Dolby System Support

Anything and everything to do with DCP-o-matic.
Santiago
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Joined: Thu Dec 14, 2017 11:58 pm
Location: Mendoza, Argentina

Dolby System Support

Post by Santiago » Thu Jan 11, 2018 3:08 pm

Hello everyone! I'm new in this group.

I've read something about Dolby supported -at least- on recently versions. I found it out when i was making a DCP project and there was a moment when i wanted to adjust audio levels for the right volume. Soon i will make a DCP for a cinema that has Dolby Atmos.

"Current versions of DCP-o-matic only know about the Dolby CP650 and CP750"

Kind of a feature request: Would be possible to have Dolby Atmos support as well? I think i could help giving some information about the equipment next time i be there, in the projection room.


Thank you.
Santiago

Carsten
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Location: Germany

Re: Dolby System Support

Post by Carsten » Thu Jan 11, 2018 4:30 pm

Hi,

Dolby was 'always' supported by DCP-o-matic, but there was a problem with some of the recent test versions that prevented DCPs to play on select Dolby and Barco servers. That has been fixed now.

'Current versions of DCP-o-matic only know about the Dolby CP650 and CP750' - that only refers to volume adjustment based on the cinema specific 'Dolby Level'. It's a feature that probably few people actually use. It doesn't indicate any special Dolby support, just one possible way to choose audio levels in addition to the standard +/- dB approach.

ATMOS is very far away. I know a free DCP creation software supporting ATMOS - but it only puts a standard ATMOS sync audio track into the DCP. That doesn't help much, you still need to do the whole ATMOS audio mastering and packaging. There is much to say about ATMOS, but for now, a 'real', working ATMOS solution is beyond the possibilities of open source software. This may change once SMPTE finishes the standard for object based audio.

DCPs created with DCP-o-matic simply play on all ATMOS systems, as all ATMOS systems have standard cinema Stereo, 5.1 or 7.1 modes. You just don't have the benefit of the individual speaker addressing (among many other aspects of ATMOS).

- Carsten

Santiago
Posts: 3
Joined: Thu Dec 14, 2017 11:58 pm
Location: Mendoza, Argentina

Re: Dolby System Support

Post by Santiago » Thu Jan 11, 2018 5:25 pm

Carsten, thank you for the answer!
Sorry, i was not clear for the first time. What I'm trying to say is:

I know that Dolby has position numbers that refers to audio levels in dB. (I think most systems work at fader 7 as maximum). Is that panel in dcp-o-matic compatible with that? I mean, if I want to adjust level to 85dB (Dolby level 7) and -27 LUFS, is it work this way? I think I'm a little confused

Thanks!

Carsten
Posts: 1355
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Dolby System Support

Post by Carsten » Thu Jan 11, 2018 7:14 pm

Yes, the Dolby Fader adjustment is based on the idea of the Dolby Fader reference.

'7' ? We'll see...

The Idea is, you want to create your DCP so that the cinema can use it's standard audio fader setting, but for some reason, your DCP is too loud or too weak. You then adjust the level in the cinema so that you like the level that you hear - say, 4.5. You then tell DCP-o-matic, 'This DCP plays fine at 4.5, but I want it to sound at the same loudness with the cinema standard fader setting'. Dial in those numbers, and DCP-o-matic will create the gain or attentuation needed to achieve that. This calculation is based on the specific fader curve of Dolby processors (a specific number - dB relationship). DCP-o-matic has this relationship stored for Dolby processors. Other manufacturers use slightly different curves/relationships, e.g. USL, or Datasat. If someone tells Carl (the programmer) their specific processors number/dB relationship, Carl could implement these curves as well.
Yes, in theory, the cinema standard playback fader level SHOULD always be 7, but everyone working in cinema projection knows that no one uses that reference, at least not during pre-show. Typical actual fader settings that I have seen and hear about over the years vary between 4 and 6 for main features. Our standard fader setting is 5.5 (we play preshow at 4.5). I often adjust the main feature slighty up from there, towards 6, rarely 6.5. Only VERY rarely do I have to reduce main feature level below 5.5 to make it acceptable. Maybe once in two or three years.


LUFS is not a proper cinema loudness scale. It's for broadcast - TV, radio, starting to get used for internet media as well. But the calculation for this (complex) analysis is available through FFMPEG, one of the underlying frameworks DCP-o-matic uses, so, Carl can use it easily. dB LEQ(m) is the proper cinema standard, but that is not available through FFMPEG (yet), and it would be too much work for Carl to implement it all on his own. It's better to wait until dB LEQ(m) turns up in FFMPEG, and use LUFS until then.

