Joe Clark: Media access

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Cinema → Behind the booth

Updated 2002.06.14

VH1: Behind the Booth

Civilian, armed only with his wits, visits the projection booth at a MoPix-equipped accessible cinema!

In early April of ’02 I was granted superexclusive access BEHIND THE MUSIC of a movie theatre equipped with the MoPix system of captioning and audio description.

Famous Players generously lined up a visit to their SilverCity Yonge & Eglinton location, one of the first five cinemas in Canada equipped with MoPix. (I’ve seen a half-dozen movies there with captions and descriptions. Read my reviews.) Manager Dave Woods and Naeem Choudhary from “technical services” met me and we immediately moved inside the velvet rope.

No, I didn’t take pictures. Next time, I bring my friend’s digicam. This was a fact-finding mission, as they say.

The projection booth

At a multiplex cinema (or, if it’s the house Lisa Simpson goes to, a Googolplex), we no longer have cranky, stooped, chain-smoking projectionists lovingly threading priceless cinematic artworks through creaky, stooped, chain-smoking movie projectors. In other words, Cinema Paradiso is a kind of retro science fiction now.

Instead, automated projectors, covered in an air-cooling enclosure that turns them into the approximate size and shape of a centaur, continuously unspool a movie off stacked metal platters. The platters are about three feet in diameter, sit parallel to the ground, and are stacked with about two feet of space between them.

Platters are industry-standard now; the Milford Drive-In’s installation (in scenic New Hampshire) looks a lot like the one at SilverCity. Christie is one platter manufacturer.

Movies may still arrive at the theatre in individual reels packed in heavy hexagonal film canisters, but the reels are all spliced together into a continuous strip of film that runs automatically off the platter.

Note the absence of human beings here. The systems essentially run themselves. You tell me whether this is for good or ill.

Theatre layout

The SilverCity movie auditoriums all extend outward from a common hallway. The back walls of the auditoriums (all nine of them) sit side-by-side along facing edges of an overhead hallway that is – incredibly enough – the single, common, uninterrupted projection “booth.” It’s more like a projection hallway.

As you walk up the stairs (quite a distance – these places are tall), you enter a wide, very long, convoluted hallway, quite dark and either cool or overly hot depending on where you’re standing, equipped with nine projectors beaming movies out into the auditoriums. It is all to reminiscent of a more cybernetic Alien breeding lair. You’ve got these gigantic whirring machines that grow out of the floor, and they extend as far as the eye can see. Fortunately, they’re all facing away and never manage to notice you’re there, which I suppose is more of a Borglike quality.

DTS equipment

SilverCity has or will soon have a rather sophisticated MoPix installation.

That means four of nine cinemas are capable of showing accessible movies, though only two of them at at time may actually show captions and descriptions.

Why hardwire theatres? It has to do with theatre capacity and contracts. Studios distribute films with the expectation that they will run in a movie house of a certain size for a certain period of time.

When, as is inevitable, popularity dies down, movies either disappear from the cinema altogether or are shifted to a smaller auditorium. And that’s where you lose the access: Your captioned and described film is suddenly showing in an auditorium that does not have the equipment.

Quite arguably, leaving any auditoriums unequipped is a violation of basic equality rights. Two out of nine, while still an infraction in this view, is significantly better than nothing and is very unusual in MoPix installations.

DTS hardware

The other hidden equipment is in fact the DTS controller. The MoPix system is controlled by a DTS-CSS box (now it is, anyway – the system was recently upgraded). DTS is the same company that produces digital audio systems for movie theatres, like the DTS-6AD.

The DTS-CSS controller is a visually unremarkable rack-mounted device. Naeem tells me it’s a Linux box; the predecessor system ran under DOS and was more expensive because of Microsoft royalties. It’s got a CD drive and a small backlit LCD.

Cinema 8 (and apparently the entire Silver City Yonge & Eg house, if not all of Famous Players) use DTS only for the captioning/description capacity and not for digital audio; that’s handled by Dolby, THX, or other systems, depending on location.

Now here is the fun part of my little visit. Also in attendance was Hans Burgschmidt of the Toronto International Film Festival (plus his assistantrix). He was just across the street at the Canada Square cinema setting up the Sprockets film festival for kids. One likes Hans’s no-bullshit style. Anyway, Hans grabbed a chunk of the film off the platter (“Hans gets to touch the film!” I exclaimed) and showed me the various encodings used in modern films.

