What is Dolby Cinema? Bringing Dolby Vision and Dolby Atmos to the cinema - MrLiambi's blog


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Wednesday, 12 January 2022

What is Dolby Cinema? Bringing Dolby Vision and Dolby Atmos to the cinema

You know the phrase "seeing is believing"? On a trip to Dolby Laboratories in the USA, we got to sample first hand exactly what that means in terms of theatrical installs, having sampled the reference Dolby Cinema on-site at the company's headquarters.

Dolby audio-visual technologies were in eight Oscar-winning movies in 2019 - including best sound mixing and editing for Bohemian Rhapsody and best cinematography for Roma - which has only increased dramatically since.

There are now over 250 Dolby Cinema installs worldwide, with Dolby committing to an additional 200 sites worldwide. There are now more than 6,000 Atmos-enabled cinema screens in 90 countries. In the UK, the Odeon Luxe Leicester Square was the first Dolby Cinema, which was since followed by a second location in Leeds and a third location in Manchester's Trafford Centre. 

Dolby Cinema's combination of Dolby Vision projection and Dolby Atmos surround sound makes it a potentially unrivalled proposition for cinema-goers.

Picture quality

  • Dolby Vision projection - dual HDR RGB laser system
  • 1,000,000:1 contrast ratio
  • Double the brightness of conventional cinema setup

Over recent years there's been a big behind-the-scenes shift in content production. From standard definition, to Full HD, to Ultra-HD 4K, the resolution stakes have been climbing. But beyond that - and perhaps more importantly - is that dynamic range capture has been widening and, through HDR (high dynamic range) presentation, the depth of black levels and peak white brightness for improved contrast, along with a broader colour palette, has increased considerably. It all makes for a more detailed and vibrant picture.

Which brings us to the first key point about Dolby Cinema: the dual laser system - which uses an array of HDR-capable RGB laser systems - that can deliver an image with a contrast ratio greater than 1,000,000:1. That's to say, there are over one million "steps" of discernible levels between the blackest black and the whitest white. A typical cinema might offer a 2,500:1 contrast ratio.

Back in 2013 we spoke to Brian Bonnick, IMAX's chief technical officer, and he pointed out how "IMAX projection film is in and around the 4,000:1 range," continuing that IMAX with Laser is "double that, at around 8,000:1". Now, IMAX with Laser is already impressive - plus it has the unique selling point of an ultra-tall 1.43:1 format (movie/scene dependent) - so imagine a system with some 12,500 times more contrast, which is what Dolby Cinema offers.

Which is all well and good, but moviegoers won't necessarily care about numbers - it's all about the image and the immersion. Dolby showed us an excellent demonstration trailer at its HQ to show-off its point of difference. First we were presented with greyer blacks than its standard system was capable of presenting; then, after "flicking the switch" at the end to show, the true Dolby Cinema capabilities were shown, revealing the depths available. And we're not talking something only highly trained yes will see - the difference was night and day, much like comparing backlit LCD to OLED.

The second key point about Dolby Cinema is that it's roughly twice as bright as a typical cinema system, with a peak brightness of around 31Lv (foot-lamberts). Interestingly, IMAX with Laser claims to be 50 per cent brighter than a typical cinema, meaning a Dolby Vision laser projection is 50 per cent brighter than that again. If our calculations are correct then a Dolby Cinema 1275 square-foot screen would require projectors to deliver around 40,000 ANSI lumens, which is immensely bright for a screen presented in near darkness - and you can really feel that when sat in front of the image.

A third key point is Dolby 3D. Well, if it's your thing. As 3D glasses typically negate around a stop of light, the increased brightness of Dolby Vision projection helps make for a more distinctive picture through those lenses. Dolby also uses a different set of colour wavelengths for the left and right lenses of its glasses, with the laser system's use of six primary light sources being tuned to for the best perception of three-dimensional separation. Not that we see 3D as a key to cinema's future, really, but the support is there.

Overall, while Dolby Cinema isn't going to display the scale or ratio of IMAX - there is a 70 x 125ft IMAX screen, for example, which opened at the Traumpalast Multiplex in Leonberg, Germany, late 2021 - it certainly can be called the king of brightness and contrast. It has to be seen to be comprehended.

3D surround sound

  • Dolby Atmos surround sound system includes overhead speakers for 3D sound experience
  • Sound 'objects' can move individually through 3D space; up to 128 sound objects

There is one part of the Dolby Cinema package that a number of theatres already have installed: Dolby Atmos, the three-dimensional surround sound system (not to be confused with the pseudo Dolby Atmos that is offered in so many consumer products but without the same true channel outputs as a cinema install).

Dolby Atmos works by positioning speakers throughout a hemispherical-like arrangement - including directly overhead - for a fully immersive sound experience. Unlike with a 5.1 or 7.1 surround - which offer five or seven surround speaker points with a single bass point - Atmos has potentially unlimited range, although at present that's 64 speaker fields maximum.

Sounds aren't channelled together into groups but instead defined as individual objects which, as they fade speaker-to-speaker, give the impression of moving through space. So a jet flying overhead really does fly over you. Sound designers can manipulate up to 128 objects at once - not that they likely will in any one scene - so the creative potential is huge.

Part of an Atmos install involves intelligently positioning speakers. At the front is a video wall, behind the projection screen, to give a true frontal sound, without being able to see the speakers themselves. Such concealment is key for many of the other speakers as, psychologically, if you can't visually pinpoint a sound's source then it's more convincing and immersive.

At the Dolby Cinema reference theatre in San Francisco, the company has also invested heavily in sound-proofing - which is a recommended part of the install. In this instance, concrete walls and reflective internal insulation ensure the outside world can't be heard, so when those extra quiet scenes are playing out, you won't miss a single nuance.

Dolby Cinema is what we should expect from our movie viewing: the very best. During difficult times for theatres, we do hope that technology such as this will add a lease of life to cinema. Long live the theatrical experience!

Source : https://www.pocket-lint.com/tv/news/dolby/142028-what-is-dolby-cinema

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