As LUFS and dB LEQ(m) use different methods and references, you can not simply compare numbers. dB LEQ(m) for instance uses typical numbers in the 70-80 range, e.g. 82 or 85 dB LEQ(m), while typical LUFS numbers are in the range -15 to -30. Lower LUFS numbers (note they are negated, so mathematically, they are higher values) mean more loudness, while with dB LEQ(m), higher numbers mean more loudness. There is no simple relation between these numbers, although one could establish one that allows to use LUFS in cinema with some confidence.

Remember, though, that neither LUFS nor dB LEQ(m) actually indicate 'target values'. They only indicate max allowable loudness. It's a complaint level. If you choose to make a short film with people whispering to each other, and level to 85 dB LEQ(m), or -14 LUFS, their whisper will sound like a hurricane. Something MEANT to be perceived soft, must be played back soft. On the other hand, if DCP-o-matic indicates -12 LUFS for a dialog short or advertising spot, something is severly wrong with it, because it is far over complaint loudness.
As such, it is completely okay if your clip is indicated at LUFS -30, IF it is a very soft trailer and intended to play like that. It doesn't violate any regulation.
But if people actually speak in it at their normal voice level, there is probably something wrong, and a cinema audience will not understand what is said.

IF, however, you are working in advertising, then the max allowable loudness IS indeed your target level, because you are not paid to care for subtlety, but to create your spots at the maximum allowed loudness to compete with everyone else's. Kidding. Or not?

So, if you're mad about proper audio level in cinema, you need to take your DCP to a properly calibrated cinema and play it there. Using LUFS is just there to get into the right ball park. I consider 'normal' informative spots, trailers, etc, around -20 LUFS as 'okay'. If there is spoken word and music, people will understand what is being said, and the music wont blow their heads off. Fine tuning MUST then be done on a calibrated system, especially if your content varies wildly in loudness over it's length.

Broadcast LUFS standard is -23LUFS. However, that is based on typical long term living room TV or radio listening - people expect and tolerate higher loudness in a cinema, so allowed cinema LUFS number should be lower (which means higher loudness). Therefore, I think -20 LUFS is a useful number and easy to memorize.


By the way - as DCP-o-matic can import DCPs, and perform LUFS calculation on them, it's a nice education to load a range of 'real' DCP ads and trailers into it and watch their LUFS values.


- Carsten
Last edited by Carsten on Fri Oct 19, 2018 5:45 pm, edited 16 times in total.

Carsten
Posts: 1355
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Location: Germany

Re: Dolby System Support

Post by Carsten » Fri Jan 12, 2018 12:23 am

Have a look at some interesting examples (keep in mind, these files are actual official trailer DCPs, not trailers ripped from YouTube and converted...):

The first one is cinematic Trailer D for Star Wars 8, currently in cinemas. US TASA regulations demand that trailers have to obey a limit of 85dB LEQ(m). As Star Wars 8 is a high profile release, certainly only highly skilled people are allowed to master these trailers, and they are certainly mixed to spec.
The german version of this trailer computes to -14.11 LUFS. That is very loud. As I wrote earlier, we play preshow at Dolby Level 4.5, because trailers always max out their allowed limits and we don't want to annoy our audience before the main feature even starts.
But, even at 4.5, these trailers still play 'loud'.

StarWars8_TrD_de.jpg
StarWars8_TrD_de.jpg (108.95 KiB) Viewed 3263 times

The original english version of the same trailer computes to -13.37 LUFS. Even a tiny bit louder (though in fact, not noticeably). That's an action packed SciFi Trailer. I don't think you find something louder than this when you visit a cinema.

StarWars8_TrD_eng.jpg
StarWars8_TrD_eng.jpg (110.08 KiB) Viewed 3263 times

So that is certainly the upper level. Let's assume -14 LUFS to roughly equal 85 dB LEQ(m)?

