness will change, even if you have not altered the actual Atmos mix. This takes a few minutes to get your head around.

Loudness measurement is something that you need to factor into your workflow. Personally, I get it about right then (for an album) open everything in the Album Assembler and tweak it there in context.

Mark

Can you please tell me where I can find this passage? I can’t find it in the manual for Nuendo nor in the manual for the (external) Dolby Atmos renderer. Thank you.

Dolby_Atmos_Renderer_Guide.pdf

Page 255, bang in the middle. It’s the last part of Section 20.1 Re-render output matrix.

M

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