Demonstrations in three cities offered the AV press—and several AVS members—the opportunity to experience Dolby Atmos for the home first hand.
Dolby Atmos for home theaters is generating a big buzz these days, and the company behind it is pulling out all the stops to demonstrate the technology to the AV press and several members of AVS Forum. Last Monday, 20 people, including AVS members sdurani, Rayjr, FilmMixer, and Scott Simonian, gathered at Dolby's offices in Burbank, CA to hear the commercial-theater version of Atmos followed by the home version. We also had plenty of opportunity to pose questions to Brett Crockett, Senior Director of the Research Sound Technology and Advanced Technology Group, Stuart Bowling, Director of Market Development for commercial cinema, and Craig Eggers, Director of Home Theater. (A similar event was held in New York City on Wednesday, which AVS Senior Writer Mark Henninger attended with several other AVS members; he'll share his experience later in this post. The same demo was also presented in San Francisco on Friday.)
The Burbank demo was actually held in two separate locations—first at Dolby's Southern California headquarters, which includes a 60-seat commercial cinema-like screening room, and then a suite of offices down the street where Dolby had set up a home theater-like room. In the screening room, Brett started by explaining what Atmos is—an object-based audio system that lets movie-soundtrack mixers place individual sound-emitting objects anywhere in a 3D space around the audience. This is accomplished in commercial cinemas by mounting speakers on the ceiling in addition to the speakers behind the screen and on the side and back walls. A powerful Atmos rendering cinema processor decodes the data for each object and sends its sound to the appropriate speaker(s) so that it appears to be in the intended location.
The screening room at Dolby's Burbank headquarters includes a full-blown Atmos cinema system. (Photo by Ray Coronado)
The demo started with two Atmos trailers—"Amaze" and "Unfold"—that are commonly played in Atmos cinemas before the movie, and both utilize the 3D space quite effectively. Next up was the volcano scene from Star Trek Into Darkness, which has plenty of overhead sounds, though the system was too loud to fully appreciate the effect. (I measured an Leq [average level] of 98.3 dBC over seven minutes; reference level is 85 dBA, and dBC is typically about 10 dB higher than dBA, so this was above reference. In any event, it was too loud.)
Following that was a short about Formula 1 race cars commissioned by Red Bull, which was also pretty loud, and I didn't perceive that much sound coming from overhead. Finally, we saw and heard the "Leaf" Atmos trailer, which was created by Oscar-winning sound designer Gary Rydstrom; like the other two Atmos trailers, this one makes great use of the entire 3D soundfield.
The 7.1.4 home-theater setup in Dolby's other office suite included four speakers mounted on the drop ceiling (two of which can be seen here) as well as Atmos-enabled upfiring speakers at the front LR and back-surround LR positions. (Photo by Scott Wilkinson)
After being shuttled over to the other offices, we broke into small groups that rotated in and out of the home-theater demo room, which could accommodate only six people at a time. The demo room had a 7.1 audio system in which the front LR and back-surround LR speakers were "Atmos-enabled" with upfiring transducers that sent their sound up to the 9-foot ceiling, where it was reflected back into the listening area, providing the overhead audio. The room also had actual overhead speakers mounted on the ceiling, allowing the demo to include a comparison between direct and reflected overhead sound.
The Dolby rep started with "Amaze," "Unfold," and the Formula 1 short using the ceiling-mounted speakers, after which he played two audio-only demos—a helicopter flying around the room and a rainstorm—starting with standard 7.1 and then adding the overhead channels, switching back and forth between the ceiling-mounted speakers and the Atmos-enabled upfiring speakers. Adding the overhead channels made a huge improvement in the immersiveness, and I could hear a slight difference in timbre between the two overhead setups. But more importantly, the ceiling-mounted speakers were much more localizable, which was a bit distracting, while the Atmos-enabled speakers produced a more diffuse overhead soundfield that nevertheless represented the position of the object well. We ended with "Leaf" and an abbreviated clip of the volcano scene from Star Trek Into Darkness (at a much more comfortable level) with the Atmos-enabled speakers, and both sounded excellent.
