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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » A Hobbyist asks: Audio-visual trailer and sound levels

   
Author Topic: A Hobbyist asks: Audio-visual trailer and sound levels
Guy Burns
Film Handler

Posts: 15
From: Melbourne, Victoria, Australia
Registered: Jun 2017


 - posted 07-11-2017 08:05 AM      Profile for Guy Burns   Email Guy Burns   Send New Private Message       Edit/Delete Post 
Questions first, background below.
Trailer Question
If I came into your cinema asking to hire it for two Monday nights; and as well, asked you to show my trailer amongst the other trailers (as described below), what would be your response?

Sound Question
Where can I download movie trailers whose audio wouldn't have been altered too much from when shown in the cinemas? i.e. the audio is still at 85dB leq (m) which, I'm assuming, is what most trailers aim for.

If such trailers are available, I could sandwich mine between two of them on my computer, and adjust the sound level of my trailer so it fits in with the others. It would then be at a suitable level for cinema – I hope.

AV Trailer
I've had the idea to produce a 60-second trailer for my home-grown AVs. The audio would be mostly narration, accompanied here and there by classical-type music. No guns, no explosions, no car chases – just music and narration with limited dynamic range. A simple trailer about local people, which, if I do it professionally and with restraint, I suspect will have more impact on the local audience than the big Hollywood trailers. A local product always has inherent interest.

I reckon I could easily arrange to have it shown amongst the local ads with the lights on and the sound level low, but it wouldn't have much impact. I'd like to see it amongst the Hollywood trailers, after the lights are dimmed.

For the sake of discussion, let's assume the trailer in not technically deficient (i.e. the focus, lighting, colour, sound, editing are pretty good, and it's in DCP format), but it hasn't got that typical trailer look. It's not amateurish or boring for a local audience, it's just subdued and different.

Reasons why it might be declined
I can think of several reasons why a cinema might not be interested in showing it with the other trailers:

1. Even though it's technically OK, it's not Hollywood, it's not from a real movie, so they're not going to show it.

2. It's not slick and exciting enough.

3. The cinema isn't allowed to show any trailers other than the ones that are provided with their movie packages.

4. It would be too much bother to insert the DCP trailer into their normal programming.

One reason why it might be accepted
I offer several times the normal ad rate!

Trailer Sound
During a short audio/video test, I will determine a suitable setting for the Dolby fader for the presentation itself. I will ask for the same Fader setting on the actual night.

But the trailer is a different matter. It's not standalone like my presentation. I can't be sure what Fader level will be used for the other trailers (it might change during the week, movie to movie), so I need to adjust the audio level of my trailer to roughly match that of the other trailers. I don't want it to sound out of place by being too soft or too loud. It'll be subdued, but it needs to fit in.

I've asked some technical questions about this over at: https://www.gearslutz.com/board/post-production-forum/1164120-hobbyist-several-questions-about-82-db-leq-m.html#post12730460

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Carsten Kurz
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From: Cologne, NRW, Germany
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 - posted 07-11-2017 09:19 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
First - forget about LEQ(m) 82 or 85. These are agreed upon maximum levels. It's important to understand that these are perceptually weighted levels. They are meant as 'no complaint' levels (which actually means, they are close enough to actually cause complaints from typical audiences). If you approach an audio studio with your mix and tell them 'conform this to 82 or 85 LEQ(m)', the audio will typically come out too loud, because they will not consider the LEQ(m) as a limit, but as a target. You don't want your stuff being heard as loud as the Transformers5 trailer, do you?

DCP-o-matic so far offers the EBU R128 loudness analysis, because R128 is part of the underlying libraries/framework, and LEQ(m) is not (yet).

EBU R128 shares some concepts with Dolbys LEQ(m) system, but it is not the same - LEQ(m) is for cinema, R128 is for broadcast. But it can be used to get a decent idea wether you are in the right ball park, because the weighting concepts are similar, and both are based on an absolute full scale referenced perceived loudness.

The problem with soundtracks not going through a 'prodessional' mastering like your's (sorry for that) is that there is usually little compression or level optimization, which means, there are many spurious peaks that may force you to keep the overall level rather low in order to avoid those peaks to clip/distort.

