Info LUFS for cinema

[unkle]

Hello everyone,
first of all, thank you for this magnificent software: it is literally magic.

I am writing you after reading several other threads here, because I'd want to be sure about what I'm doing in Dpc-o-matic.
I'm trying to make a DCP for my shortfilm in order to present it at film festivals, but I have some doubts about audio settings, in particular loudness. I read that a good compromise would be to have integrative loudness around -20 LUFS (mine is -21 LUFS, as you can see in the first image attached).
But analyzing the audio track with a loudness meter (as you can you see in the second image attached) at some points it shows a momentary max LUFS of -15.2. Would it be a problem? Will these very short peaks be too loud in a cinema theatre? Or does the "critical" value of -14 LUFS refer only to the integrative loudness and not to momentary max one?

Another question: is there also a minimal critical value of loudness in order to listen also a quiet ambient track? In the graphs attached there are several fragments where LUFS are around -45. Are these too quiet?

I do want to say that in the audio track there are no dialogues. It is all an immersive combination of suspended sounds and music, except for the last fragment where there is only a forest ambient.

Thanks in advance to those who will help me!

[Carsten]

The LUFS calculation in DCP-o-matic is meant to be 'overall'. You shouldn't count on that single number only for long features (no one has found a solid method to evaluate loudness for full feature length). But for ads, trailer, shorts, that number does help. From what I see in your screen shot, it looks okay. If there is no dialog, even with the numbers, it is hard to say without hearing, and without knowing your intention, if the audio is meant to be 'loud' or 'soft'. You can create a thunderstorm from a beehive, or a soft bee-dance romance. There is no technical term that is able to tell you how your audio is 'meant' to sound.

The momentary max -15.2LUFS is indeed 'loud'. If that is meant to be like this, I guess it's okay. This is not necessarily a complaint issue if it doesn't last too long.

But again, without having heard it, and without knowing your intention, hard to give a definitive answer (no one can from a distance). At least you're in the right ball park. That means, it is quite certainly neither too loud nor too soft.

- Carsten

[unkle]

Thank you very much , Carsten!
You have perfectly clarified my doubts.
I wanted to be sure there would not be any evident loudness mistakes or bad complaint issues, thus avoiding very too loud screenings at cinema.

In this shortfilm sounds and music play a really key role because they are not “real”or “daily”, but it is like they belong to another world different from one we listen to every day. For this reason my intention was to give sound a sort of “strenght”. Therefore I certainly do not want that audio track plays “soft”, but obviously not so loud as to make irritating listening.
With this aim, is it possible (and recommended) to slightly increase the gain in order to reach a -20LUFS (or even more)? Or in that case would there be a risk of “pushing” the -15 LUFS momentary max to intolerable values despite its shortness?

Thanks again for your help!
-unkle

[Carsten]

It's most certainly no problem to push it +3dB towards -18LUFS or so.

[Antti N]

Is your audio track actually mono – that is, 100% identical audio in the left and right channels? (It sure looks like that in your DoM graph, but it's not accurate enough to say for sure.)

If your mix is indeed pure mono, then you should create a proper mono DCP. Simply check one of your (identical) channels and route it to Center, and leave the other channel unchecked:



Then run the DoM audio graph tool again to get correct LUFS and peak values for mono playback. Finally, label the DCP as mono by putting "10" (instead of "20" or "51") in the CPL title.

This way, your mono audio will be directed to the center speaker only, instead of "dual mono" coming out of the left and right speakers. It's particularly important for dialogue-heavy films with, but even dialogueless content will benefit: Diegetic sound effects appear to be coming from "inside" the picture (helps a lot with immersion), and the overall sound will be clearer regardless of where you happen sit in the cinema.

Of course, a proper 5.1 audio mix would sound even better. But in my experience, a good mono track is in many cases preferable to 2.0 stereo in a cinema setting.