The entire surface area of the film is now used – even the space inside the sprocket holes. The DTS digital timecode data has the visual form of a jittery white line just beyond the visible frame. (The Movie Sound page shows various digital sound formats, and this chart gives you a nice clear picture of multiple digital formats all stacked together on the same film, which is indeed the norm these days.)

The DTS-CSS reader, true to its name, merely reads the timecode off the film stock and plays the captions and descriptions that coincide with the timecode.

The captions and descriptions, then, are not stored on the film stock. This is one of the big advantages of the MoPix and CSS systems, actually – there is nothing unusual about the film print, which can be sent around the world and reused at will with or without accessibility. (You could go really crazy and open-caption that same print by burning in titles.)


Captions and descriptions are, in fact, stored on a CD-ROM, which is copied onto the hard disc inside the DTS-CSS machine. The predecessor model ran directly off the CD, which made it slower and more prone to malfunction.

Naeem handed me an actual DTS MoPix CD-ROM (what an honour!) for Panic Room. It was an ordinary CD-R (you can tell by the blue colour) with a laser-printed tan-coloured adhesive label – using Avant Garde Gothic, if you want the font details. The disc was just over half full – the tiny text file containing captions and the full compressed description track occupied that little space. Recall that descriptions for MoPix are descriptions only and not main audio plus descriptions, as you find on TV and in home video. (Why? A full mix causes an echo in the movie theatre; it takes noticeably longer for the sound waves from the wall speakers to hit your eardrum than the sound waves from the headset.) A full mix would presumably occupy more than a single CD.

(I’ve been told that “encoding” of these CDs must take place at a DTS facility. The resulting encoded, encrypted, protected files can then be E-mailed anywhere else for CD burning. In practice, all MoPix CDs are burned right at DTS in L.A. This will eventually have to change if hundreds of cinemas worldwide install the apparatus.)


Strange timecode fact: Film runs at 24 frames per second. TV here in Canada, using the NTSC standard, runs at 30 (actually 29.97) frames per second. (In Europe and other PAL-standard countries, it’s 25 fps.) The entire DTS system assumes 30-fps arithmetic, which finally explains how captioners and describers can work from videotape and not film.

(This will become a problem if the system is ever used in Europe, where technically it already is. Either the DTS system has to accept 25-fps arithmetic or everyone’s gonna have to use NTSC edit suites. The former is much easier to do.)

What happens if the film breaks or something? Apparently the DTS system uses absolute timecodes – every frame refers to a specific position in the film unrelated to all other positions. Allegedly, the system will immediately snap back into correct alignment and show the right captions and play the right descriptions. Allegedly.

When asked what the hell happened in the E.T. case, in which captions were out of sync and repeated themselves for 10 or 15 minutes, Naeem told me there was a bad batch of CDs pressed.

So why did the “playaz” at the cinema that night tell me they had to wait for the CD to come in from some other theatre? Didn’t every theatre have its own copy of the disc? Yes. But the hope was that the other cinema’s copy wasn’t busted. (It was. They had to wait to be re-serviced by DTS.)

I guess there is a moral to this story: There already are too many MoPix installations to get away with just sending the discs out assuming they’re good. Somebody has to sit there and watch the whole movie with captions and descriptions after the disc is premastered. Yes, that will be inconvenient. But just imagine how much shit will hit the fan when this happens again, particularly if there are, for example, 810 installations in the world. Would you want to be responsible for 810 movie houses each of which has angry blind moviegoers to contend with all because you thought it was too much bother to do a final continuity check?

And listen, there’s always two hours’ slack time in the schedule to watch the film before distribution. And if there isn’t, that much extra time needs to be built in from now on.

DTS control interface

I played with the display of the DTS box. Naeem tells me the entire system is geared toward the DTS-CSS projected-title system (according to the operator’s manual), with next to no mention of Rear Window. The only interesting point is the range of languages selectable from the menu:

So I guess we see where the national markets are. Note that, while the difference between subtitles and captions is recognized for English, no such distinction is made for other languages. (There is such a thing as open captioning in French films. It happened with Une crabe dans la tête, though probably with no other film for decades previously.)

Auditorium inspection

Hans had to leave. Naeem, Dave (somewhat overwhelmed by everything), and I headed down to Cinema 8 to look at the actual hardware. Whoops! People there already, waiting for the next show. We spoke in stage whispers.

The caption display, the reflector panels you use to read the captions, and the description headsets are reasonably well-understood. There are two items of hardware that are, however, not immediately obvious.