Now here is an interesting one - it's a short that we played last year on the international day against homophobia. It is not a high profile cinematic production, it's stereo, and it probably hasn't received a professional cinema audio mastering. We played it immediately before our main feature, after the preshow program.
The day after we played it, we received an email complaint by a patron who found the short much too loud, especially towards the end, where 'high impact' music is played. We rarely ever receive such explicit complaints afterwards, so, unless this person was extremely sensitive, I was sure there was something wrong about this clip. I loaded it into DCP-o-matic for an R128 analysis, and found this:

PorUnBeso.jpg
PorUnBeso.jpg (85.68 KiB) Viewed 3263 times

It's indeed very loud. At 13.89 LUFS, it reaches the same values as the StarWars 8 trailer. And this is not an action packed SciFi trailer.
And that using only the two Left and Right speakers. Watch the StarWars 8 trailer achieving the same loudness using all speakers, Left, Right, Center, Surround, LFE...
But was it actually TOO loud? Yes, because I played it after the preshow program, our cinema sound processor was already set to main feature fader setting, up to 5.5 from 4.5...
Remember I wrote earlier that LUFS and LEQ(m) indicate 'complaint levels'? Well, there we are, it seems that -14LUFS or our assumed 85dB LEQ(m) is indeed our complaint level. I should have played it at 4.5 as the pre show program, and we might have avoided that complaint...
I wrote an excuse to the complaining patron and admitted, that while I actually did check the volume during a test run, it had escaped me that I tested it in the auditorium at preshow level of 4.5, before I created the show playlist and missed the fact that the new fader level 5.5 cue was placed before the short, not after it...
Last edited by Carsten on Fri Jan 12, 2018 11:38 am, edited 11 times in total.

Carsten
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Re: Dolby System Support

Post by Carsten » Fri Jan 12, 2018 12:40 am

And another one from the opposite side of the scale...

This is a local advertising spot we currently play as the first clip in all our shows. It's a commercial spot for a local media agency.
We received it in DCP format, so someone claimed he knew what he was doing and he certainly was paid quite some money... ;)
Obviously, it did not receive a professional audio mastering either, it is stereo, and much too soft:

Rheinland.jpg
Rheinland.jpg (88.04 KiB) Viewed 3255 times

This one annoys me, because only very reserved audiences will understand the dialog spoken in it. In situations with a 'normal' crowd, the speech intelligibility drops to near zero. Why? Because it's at a mere -28.76 LUFS. With a normal attendance in our auditorium, the audio is practically wasted. See how the RMS is hovering just below -30dB FS? That is far too low for a commercial, featuring an off-voice and some music. Even if I'd play it at 5.5 instead of 4.5 preshow level, it would still be too soft. So I took it into DCP-o-matic and created a new DCP, raising the audio by +10dB.

So, find yourself somewhere between -28 and -14 LUFS. I suggest to start around -18 to -22 LUFS, depending on your own estimate wether your clip/short/movie should be perceived as more intense, or more on the subtle side. Then take it to a cinema, ask the projectionist to play it at their normal level (for either preshow, or main feature, depending on your content), sit down around the back third of the auditorium, and listen to it.

If your auditorium session is time or staff limited, you may create three versions of your clip at different levels. Say, one around -23 LUFS, one around -20 LUFS, one around -17 LUFS. (+/- 3dB gain). Have all three ingested and played for a comparison.

DCP-o-matic is so fast in creating DCPs with audio gain changes only, you could even do that with a notebook in the auditorium, and immediately have these versions ingested from a USB stick or portable disc.

- Carsten

Santiago
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Joined: Thu Dec 14, 2017 11:58 pm
Location: Mendoza, Argentina

Re: Dolby System Support

Post by Santiago » Sun Jan 14, 2018 9:41 pm

Carsten,

Thank you very much for your time and your words! It took me some days to sit down with my computer and analyze all this. Definitely, this information helps me a lot. Now, i should go to the cinema and do some tests.

I will write you soon

Thank you

Santiago

StudioCompyfox
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Joined: Sun Sep 01, 2019 6:01 am
Location: Germany

Re: Dolby System Support

Post by StudioCompyfox » Sun Sep 01, 2019 6:36 am

Hello everyone, I'm new here, nice to meet you.

I'd like to revive this old thread. I'm an audio engineer, currently working on two short films that are supposed to be presented on a big screen in 1,5 weeks. My current task is to mix all films (music, original soundtrack/on-site audio, etc), then render it out in stereo. If the budget even allows that, maybe surround (up-mix to 5.1).


My clients are already in talk with the cinema operator, and he would create the DCP from the provided MP4s/MOVs. But the missing key is the loudness of the audio stream - which is my task, after I'm done mixing.