Three Dolby reps were peppered with questions from the journalists and AVS members in attendance. At the far end of the table are (L-R) Stuart Bowling, Craig Eggers, and Brett Crockett from Dolby; sitting at the table in the right of this shot are (L-R) Tom Norton of Sound & Vision and AVS members sdurani and FilmMixer. Behind Tom and to his right is Rob Sabin, editor of Sound & Vision, and in the lower-right foreground is Gary Reber, editor and publisher of Widescreen Review. (Photo by Scott Wilkinson)
While small groups were in the home-theater demo room, the rest of us were in a conference room, posing questions to Brett, Craig, and Stuart. Brett mentioned that installing speakers on the ceiling of many home theater is not always practical for many people, either logistically or from a spouse-acceptance perspective, which is why his team invented the concept of upfiring drivers on top of the front LR and rear-surround LR speakers to provide the overhead sounds. Craig mentioned that these Atmos-enabled speakers should be at least three feet from the closest listener.
This Atmos-enabled speaker (maker unknown) includes a small upfiring driver that sends the overhead signal to the ceiling, which reflects it down to the listeners. (Photo by Mark Henninger)
But there's more to it than simply adding some transducers to the top of a speaker—the system must replicate the effect of a human head as sounds from above, especially high frequencies, bend around it. This height-cue filtering is performed using standard analog components built into each Atmos-enabled speaker.
Of course, many rooms don't have a horizontal, reflective ceiling, which is required for upfiring speakers. ("Popcorn" and drop ceilings are fine.) For pitched or vaulted ceilings, installing speakers overhead might be the only solution. In-ceiling speakers can also work, but Craig emphasized the importance of timbre-matching the ceiling speakers with those at ear-level—ideally, all speakers should come from the same product line of a given manufacturer, but room EQ can help if they don't. Also, ceiling-mounted speakers do not need the same psychoacoustic processing as Atmos-enabled upfiring ones.
As you have probably gathered by now, a Dolby Atmos system requires speakers with upfiring drivers or actual speakers on the ceiling as well as a new AV receiver or preamp/processor with Atmos decoding. But the good news is that an Atmos soundtrack can be included on any Blu-ray disc and played on any existing Blu-ray player that is in full compliance with the Blu-ray spec and HDMI 1.4 or later. You do need to turn off the secondary-audio function in the player (which mixes the director's commentary and other secondary audio streams with the main multichannel soundtrack) in order to play the Atmos soundtrack.
I asked how much data overhead—storage capacity over and above what a conventional soundtrack would need—is required on the disc. Craig replied that it depends on the number of objects and complexity of the mix, but Dolby's goal is to keep it under 20% with Dolby TrueHD lossless compression. Atmos can also use Dolby Digital Plus lossy compression, which would reduce the data overhead significantly.
Atmos for commercial cinema uses a 9-channel "bed"—front left, center, and right; left and right side surround; left and right rear surround; left and right overhead. The four surround channels and two overhead channels are typically reproduced by multiple speakers that all play the same thing in a channel-based mix, and individual objects are overlaid on top of that, using whatever individual speakers are needed to reproduce the sound of that object from the desired position.
In the home version, the Dolby Atmos mix can include any combination of dynamically moving objects and fixed-position bed objects, up to a total of 128. Using Dolby's spatial-coding technique, the company is currently finding the best way to translate the cinematic experience to the home using all dynamically moving objects with no bed objects.
It's also important to understand that AVRs and pre/pros without Atmos capabilities will still play an Atmos soundtrack with the individual objects folded into the 5.1 or 7.1 mix, thanks to the Dolby TrueHD decoder. In fact, Brett said this was the most difficult thing they had to do to bring Atmos to the home. In addition, an Atmos-capable AVR or pre/pro can expand a 5.1 or 7.1 soundtrack—or even a 2-channel mix—into the entire 3D soundfield. Interestingly, if you have a 9.1 system with front wide speakers, the new expansion algorithm won't include those two channels. According to Dolby, this was a conscious decision in order not to smear the front soundstage.
