Film-Tech Cinema Systems
Film-Tech Forum

Post New Topic  Post A Reply
my profile | my password | register | search | faq & rules | forum home
  next oldest topic   next newest topic
» Film-Tech Forum   » Operations   » Digital Cinema Forum   » Native Audio Input Levels for a DCP

Author Topic: Native Audio Input Levels for a DCP
Grant Chambers
Film Handler

Posts: 29
From: Branson Missouri, USA
Registered: Jul 2012

 - posted 01-06-2014 09:05 AM      Profile for Grant Chambers   Email Grant Chambers   Send New Private Message       Edit/Delete Post 
Hello all! I am curious if anyone has a rough idea of what the levels (DB I'm assuming) need to be for a DCP. (input, from DCP itself, .wav files)

I make DCPs often. I use OpenDCP. The only real hassle that I ever come across is trying to figure out how loud my audio should be.

Here's a typical example -

I make a slideshow or intro of some sort. I use royalty free audio and crop it using Adobe Audition (not touching levels mind you). Upon ingestion and testing... WAY too loud. The fix is usually somewhere between dropping 10 - 15 DB.

It would just be great to have a consistent value to go by. I couldn't find any DCI specs on the matter.


 |  IP: Logged

Carl Hetherington
Film Handler

Posts: 88
From: York, North Yorkshire, England
Registered: Jul 2012

 - posted 01-06-2014 09:38 AM      Profile for Carl Hetherington   Author's Homepage   Email Carl Hetherington   Send New Private Message       Edit/Delete Post 
To be honest I don't think you'll get a much better rule than "about 10-15dB". It depends on the nature of the audio that you are using, and in particular its frequency content and how much dynamic-range compression has been applied to it: these and other things will govern how loud it sounds.

There are various perceived-loudness measurements that you can do, but I think you'd do well to get reliably within 3dB of the "correct" answer without listening to the audio either on some speakers that you get to know, or in your auditorium.

 |  IP: Logged

Grant Chambers
Film Handler

Posts: 29
From: Branson Missouri, USA
Registered: Jul 2012

 - posted 01-06-2014 11:01 AM      Profile for Grant Chambers   Email Grant Chambers   Send New Private Message       Edit/Delete Post 
Thanks Carl. That's what I was afraid of.

 |  IP: Logged

Kenneth Wuepper
Jedi Master Film Handler

Posts: 996
From: Saginaw, MI, USA
Registered: Feb 2002

 - posted 01-06-2014 12:01 PM      Profile for Kenneth Wuepper   Email Kenneth Wuepper   Send New Private Message       Edit/Delete Post 
Do you know what your metering system is looking for? In other words, are you mixing at -10 dBV or at +4 dBu for the system reference?

This could easily explain the difference in your recording level and the ultimate playback level in the theatre.

 |  IP: Logged

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12204
From: Annapolis, MD
Registered: Dec 1999

 - posted 01-06-2014 12:19 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
The issue is that music for normal playback and cinema audio are two different animals.

In order to have the volume capability need for explosions or other loud situations, in cinema one has to record 20dB down so that they have the headroom for the loud stuff. Remember, at -20dBFS, we have 85dBc (using pink there is a crest factor in there) in the theatre. Prolonged 90dBa levels will cause hearing damage. So think of dialog in the "average" seat as getting to around 80-85dB...a full 20-25dB down. Music and Effects have to be balanced with that (though they often are not). We willingly give up our noise floor in a theatre so we have that 20dB headroom given that even a quiet/empty theatre is going to be NC30 or there isn't really any penalty.

Now...lets look a music recording. That is completely different. One merely needs to keep the signal from clipping and then allow the maximum dynamic range to capture the recording. The end user will turn down the volume knob to what they feel is a "comfortable" or "appropriate" level.

This is NOT the case in a cinema...where a volume knob normally stays in one place for any given sound format...or in slicker systems, the volume may have a few presets to deal with LOUD TRAILERS and/or ads.

So, knocking the level down on a music (e.g. CD) recording so it is at a comfortable level in a cinema makes perfect sense. I would guess that 20dB down would be a starting point. If the theatre doesn't run their fader at 7.0 or 0.0dB...then you may feel the need to be a bit higher.

 |  IP: Logged

All times are Central (GMT -6:00)  
Post New Topic  Post A Reply Close Topic    Move Topic    Delete Topic    next oldest topic   next newest topic
 - Printer-friendly view of this topic
Hop To:

Powered by Infopop Corporation

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.

© 1999-2018 Film-Tech Cinema Systems, LLC. All rights reserved.