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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » What's up with these 2.0 channel trailers? (Page 1)

 
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Author Topic: What's up with these 2.0 channel trailers?
Michael Brown
Phenomenal Film Handler

Posts: 1516
From: Bradford, England
Registered: May 2001


 - posted 06-02-2012 12:53 PM      Profile for Michael Brown   Email Michael Brown   Send New Private Message       Edit/Delete Post 
Is anyone else getting trailers that are just made in stereo (rather than 5.1).

It's not happening often admittedly but i've had a few in.

The first was for Robert Rodriguez's Machete. When we ran this trailer my theatre was still a mix of digital and 35mm houses. The digital trailer was a 2 channel stereo mix, yet the exact same trailer on 35mm had a full 5.1 SRD track.

Had this happen with a few other trailers too since. (think it was either Haywire or Cold Light of Day where the trailers were a 2.0 mix)

Most recently - the trailer we are running right now for 'Seeking a Friend for the End of the World' the mix is 2.0 stereo. It sounds really weird playing in the middle of a set of other trailers that are all 5.1. (mainly because the dialog is coming from the left and right channels rather than the center).

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4196
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 06-02-2012 01:02 PM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
I'm running a 2.0 trailer for "The Deep Blue Sea."

But it gets even better: Not only is the audio 2.0 -- it's mixed so "hot" that I have to play it with the volume turned way down to 3.8 [Eek!]

Oh, yeah -- and the aspect ratio is 1.85 letterboxed inside 16x9 -- so with "true" 1.85 masking the trailer looks "bread-boxed" with a black border all the way round.

I guess we're just lucky to have a trailer at all.

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Paul H. Rayton
Expert Film Handler

Posts: 199
From: Los Angeles, CA , USA
Registered: Aug 2003


 - posted 06-06-2012 02:09 PM      Profile for Paul H. Rayton     Send New Private Message       Edit/Delete Post 
This was discussed previously in this thread Mono sound in Universal legacy movies . I awoke Universal to the same problem in the audio mastering of their legacy movies, as they were being rendered in to digital (d-cinema) versions. My guess is that the audio tracks created for DVDs were simply being applied to the DCP, which was wrong. Those DVD (?) two-channel tracks were, similarly, L and R, and no center.

To their credit, Universal saw the error of their ways and will subsequently render out mono tracks on C channel only. And they will, they say (and we hope) re-do the ones they've already done incorrectly, which, FWIW, includes all the original Marx Brothers movies. Center channel mono will be in center channel only.

But that case was for old mono tracks. Your situation is more contemporary stereo. Same problem, different situation.

These post-production houses (just as in the case of Universal) didn't pay attention in class, and don't seem to understand that d-cinema is not the same as film sound. DCI specs are quite clear on the subject: there is no such thing as matrix-decoded audio. It's discrete tracks only. Left is left. Right is right. Center is center. Etc. If these post houses send out DCP material with two channel tracks (LT/RT), they are NOT going to play back as proper stereo! NO! It is NOT the same as Dolby SR, or any other analogue process.

And, you are quite right: the sound field feel, in that mode, will be somewhat strange in the seating area, because there will be no C (Center) channel. The room will feel (depending on where one is sitting) like the sound is off to the far left, or far right, and nowhere near where sound "should" be coming from, i.e., the center. Dolby techs would describe it as being "left heavy", or "right heavy". The sole seats in the venue that would hear anything approaching a semblance of correct stereo sound would be those along the precise centerline of the theatre. One seat per row of seats! Quite ridiculous!

Wake up, you post-production houses! LT/RT is not what you are supposed to put on d-cinema tracks! It's like putting square tires on a car -- it doesn't work! You can NOT simply apply the same master track that you're going to throw on the film print! It's a whole 'nother type of sound! Wake up!!

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4196
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 06-06-2012 02:41 PM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
quote: Paul H. Rayton
The room will feel (depending on where one is sitting) like the sound is off to the far left, or far right, and nowhere near where sound "should" be coming from, i.e., the center. Dolby techs would describe it as being "left heavy", or "right heavy".
FWIW - This is more correctly the result of the "precedence effect" or the "law of the first arriving wavefront."

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Aaron Garman
Phenomenal Film Handler

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From: Notre Dame du Lac, Indiana USA
Registered: Mar 2003


 - posted 06-06-2012 03:31 PM      Profile for Aaron Garman   Email Aaron Garman   Send New Private Message       Edit/Delete Post 
While I support discrete audio for DCinema, it is a bit unfortunate that matrix processing wasn't put into the spec. I mean say an older film only has a matrix stereo element available, how would you get that to play correctly on dcinema equipment without remixing? Not that this is likely, but one never knows. Once again, home theatre in many ways has a lot more audio processing flexibility.

