26 Nov
2018
26 Nov
'18
1:11 p.m.
Confirm that LUFS (and probably LEQ(m) as well) will only get you into the right ball
park. This (LUFS) is for people without or with limited options to check levels in a
calibrated cinema. Adjusting to LUFS/LEQ(m) will get you out of the complaint area (or
allow to pass regulations/QC), but that's it.
I think there is no way to get this right without listening to the content. A perfect
'auto level' would need to guess at the dramatic intent of the audio.
Maybe AI will do that at some point in the future (it would probably even have to look at
the image ;-) ).
- Carsten
Am 26.11.2018 um 12:11 schrieb Jim Dummett via DCPomatic:
I'm slow to reply on this. Sorry - been very busy.
Thanks to both Carsten and CJ - fascinating stuff.
CJ do you have any more info on James Gardiner's work? I can't find anything on
his blog about this.
For anyone else who's interested, this appears to be the open source implementation
of LEQm that CJ mentioned: https://github.com/lucat/leqm-nrt
But what is "Luca"? And are you able to say anything about this mysterious
"something else"?
I often make packages of shorts and getting the audio level of all the films in line with
each other has been a consistent bugbear. Levelling everything using EBU R128 (LUFS) gets
everything in the right ballpark, but it's not perfect. Some films should be played
louder than others due to their content e.g. a music video will want to be louder than a
film which is mostly dialogue. But even comparing 2 films which are similar (e.g. both
primarily dialogue-based films) sometimes produces surprising results with LUFS.
Comparing a film with stereo sound and another with a 5.1 mix also seems to be difficult.
I get very limited time to do in cinema tests, so am looking for methods to get as close
as possible to a good result without access to a cinema auditorium.
Would be great to hear any thoughts from anyone who's been pursuing this...
Jim
On 12/11/2018 16:34, CJ | Digital Test Tools via DCPomatic wrote:
This reminds me to mention that James Gardiner in
Australia (cinetechgeek) has been working just in the last week with the legm-nrt software
and Luca to integrate that into his system that is already running 5.1 channel material
through to get LUFS and LEQm and Peak and ...something else...
ISDCF is also trying to make a move to get LEQm motivated to change so trailers can’t be
gamed...and hopefully lowered.
But wow...this is such a complex topic, both technically and politically
Typeos from CJ's iPad
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http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic On Nov 10, 2018, at 9:53 AM, Carsten Kurz via
DCPomatic <dcpomatic(a)carlh.net> wrote:
DCP-o-matic applies EBU R128 loudness analysis (if enabled in prefs). This is a method
targeted at broadcast/home listening experience. Established Cinema loudness measuring
standard is LEQ(m). LEQ(m) is not available in DOM (yet). It shares some concepts with EBU
R128, but you can't compute a straight relationship between the two.
However, after a bit of testing, I found out some relations that make DOM's R128
usable for general cinema applications. Keep in mind, even if you'd use LEQ(m)
metering, you would still need to test your DCP in a well calibrated cinema, and even
then, results in other cinemas will vary due to complexities not being addressed by common
calibration techniques. For all the work I do, DOM's R128 is working nicely.
I wrote a longish article here, which contains some advice on usable numbers and
practical implications:
https://dcpomatic.com/forum/viewtopic.php?f=2&t=980&p=3576#p3576
Something that many people have a hard time to understand is that there is no such thing
as an objective correct measure for 'the right' loudness in cinema. Just as there
is no objective measure for the color of a sunset in a movie. The established EBU R128 or
LEQ(m) numbers are 'complaint' levels, they are max allowable loudness figures.
You should not level higher, or you will get complaints from your patrons/visitors, or you
violate certain regulations. But these are not target levels that everyone has to adhere
to. If you want your movie or ad to play softer - that is okay, and it may be right for
your specific work. Just make sure you don't level higher, because that will cause
trouble sooner or later.
Also, keep in mind, so far, regulations are only in place for ads (max 82dB LEQm) and
movie trailers (max 85dB LEQm) in cinema, not for short films or full length features.
You are still advised not to create content louder than these numbers. The more your work
deviates from the numbers I mention in the forum article linked to above, the more
important it is to check your levels in a well calibrated cinema auditorium of appropriate
size and proper facilities.
- Carsten
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http://main.carlh.net/cgi-bin/mailman/listinfo/dcpomatic Am 10.11.2018 um 15:10 schrieb Gérald Maruccia
via DCPomatic:
Hi,
what is the method or norm used to display loudness in DCP-o-matic ?
Victoria5 has asked this here
https://www.projectionniste.net/forums/viewtopic.php?f=2&t=9946 and, well, I don't
know the answer ;-)
Best Regards,
Gérald ⋅ Cœur Noir
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