The first short film is fairly dynamic - think half-musical, half fairy tale (a blend of of Descendants, Harry Potter and House of Anubis). The second short film is very music heavy, with three distinct sections where you hear the on-site sound fairly quiet - the concept is resolving around "Drowning out Noise", so I really do not want to blast people's ears away but still have the impact of audio alongside the visuals. Additional to that, this special event will also show a multi-part making of. I'm not mixing this, but I have the final word on the average loudness.



I've read a lot of articles recently. Mostly the white paper by Eelco Grimm (Grimm Audio), called "cinema_loudness_aes_rome_2013.pdf" (very informative, I really like the simplistic approach, Eelco Grimm sits in the P-LOUD group that basically created/pushed the LUFS measurement standards), lengthy articles on Pro-Tools Expert (I didn't know that Belgium banned Setting 7, because of a hearing loss incident), but I also found this:

https://simpledcp.com/sound-levels-in-cinema/


The cinema operator told us recently, that he runs his main program on Setting 5.5. We do not know if he means "trailers" or "movies". The posts above (from you, Carsten) mainly talked about trailers, and they're mostly clocking in at/around -14LUFS, which is actually a level for "Streaming on Youtube". According to the article on SimpleDCP, that must be setting 2.5 or 2.8.

You on the other hand, you (Carsten) said, that you play Pre-Shows at 4.5, and the regular shows at 5.5.

But we're still talking trailers only, not movies. I'd go the Broadcast route, I'd actually submit a mix at -23LUFS ILk for Dolby Reference 5.5. Although technically it is "recommended" to go -27LUFS ILk. Which made me curious...

Did you maybe create a list of LUFS values for regular movie programs?
Just to get a basic idea of the overall loudness that movies are provided at?



I'd love to know how certain movies were set up (Dolby Reference <nr> and LUFS).

Especially musicals like "La La Land" and "Rocketman", action movies like Deadpool, Star Wars 8, How to Train Your Dragon 3 (I found 2 a bit loud in this one Indie Cinema I've watched), etc. Maybe even Godzilla 1 and 2 (just because I found the dynamic transitions quite well made in the first one from 2014) and (if available) "War of the Worlds" (2005). Just to get an idea of where the route could go.

And whether or not -23LUFS ILk would be too loud/too quiet at the Dolby Reference 5.5 setting (by the articles I've read, it might be a tad loud -- by your comments, Carsten, it's too quiet).


I know that surround mixes in cinemas can only be done at a movie house. But it would be so much easier for independent studios, to have an official reference list, where Audio Engineers know "ah - this route - like Netflix's -27LUFS +-2LU (so called "Dialnorm") or the European Broadcast -23LUFS +-2LU (plain EBU R-128/ITU-R BS.1770-4 specs)", then be done with it.

Any feedback on this would be gladly appreciated.

Carsten
Posts: 1355
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Location: Germany

Re: Dolby System Support

Post by Carsten » Mon Sep 02, 2019 2:38 am

Hi,

you probably noticed that I already wrote quite a bit on that topic, also in other threads (and on many other forums). It is one of the key problems many users have when creating DCPs (and not limited to DCP-o-matic). Even if we'd had leq(m) metering in DCP-o-matic (it is certainly coming), it wouldn't help much, since R128 or leq(m) mainly aid in meeting formal constraints for short-term media (ads, trailers, SAWA/TASA), not artistic judgement.
This may be another interesting read for you: https://isdcf.com/papers/ISDCF-Doc11-Mo ... 160315.pdf


If you are an audio engineer with the necessary background and the ambition to do it right (the way you explain the dynamic properties leaves no other conclusion), there is no other way than to check the mix(es) in that cinema.

Many people overestimate the problem of proper cinema loudness. In my opinion, it is mainly an issue of trailer loudness. We do need to adjust our standard setting from time to time for main features, but all in all, I think it's running pretty well. Keep in mind though, that loudness perception varys with room conditions, and highly sound dead small auditoriums have more issues than our large traditional cinema.

My main intention in the above articles was to aid in utilizing LUFS for practical work. LUFS (and leq(m) still) is not sufficient for long pieces to express a simple proper overall loudness. For ads and shorts, I think it can be used effectively to find acceptable/non complaint levels. -14 to -16 LUFS is certainly the complaint level threshold. For shorts, I would recommend leveling to -18 to -20 LUFS. That is, if common methods of decent loudness maximization (aka compressors) are used. 'Clean' documentary style location sound (or should I say 'amateur sound') will often come out too weak at that LUFS level.

