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Bringing it all Back Home - Dolby Demonstrates Atmos for the Living Room

AVForums gets its first experience of the domestic version of Dolby Atmos

by Steve Withers Aug 13, 2014 at 2:20 PM


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    Bringing it all Back Home - Dolby Demonstrates Atmos for the Living Room
    We’ve been talking about Dolby Atmos for a couple of years now, ever since we got our first taste of the exciting new audio format back in 2012.
    Dolby were kind enough to give AVForums an exclusive demonstration of Atmos at their main facility in Royal Wootton Bassett and we were impressed by the way the use of separate objects in the mix created a greater sense of a three-dimensional space. At the time only a handful of films had been made with an Atmos soundtrack, starting with Disney.Pixar’s Brave in the summer of 2012. Since then the format has gone from strength to strength, with over 120 films boasting Dolby Atmos soundtracks. In fact the success of Atmos has rather caught Dolby by surprise, becoming the fastest growing technology they have ever released.

    You can read more about Dolby Atmos and how it works in our article - Dolby Atmos - Giving film soundtracks a new objective


    Back in 2012, as we sat there in Dolby’s lovely 100-plus seater screening room we immediately wondered if the system could be implemented in the home and so we asked the question. Dolby said they were investigating the possibility but, at the time, stressed that the system was primarily intended for commercial cinemas. We loved the idea of Atmos in the home but looking around at the two arrays of overhead speakers and the dozens of side and rear speakers, we thought the possibility of a domestic version was a long way off.

    Well ‘a long way’ turned out to be two years and back in June we broke the news that Dolby was indeed launching Atmos for the home in conjunction with a number of industry partners. The roster of manufacturers involved with the launch was impressive, with almost every major receiver manufacturer and quite a few speaker manufacturers announcing new Atmos models for the autumn. Unlike the competing Auro3D format, which has currently only been announced for some very high-end products, Dolby were clearly targeting the mass market. The company pointed out that backwards compatibility with Blu-ray, special Dolby Atmos speakers and even firmware updates for certain existing receivers meant that consumers could get Atmos into their living room or home cinema with the minimum of fuss.

    We discussed the domestic version of Dolby Atmos in more detail in our article - A Guide to Dolby Atmos in the Home
    Dolby Atmos in the home has arrived much sooner than we initially thought.
    However some of the information in that article was educated guesswork and until yesterday we hadn’t actually experienced the home version of Dolby Atmos. Once again Dolby were kind enough to invite AVForums to an exclusive demonstration of Atmos but this time at their Soho Square facility in London. The company has a fully equipped Atmos screening room at this facility, a 35-seater this time, but in addition they have a demo room that is designed to emulate a standard home cinema setup. The exciting aspect of this demonstration wasn’t only the opportunity to hear Atmos in a home environment and ask questions but also to compare exactly the same demo content played in both the big screening room and the home cinema.

    The demonstration was conducted by Jonathan Jowitt or JJ, as he prefers to be known, who within Dolby has the somewhat unusual job title of ‘Evangelist’. JJ started by explaining that the feedback Dolby have been receiving from filmmakers has been incredibly positive because they feel they now have a more realistic palate from which to create sound fields that genuinely envelop the viewer in a 3D hemisphere. When creating a traditional 5.1 or 7.1 mix, the sound designers are often debating about where to place sounds or dialogue and how loud they should be within the mix, giving certain sounds precedence over others.


    With Dolby Atmos you can have up to 128 concurrent audio objects or sounds, which the sound designers can position wherever they want within a three dimensional space. This means that the resulting mix is not only more immersive but also that any one sound doesn’t need to be louder than everything else to be heard. A Dolby Atmos sound mix is composed of these objects which, in turn, are composed of metadata relating to their amplitude in that instance and their X,Y, Z position within a specified three-dimensional space. The sound files for each object are monophonic and are read by the Atmos processor which then positions them within this three-dimensional space.

