Dual Screen DCP playback.. is it possible ?

[Barry Floyd]

I have a unique situation where we have been offered the opportunity to premiere a major motion picture in the month of October at the drive-in. The studio and their marketing partner want to buyout the entire theater (both screens) and have an invitation only audience in attendance.

The catch is.. none of the attendees vehicles will have radios so we will need to setup some type of outdoor live PA systems. Being 35 miles from Nashville, an outdoor PA system isn't going to be an issue.

The draw back to outdoor PA systems would be that our theatre layout is configured where both screens face each other, and I don't know of a way to synchronize both screens so the sound traveling from the opposing side doesn't affect the other.

Last year when we were doing "live" concerts, we tried having patrons on both screens (one with live sound, the other listening via car radio) and it ended up being a garbled mess. The sound would instantly come out of the radio, then 2 seconds later it came "live" (but delayed) from behind from the opposing side, then hit the screen and bounced back again. It was horrible.

Anyone know of a way to either play one movie on two projectors exactly in synch at the exact same time?

[Carsten Kurz]

What servers do you use? Some allow syncing. Also, it would probably be best anyway to feed both PA systems the same signal from only one server.

[Barry Floyd]

We have brand new GDC SR-1000's. Projectors are Barco DP2K-23B's, and USL JSD-60's for sound processing.

[Leo Enticknap]

Two SR-1000s can by synched together, using IP multicasting. The feature is intended to enable separate left eye and right eye projectors for 3-D, but I can't see any reason why it couldn't be used to ensure simultaneous projection of a 2-D CPL by two systems. The bummer is that you need to buy a license from GDC to enable it. The dealer from whom you bought the SR-1000s could give you a quote. Assuming that the audio delay is set the same on both, that should sync the audio playback.

[Marcel Birgelen]

Last year when we were doing "live" concerts, we tried having patrons on both screens (one with live sound, the other listening via car radio) and it ended up being a garbled mess. The sound would instantly come out of the radio, then 2 seconds later it came "live" (but delayed) from behind from the opposing side, then hit the screen and bounced back again. It was horrible.

I'd say, make sure you get yourself a bunch of line arrays and a bunch of people who know how to aim them correctly. That should get rid of most of the reflections and accompanying echo and distortion. Since you're aiming your PA at cars, there will always be some reflection, but due to the shapes of them, I expect them to get diffused quite efficiently.

As for the delay, there is nothing much you can do, as there isn't an easy way to speed-up sound. If both fields are about equally sized, I'd say that the half-way point of the largest field should be your "zero" reference for your delay settings, in order to keep the sync in somewhat acceptable ranges across the field.

[Kenneth Wuepper]

When providing sound to vehicles from outside, rmemeber that the picture is accessed through the windshield while the external sound comes through the open windows on the sides of the vehicle. Playing the sound across the field would eliminate the bounce off opposing screen surfaces while getting sound where it can enter the vehicles.

Lip sync will be nearly impossible with the distance factor.

[Gordon McLeod]

Find some Altec A2's

[Marcel Birgelen]

When providing sound to vehicles from outside, rmemeber that the picture is accessed through the windshield while the external sound comes through the open windows on the sides of the vehicle. Playing the sound across the field would eliminate the bounce off opposing screen surfaces while getting sound where it can enter the vehicles.

Lip sync will be nearly impossible with the distance factor.

Given that the fact that the sound will enter through the open side windows of the cars/vehicles, maybe it makes sense to put the speakers to the side of the field, aimed at the open doors/windows. That way, you may actually even get some stereo.

[Mike Blakesley]

Three questions:

1. How is it possible to have that many cars with no radios, considering every single car built in the last 60 years or so comes with a radio as standard equipment?

2. Has anyone mentioned to the film owner that their film is probably going to sound terrible in this setup, which is probably the exact opposite of what they're wanting?

3. If the cars truly have no radios, how about working with somebody who makes portable radios and equip everybody with a radio boombox? They could be provided as a promotion.

