Confusing sound error

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Tmutarakansk
Posts: 3
Joined: Tue Aug 25, 2020 2:09 pm

Confusing sound error

Post by Tmutarakansk »

Hello!
I'm trying to encode my film.
DCP-O-Matic says the sound is too loud.
I tried to investigate the issue, and it looks like the software thinks there is an error in a central channel (see the attached screenshot).
Still, I'm really confused what's exactly wrong with that central channel? According to the dolby spec. my levels can be up to 0 db, here it's -1,89.
So, why DCP-o-matic doesn't like my C audio and what should I do to improve it?
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carl
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Joined: Thu Nov 14, 2013 2:53 pm

Re: Confusing sound error

Post by carl »

Hi,

You can take your levels up to 0dB but in the vast majority of cinemas such a soundtrack will be extremely loud at their typical playback settings - that is what DCP-o-matic is warning you about.

A reasonable starting point would probably be to lower your audio levels by 10dB. DCPs typically have much more headroom than, for example, commercial audio CDs.
Tmutarakansk
Posts: 3
Joined: Tue Aug 25, 2020 2:09 pm

Re: Confusing sound error

Post by Tmutarakansk »

I don't think that -1.89 is an issue.
1. Previously, I encoded a movie that had a sound at almost 0db, and everything was pretty much ok.
2. All sound channels have more-or-less the same volume, and DCP-O-Matic fires an error ONLY for the central channel. If I switch off the file for the central channel, everything works fine - all error messages disappear
carl
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Re: Confusing sound error

Post by carl »

I don't think that -1.89 is an issue.
1. Previously, I encoded a movie that had a sound at almost 0db, and everything was pretty much ok.
Great, you go for it. It's only a warning. The collected experience of most DCP-o-matic users is that hitting -2dB peak is probably much, much too loud, but it's not an exact science. The warning is really there for those who cannot test their DCPs in a theater, and for those people it's generally better to be too quiet than too loud.

I don't know if the translation you are using is accurate but it should only say something like "you should reduce the gain of your audio content."
2. All sound channels have more-or-less the same volume, and DCP-O-Matic fires an error ONLY for the central channel. If I switch off the file for the central channel, everything works fine - all error messages disappear
The red text and hint is only triggered by audio being above -3dB, so perhaps your other channels are slightly quieter.
Carsten
Posts: 2648
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Confusing sound error

Post by Carsten »

@ - can you translate the russian warning into english, keeping it's original meaning and sentiment? Maybe it has been translated with too much intention. As with the other hint dealing with the 24/25 fps issue - it is a hint to keep an eye on your levels, not an error. From what I see in your audio graph, the audio should be okay. What Dolby spec are you referring to?

- Carsten
Tmutarakansk
Posts: 3
Joined: Tue Aug 25, 2020 2:09 pm

Re: Confusing sound error

Post by Tmutarakansk »

First of all, thank you very much for your answers- they are really helpful.
The message (sorry for a screenshot in Russian - I really hate localized versions, but sometimes they install the language without asking) says "the audio is too loud"
What was confusing me, were the words Sample peak and True peak. I don't really understand why the developers used the word "Sample", according to your explanations, the words "Maximal recommended peak" or something like this, would be better.
As for the spec- I don't really exactly know, because this time the studio made this audio for me.
The previous time I made the audio myself, and as far as I remember according to some spec. the levels can be up to 0db.
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