Engadget goes behind the Dolby logo

Steven Kim
S. Kim|07.08.09

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Engadget goes behind the Dolby logo
Dolby front door
With AV software and hardware alike carrying at least one Dolby logo, not to mention the presence of that same branding on big screen cinema, Dolby is truly a household name. If you ask people exactly what Dolby does, however, you're likely to get a pretty fuzzy picture, which isn't too surprising -- the brand is so prevalent in the media space that it's kind of like asking a fish to describe what water feels like. So when Dolby invited us to spend a day with them to talk about their current goings-on in home theater, we just couldn't pass up the opportunity.

To get a look behind the familiar logo, we spent a day at Dolby's lab in San Francisco. During our time there we talked about TrueHD, Digital Plus, Dolby Volume, the new Pro Logic IIz, and even got a short peek at some current research efforts. It was a fast run over a lot of ground, for sure!
One theme that consistently popped up during our visit was the concept of fidelity. A lot of the folks at Dolby have music backgrounds, and it shows in subtle but significant ways. While the engineering that goes on at Dolby is certainly advanced, and the company makes its name on technology, a strong theme of not messing with the intent of the original artist runs throughout the company's DNA. While this approach of doing "just enough" may not make for the most mindblowing demos, it's the approach our ears prefer. Recreating a whole cathedral within the confines of your closet may be impressive, but trust us, it won't age well. Dolby's restraint and insistence on technology serving the content, and not vice versa keeps this kind of bloated excess from fouling up the listening experience.

Another trend we picked up on was room treatment. As you'd expect from a professional setup, there was a goodly amount of acoustic foam in every room we auditioned, and every room sounded way more controlled than any conventional home setting we've experienced. Going along with the acoustic foam was a large presence of active monitors -- again consistent with pro setups -- and wouldn't you know it, every setup showed lots of dynamic headroom with gobs of detail.

But as you would expect from a technology solution provider, we didn't spend much time talking about gear. Dolby wants as many CE companies as possible to license its solutions, and based on the volume of gear that carries one Dolby logo or another, the company has been quite successful in its efforts!

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Dolby TrueHD
Since our visit was prompted by our post about using Dolby TrueHD with a PS3, we'll start with the lossless format. Specifically, we received several field reports about sonic differences between decoding the TrueHD track in the player (sending LPCM to the receiver) versus bitstreaming the TrueHD to the receiver for decoding. Well, you can take off your tinfoil hats -- Dolby TrueHD is not only encoded as lossless, but it also has a built in CRC (cyclic redundancy check) that ensures that the decoding process is lossless as well. Additionally, Dolby does do testing of components to ensure, for example, that the amplifiers are accurate.

That said, the amount of signal processing in modern AVRs can introduce some wrinkles that, quite frankly, are beyond Dolby's control. For example, on a PS3 it is important to disable Dynamic Range Control to ensure that the decoded TrueHD bits aren't being subjected to additional gain stages before being passed into your receiver. Also common are signal processing steps in the receiver that depend on the source data -- for example, some receivers apply room EQ to LPCM, but not Dolby TrueHD. At the end of the day, it's up to you to make sure that the signal processing chain you set loose on your Dolby TrueHD signal is under control before making comparisons.

A few readers commented about stacking up TrueHD against DTS-HD MA. Dolby's staff was way too professional to get into a name-calling contest, but quite honestly, we liked their pragmatic answer -- having access to a choice of two lossless formats is an embarrassment of riches, so pick whichever sounds best to you. In its own testing, people we asked said that in head-to-head testing, audible differences between the two lossless formats were on par with codecs rounding a value up or down. Quite honestly, the biggest technical advantage we can pick out for DTS-HD MA is the way it "scales back" to a DTS core track, whereas TrueHD is an entirely standalone codec that doesn't fall back at all. That said, we do appreciate the fact that Dolby's standalone approach on TrueHD versus the lossy codecs was taken to avoid any possible coder unmasking artifacts. We'd be eager to get a demo of coder unmasking artifacts, especially with respect to actual content and not specialized test tones.