Another interesting tidbit is that the Dolby Atmos system includes a new upmixing algortihm designed to be compatible with conventional channel-based and Atmos playback systems. Manufacturers can choose to include Dolby Pro Logic in Atmos-capable receivers, and Pro Logic will continued to be offered in channel-based receivers. This new upmixer is called Dolby Surround, which is a somewhat unfortunate moniker, since it's also the name given to the earliest consumer version of Dolby's multichannel analog film-sound format back in 1982. Perhaps that's so long ago that few will remember the term from those days.
After the event, sdurani, Rayjr, FilmMixer, Scott Simonian, and I talked about the experience. Surprisingly, all of us preferred the upfiring Atmos-enabled speakers over the ceiling-mounted speakers because they provided a wider, more enveloping soundfield. And as I mentioned earlier, the ceiling-mounted speakers were too localizable, at least at a ceiling height of nine feet or so.
All in all, it was a very interesting and informative demo, and I thank Dolby for hosting it.
Here are Mark Henninger's impressions from the New York demo:
Two days after the West Coast crew attended Dolby's Atmos demo, I heard the same demonstration in New York. AVS members Ralph Potts, Jwhip, Orbitron, and Paradyme joined me for the three-hour experience.
We started out in Dolby's Atmos-equipped screening room. First things first: Atmos works as advertised—it creates an enhanced sense of atmosphere. With the right sound effects, Atmos provides a significant boost in immersion. The first two trailers from Dolby, although short, demonstrated the system's capabilities quite well.
Brett Crockett explains Dolby Atmos to journalists and AVS members in Dolby's New York screening room, which is decked out with a full cinema Atmos system. (Photo by Mark Henninger)
The third clip was the opening scene from Star Trek: Into Darkness featuring the volcano. Although it made use of the height capabilities offered by Atmos, I found the sound quality was a bit harsh and overly bright. The entire presentation was too loud to appreciate much subtlety, and sibilance negatively affected the dialog. Ralph Potts, Jwhip, Orbitron, and Paradyme (aka Theo Kalomirakis) all made similar comments about the theatrical demo of Star Trek in Atmos—it was too loud and too harsh to appreciate the benefit of the added channels.
The Red Bull-sponsored Formula 1 trailer sounded good, though I agree with Scott Wilkinson's assessment—it did not make effective use of the Atmos height channels. I'm curious how that clip would compare to a 7.1-channel mix. I also agree with the Cali crew about the Dolby-produced "Leaf" trailer; it featured excellent sound design and showed off the system's true potential.
Of course, the point of the demo was to compare a theatrical system to a home-theater setup, so our group moved to a smaller space, which looked like an office or conference room. The home theater segment played on the same 7.1 system Scott and his group heard in LA, including Atmos-enabled speakers and overhead speakers.
In Dolby's New York home-theater room, small groups heard Atmos for the home after a short presentation. (Photo by Mark Henninger)
Our experience and impressions of the home-theater demo differed from Scott's group—namely, we all thought the overhead speakers sounded better than the reflected sound coming from the Atmos-enabled speakers. The dedicated overheads were clearer and a better match for the main speakers. I found that the reflected sound from the Atmos-enabled speakers had a tinny and artificial sound compared to the in-ceiling setup. When I chatted with Scott about this, we identified one possible cause: In the LA demo, Dolby positioned the Atmos-enabled speakers away from the walls, which is appropriate for bookshelf speakers on stands. However, in New York, the speakers were right against the walls. It's not clear how that affected the overall sound, but proper speaker position is a very crucial part of any system setup, one that influences the results of any audio demo.
We re-watched the Star Trek clip on the home-theater setup, and the modest nature of the system Dolby demoed diminished the impact of the presentation. Nevertheless, it possessed many of the same characteristics we heard in the screening room—namely, it was a bit harsh, dry, and bright. Atmos did not seem to add much to the immersive experience in that clip versus what I've heard in the past. Orbitron and the other guys agreed that our own systems did quite well with the same material.