Listening to cinematic trailers to compare the level is not a bad idea. Before DCP-o-matic introduced EBU R128, it was my suggested way to achieve decent level compatibility if no cinema test run was possible. Of course, it needs to be cinema audio files from trailer DCPs, listening to movie trailers on Youtube etc. is completely useless.

You need to make sure you choose a trailer that has comparable tonal aspects to your own AVs. That is, do not use a Transformers5 trailer as a reference, but a documentary, or a dialogue movie with some music.

I suggest you re-open your AVs in DCP-o-matic, check 'Find integrated loudness...' in prefs, do an analysis of the whole project (full length, this is important). Then under the DCP tab, choose 'Audio' -> 'show audio', and post a screenshot of the audio levels to the DCP-o-matic forum.

I'm sure, someone (maybe me) can supply a suitable trailer audio track for a comparison. I would even offer to try your audio in our cinema play at reference level, it's no big deal to send it over nowadays. I don't need the picture with it.

Are there any other cinemas in your area?

- Carsten

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Guy Burns
Film Handler

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From: Melbourne, Victoria, Australia
Registered: Jun 2017


 - posted 07-11-2017 12:57 PM      Profile for Guy Burns   Email Guy Burns   Send New Private Message       Edit/Delete Post 
Thanks for the interesting read, Carsten.

I searched the DCP-o-matic manual before I posted (amongst hours of other searching), typing in BS 1770, EBR, LEQ, but nothing came up.

And in this forum I came across Frank's thread about DCP-o-matic (which included a graph). Then I saw your post in that thread: "The graphs are of limited use", and I thought, "Well, if Carsten reckons they're of limited use, they're no good to me."

Anyway, that thread was 3 years ago, and I thought DCP-o-matic might have gained some features since then. So I've just opened up DCP-o-matic, and up came the graphs with loudness numbers. I checked the Integrated Loudness of 6 audio files: a couple of Beatles songs, two of my AVs, and two files with a music/silence combination.

Then I did the same with Adobe Audition, noting the BS 1770-2 level.

In all cases, Integrated Loudness was within 0.05dB of BS 1770-2. That's handy to know. It means I can trust both to give the same reading. But they use different methods, don't they?

Compression
Yes, I'm a purist. I don't limit or compress any of my audio, except manually. I hunt down those peaks (if they're causing a problem), and individually lower the gain from zero-crossing to zero-crossing. In my type of audio, there aren't many of them.

I've got a thing about those effects. iTunes once sold me a pop song that had the crew-cut look on top, and I demanded my money back – and got it.

Trailers
You need to make sure you choose a trailer that has comparable tonal aspects to your own AVs.

Wouldn't it better to have two ordinary trailers as a comparison, sit mine in the middle, listen, compare, and adjust mine? From my reading, I thought all digital trailers were mixed to come just under 85dB leq (m), the volume-wars thing.

I'd like to think that at whatever volume setting I use on my home amplifier, that I could tell that Transformers 5, say, was at too-high a level; that it would sound too full and noisy. But I'm just guessing there.

If anyone is willing to send me the audio from two trailers, preferably with the Leq value of each, please gmail me at gdburns.

Local Cinema
Thanks for the offer of playing audio in your cinema. I wish the local cinema was as helpful. They're not unhelpful, but it's just a job for them. They've got little interest in the technical side.

I'm in a small, one-cinema town. They do an excellent job. People come from 100 kms away to see the Met operas. The General (1925) is on soon, with a jazz band playing the music. The next closest cinemas are 50 km one way, and 120 the other, so I only have one option at the moment.

Cinema Volumes
I've spent more time looking into audio volumes in cinemas, than I have trying to learn about Blu-ray playback, DCP, and VPF combined. Dolby sets a standard, then cinemas have to flout it because trailers come in too loud, then directors complain because their movie is too soft, so then they try and reign in the trailers…

The human voice – dialogue, narration – is the most important aspect of audio, in my view. Two standards that I would find useful would be:
  • Male voice, close-miked, matched to some standard, when played in a cinema at Fader 7 gives a comfortable voice level.
  • Same for female voice.
If there was such a standard (is there?), I wouldn't have to be asking all these questions.