    As part of the installation in a professional cinema, the dimensions of the theatre are programmed into the Atmos processor and it adjusts the sound mix on-the-fly to fit that specific room using real-time rendering. After this initial briefing, which we largely knew already from our previous visit to Royal Wootton Basset, we moved onto the actual demonstration. Since we had the entire screening room to ourselves, we sat about half way back from the front and central to the screen. Hopefully we would be able to replicate this position in the home cinema demonstration.
    The demonstration of Atmos in the main screening room was very impressive.
    The first clip was a specially produced Atmos trailer created by Dolby that showed a forest in a thunderstorm and obviously made use of extensive natural sounds. The experience was very immersive, with wind rushing all around you and over you, rain drops coming down from above and deep thunder shaking the subwoofers and completely surrounding you in a three-dimensional hemisphere. It was very impressive and reminded us that these more immersive sound formats work just as well with atmospheric effects as they do with explosions or helicopters.

    The next trailer was called ‘Leaf’ and was made especially for Dolby by Pixar to be shown in front of Atmos screenings of Brave. This computer animated sequence follows leaves as they’re blown around and a sycamore seed as it spirals down through a tree. Again there are a lot of natural sounds being used to create a very immersive surround experience with sounds moving around you and above you in a 360 degree sound field.


    This was followed by the opening sequence of Star Trek Into Darkness, where Kirk and McCoy are being chased by aliens and Spock has to descend into an active volcano. This was an incredibly active sound mix, perhaps a bit too active, because you almost felt punch drunk afterwards. The sound design was very complex, with effects, music and dialogue being mixed to completely draw the viewer into the action, not to mention some serious levels of bass. Compared to some of the earlier Atmos film soundtracks we have heard, it was clear that the sound designers are becoming more adept at using this object based approach.

    Next we watched a trailer created in conjunction with the Red Bull F1 team and once again the sound design drew you in, making you feel like you were actually inside the racing car at times and completely surrounded by the noises of the engine. Finally we watched a short trailer called 'Unfold', which was conceived by the sound designer for Transformers. This object only sound mix was created first and the animation added afterwards, so there were no limitations. He was obviously using his library of transformer noises but the result is 15 seconds of constant sound moving around and over you.

    Dolby are employing the same spatially encoded bitstream that they use in the cinema to deliver Atmos at home.
    Once this demonstration was finished, JJ began to explain how Dolby have taken Atmos out of the cinema and delivered it into the home. The main problem for Dolby was how to condense all the data in an Atmos soundtrack so that they could deliver it in a domestic environment without losing any of the original sound design. Dolby Atmos works by using spatial coding that takes into account the locations of the objects. In the cinema the Atmos decoder uses an Object Audio Renderer to read the specially coded bitstream and combine this with the dimensions of the room and the location of all the speakers.

    Dolby essentially use exactly the same technology to deliver a similar experience in the home, although they obviously have had to scale down certain aspects of the system for the domestic environment. However the Atmos equipped receivers will render the specially encoded bitstream on-the-fly. The really clever part is that Dolby have managed to compress the metadata into a Dolby TrueHD soundtrack, which makes the format backwards compatible. There’s no need to buy a new Blu-ray player and if you have a non-Atmos receiver it will still be able to take a standard 5.1 or 7.1 mix from the Atmos soundtrack on the disc.


    However if you have a receiver that supports Atmos, either through buying a new one or perhaps because your existing receiver can be enabled using a firmware update, then it will recognise the Atmos soundtrack on your Blu-ray and recreate the full cinema experience. The receiver will use your speaker layout, the type of speakers, the distances from the main listening position and the dimensions of the room to decide how many objects to render within that environment.

    Whilst the initial receivers will offer up to nine channels including the overhead speakers, the main limiting factor will be how much amplification can practically be squeezed into the chassis of a receiver. However there is at least one domestic Atmos processor that can use up to 32 channels, including two arrays of overhead speakers, which is the same as Dolby’s screening room in Soho Square. It’s likely that setting up your new Atmos receiver will involve either manual input or an automated process, possibly a combination of the two.
    Dolby Atmos sounds just as impressive in the home theatre demo as it does in the fully equipped screening room.
    Ultimately, exactly how Atmos will be delivered will depend on each manufacturer, Dolby obviously license the technology and provide guidelines but exactly how Atmos is deployed will depend on each individual company, For that reason the home cinema demonstration was totally agnostic and wasn’t about pushing any particular manufacturers products. It was more about showing what can be achieved with a fairly standard Atmos configuration in the room.