If you're a "belt and suspenders" kind of person who needs to know you're getting all the bits, rest assured -- as much as possible, Dolby is making sure you're getting the bits and has no plans to back away from TrueHD.

Dolby Digital Plus
Which brings us to Dolby Digital Plus. Even knowing we were big into audio, Dolby dedicated a lot of our visit to technologies besides TrueHD. Now we know that Digital Plus isn't exactly new to the scene, but we'll spill some ink over it because to simply lump it in with other lossy codecs would be a great disservice.

Digital Plus is a major part of Dolby's strategy going forward, and it's easy to understand why. Digital Plus is clearly designed for expansion, with support to as many as 15.1-channels at 6Mbps (limited to 7.1-channel, 4.7Mbps on Blu-ray), with mixing of additional content -- like Bonus View and BD-Live tracks -- on the fly, Dolby Digital Plus is future-ready, both on physical media and downloaded/streamed content. Even as implemented on Blu-ray, the Dolby Digital Plus track carries 9.1-channels of information that is used to deliver either the 5.1-channel Dolby Digital "core" or a 7.1-channel mix without any rematrixing.

Oh yeah, and it sounds awesome. We didn't put our ears to a TrueHD vs. Digital Plus blind test, but after an afternoon of not being able to tell the difference in demo loops, we're won over -- if it's good enough for our ears in Dolby's labs, it's good enough for our home.

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Dolby Volume
We first saw Dolby Volume on devices at this year's CES, but the convention floor is no place to get a demo. After spending lots of time, effort and money on the audio side of our HT setup, we're not keen on doing any sort of compression, but we do have to admit that during non-critical viewing, having to fiddle with the volume is a real pain.

For night-time listening, channel surfing, or times when you're victim of commercials (rare in a DVR household, but it still does happen), Dolby Volume can keep you from dashing to and from the volume control. Dolby showed us the feature as built in on a Toshiba REGZA TV, and we have to admit that it did a fine job of balancing the volume between two programs with very different levels -- the effect was instant switching in both directions, and within a given program didn't exhibit any "pumping" artifacts.

Again, in our DVR-centric household, we tend to soak up a single program at a time and skip over commercials, so the volume is pretty easy to regulate. But, it would be interesting to live with Dolby Volume for about a month -- perhaps switching it on when some of the house is asleep -- and then weigh in on whether we'd be willing to give it up. We've got a feeling it might find a place in even our audiophile hearts as something that can move casual viewing a little closer to critical quality.

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Dolby Pro Logic IIz
Dolby Pro Logic IIz has received its share of attention since it rolled out, and not all of it has been glowing. After taking in Dolby's own demo of the technology, however, we're won over. Here's the deal -- Dolby agreed that 5.1-channels is a kind of "sweet spot" for surround audio, and we would guess that most multichannel surround setups are sticking to that channel count. If an additional two channels are thrown in, however, there's a choice between putting them in the rear surround positions or, in the case of Pro Logic IIz, the front height positions. Common sense would tell you that your highly evolved ear-brain combo is more attuned to spatial cues delivered in front of you than from behind, and you'd be correct in that assumption. Market forces and standards being what they are, however, there's no point in wishing that 7.1-channel audio would have made provisions for discrete front-channel height signals -- that ship sailed long ago. But Dolby's Pro Logic IIz is a matrix decoder technology that attempts to extract front height audio cues from traditional multi-channel audio (we demoed sources ranging from stereo to 7.1-channel).

Essentially, the Pro Logic IIz decoder analyzes the audio signal in real-time and attempts to extract as many audio height cues as safely possible. So, for stereo recordings, the effect tends to be quite mild; at the other extreme, audio can be engineered to maximize the amount of height-specific audio content.

We came away from our demo of Pro Logic IIz very impressed. Knowing full well that we were being treated to a very controlled setup and demo, we'd go as far as to say that if and when we ever move from our 5.1-channel setup to 7.1-channels, we'll put those two additional channels up front, above the primary L/R speakers. In our demo, we were able to switch between 5.1, 7.1, 5.1 + Pro Logic IIz, and 7.1 + Pro Logic IIz decoding of various content, and in every case we preferred the presentation of the 5.1 + Pro Logic IIz over the 7.1 decoding. To our ears, in this setup, the additional imaging solidity those two height channels gave Pro Logic IIz the nod.

