If you’ve been to the movies — or even watched one at home — anytime in the last, oh, 40 years or so, then you’ve no doubt seen the Dolby name before. These days, the company has evolved past the technology that made it famous and moved onto new and improved technologies: Dolby Digital and, more recently, Dolby Atmos.
But how do the two compare? What sets apart Dolby Atmos from Dolby Digital? Let’s take a closer look, making a side-by-side comparison between the two and paying close attention to their key differences.
Dolby Atmos vs Dolby Digital: Side-by-Side Comparison
|Horizontal and vertical
|3D surround sound
|2D surround sound
|subwoofer, center speaker, left and right front speakers, left and right rear speakers, two side speakers
|subwoofer, center speaker, left and right front speakers, left and right rear speakers
Dolby Atmos vs Dolby Digital: What’s the Difference?
For those unfamiliar with the finer aspects of sound system technology, it helps to break down some of these key differences between Dolby Atmos vs Dolby Digital into simpler terms. The two are very distinct technologies (despite belonging to the same technological family). And, as such, the differences between the two deserve to be understood. Here are the three most prominent distinctions that set Dolby Atmos vs Dolby Digital apart.
Number of Channels
Firstly, there’s the number of audio channels used in Dolby Atmos vs Dolby Digital. As the older technology, it’s not surprising that Dolby Digital uses fewer channels than Dolby Atmos. In its simplest form, you can achieve Dolby Digital sound with just a left and right front speaker.
This would be what’s called a 2.0 surround sound setup. Dolby Digital speakers are arranged horizontally, and though they can theoretically support a setup as large as 15.1, their number of channels will never stretch beyond this two-dimensional layout.
Dolby Atmos, on the other hand, is inherently three-dimensional. For this reason, the least possible number of channels for a certified Dolby Atmos has to be 3.1.2. (That’s a center speaker, a left and right speaker, a subwoofer, and two height channels or side speakers.)
On the higher end of the spectrum, you can theoretically have a setup as large as 24.1.10. Though, of course, the only people with Dolby Atmos setups this large are probably audio professionals only. Nevertheless, Dolby Atmos will always have more channels than Dolby Digital by design.
Projection of Sound
This difference in channels leads directly to our next distinction: the difference in the way sound is projected in Dolby Atmos vs Dolby Digital. With Dolby Digital, the sound is projected through the speakers based on the idea that sound should be coming from all around the listener in order to be truly immersive.
Rooted solely in horizontal channels, the Dolby Digital surround sound audio will be projected from the front and the back and on the left and the right of the listener. In other words, it’s “surrounding” the listener.
Dolby Atmos, on the other hand, moves beyond the confines of horizontal setups to create a projection that is decidedly more three-dimensional. Instead of limiting the projection of sound to the horizontal plane around the listener, Dolby Atmos incorporates height channels to create virtual “objects” within the room.
In a Dolby Digital setup, a car driving by might start behind you on the left, move to the front left, and then fade. In a Dolby Atmos setup, corresponding sounds will play on all speakers both horizontally and vertically at different levels to create a more realistic sound.
Following that train of thought, the listening experience with Dolby Atmos vs Dolby Digital varies tremendously. Surround sound is all about creating an illusion, and the overall quality of your listening experience directly corresponds to the quality of that illusion.
For Dolby Digital surround sound setups, the listening experience is limited to those aforementioned horizontal channels. Sure, you might hear those sounds coming from all around your head, but the illusion is limited to that single dimension.
Dolby Atmos, on the other hand, has a superior listening experience in the way it creates a superior illusion. The height channels inherent to a Dolby Atmos setup are truly revolutionary for the way they take sound from a 2D feature to a 3D one. In real life, the sound is not limited to just one plane.
In reality, it comes from up, down, side to side, diagonally, and so on. Dolby Digital limited things to simply side to side. With Dolby Atmos, the illusion is a lot more convincing — and, as a result, the listening experience is far superior — when it sounds more lifelike. 3D sound helps achieve this.
The History of Dolby Atmos
If the Dolby Atmos vs Dolby Digital debate boiled down to the sheer number of audio tracks, then Dolby Atmos would have it in the bag. Here’s how it works: Dolby Atmos takes up to 128 audio tracks and their corresponding metadata, complete with spatial audio descriptions (i.e. location and pan data, plus data detailing sound movement, type, speed, volume, and intensity).
From there, Dolby Atmos translates all of this information and assigns it to audio channels. Before Dolby Atmos, these channels were either 5.1.0 or 7.1.0 systems. With Dolby Atmos, it goes all the way up to 24.1.10.
First installed at the fabled El Capitan Theater in Hollywood, the first moviegoers to experience the Dolby Atmos surround sound technology were the ones in attendance for the premiere of Disney-Pixar’s Brave in June of 2012. During the remainder of the year, Dolby installed their revolutionary new surround sound tech in 25 other theaters around the world.