    In the case of this demonstration, Dolby were using a standard 7.1 configuration with four overhead speakers (7.1.4) and they also had special Dolby Atmos speakers over the front and rear left and right speakers, so that we could compare the two approaches to adding overhead sounds. If you’re planning on installing overhead speakers, the ideal position will depend on where your sweet spot is. In the case of our home theatre, the main listening position is about two-thirds of the way back, so Dolby recommend the front overhead speakers be positioned about halfway between the front speakers and the centre of the room and angled slightly towards the listening position. Whilst the rear overhead array should be just behind the listening position and firing directly downwards.


    When it comes to the special Atmos speakers, Dolby realise that most people won’t want to fix speakers to the ceiling and so have developed technology to address this reality. When you fire sound directly at a listener from above, the sound reaches each ear at the same time. However as the sound rolls overhead reflections create a ‘notch’ in the frequency that allows the brain to recognise that this sound is above rather than directly in front. Dolby Atmos speakers recreate this ‘notch’ and thus when the sounds are reflected off the ceiling the brain thinks the sound came from overhead.

    The demonstration was run from a laptop, rather than a specific Atmos-capable receiver so that JJ could use an on-screen GUI that showed which speakers were being used, how the room was being modelled and where the objects were within the room. It also allowed JJ to switch between the overhead speakers and the Atmos speakers on-the-fly, something you wouldn’t be able to do with a commercially available receiver. The idea was to not only show us how good Atmos can sound in the home but also how effective Atmos speakers are at creating the sense of overhead sounds.
    The Dolby Atmos speakers were surprisingly effective, creating the illusion that sounds came from overhead.
    We sat in a seat that basically approximated where we were sat in the main screening room and JJ went through exactly the same demonstration material as before. He did however play the first two clips, the Dolby Atmos and 'Leaf' trailers using the Dolby Atmos speakers without initially telling us and it was genuinely hard to tell that the sounds weren’t emanating from speakers overhead. Whilst the sound wasn’t quite as impressive as a full cinema setup, the results were excellent and the overall experience was very immersive.

    JJ then moved on to the Star Trek Into Darkness clip, this time starting with the overhead speakers and showing us the speakers being used on the GUI, so we knew when he switched between the overheads and the Atmos speakers. The Star Trek soundtrack didn’t sound quite as active as it did in the cinema but that might not be a bad thing, as it was almost over-powering before. This time it was still very active and immersive but you didn’t feel like the sound designers were throwing in everything but the kitchen sink. After that JJ played the Red Bull and 'Unfold' trailers, which again felt very immersive with plenty of movement around and above the listener.

    What surprised us wasn’t how good Atmos was, we rather expected that, but how effective the Atmos speakers were at creating the sensation of overhead speakers. When they were first announced we cynically thought they might just be a gimmick for selling Atmos to people who don’t want speakers in their ceiling. However having had a chance to hear them, they really do work and offer a genuine alternative to drilling into your ceiling. As with the receivers, Dolby is agnostic with regards to manufacturers and although they were using KEF speakers in the demo, there will be plenty of alternatives and Onkyo have already announced Atmos Speakers for customers who buy their new receivers.
    The big question is when will Atmos encoded Blu-rays be released and which studios will support the format?
    Of course the big question is what about Atmos encoded content? Dolby said that Atmos Blu-rays would be announced soon. Whilst they couldn't give specifics on studios or titles they did say that new titles would include Atmos soundtracks going forward and that some films that had already been released might be re-released in Atmos as well. They said that the studios were still deciding on how best to label the new Blu-rays without confusing the consumer. We think that given Paramount already use Dolby TrueHD a lot on their Blu-rays, it's a safe bet that they will support the new format.

    The real question is what about all the other studios? Will they support Atmos, especially as most of them tend to use DTS-HD Master Audio as their default soundtrack on Blu-rays. There are plenty of studios that use Dolby Atmos soundtracks in the cinema, so there should be enough films to release and it might be a good selling point for Blu-ray as it reaches the end of its life-cycle. Whatever happens the good news is that Dolby Atmos sounds just as good in the home as it does in the cinema. The even better news is that you can get this immersive experience without having to resort to a step ladder and a drill. Isn't technology wonderful.

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