Get started with Dolby Atmos
It’s next generation surround sound – but what does Dolby Atmos mean for your living room?
Email your queries and your questions to letters@macformat.com
Contact us
Keep up to date by following us on Twitter @macformat
Join the conversation at facebook.com/ macformat
Get the latest subscription offers at macformat.com
You’ve heard the name. Dolby is, and has been, everywhere in the world of audio, from noise reduction on your ’80s Walkman to kitting out your local cinema screen with industrial-grade amplification. It’s taking a stab at the visual market, too, with Dolby Vision
– more on that in future issues.
We’re here to talk about Dolby Atmos, an audio tech which some have claimed is the biggest upgrade to surround sound in 20 years. It’s trickled down to the home from beginnings in cinema screens, and literally adds a new dimension to living room sound by adding height channels to audio. Or, at least, that’s one thing it does. Let’s first explore what Dolby Atmos is.
Dolby Atmos isn’t, in itself, sound; it is a system of turning that audio into objects. Up to 128 individual elements in a scene are separated out into their own discrete tracks, each of which is given its own metadata which communicates to a Dolby Atmos-compatible receiver the way it should be handled. That metadata might include height channel or other positional information, or designate the track as a voice or background, but it doesn’t make explicit demands; it’s merely a way of communicating to compatible equipment.
It’s the end-user kit that does the real heavy lifting. A piece of Dolby Atmos hardware will typically know what it is working with, be that a stereo setup or a full 7.2.4-channel speaker array, and determine how to send the sound to the correct speakers based on that metadata.
This doesn’t just open up new possibilities for amplification. It gives you a lot more control; if a source has a Dolby Atmos audio track, it’s almost guaranteed that the main vocal tracks, for example, will be separated out from the bed tracks. With a couple of button presses, you’ll be able to bring those tracks right up in the mix. Prefer to watch sports with the field mics only and blot out the crowd? With the right Dolby Atmos mix, you’ll be able to do that. This versatility has helped Dolby Atmos grow fast. Three-dimensional mixes produced for the cinema (locations which could, but rarely do, use up to 400 ceiling-mounted speakers over 64 individual addressable speaker channels) can basically just be sent straight to the home, where they’re reinterpreted for living room setups. It’s rarer to see a modern Blu-ray release without a Dolby Atmos audio track than with, because there is no sense in mixing that audio down to stereo or 5.1 on disc when Dolby Atmos is built to be mixed, live, to fit the hardware on hand.
Mixing it up
Dolby Atmos is also being helped by projects like MDA, or Multi-Dimensional Audio, which is an open-source platform designed to help audio engineers master soundtracks as easily and cost-free as possible. Dolby’s own virtual surround technology, which can fiddle with output frequencies in such a way that a full three-dimensional audio effect can be reproduced even with a single pair of stereo speakers, is another neat extra.
The latter tech isn’t a new concept – if you’ve ever picked up a pair of flashy headphones that claim 7.1-channel support, they’re doing the same thing – and it’s not a patch on a full set of speakers. It is, though, remarkably effective, and means full-scale upgrades of home audio equipment aren’t immediately required.
If you want to enjoy Dolby Atmos, you’ll need a few things. One is a source with Dolby Atmos support, and another is a receiver with which to interpret those audio tracks.
For the former you have a few choices. Just about any Blu-ray player will do the job, as long as it’s capable of outputting raw bitstream audio. Media streamers, too, don’t seem to have too
Dolby Atmos isn’t, in itself, sound; it is a system of turning that audio into objects