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Author
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Topic: Multi Technology Projection Booths
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Adam Towill
Film Handler
Posts: 27
From: North Adelaide, South Australia
Registered: Jun 2013
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posted 01-01-2018 06:22 AM
For those of you who have projection booths that use multiple technologies - for example: changeover 35mm with DTS, Dolby Digital, and optical; digital projection with DCP capabilities, plus a scaler for external inputs; and for argument's sake, 16mm - how do you go about dealing with different processing requirements?
For example, Dolby CP500 and 650 units have the inputs for both optical and Dolby Digital for two projectors, as well as an input for external multichannel, but you'd need multichannel input for the DTS, the DCP playback, the scaler, and it seems like you'd run out.
Do you try and shoehorn everything into a single processor? Do you use multiple processors, and switch between them depending upon the requirements?
Given technological advances, such as no film support at all in the CP750, and obviously the advent of Dolby ATMOS, does/will this change how you currently have things configured? As in, if you currently have everything within one processor and you do go down the Dolby ATMOS path, where you will need a new processor, is multiple processors how you'd go about it? Is that the only way to go about it? Have you done this already to "future proof"?
If you require any clarification on this question (or collection of questions) go right ahead and ask, and I'll do my best.
I'm trying to replan an existing projection box, and would like to make things as painless and future proof as possible for myself and anybody else who comes across it down the track.
Thank you all for your time.
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 01-02-2018 07:23 AM
I've been doing the "multi-technology" for some time now.
Prior to DCPs (let's say, pre-2010 as the big switch to DCPs though clearly it goes as far back as 1999 and in limited amounts in 2004-2009, mostly 3D), I would get everything through the cinema audio processor. If you were to look at the AFI/Silver pictures in the warehouse, you'll see a couple versions whereby everything gets a path that ultimately goes through the cinema processor (Dolby CP200 or Panastereo CSP1200/4600).
I briefly continued this concept in 2010/2011 using the Dolby CP650 since it could "handle" film and DCinema but several factors moved me away from that concept. The CP650 was unreliable for DCPs with its "Robosound." By that time Surround 7.1 was coming out so using the 6-channel analog input for DCP seemed like a waste as well as requiring a digital signal to first be converted to analog, only to be immediately converted back to digital. So you lose two channels AND get extra D/A and A/D stages, all for the privilege of forcing a film processor to function as a combo DCP/Film processor. Furthermore, the CP650's Ethernet port has proved to be less than robust. If it gets "flooded" it quits. It can only talk to one thing at at time and if something has opened the port, it ignores everything else. So the CP650, for me, remains as a film processor, which it does quite well and is in a nice tidy 3U package for analog and Dolby Digital, with the 6-channel analog for DTS, if the site is so equipped.
I would say that the Datasat AP20 is a viable solution since it was built to be a DCP processor that can accommodate film. It is a matrix box so you have a degree of flexibility in how you want the inputs/outputs to function. It, for the moment, uniquely can decode off of HDMI both Dolby (low-bandwidth) and DTS (high bandwidth) audio so it provides a solution to deal with conventional video. For film, you only get the analog portion covered, if you buy the option board for it. You still have to deal with Dolby Digital and/or DTS and consume analog inputs to do so. I believe it only has one analog multi-channel input. There have been reports of very slow distribution of the product. I cannot speak to the company's long-term support of it either.
Another product we have used is the QSC DCP line. The DCP300 has a plethora of analog and digital inputs. in particular, it has an 8-channel analog input (called "Main") and a 6-channel analog (called "Option") so one can feed a film processor and a video processor into it. There are 16-channels of AES inputs split over two DB25 connectors and how those channels are assigned are configurable. There is also a Mic/Line input on XLR, stereo on RCA connectors and a coaxial S/PDIF connector. Lastly, it supports the grand-daddy Ethernet audio format: Cobranet.
Since there are 16 configurable presets, one can create quite a few DCP and non DCP formats, as needed.
What the DCP line isn't good on is decoding. It doesn't support Dolby or DTS audio so all digital inputs need PCM only. Its matrix decoder doesn't seem to be too clever either but adequate, I suppose. It doesn't officially support matrix decoding on the Digital 1 or 2 inputs (for DCP 2.0 audio tracks) though it can do it. There is a software update that has been promised for YEARS now on it.