Audio descriptions are transmitted by infrared light waves. They have to come from somewhere, and the somewhere they come from is an emitter (mentioned above). It’s about a nine-by-nine-inch enclosure that sits on the back wall below the caption display. It has rounded corners but is square on all faces; it isn’t like a light bulb. The emitter sends out infrared light to the audience headsets.

It’s a very discreet object and I had never noticed it before, even after standing right under the caption display and staring. The emitter does not cover the entire theatre equally; something like 60% of the seats (let’s say 30% on either side of the centreline) get a good strong signal, with the other seats getting a weaker signal. I have sat at the very back of the theatre directly to the right of the emitter and still been able to hear the descriptions (with considerable hiss), so I doubt there is really a dead seat anywhere in the auditorium.

The hiss problem has been somewhat alleviated – by simply doubling the power output, as it turns out. Because of the location of the emitter, there may be no practical way to use any kind of headset other than one with the receiver on the very top. The ideal way – with a receiver you could just plop on your leg or on the seat arm or wear around your neck – would require a different location for the emitter. It would probably require several emitters on the ceiling.

That is an unlikely installation for a couple of reasons. First, it costs more. Second, it’s a pain in the arse to repair. The emitters for hard-of-hearing amplification are located in the extreme top front corners (right at the corners of the movie screen), and they are so very far up and so very remote that it takes a special service call and super-long ladders just to find out what’s wrong with them.

And speaking of amplification: Contrary to the claims on the MoPix Web site, in this auditorium you cannot have hard-of-hearing assistive listening devices and audio descriptions running at the same time. In essence, you can make films accessible to hard-of-hearing people or the blind but not both. Why? The light wavelengths used by the two systems interfere with each other. Naeem does not know of a way to fix it as yet.

(One way, I suppose, is to use an FM transmitter as an assistive listening device and infrared for descriptions. One’s radio, one’s light. But if MoPix is installed in existing theatres with infrared hearing-impaired amplification, it’s the description system that would have to run via FM. I assume that is possible, but you have to know about the interference problem in advance, and most people don’t.)

It was not clear to me how many lines of text the display can show. Answer: Three lines of 32 characters in a 7 × 5 dot matrix. According to Boston Light & Sound, there is now a new supplier of LED displays: Instead of Trans-Lux, it’s Data Display, owner of the worst Web site of 2002 (check the missing images, all with identical alt text, here). And the displays are made in... Ireland!

(Apparently the Ottawa display was dead on arrival. It arrived the day the system was supposed to start running. So they got people on the phone, opened ’er up, and found a simple plug that had to be re-seated.)

Display quality is a serious issue. For smaller auditoriums, there is no reason not to use a plasma display with its higher resolution. (They aren’t as bright as LEDs, my expert tells me. I have more sources than you might think, and usually more than I let on. But enough about me.) You need to output bitmaps in that case, which brings up further typographic issues (no frigging Arial, OK?), but the appearance and readability are hugely improved. This isn’t a twee, extraneous æsthetic issue. When people complain about the Rear Window reflector system, it’s a sort of referred pain: What they’re complaining about is readability.

Anyway, we looked at the display and emitter. For the ultimate purpose of moving displays from theatre to theatre, Naeem mused about the inadvisability of hiking people up on ladders to schlep the display around. He envisions an electric lift system. (The emitter will have to be moved to alongside the caption display.) Wouldn’t it be cheaper to just buy another display?

You know the placeholder text “Welcome to Rear Window. Please adjust your reflectors”? It’s displayed before the movie so you can aim your reflector, a process that can take seconds or unending minutes, depending on your luck. On many occasions the placeholder text has been missing. Naeem tells me they noticed that, too; the placeholder text is produced by separate application software that had to be ordered and loaded. I do not entirely understand why (a) the software isn’t always running and (b) why, when it does run, it tends to run only as the “And now for our feature presentation” bumper runs and not during, say, ads and trailers.


The behind-the-scenes equipment in a MoPix installation is visually unremarkable; it’s essentially a computer. And it uses visible timecode that’s been part of commercial film distribution for a decade.

As for hardware inside the auditorium, what you see (assuming you actually can) is what you get. The display displays and the emitter emits.

But amid all this simplicity lies complexity. A lot of little things can go wrong: Caption and description sync, placeholder text, hiss in headsets, interference with assistive listening devices, displays that are dead on arrival. A very long and involved chain must work without a single break: Timecoded film stock, encoded captions and descriptions, files copied correctly to hard disc, separate software for placeholder text, functioning displays and emitters, and, of course, competent in-house staff.