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Audio-visuals shown at a cinema: what might be the problems?


Guy Burns

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Background

I'm converting my three-screen audio-visuals to Blu-ray format, with the aim of presenting them at the local cinema. Basically they're slide shows from the 80s and 90s, with a few added clips from my GH3, and new soundtracks. I'll let a few friends know, and they can pass the word around.

 

It's just a hobby, but I want to do the absolute best job I can. Editing is in Premiere at 23.976 fps, and all slides enter Premiere in sRGB. Video output if rendered to m4v format at 20-35 Mbps, and passes through Adobe Encore (without transcoding) onto a Blu-ray disk.

 

What I see on my iMac screen is pretty much what I see on our 3-metre home theatre screen – my test bed.

 

 

At the Cinema

What I am concerned about is how the presentations will look and sound in the cinema. I've had a short tour of the projection room. They run four Barco projectors…

 

https://www.barco.com/en/Products/Projectors/Cinema-projectors/Lamp-based-cinema-projectors/C-series/Compact-DLP-Barco-Alchemy-Cinema-projector-for-screens-up-to-20m-65ft.aspx#!specs

 

… and the operator assured me the setup can accept HDMI input. So my idea is to take along my Oppo Blu-ray player, a HDMI cord, and have a test run. I will only be allowed 5-10 minutes of testing.

 

 

Questions

​Before I go to the cinema for a test run, I want to have a pretty good idea of what to expect, and where problems might occur. Thus these questions.

 

Ques 1: HDMI

The Barco processor has one HDMI input, but the specs make no mention of a 23.976 frame rate. Does having a HDMI input imply the Barco will work with all signals from a Blu-ray player, including 23.976 fps?

 

 

Ques 2: Gamma

My entire workflow is in sRGB (with a gamma of ~2.2), from scanner (or GH3), to my iMac, through to my BenQ W7000 projector. However, Cinema projectors, I read somewhere, have a gamma of 2.6.

 

What effect will that have on my images?

Will the effect be noticeable?

Should I correct for it?

How would I correct for it?

 

 

Ques 3: Test Material

The best test material would of course be the actual presentation, but I'll be limited to only a few minutes of projector time. My idea is to take along on Blu-ray disk:

 

1. A projector Calibration Pattern for Blacks (levels 0 - 16).

2. A similar pattern for Whites (levels 239-255)

3. 30 seconds of a typical dark scene

4. 30 seconds of a typical bright scene

 

Items 1 and 2 are not for calibrating the Barco, of course. If levels 0-16 all appear black, say, I'll have an indication that something's not right.

 

Are the four items listed above, the most suitable?

 

 

Ques 4: Sound

Is there a loudness standard for films?

 

All my audio is matched to ITU-R BS 1770-2. My guess is that the cinema runs a constant volume setting on their amps, a setting which suits most films. And I'd rather not ask them to change that setting just for me.

 

 

Thanks in advance for any comments.

Edited by Guy Burns
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If possible, hire a post sound mixer with a home studio to run it through their system and tweak the levels at least. They should at least have a 5.1 setup that approximates the movie theater.

 

No idea about the video settings, sorry. Your test sounds like a good idea. Maybe also test to see if you can simply plug in your laptop directly to the HDMI on the projector. Just in case the Blu-Ray player doesn't work.

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Most bluray players have a USB port for playing files directly from a flashdrive. That's always more reliable than an actual disk.

 

I've traveled to screenings with a backup projector at times just in case and have had to use it on more than one occasion.

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