What is Dolby Atmos?
With all the surround sound formats on the market and in our AV equipment, it’s not surprising that when a new one comes out it might slip by unnoticed. Dolby Atmos is one of the newest audio platforms showing up in movie theaters. It debuted in 2012 and ‘s unique in that it claims to work well with almost any speaker configuration. That’s extremely different than the THX certifications of years gone passed—which rely heavily on standardization and adherence to specific guidelines. Dolby Atmos is a system that combines products, services, and technologies.
And, because it claims expandability, it also aims to be one of the last audio systems a movie theater will ever need.
Dolby Atmos Basics
Dolby Atmos is very different from the Dolby Digital or THX audio methods of delivering content, For one, the system supports up to 128 simultaneous and lossless audio streams. These can be individual channels (like in a 7.1 soundtrack) or individual sound elements that can be placed within the mix as well. Dolby Atmos also allows for up to 64 discrete speaker feeds.
Yes, you heard that right—though we have yet to see a theater or content creator crazy enough to utilize all 64.
The other thing Dolby Atmos does that other surround systems don’t, is provide for discrete point source sound reproduction. Two main things that could come out of this are overhead sound effects (something that’s very hard to simulate using current technology) and sounds which originate from discrete sources in specific theater locations.
While it may just sound like somebody is jamming more speakers down our throats, overhead sound isn’t a bad idea for theaters. It’s a miserable idea for home theater, but it’s got potential in the local cinemaplex. In theaters, sound is currently generated from a single horizontal plane that extends both in front of, and behind, the listener. That mens that any audio overhead, be it a helicopter hovering overhead, or a rocket being shot from behind to a location high in the air and just off screen, the effect is simulated. A quick pan from the rear surrounds to the front with a bit of high frequency EQ is all you get.
Having more elevated speakers helps, but there’s nothing like having an actual speaker to handle that sound. As films progress into more of the third dimension, filmmakers might be a bit more enthusiastic in experimenting with the same expansive 3D audio. Atmos seems to offer that option. Because of the way Atmos is designed, DSP allows for the use of an ever-expanding array of speakers.
Point Source Effects
Current surround sound is meant to be diffuse. While the Surround Left and Right speakers are discrete, the surround field is, by design, never completely oriented for point-source effects that occur in a very specific location. A theater with fewer speakers will be able to offer less specific point source surround effects, but the DSP (digital signal processing) will compensate to do the best job possible. As a theater adds more loudspeakers, the system will automatically compensate to deliver even more precise audio.
Where this shows up is in the way that on-screen characters might interact with elements that are supposedly in the theater space. Instead of having to synthesize a sound using a few channels of information, Dolby Atmos will allow for a greater level of pinpointing, particularly when that information is nearer to the screen or higher up in the room.
Can a New DSP Improve Existing Theaters?
One of the hard sells in bringing a new theater decoding system to market is the effect it will have on existing theaters. What’s got the industry abuzz about Dolby Atmos is the way in which it can utilize existing loudspeakers and systems. In fact, Atmos claims it will make these systems better by adding such things as better bass management for surround channels and room equalization.
The idea is that movie theaters would eventually want to upgrade their speakers and even add more. Currently, surround speakers don’t need to be able to handle full-range audio like the main speakers do. There simply isn’t a lot of information making its way to the surrounds, so theaters can cut back a bit on these speakers. With Atmos, the surround speakers become more important. Hopefully, theater owners would them be incentivized to up their game and match the potential of the system with new equipment. Another benefit for point source speakers is that a specific sound sent to a specific location doesn’t suffer from the effects of reproducing sound via an array.
Also, if you look around most theaters today, there are a series of speakers both behind and along the sides of the theater. Currently these speakers are simply delayed properly for 7.1-channel reproduction.
But with Dolby Atmos, they would be instantly available for point-source effects and greater surround sound definition. The system instantly adapts to whatever speakers exist currently and brings them into compliance with the new capabilities of the multi-channel soundtracks. Dolby calls the existing 5.1 or 7.1 streams “Beds” and continues to view those as important for backgrounds and non-specific effects. The other sounds it refers to as “Objects”. These objects are overlaid with the beds and the result is sent to the speakers. The DSP and the Dolby Atmos CP850 Cinema Processor decode everything in its proper place. Here’s what that looks like:
It’s the rendering algorithm in the processor that does all the magic. Because of the intelligence built into the system, authoring can be done once, and nearly any theater configuration can be made to put out a best representation of the content as it was designed.
Coming to a Theater Near You
The two things that need to happen for Dolby Atmos to have complete adoption is to see it used in both the authoring process as well as the theaters. When those two areas align, you’ll start to see the technology really take off. Whether Atmos takes off in the home remains to be seen (It’s certainly not being marketed or leveraged there as of yet). While Dolby Atmos is a commercial-only technology for now, the premise is a sound one for the home theater. Combining room EQ with DSP and speaker identification, an Atmos-like system would allow you to have as many speakers as you wish in your home theater, and perhaps even experiment with easing the transition between the front soundstage and the surrounds and, of course, creating a potential for overhead surrounds.
That is, if you want to buy more speakers. It’s hard enough to convince most of my friends and family to adequately support 5.1 in their homes. I suppose we’ll have to wait and see.
So have you experienced Dolby Atmos yet? If you have, let us know via our Facebook page or comment below to let us know what you thought.