You may do some surround work (the classic ambient style is not too complicated to achieve), but, if possible, try to create a separate center channel for dialog.

EBU R128 is aimed at the living room. -23 LUFS is targeted at a convenient home listening experience. This is typically too soft for cinema. So, -18 to -20 LUFS should be your primary target, and I mean this based on the cinemas processor setting for main features. This is typically 5.5 to 5.8 for Datasat or USL Processors, and often around 4.5 for Dolby processors (yes, unfortunately, the reference is not universal)


If someone else is creating the DCP, make sure they don't apply their standard gain adjustments. I know that some people attentuate everything that goes into a DCP by -6 to -12 dB. That may make some sense for YouTube, MP4, music, etc. conversions, but if you level your work to e.g. -18 LUFS, they shouldn't mess with the level further.

Oh, and just to make that clear - I understand for some countries/cinemas, preshow is advertising, then comes trailers, then main feature. For us, preshow is the full advertising and trailer block, so we play ads and trailers both at reduced level. Our preshow setting is 4.5, and our standard main feature level is 5.5 (Datasat processor). When I watch/check the movie in our auditorium myself, I tend to dial up the main feature level to 5.8, sometimes 6.0, which seems to suggest that at least for my personal preference, our standard 5.5 is a bit on the conservative side.

- Carsten
Last edited by Carsten on Mon Sep 02, 2019 11:19 am, edited 1 time in total.

StudioCompyfox
Posts: 2
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Location: Germany

Re: Dolby System Support

Post by StudioCompyfox » Mon Sep 02, 2019 9:40 am

Hi Carsten,


thank you for investing the time. Yes, I am aware of your presence in various forums. Hence me reaching out directly to you. Even wanted to send a PM, but that feature is not possible to me (yet).


I did indeed also read the PDF by Ioan Allen. Along with Eelco Grimm's commentary, and the article on SimpleDCP, that definitely was some interesting and insightful read. And yes, I have to agree - we need to find a certain standard - for everyone to use. Not just big mixing houses (cinema stages), but also independent movie makers (which are more and more).

Youtube and Vimeo are big players, but even then everyone does their thing. Loudness values all over the place. Youtube does auto-adjust, Vimeo doesn't (at least from what I saw). It's worse in cinema halls for sure.

I think the trailers are also fairly "dynamic limited" because of the "wow factor". What is not part of the picture is, that the more dense the mix, the higher the LUFS value, the higher the Leq(m). So to compensate, trailers have to be pulled down with the Dolby Setting to 4.5 or lower (3.5). Which is indeed insane. A "Loudness War" in cinema - and no suitable end in sight - unless movie studio also adapt schemes like the music realm (first there was RMS - didn't work out, then we had the K-System, and ultimately people adapted the ITU-R BS.1770-x, ATSC 85/A, EBU R-128, etc specs).



I sadly ran out of time and I have to submit the production today. I did some tests last night with Nugen Audio's VisLM, which has a Leq(m) TASA/SAWA measurement built in. I then compared it to ITU-R BS.1770-4 with "Dialnorm" activated (now part of Netflix's requests), and regular ITU-R BS.1770-x as well. My endresults were (after 15:30min of runtime / the whole program feed):

Code: Select all

LKFS -23,9
LKFS DIAG -28,4
Leq(m) 78,1dB
Leq(a) ca -24,5
I can still adjust it upwards a dB, and I'd still be below 80dB/Leq(m) TASA, which should work quite nicely with Dolby Setting 5.5 that this cinema is using. Pulling it up to -16LUFS would result in a Leq(m) of 85,8, which would be a tad (understatement, as 6dB gain boost would result in perceived twice the volume) loud at Dolby 5.5. It would be more suitable for a Dolby 6,5 setting.

Shortfilm_Analysis.png
Shortfilm_Analysis.png (555.6 KiB) Viewed 168 times
(opening the image in a new window shows more detail)



Did we mention already, that we should reach for a more unified solution to end the Loudness War in cinemas as well?


Either way... I think -23LUFS in this case is the route to go. But it'd still love to see some numeric comparisons (textform would be fine) of current day movies. Just out of pure interest. Thank you in advance for all the work you're doing.

Other than that... I think a 5.1 mix night not be possible in time. So stereo it will be. Maybe I can ask the cinema operator to "mix in some center" (at -12dB each), but this would definitely shift the loudness, and both the music and Dialog would be in the center speaker.



Let us keep up the conversation. This is highly interesting for me as Audio Engineer. :)

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