What format do movie theaters now use?

Former projectionist here, let me weigh in on what's happened in the last 7 to 8 years.

A bit of background: I started working projectors for my local theater in February 2007, and my last night was in March 2011. I no longer work this position because they transitioned to being completely digital, and I was among the first cut as I was only in one or two nights a week. Over the next 4 to 5 months the rest of the projection staff was gradually cut as the transition to 100% digital took place.

Alright, so now that we have that out of the way, I'll tell you what I know.

When I started, film was still distributed on 35mm reels. Depending on the company that pressed the movie to film, it would come in either a large, cardboard box, or several metal cans. The boxes could hold about 6 to 7 reels, the cans could hold about 3 reels.

Now, "Back in the day," my dad also worked projectors for a bit. This would be back in the 70s, and you would have two projectors for each theater. He'd load up reel one, start it, then he'd wait to see the cue mark, or "Cigarette burn," in the upper right corner, he'd start up reel two on the other projector, and when the second cue mark appeared, he'd cut over to this other projector. There's a reference to this in Fight Club, and it's completely legit. You can also see an example of this process in Inglorious Basterds, as Shoshana runs the Nazi propaganda film towards the end of the movie.

Flash forward about 35 years, and when I started working projectors you no longer had to do this. Cue marks would still appear in the upper right corner, but in the last 15 to 20 years of film still being on 35mm, things transitioned to what's called a platter system, which is why my theater used.

Here's what that looked like:

Rather than cut projectors between reels, we could now build the movie into one large reel to be fed through the projector. The film would "pay out" from one platter, and "rewind" on any empty platter. There were three platters so we could show two movies on one screen, though only one movie at a time, for example: a kid's movie during the day, and a R-rated film at night. Each week as movies would move to smaller and smaller screens in the building, we'd also have to move the prints from one projector to another. Some movies were so large they had to be broken down by a few reels, then put back together (Lord of the Rings for example). Each reel was about 15 to 20 minutes of film. We could easily tell each individual reel on the larger reels because they'd form a sort of tree ring pattern, making it easy to identify problems like, "There's a large scratch halfway through reel 4 that needs to be changed out."

How did we piece the movies together? Very clear tape. I'm not even kidding. Your entire movie was held together by tape. We'd use a special table to build the movies, that would pull the film off the reel and onto the platter. You'd put a small film ring in the middle for any pre-show ads and trailers, then would build the movie onto that (the small reel on the lowest platter in the picture above is what a trailer reel might look like, though a bit smaller in most cases). You'd start with reel one, and continue until you were finished.

Further, movies were either flat (1.85:1 aspect ratio), or scope (2.35:1 aspect ratio). Depending on the movie, we'd simply rotate the lenses in the projector, and slide a plate into place behind the lens to channel the bulb's light directly into the frame of the film. We'd then have to walk into the theater and adjust the masking to change it from 1.85 to 2.35 or back the other way, depending on the movie being shown.

All in all, the process could take a few hours. Busy summer weekends could take as many as 4 hours to build all the movies.

My theater also had rollers setup to allow us to "sync" single prints of a movie between two or more projectors. All the projectors were networked, and we could put them in sync groups so when the movie was started on the first projector in the group, it would start all the other projectors in the same group. We'd thread a single print through 2, 3, or even more projectors for midnight shows, or if demand for a movie was really high. This way we could show movies on more screens with fewer prints. One of my last summers there we ran all our projectors, over 15 in total, on 4 prints of the latest Harry Potter film. Set some sales records that night, and we bit our nails the whole time.

When a movie left the theater, we'd tear the movie back down to its individual reels, put them back in their respective box or can, and leave them at one of two areas of the theater (depending on the company that sent them) for some guy to pick up. They might go to a second run theater, they might go back to the studio.

Those days are long gone, though, and nearly everyone is using digital projectors now. The first projector our theater got was around the time Journey to the Center of the Earth came out, and was also our first 3D projector. We eventually added two more over the next 1.5 years, and finally the decision was made to go all digital. Early on, the movies would arrive on small hard drives and we'd load them onto the computer for each digital projector, and unlock it with a key on a USB drive sent with the film. Now they can load the movies onto a central server, and serve it up to each projector based on need, along with pre-show ads and trailers. Everything can be fully automated now. Digital projectors are also capable of showing movies in 4K resolution or higher. Contrary to popular belief, digital movies are NOT run off a DVD or Blu-ray, because the amount of data for a full resolution film with completely uncompressed audio is far too large to be held on a single disc.

Sorry if my answer is long winded, but it's a part of the industry I miss and could provide a good amount of detail on to really flesh out any questions you may have regarding the old way things were done. I'd be happy to flesh out any bits anyone has questions on, though I can't speak too much about the current state of digital, as it was, "After my time."

Whilst there are some cinemas that still retain use of 35mm projectors, it's fair to say that these are only used for special events. Modern cinema, by which I mean the industry that distributes and exhibits mainstream content (so any new releases), are exclusively distributed in digital format.