By the following year, Dolby had increased that number to more than 300. Today, Dolby Atmos is installed in more than 10,000 theaters throughout the planet. (It’s also available in the home theater format, with most major sound technology integrating support for Dolby Atmos since 2016 or so.)
This home theater integration can be seen in the way Dolby Atmos was integrated into the mix for television shows and albums throughout the back half of the 2010s. For instance, in 2016, the third season of Starz’s crime drama Power became the very first television show to be mixed and shown in Dolby Atmos.
Likewise, Game of Thrones was remixed in Dolby Atmos for its Blu-ray releases. Furthermore, ’80s rock band R.E.M. became the first music group to embrace the new technology for the 25th-anniversary rerelease of their hit 1992 album Automatic for the People.
How Dolby Digital Remains Relevant
While another company might phase out its old technology in favor of the new, Dolby knows that not every movie theater or home theater can afford to completely overhaul its sound system with each new technological leap forward.
For this reason, Dolby Atmos prioritized backward compatibility with Dolby Digital — the previous technology standard for Dolby Technologies since 1986. Here’s how it works: Dolby Atmos bitstreams are specially encoded to support Dolby Digital Plus decoders. For this reason, Dolby Digital Plus can decode and compress Dolby Atmos signals.
Dolby Technologies markets these capabilities to theaters and home audio setups under the name “Dolby Digital Plus Atmos.” It’s important to note that this compression is lossy. That means irrelevant or incompatible data is permanently removed from the signal.
It’s not noticeable, but it’s nevertheless important because original sound data is being altered. (Compare this to the lossless variation, Dolby TrueHD, which only removes irrelevant metadata.) These days, any bitstream still using Dolby Digital Plus is typically going to be encoded in Dolby Atmos.
Dolby Digital Plus serves as the most recent iteration of Dolby sound technology before Dolby Atmos came to be. Prior to Dolby Digital Plus’s introduction in 2005, Dolby Digital was the standard.
Dolby Digital — introduced in ’86, as stated above — is far from the most revolutionary sound technology by today’s standards, but there’s no doubt it was an even more revolutionary technological advance than even Dolby Atmos. In the end, this is why Dolby Digital has endured for all these decades (even alongside Dolby Atmos): it’s the most efficient method of audio compression around.
Dolby Atmos vs Dolby Digital: Pros and Cons
|Pros of Dolby Atmos
|Cons of Dolby Atmos
|Revolutionizes surround sound by introducing a third dimension of audio
|Still relatively new, which means not all media is encoded for Dolby Atmos
|Relies on 3D “objects” instead of more traditional 2D surround sound methods of audio projection
|Not everything needs 3D sound — such as your average sitcom, for instance — which means Dolby Atmos can sometimes seem excessive
|Most modern Blu-rays, 4K discs, video games, and streaming services come Atmos-enabled
|Dolby Atmos setups can get expensive fast
|Backward compatibility with Dolby Digital Plus
|Works best on flat ceilings, making Dolby Atmos less ideal for those with vaulted ceilings
|Pros of Dolby Digital
|Cons of Dolby Digital
|Still the industry standard for thousands of theaters and home setups
|The more Dolby Atmos is adopted, the more outdated Dolby Digital will become
|Can decode and optimize Dolby Atmos signals
|No height channels
|More affordable surround sound system than Dolby Atmos
|Supports fewer horizontal channels than Dolby Atmos
|Still capable of delivering a 5.1 or 7.1 setup
|Less immersive surround sound system than Dolby Atmos
5 Must-Know Facts About Dolby
- The very first instance of Dolby Digital sound was in accompaniment with 35mm film prints. Today, its uses far exceed just this one. From broadcast television, satellite radio, streaming services, video games, and home video formats, Dolby Digital is the standard in digital audio compression.
- Most Dolby Digital sound formats are lossy, which means they delete certain data to reduce file sizes. The exception is Dolby TrueHD, which is lossless — this means it reduces its file size by removing metadata instead of audio data.
- The compression algorithm behind Dolby Digital’s origin was actually intended for compressing images at first.
- Dolby Digital is not the first instance of Dolby Laboratories’ audio technology. Dolby first entered the industry with Dolby A, a broadband noise reduction system for professional recording studios in the mid-1960s.
- While Dolby A came first, Dolby B is the better-known early Dolby invention. Introduced in 1968, Dolby B was a consumer-grade sliding band system that brought high fidelity to cassette tapes.
Dolby Atmos vs Dolby Digital: Which Is Better?
When all is said and done, the winner is pretty obvious. It’s Dolby Atmos all day, every day. So long as Dolby Atmos is the peak audio technology one could possibly achieve, it will remain the superior of the two.
From its added height channels to its superior sound projection to its more preferable listening experience, Dolby Atmos takes everything that helped make Dolby Digital revolutionary and improves upon it.
Of course, credit is still due. Dolby Atmos wouldn’t exist without Dolby Digital. This deserves to be said, as the two are truly and intrinsically linked for life.