AJG

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4196
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 06-06-2012 03:37 PM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
You *can* route an Lt/Rt via a DMA8plus, if one is present.

I have a spare cable handy in case I'm forced to do that -- but I'd only do that for a feature. I'm not rewiring the system for trailers.

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System Notices
Forum Watchdog / Soup Nazi

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Registered: Apr 2004


 - posted 10-04-2015 12:15 AM      Profile for System Notices         Edit/Delete Post 

It has been 1214 days since the last post.


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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4196
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 10-04-2015 12:15 AM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
Also -- I would expect to find a 4.0 discrete master "in the vault" for any film released with an Lt/Rt matrix. THAT's what they really SHOULD use.

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Leo Enticknap
Film God

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From: Loma Linda, CA
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 - posted 10-04-2015 12:34 AM      Profile for Leo Enticknap   Author's Homepage   Email Leo Enticknap   Send New Private Message       Edit/Delete Post 
A lot of homebrew DCPs and shows that have a "TV mix" that we get are 2.0 ProLogic, too. One of the things I like about the AP20 is that it can matrix these. Using serial cues in our DSS200, it's pretty easy to swap between DCP "straight through" and DCP 2.0 matrix, even between individual ads and trailers.

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Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4196
From: Bloomington, IN, USA
Registered: Feb 2002


 - posted 10-04-2015 12:48 AM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
I also use DSS200 serial cues to trigger sound format changes (that are not part of the built-in capabilities).

Lately, I've taken to using the "U1" input of the CP650 for Master Digital In with Pro-Logic decoding, instead of re-wiring to use the DMA8plus. I have to re-assign U1 when I'm showing 16mm, but that's become something of a rarity, compared to how many DCP's I'm getting with 2.0 sound. In the end, I realized it is easier to assign/reassign U1 as-needed, rather than rewire as-needed.

Even so, I still need to use serial commands to control the (QSC) DCP-300 processor, for handling things like:

Dual Mono -- with/without Academy roll-off
Stereo -- wide versus narrow
Surround -- 5.1 versus 7.1

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Jim Cassedy
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From: San Francisco, CA
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 - posted 10-04-2015 09:48 AM      Profile for Jim Cassedy   Email Jim Cassedy   Send New Private Message       Edit/Delete Post 
quote: Michael Brown
Is anyone else getting trailers that are just made in stereo (rather than 5.1).
Yes, but I'm not loosing any sleep over it.

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Dave Macaulay
Phenomenal Film Handler

Posts: 1930
From: Toronto, Canada
Registered: Apr 2001


 - posted 10-04-2015 10:00 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
You can do matrix decoding from L/R with a CP750 as well, the command is in the long list. The setting is sticky though, if it doesn't get set back for a normal movie you get matrix'ed L/R instead of 5.1 or 7.1.
This is not an unusual requirement with an IMB, IMS, or ICMP system where HDMI audio is passed through the projector to the audio processor. They want to play a Blu-Ray that only has DTS digital audio - but for some unimaginable reason the Dolby CP750 will not decode DTS digital!
I set up a "HDMI sound" server macro that changes the CP750 to L/R decode mode and add a cue setting it back to discrete in every digital movie macro.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 11692
From: Annapolis, MD
Registered: Dec 1999


 - posted 10-04-2015 02:22 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Our "END_SHOW" cue always puts the CP750 (or whatever processor) back to normal 5.1 mode.

Left should go to Left

Note, the DCP 200/DCP300 CAN do a matrix decode...they just forgot to make it available to the Digital 1/Digital 2 input formats. It WILL be there on the next release of the DCP software. The problem really is in the omission in the DCP software itself, not in the DCP firmware.

If you create a 2.0 format. Set up everything properly for say 5.1 in Digital 1. Save it and then open up the dcg file (it is a text readable file) and search for "MatrixType". On the format you created, change the type to:

<MatrixType>SurroundDecode</MatrixType>

In the SurroundDecode format, it should make it an Lt/Rt decoding format.

Upload that file to your DCP

Naturally, use this at your own risk but I have a theatre where this is working as they get a LOT of DCP 2.0 formats movies (they run festivals).

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Dave Macaulay
Phenomenal Film Handler

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From: Toronto, Canada
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 - posted 10-04-2015 04:04 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
Steve: I put that cue in "Show End" but of course someone ejected a Prologic show before the end and, the next 5.1 was L/R and the results of Prologic on non-encoded content. So it goes in each 5.1 format macro now...

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 11692
From: Annapolis, MD
Registered: Dec 1999


 - posted 10-04-2015 07:36 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Yeah...all of my Flat/Scope cues presume 5.1 as well and force the end user to choose 7.1 (let alone 2.0) for the same reason. You can't idiot proof everything...the idiots are just too clever in their desire to circumvent the best of intentions.

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