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Carsten Kurz
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From: Cologne, NRW, Germany
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 - posted 07-11-2017 04:05 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
It is true that normal VU meters, peak levels, even RMS, is of little use in general, that was the current state when I made that statement concerning DCP-o-matics audio level display. Carl Hetherington understands about these things. He is an audio guy. However, getting audio levels right is just not so easy, so, initially, having these graphs was better than nothing. Just as now, having EBU R128 is better than not having it. I have analyzed many commercial trailers with DCP-o-matics R128, so I gained some insight in the meaning of R128 for cinema trailers. The standard you are referring to, male voice, actually does exist, it existed even before digital cinema. It is called 'dial norm'. That is to say, it is expected to be 'normal' to have standard dialogue level at around -20dBFs RMS (btw - thats the same level the cinema audio system is calibrated at level 7). This does work, you can also judge this in DOMs audio level display with the RMS curves. But it only set's your dialog level into the right ballpark. And very often you don't have dialogue passages long/constant enough to give a nice reading, especially with uncompressed audio.

Now, go to that cinema again and ask them at what fader setting they play their trailers and main features. Quite probably, not at 7...

Also, you shouldn't expect every trailer to hit LEQ(m)85 - there are many trailers much lower than this. As I said, this is a maximum not to be exceeded. It is completely okay if a family comedy or love story uses much less. Why would you need the loudness of a nuclear blast in a love story?

quote: Guy Burns
But they use different methods, don't they?
https://en.wikipedia.org/wiki/LKFS

- Carsten

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Guy Burns
Film Handler

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From: Melbourne, Victoria, Australia
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 - posted 07-11-2017 11:13 PM      Profile for Guy Burns   Email Guy Burns   Send New Private Message       Edit/Delete Post 
Thanks Carsten.

I'd visited that wikipedia article several times over the last few weeks. Still throws me. It seems to be saying that:

1. LKFS is a loudness standard – a certain algorithm that comes back with a dB figure for a piece of audio.

2. But LKFS does not stand alone. It actually is part of, and first described in, BS 1770.

3. BS 1770 has had a few revisions: BS 1770-2, BS 1770-3, and BS1770-4.

4. Then EBU R128 came along and introduced LUFS.

5. But LUFS is identical to LKFS.

No wonder I was confused!

Narration Test
If your offer is still open, I might take you up on testing narration for me. I've got narration recordings for my AVs from the 1980s (recorded on Tascam 4-track) through to recent digital recordings. A variety of ages (7-87), male and female.

Would the following be suitable:

• 10-15 seconds of each
• 10 different voices, say, each normalised to -23LUFS
• 3-second gap between each
• all in one m4a file (or other format)

About three minutes in total. I'll upload it, and post the link here. I'd like to know the Fader setting used (7 or whatever), and also whether the volume for each voice is:

• acceptable
• too loud
• too soft.

If you're able to do that, please let me know, either privately or here.

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Marcel Birgelen
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From: Maastricht, Limburg, Netherlands
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 - posted 07-12-2017 07:50 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
Unfortunately trailers are also copyrighted content, some of them even require KDMs to play. So, those DCP trailers aren't always freely available.

If you do a bit of Googling, you'll find some independent distributors who will provide some DCP trailers.

EBU R128 started to become a real thing for professional ads in Europe and many broadcasters now require ads to conform to it. But LEQ(m)=85 still isn't something that seems to be commonly employed by Hollywood trailers or a LEQ(m) of 85 is still too loud... (Or let it put it this way, Hollywood now has a "new" challenge: make it sound as loud as possible but still hitting LEQ(m)=85 or 82.)

So, in order to compensate for over-zealously compressed sound in trailers, many theaters still pull their volume down a few notches once the trailers start.

Also, do you already know in what part of the show your trailer will be played? In many cases, part of the pre-show is sold to an external provider, who supplies the content to the theater, mostly in DCP form. Most theaters also reserve a slot for personal and local advertisements, it's often easiest to get a slot right there.

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Bill Brandenstein
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 - posted 07-12-2017 02:53 PM      Profile for Bill Brandenstein   Email Bill Brandenstein   Send New Private Message       Edit/Delete Post 
Pardon me for asking a dorky question, but now that DCPs are the norm and Dolby Digital is basically dead for theatrical delivery, is there nothing to replace the DialNorm spec? I'm assuming that theatrical equipment did/does the same as home theater receivers and compensates the playback level based on the encoded DialNorm level (-31dBFS = +4dB gain compensation, unity at -27dBFS, and reduction of -26dB if DialNorm were -1dBFS). Of course those numbers are often incorrect, which wastes it, but in theory it shoulda been a good thing.