In early 2002, Hollywood sought to standardize this technology for the incredible advantages it possessed. Digital projectors have been industry standard since 2005 in the UK, but much earlier in America and China. Due to its cinematic heritage and relative size, the UK is almost always used as the 'control' in rolling out cinematic technologies. It is usually measured as an experiment, and just as the introduction of sound, colour and 3D cinemas required refits and refurbishment, this is now happening with digital distribution.

The rest of the world is moving in exactly the same direction, but with different levels of immersion in the cinematic process.

Many cinemas use a system called DCP which is literally a USB pen that gets shipped around inside a case. It improves accountability on behalf of cinema-pirates, as each Pen has a certain number of licences on it. A slightly more old fashioned variation of this is large portable hard-drives, but these are being phased out of circulation too.

A DCP is simply a file that requires activation from a licence. The DCP is signed for by the cinema, and then the projectionist is given the licence activation code to allow the content to be played. Some cinemas have a licence retainer, or master licence for content.

Because most multiplex cinemas are part of an exhibition chain, they are typically less vigilant in safeguarding their content, and will handle the management of their content internally, negating such stringent protection.

Increasingly, satellite technology is being explored in order to reduce the cost of distribution (which has already more than halved in the past 10 years). Under satellite systems, the film is literally downloaded from a secure server and the film is activated for use via satellite; projectors can even be controlled remotely through the satellite, which centralizes the entire process externally.

This is a method that has been spearheaded in the UK by such projects as National Theatre Live and Opera Live. Whilst they do broadcast globally, they remain a minority interest for exhibitors (although a growing one, due to their success). The legacy of these projects will not, however, come from their content but by their method of distribution. Even now, many distributors are promoting their ease of use as leverage to persuade developers to pursue satellite distribution as it reduces the overheads dramatically.

As with many instances of private enterprise, the real driving force behind satellite distribution is the revenue stream it creates, and the relative immediacy of this income.

It's the worst kept secret of most cinemas that the most lucrative single-income source is the adverts that are exhibited before a feature.

To explain: a single multiplex may have an opening weekend for a particular film that takes a significant box office. To take this quarters tentpole (Avengers:Age of Ultron) as an example;

A 12 screen MP may take an optimistic BO:W/E of £36k (approx $55)... so if a film has legs for a month and its returns are inevitably diminishing week by week, we're looking at a best case scenario of £70k ($100,000 dollars): and let me stress this would be an absolute wet dream for a cinema to make these numbers on a single film. Advertisement, by comparison? for a modest 5 screen art house cinema, you're looking at an annual income of about £200K ($300K)... and that is, most importantly, guaranteed.

Adverts don't need to be good; infact, they're often awful. They don't rely on word of mouth, critical acclaim or any amount of audience reception. They're a guaranteed revenue stream that will double the best possible B/O of any film, they're value increases proportionately to box office takings: they (sadly) represent the backbone of modern cinema.

Here's the hook: almost every advertisement content company in the world is moving not only in the direction of digital content, but they're universally moving towards satellite. Why? because, comparitively, it costs pittance.

With the exception of implementation (which usually consists of a satellite receiver and something called a [LANSAT processor][4] [Loca-Area-Network-SATellite]), this type of distribution entirely cuts out the cost of getting the content to cinemas. Distributors simply author a file, fire it out over their satellite connection for their respective exhibitors to download (or stream if its live content: hence satellite and not unpredictable fibre/internet connections) and deal with any potential problems through modifying the coding; which is in itself rare.

If we compare this to traditional methods of P&P (Print and postage), the gains are obvious.

Film has to be printed onto celluloid, which is costly and creates only one copy. If you want to open in every cinema in the US (unlikely, but lets pretend this example is a Star Wars Scenario) you're looking at 40,000 prints. Now try and imagine a global box office...so quadruple it, at least.

You also have to factor in the cost of transportation of said prints, degradations and recirculation, repair (the days of 35mm splice jobs are long gone, and not soon missed) and, most overlooked of all...insurance.

Many people realise that films stock used to be made of the incredibly flammable silver nitrate, as demonstrated during the finale of Tarrantino's Inglorious Basterds. During these early days of cinema, the relative hazard of transporting these prints was absorbed by the distribution companies.

When insurance firms became common practice, this cost was phased onto them... and when the film stock changed and became less hazardous, what did the insurance firms do.....?

Not give a f%!k.

Even up until digital content distribution, insurance companies refused to acknowledge that the relative risk of transportation had diminished, and were able to charge disproportionate costs for film distribution; a practice that continues with 35mm, although it's a dying market so prices are dropping significantly.

Satellite distribution has removed all these overheads completely, and there is simply no feasible alternative on any medium to large scale operation.

It's fair to say that most if not all cinemas are now fitted with digital projectors, and within the next 20 years (as they become satellite compatible) we will probably see the extinction of the projectionist: they'll become something that's wheeled out on special occasions to demonstrate a vestigial technology, to show off its novelty. That's more or less the case now, actually.

[4]: http://lansat.com/ a brand name

As others have mentioned, celluloid film (35mm, 70mm etc) is now largely obsolete.

As part of the Digital Cinema Initiative, modern movies are now distributed as Digital Cinema Packages (DCPs).