[Marcel Birgelen]

Barry, the topic starter, mentions vehicles, so it could be anything: boats, planes and even trains.

[Jim Cassedy]

As several others have suggested, "yes" it is possible to sync two servers. I've seen it done for an experimental installation, and although I ran that system at several events, I had nothing to do with its' installation or set up, so I can't say how it was done. It it required two DCP's, & two KDM's, and everything ran in frame-for-frame sync. Your big issue, as you are already aware, is going be figuring out how to deal with the audio issues. The dual system I worked with was a big indoor installation, and the audio was only pulled from one of the DCP's, although, in the event of a failure, (or just for fun!) I could fairly easily switch the audio from the 2nd DCP into the amps through a back-up CP-850 in the racks. There were back-up amps for the main speaker channels too that could be re-routed if necessary. We only had two instances where the show started and the DCP's were out-of sync by several frames. Fortunately, both of these happened during rehearsals, and a re-boot fixed everything, Somebody finally figured out that achieving successful server synch was somewhat dependent on the order that the system was powered up at. One server was the "Master" and the other was the "Slave". (and you thought slavery had been abolished!)
If I recall, I think we had to wake the "Slave" server 1st, which was a bit counter intuitive to me, but whattheheck- - it worked.

[Harold Hallikainen]

The physical location where audio and video should be in sync, considering propagation delays, was mentioned. I've always thought they should be in sync for the person closest to the screen and the audio running behind the video for people farther from the screen. We are used to sound arriving late due to the propagation speed of sound, but early arriving sound "messes with our brains." During the writing of the SMPTE recommended practice on sound system adjustment, I suggested sync in the first row, but the RP ended up setting sync at the "reference position." This, to me, results in everyone in front of that position getting early sound and messed up brains.

Harold

[Barry Floyd]

The "vehicles" in question would be motorcycles. Likely 350 - 500 motorcycles.

[Marcel Birgelen]

I guess for motorcycles, it's best to have the sound coming from the front instead of the sides.

The physical location where audio and video should be in sync, considering propagation delays, was mentioned. I've always thought they should be in sync for the person closest to the screen and the audio running behind the video for people farther from the screen. We are used to sound arriving late due to the propagation speed of sound, but early arriving sound "messes with our brains." During the writing of the SMPTE recommended practice on sound system adjustment, I suggested sync in the first row, but the RP ended up setting sync at the "reference position." This, to me, results in everyone in front of that position getting early sound and messed up brains.

According to "common knowledge", the threshold of detectability lies somewhere between -40ms and +80ms, so this gives you some "wiggle room" in both directions and ideally you want to cover as much of your audience as possible within this "threshold of detectability field".

The nice thing about recorded stuff is that you have the possibility of a negative delay, which you simply don't have with any live performances.

Ideally, if the surface you need to cover is too large, you'd have multiple lines of PA speaker arrays, to cover the field more uniformly and to reduce delays.

[Jack Ondracek]

So, just from what I've done in the past: You only need one DCP and the normal set of KDMs that cover all of your projectors for a particular show. Nothing unusual about that. We've run the same shows on multiple screens already... just not at exactly the same time. We commonly load our DCPs into all of our screens, which makes it easier to move the shows around, if the response to one of them surprises us.

If the servers can by synched, then I'd take a look at individual timing, In the Doremi servers, audio timing can be adjusted, to an extent. Perhaps it can be done in the same way with Barry's.

If I was presented with something like this, and I haven't, so this is just speculation on my part, I would look into bi-amping, elevating the mains on the sides of both screens so they angle down toward the center of the fields, more or less, then advance the sound from the servers to synch with the video in the middle of the fields. In some places, the delay might be a compromise, but probably not enough to be distracting. That might also help with the reflections from the screens, since the speakers wouldn't be pointing directly at them. Get the timing equal at the center and then heading toward the screens would be far enough away not to matter... or that's the thought.

I'd put a woofer or two on the ground at the center of the screens for the lower frequencies and would not worry about subs. Synch would likely not be critical for that.