I guess it's a part of the HDTV spec, but couldn't tell you how well it's implemented.

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Frank Cox
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 - posted 07-12-2017 03:10 PM      Profile for Frank Cox   Author's Homepage   Email Frank Cox   Send New Private Message       Edit/Delete Post 
As far as trailer volume is concerned, my system is cued such that the trailers play at a lower volume than the feature; the "feature start" cue turns the volume up among other things.

Otherwise some of those trailers would blast people right out of their seats. I guess the folks that make them subscribe to the louder-is-better school of art.

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Monte L Fullmer
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 - posted 07-12-2017 03:51 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
When I create DCP content using DCP-O-Matic, I set the sound level down to -13dB in the audio tab where this matches with our system for feature levels for the final result from the DCP production.

When I am creating background music with the same program, I set the audio down to -26dB where the sound is at a subdued level where it's definitely not disturbing for the guests.

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Carsten Kurz
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 - posted 07-12-2017 08:44 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
quote: Bill Brandenstein
I'm assuming that theatrical equipment did/does the same as home theater receivers and compensates the playback level based on the encoded DialNorm level (-31dBFS = +4dB gain compensation, unity at -27dBFS, and reduction of -26dB if DialNorm were -1dBFS). Of course those numbers are often incorrect, which wastes it, but in theory it shoulda been a good thing.
No, the dialnorm function was never part of Dolby Digital for Cinema, it was only used for DVD/Bluray/Broadcast. But film sound mixers still adhere to Dolbys rules for dialog level placement and headroom.

quote: Guy Burns
If your offer is still open, I might take you up on testing narration for me.
The offer is still open, but I think it would make more sense if you create the DCP from your finished AV presentation and send the resulting audio MXF to me, so I can play it back in our cinema at reference level. It is useless to start with voices only, as everything is taken into account for R128.

- Carsten

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Guy Burns
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From: Melbourne, Victoria, Australia
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 - posted 07-13-2017 03:59 AM      Profile for Guy Burns   Email Guy Burns   Send New Private Message       Edit/Delete Post 
quote: Marcel Birgelen

Also, do you already know in what part of the show your trailer will be played? In many cases, part of the pre-show is sold to an external provider, who supplies the content to the theater, mostly in DCP form. Most theaters also reserve a slot for personal and local advertisements, it's often easiest to get a slot right there.

Thanks for that info. I didn't realise the ad section was also going to be a problem (in addition to Blu-ray/DCP and VPF). I was wondering why the manager sent me a PDF with Val Morgan's file specifications. Never heard of them until now (http://www.valmorgan.com.au/advertise/).

So it could be that the cinema has already sold the entire trailer section, and I won't get a look in. Or maybe not – because a figure of $450 a month was mentioned in an email ($200 for a still). But it was not at all clear what the cost covered, and where my trailer would appear.

Anyway, I may not want to contribute to the pre-show getting out of hand (http://www.adnews.com.au/adnews/comment-cinema-ads-are-getting-out-of-hand)

I have also obtained some typical numbers for the theatre's Dolby CP 750:
• Movies… start at 4.5
• Trailers and local ads… 3.8

It seems I'm on a track to nowhere with my idea of obtaining a Hollywood trailer and trying to make sure mine fits in – that doesn't mean trying to make it as loud; just that it's volume is not ridiculously lower or higher. The local trailers come as block from Val Morgan, I'm assuming, with an unknown audio level, then adjusted by the cinema. The only way for me to ensure my trailer fits in, would be to listen to the trailers in the cinema, then play mine and adjust.

quote:
… but I think it would make more sense if you create the DCP from your finished AV presentation and send the resulting audio MXF to me, so I can play it back in our cinema at reference level. It is useless to start with voices only, as everything is taken into account for R128.
I'm not convinced that narration-only is useless in my case. Narration is the dominant component in my AVs. It's the central focus. The AVs are true audio-visuals, not movies, not documentaries. Sometimes the narration stands alone – no sound behind it at all. Sound effects are virtually non-existent. Music weaves in and out. Each paragraph of the narration is matched in Audition to -23 LUFS before entering Premiere. The rest of the audio has to fit in with that.