A DCP consists of a bundle of "media exchange format" files (.mxf) for the video and audio as well as .xml files that contain "metadata" about the files in the package.

These files are usually distributed on removable hard drives, USB flash drives or via satellite.

A single feature film is usually in the region of approximately 200 GB of data.

Digital Cinema Packages do not use temporal compression the way formats like BluRay do, and as such, are therefore higher quality. They also usually have a maxresolution of 4096 or 2048 pixels horizontally. Theoretically this allows individual pixels to be visible (when close to a screen), but in practice, digital projection offers far superior image quality due to the absence of imperfections such as dust and scratches which are commonplace on movie film prints.

By and large digital projectors still use Xenon Lamps like their more recent film predecessors, but there is a move towards using laser light as the light source in the future with the intention of reducing the cost of lamps.

As well as providing superior quality, distribution costs are greatly reduced, and because digital cinema packages are strongly encrypted all the way to an audited tamper-proof decoder block inside a digital projector piracy is minimised.

Of course the huge savings that digital brings over film are not passed on from the studios to the cinemas or the cinema-goers who now pay higher ticket prices than ever before.

No, film projection is a thing of past now. Not only in US, but in most of the countries around the world, the projection system has gone digital with the age.

Nowadays, most of the theatre chains use digital projectors and movies are distributed to them in magnetic hard drives. Primary reason behind this is transition cost. While making and distributing hundreds and thousands of reels cost a good chunk, Hard drives cost merely a fraction of it and distribution is easy as well. Moreover, with film projection, there was always a master copy and other reels were copied from it and even with advanced techniques the quality of film suffered (in a very minor way though), there would always be a haggle in the market over getting a higher standard print. With digital prints, it's a game of ones and zeroes and two prints can be an exact copy of each other.

By today, it's rare to find a theatre running on film projection, not because they have become obsolete quality but because people stopped distributing films.

According to Wikipedia (and a Quora answer), DCP (Digital Cinema Package) uses

• Uncompressed 24-bit linear PCM audio (up to 16 channels) at 48 or 96 kHz sample rate.
  There are lossless audio compression formats like FLAC, but DCP chose to trade space for simplicity, I guess. And maybe for simpler decode if played back directly from this format?

• 12-bit XYZ-colorspace images each compressed with JPEG2000
  Maximum [video] bit rate is 250 or 500 Mbit/s (1.3 MBytes per frame at 24 frame per second). Stereo is handled by having twice as many images (one for each eye).
  High frame-rates also require more pictures, leaving fewer bytes for each picture.

• (typically) Encrypted with AES-128, presumably with some public-key crypto for DRM.

Video resolution is up to 2048 × 1080 (2k) or 4096 × 2160 (4k), usually cropped for aspect ratio such as 2k resolutions of 1998 × 1080 (1.85:1) or 2048 × 858 (~2.39:1).

Apparently early versions of DCP also allowed MPEG-2 I-frames, but that's no longer allowed.

These slides from a 2012 talk: Compression and Distribution Challenges for High Frame Rate Digital Cinema talk about 500 Mbit/s not being enough for high-frame-rate stereo even at 2k, let alone 4k. (and total file sizes get huge). "Stress tests will show artifacts are visible at 2K 48fps 2D [at 500Mbit/s]".

JPEG2000 is based on a discrete wavelet transform, unlike the 2D discrete cosine transform that's nearly universal in mainstream video codecs like MPEG-2 (dvd), MPEG-4, h.264, h.2655, VP8, VP9, and also in the original JPEG.

JPEG2000 is single-image codec, not taking advantage of any similarity between frames of the movie. High efficiency (quality per bitrate) video codecs (such as h.264 used on BluRay, or VP9) use P-frames (and sometimes B-frames) to encode only the difference from the previous frame. JPEG2000 video is like a normal codec operating in I-frame only mode. (https://en.wikipedia.org/wiki/Video_compression_picture_types)

Early codecs (before h.264, e.g. DivX) had a bad reputation for quality decaying after an I-frame, because decode wasn't standardized, and CPUs were slow. But modern encoders model have a bit-exact model of what the decoded pictures will be, so they can use that when doing motion search and encoding the residual left over after subtracting a similar-looking region from the previous picture. This essentially avoids quality decaying until the next I-frame, as long as there's enough bitrate for the encoder to encode each frame accurately.

In theory, 12-bit 4:4:4 h.264 (Hi444PP profile) or h.265 should look as good or better than DCP's JPEG2000 at the same bitrate.

But presumably there's enough hardware out there that can accept JPEG2000 images, and software / firmware upgrades can make it work with larger files, that nobody's looking to replace DCP with an inter-frame codec for more quality with less file size.

At very high bitrates, the advantages of inter-frame compression are smaller: Looking "mostly like" a previous frame isn't good enough, and the difference between encoding an residual in a lot of detail vs. encoding all the detail from scratch isn't huge.

But the video-production industry has a bias against inter-compression codecs for high quality, probably because stuff like h.264 initially only had profiles for 4:2:0 chroma sub-sampling, and high-bit depth / higher chroma is not widely supported by decoders.