Since Dolby did not A/B 7.1 versus Atmos during that clip, it was impossible to tell how much dimension Atmos added to the mix. In fact, Dolby did not offer a comparison between regular 7.1 and Atmos using theatrical content—that comparison was exclusive to the helicopter flying around the room and the rainstorm demo, which sounded rather different depending on the speakers used for the overhead effect. In our demo, the ceiling-mounted speakers sounded clearer, and there was a greater sense of overhead space. Also, the timbre match with the main speakers was good enough to avoid distraction. The reflected sound was more diffuse; to my ears, it sounded processed—like a low-bitrate MP3. In addition, the reflected sound did not create as convincing an illusion of sound coming from directly overhead. I wonder if the speaker placement—directly against the walls—was responsible for that discrepancy.
The end of the home theater demo involved the "Leaf" trailer. Dolby did not tell the audience if the clip utilized the ceiling speakers or reflected sound. When it finished playing, the presenter asked for a show of hands if we thought the clip used ceiling speakers—nobody raised their hand. Evidently, the difference between overhead and reflected Atmos overhead channels was too obvious to fool anyone. [Editor's note: the same thing happened with the group in LA—no one thought the overhead speakers were being used.]
I chatted with Ralph Potts about the experience, especially since he gave the Blu-ray version of Star Trek: Into Darkness a perfect score of 100 for audio. Ralph mentioned that in many dedicated home theaters, the side and rear surrounds are above ear level, unlike in Dolby's home-theater demo. That somewhat diminished the advantage offered by the dedicated overhead channels. On the other hand, Ralph mentioned that he sees a lot more potential in Atmos than the Dolby demo was able to convey, and I agree. We need a better demonstration, in a dedicated home theater, to understand what Atmos can do.
As soon as the Dolby event ended, we headed over to Theo Kalomirakis' new home theater, the Roxy 2.0. Unfortunately, Ralph could not make it, but Chris Boylan, the editor of BigPictureBigSound.com
came along. Chris was part of the group we were in during the demos at Dolby, so he had the same experience we did. We watched the scene from Star Trek on Blu-ray with the Dolby TrueHD 7.1 soundtrack. I thought Theo's system sounded better than the theatrical Atmos presentation at Dolby's screening room, and quite superior to Dolby's home theater presentation. Even so, I do think that Theo's theater could benefit from Atmos, as long as it improves upon an already excellent presentation.
When I got home, I watched the same scene from Star Trek on my system, while my memory was still fresh. The next day, I received a PM from Jwhip, who played the clip on his system when he got home. He said, "In my system, the music opening to the film was silky smooth, much better than anything we heard yesterday." Regarding the surround effects, Jwhip mentioned, "I have my surround speakers above ear level, pointed down at the coach, and agree with Ralph on that point. In fact, the flying arrows at the beginning of the film were as convincing as they were in the Atmos."
My 7.1 setup, featuring Dolby PL IIz with front-height channels, immersed me in the Blu-ray's Dolby TrueHD soundtrack just fine. There was precious little to differentiate it from what I heard in the Atmos mix. I can only conclude that proper setup and calibration trumps new formats when it comes to the overall surround-sound experience. That is why it's vitally important that Atmos demos take place on properly set up and calibrated systems—it's not a blunt tool. Without a proper demo, I predict that most enthusiasts will not feel a strong urge to upgrade an existing 7.1 system just for Atmos—the format needs to up the suspension-of-disbelief ante. Achieving that requires a seamless soundfield, and I look forward to an Atmos demo that convincingly pulls it off.
There are quite a few threads on AVS devoted to Dolby Atmos for home theaters; be sure to check them out...
Here's a fairly complete list
...and here are some of the main ones:
Official Dolby Atmos Thread (Home Theater Version)
Dolby Atmos White Papers Available for Download
Dolby Atmos Demo at Pioneer
Why Dolby Atmos is DOA
(responses to an article of that name at Audioholics.com
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