Equally impressive to what Pro Logic IIz did was what it didn't do. Keeping in mind that Pro Logic IIz is a real-time signal processing technique that does not rely on discretely encoded channels, we were impressed that we never experienced dialog floating upwards or spatial cues discontinuously flying around the room. This is the kind of effect that, unlike overblown DSP surround modes, will not tire you out over the span of a two-hour movie. If you're interested in more solid imaging and have the room for two more speakers about 4-feet above your primary L/R channels, you might be interested in checking out Pro Logic IIz -- even if it doesn't work out for you, you'll still be able to enjoy conventional 7.1-channel surround sound.

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The Sandbox
As we said, Dolby itself feels that 5.1-channels are a sweet spot for surround audio. But the limits of what can be done with surround audio are being tested in what Dolby calls its "Sandbox." There are 24 speakers in this room -- 16 at ear level encircling the listener, a smaller ring of 6 above that, a single "voice of God" speaker is on the ceiling directly above the listener, and a subwoofer. Simply put, the goal of this setup is to be able to create sound anywhere in the upper hemisphere within a theater. The speakers are not perfectly arranged, to better mimic the varying speaker-listener interactions across a theater setting.

After doing some white noise pans, we were convinced that this array of 24 speakers can create a much more spatially continuous soundfield than a conventional 5.1 or 7.1-channel setup. Not a big surprise, right?

But here's the interesting part -- the Sandbox uses 5.1-channel encoding to upmix (expand) to 24-channels, and the results are stunning. The implications for this are pretty exciting -- a 5.1-channel mix that is compatible with everyone's existing surround sound setup can be upmixed to as many as 24-channels for dramatically better surround performance. As with our Pro Logic IIz demo, we didn't notice any ill effects, even when the original material was sourced from a 2-channel vinyl record -- and we believe our host's claims that improper 24-channel upmixing can make the listener seasick, change the tonality, or collapse the soundfield. Thankfully, we didn't lose our lunch, and we heard a dramatically improved sense of ambiance while the tonality of the sound made it immediately recognizable as the original 2-channel stereo recording.

Sure, finding room for 24 speakers is daunting at best and would push even our nonexistent sense of decor to the limits, but it's good to know that with some clever technology like that Dolby showed us in its Sandbox, we won't have to carry around audio files containing 24 discrete channels to create a holographic soundstage. And hey, with the onslaught of in-wall speakers, maybe this kind of sound will be possible in the living room one day. Until then, we'll be eager to see this technology find its way into the cinema space.

Dolby Labs Sandbox

As you can probably tell, spending a day at Dolby was like a run through a theme park for us. It was incredibly fun to dedicate an entire day to audio, and yet we feel we only scratched the surface. There's a reason that Dolby has managed to put its technology into so much of our media experiences -- simply put, the company develops great technology that enhances the end-user experience and avoids wandering into "gimmick" territory.

On several fronts, Dolby has more competition now than ever. DTS-HD MA has more titles under its column than TrueHD, Audyssey's Dynamic EQ and Dynamic Volume as well as THX's Loudness Plus are aiming for the same sonic goals as Dolby Volume, and Audyssey DSX is squared off against Pro Logic IIz. However, we're confident that Dolby is up to the challenge. With its deep roots in the cinema space, technical chops, pragmatic approach, and sheer brand familiarity, we've got no doubt that it will continue to impact the audio (and with Dolby HDR, video as well) landscape for years to come.

Although many decry the death of high-end audio, after our whirlwind tour and extensive demos, we'd say it's a great time to be into audio. There's a lot of great technology being thrown at every aspect of the home entertainment experience that not only makes things more convenient, but just plain better. Besides that, the fact that the tech is coming from a variety of companies ensures that the innovation won't stop and will make its way to us consumers faster.

We'd like to thank Dolby for letting us get a glimpse into its inner workings, and hope to stay appraised of more good things to come from that familiar logo.
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