Dual Screen DCP playback.. is it possible ?

[Harold Hallikainen]

Interesting! Are Lc/Rc driven at all for scope?I think we did something on one of the JSD processors to do a mix for Lc and Rc with the dialog frequency range attenuated.

[Carsten Kurz]

Yup. This will be the case for our speaker setup as well - but, mostly during preshow. I could probably create another EQ setup on our AP20 for preshow and flat movies to make up for that a little bit.

I know one cinema in germany with a L,LC,C,RC,R front speaker setup - they use the inner LC/RC speakers for flat, and L&R for scope movies.

[Harold Hallikainen]

Thanks Marcel for the comment on tolerable sound before image. I had not considered that.

Carsten, moving the left and right loudspeakers farther apart reminds me of an issue I had a few years ago. We were testing the LSS-200 in a local theater. The LSS test the various drivers in the screen speakers by sending band limited pink noise. We found that every couple weeks, the high frequencies for the left and right speakers would drop a couple dB for a week, then go back up. FINALLY figured out that the HF was lower when they were showing a flat movie. The left and right speakers were being covered by the masking, dropping the highs a bit.

Harold

[Marcel Birgelen]

Maybe another idea: What about headphones? The kind of headphones they use nowadays for this phenomenon called "Silent Disco"? I know they can be rented and they seem to use simple FM broadcasting.

[Barry Floyd]

GDC finally got back to me on the server synchronization. It can be done, but there is another piece of hardware involved. It's a box called a GEN-10 HD/SD SYNC GENERATOR manufactured by a company called AJA, and utilizes the GPIO ports on the "slave server". The sync generator has to be configured for the correct frame rates, but it looks fairly simple. They sent me instructions on how to do it, and I'd have to get the box from them as they configure it to work with the SR-1000's.

Working out the audio delivery issue is all we have left.

[Carsten Kurz]

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.

Which is probably not so much of a problem in many of todays smaller auditoriums. Would be nice if the RP mentioned thinking twice for larger auditoriums. That said, we do already have a decent size (length) auditorium, but the seats closest to the screen are rarely used. So, do I optimise for a situation that may be relevant once a year when we are sold out, or do I tailor it to the situation that covers most days attendance? The idea in the RP is probably also that if you set up sync for the front seats, it could simply be off unacceptably for the back seats.

For a similar reason, I now moved our L and R speaker sets more to the left and right. As a matter of fact, the clear majority of movies we play nowadays are scope, and most people use the comfortable rear seats. So why should I narrow the stereo field towards flat presentations, and on top of that with most people sitting in the back of the auditorium?

[Barry Floyd]

Got "ballpark" prices today on PA for both fields.....I was experiencing a little (OK, a lot) sticker shock. They pretty much wanted to lay it out almost exactly like Jack described above. Since we have no electrical power at the screens, we also have to figure in the costs of generator rentals. Got a feeling this is going to be out of their budget.. but maybe not. Still awaiting on GDC to give me a definitive yes or no on the synchronization thing between the servers.

[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.

[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.

[Barry Floyd]

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

[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

[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.

[Marcel Birgelen]

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

[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]

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.