I, and others, also HATE the dB scale fader control. Instead of a 0-10 (or 0-100, if you prefer), they went with the -90dB - +10dB scale on a multi-turn shaft encoder. End users just don't "get it." What is a little bit less from -3.3dB?
What I've used the DCP line, effectively, to do in existing film systems is to "splice" it in where the monitor/crossover would go in the signal path. The advantage here is the film system, whatever it may be, can be left untouched and bring it in on one or both analog inputs (normally just the one). Let the DCP audio get the Digital 1/2 inputs and let video's audio come in (post decode) on one of the analog inputs. Alternately, one can use an analog to Cobranet interface (e.g. from Whirlwind) to increase the number of analog inputs. Earlier in life, QSC had their Basis line of processors so there were other Cobranet means of getting audio in/out. Cobranet may be old in digital terms but it is quite reliable and of good quality audio. In the nearly 18 years I've worked with it, I've never had a failure/glitch with it. Like with modern digital audio, it also has a primary and secondary Ethernet path so it takes a lot to bring it down.
For video audio decoding, I've used products like Crestron's HD-XSP decoder. It handles everything but immersive audio and at high-bandwidth. It can be set to change its decoding mode based on the input signal type too.
I'd say going forward now, QSC's Q-SYS is going to gain steam. With their DCIO module, the sky is the limit to what one could do. You can expand it to handle as many inputs/outputs as you need. It has a Pro-Logic Decoder and starting in February (as per advertisements), with the DCIO, there will be an HDMI input that handles DTS (high bandwidth) and Dolby (low bandwidth) video audio.
So, one can let a processor like the CP650 (or whatever your favorite film processor is) be a source for film and just select it. Likewise, just create a UCI that lets one chose what is the audio source at any given time. Something changes, no big deal, just change the Q-SYS configuration to accommodate the new thing that comes out. It handles immersive audio via AES67 already. And, using networked audio, getting another I/O point is typically just an Ethernet cable away. There are 3rd party manufacturers that provide I/O modules. Depending on the core you use or if you have an I/O frame one can use the likes of Dante to interface with conventional A/V too.
Not every booth is the same and not all needs are identical so what works for one system may not be right for another but these are the systems I've personally used to handle multi-technology booths.
Lastly, you mention scalers...that is something that has fallen much by the wayside for me. Most modern devices can output 1080p and current projectors handle that just fine so what is the point of scaling? Note, most projectors have a scaler, of sorts, built into them (the ICP can scale). To deal with letterbox, I've created DCPs (some projector companies have them there for you already) to finish the job and fill the screen. Alternately, if there is enough lens zoom range, you can have the projector physically zoom the image. I'd caution that MOST A/V scaling devices will also pollute the HDMI audio down to just 2-channels because that is still what A/V works with. multi-channel A/V audio is mostly just for fancy boardrooms and the occasional home-theatre set up. By and large, they are just mono or stereo systems and the switchers/scalers are built around that. Analog Way is one such company that if the video hits their scaler, it will be calling for just STEREO audio so watch out when you can't figure out why you can't get the whizbang audio from your super-duper system. I've noted that Extron is pretty good about supporting multi-channel audio on their switchers/scalers. Always read the spec sheet/install manuals to ensure that you can support multi-channel audio.
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 01-02-2018 07:40 AM
Agreed with both Marcel and Steve that either the AP20 or Q-Sys are viable solutions. In fact, at the Egyptian, we had both - a CP200 (for film sound) fed the analog multi-channel input an AP20, the DCP server and DTS players both fed AES digital input (we had the extra card to give us 16 channels), and a CD player for nonsync went in via SPDIF. The output of the AP20 went into a Q-Sys core, and live event audio (mics at the stage, etc.) went straight into it. This arrangement had the advantage of projectionist friendliness: for straight movie shows, of whatever medium and format, the audio was a one-button selection on the AP20, and the Q-Sys front only had to be touched if there was live event audio to worry about.
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