Dynamic Range – small.

I'm pretty sure the voice is going to set the level. I want each person in the audience to feel the person talking on screen, is having a personal conversation just with them, at a normal volume.

But, I'm new to cinema audio, so I could be wrong. I'm all ears.

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Marcel Birgelen
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 - posted 07-13-2017 04:38 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
quote: Bill Brandenstein
Pardon me for asking a dorky question, but now that DCPs are the norm and Dolby Digital is basically dead for theatrical delivery, is there nothing to replace the DialNorm spec?
DialNorm is in the metadata of the AC-3 stream. Metadata and film, which isn't a random access medium, has always been a bit of a no-go. (Although Dolby managed to sideline firmware updates into their SRD tracks and this is just a single integer [Wink] ). Also, DialNorm probably was established after the SRD specs were drafted, so I guess that's the reason it never made it in there.

quote: Guy Burns
So it could be that the cinema has already sold the entire trailer section, and I won't get a look in. Or maybe not – because a figure of $450 a month was mentioned in an email ($200 for a still). But it was not at all clear what the cost covered, and where my trailer would appear.
Theaters usually still determine themselves what trailers of upcoming releases they play in front of any given show. If they're part of a chain, things might get a bit more complicated, because some kind of program manager might determine what is to be played in front of what show.

In many cases, pre-shows consist of blocks, here's an example, your mileage might obviously vary depending on your locations, local habits, regulations and whatnot:

- Local advertisements, often just slideshows or simple animations with no audio, often sold to a separate agency
- Big Business advertisements, often managed by some bigger central agency like Val Morgan in your case
- "In-house" advertisements, usually provided in-house, by the mothership or a combination of those
- Trailers of upcoming attractions
- Stingers and logos
- And finally: The main attraction

Again: Highly dependent on your local theater. The example above is more in line with the average multiplex, many local theaters try to keep the preshow reasonably short.

In some cases, ad agencies demand some kind of exclusivity, but this almost never covers local advertisements. In some cases, a theater or a chain might have a deal with the agency, where they pay a reduced fee to have their own content delivered to be shown as part of the pre-show. They usually do this, because they do not have an in-house content team. So, they often just fire a PowerPoint to them and they convert it into some kind of DCP deliverable for them or integrate it right into the show they deliver (often as a single DCP).

So, it again comes down to your local theater. Are they willing to put it in the "Trailers" section for you? Or are they just referring you to the agency that manages the ads for you?
This entirely defines where your trailer will end up and what it will cost you to have it shown. It definitely couldn't hurt to contact Val Morgan and get a quote from them, at least you have an indication for "Option A".

quote: Guy Burns
The local trailers come as block from Val Morgan, I'm assuming, with an unknown audio level, then adjusted by the cinema. The only way for me to ensure my trailer fits in, would be to listen to the trailers in the cinema, then play mine and adjust.
If you submit your trailer via an agency like Val Morgan, chances are they will normalize it for you, so it conforms better to the other ads and trailers they show. If you contact them, ask them if this is already part of their services or if this option is available.

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Carsten Kurz
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 - posted 07-13-2017 04:32 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Guy, -23LUFS is for broadcast, that is, for acceptable 'living room' experience. You want it a bit more intense in a cinema. I wouldn't start at less than -20 LUFS. Even that is probably not enough. For a trailer, you need even more, because they play the trailers at a lower setting, which means, you somehow want to fit in between the other trailers.
There you are, right within the loudness war...

- Carsten

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Bill Brandenstein
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 - posted 07-13-2017 05:11 PM      Profile for Bill Brandenstein   Email Bill Brandenstein   Send New Private Message       Edit/Delete Post 
Carsten and Marcel - thank you.

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Guy Burns
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 - posted 07-13-2017 11:38 PM      Profile for Guy Burns   Email Guy Burns   Send New Private Message       Edit/Delete Post 
And a thank you from me, too, Marcel and Carsten.

Marcel's post leads me to quite a number of questions directed to the local cinema manger. At least I know what to ask now.

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