Dolby Atmos vs Dolby Digital (Comparison)

Dolby Atmos vs Dolby Digital

Dolby Digital vs Dolby Atmos: You may have heard the terms “Dolby Digital” and “Dolby Atmos” when talking about home theater sound systems, soundbars, or other media devices. While both are popular surround sound formats, one is better than the other. Therefore, it’s essential to learn the differences between these two audio technologies.

We’ll break down how Dolby Digital and Dolby Atmos work and compare them in this explainer guide. You’ll find everything you’ve always wanted to know about these Dolby surround sound formats but never bothered to ask. Read on to learn more about Dolby Digital vs Dolby Atmos.

What is Dolby Digital?

Dolby Digital is one of the oldest multi-channel surround sound technology, commonly referred to as “5.1 surround sound.” It consists of six discrete audio channels, providing sufficient bandwidth for five full-range (20 Hz – 20,000 Hz) front, center, and rear speakers and one low-frequency subwoofer.

Dolby Digital is the first “surround sound” format offering a theatrical listening experience at home. Dolby Digital Plus is the direct successor, with Dolby TrueHD leading the current generation of lossless multi-channel audio.

What is Dolby Atmos?

Dolby Atmos is an object-based spatial surround sound technology first introduced for the commercial theater market and later adapted to home cinema. It doubles down upon existing Dolby 7.1-channel surround sound formats with additional height channels, allowing users to interpret sounds as 3D objects.

Atmos’ consumer implementation is vastly different from its commercial counterpart. Instead of the full object-based mix, Atmos exists in Dolby TrueHD or Dolby Digital Plus codec as a more efficient sub-stream. Dolby Atmos in consumer home theaters can drive up to 24.1.10* audio channels, more if not for the limited available bandwidth and processing power.

Dolby Atmos also has headphones and smartphones implementations, but they use software algorithms to transcode Atmos metadata to a binaural stereo output through the L (Left) and R (Right) channels. It offers an immersive 360° virtual surround experience. However, it’s nowhere near as convincing as the real deal.

*Note: Dolby uses a different nomenclature for Atmos systems. For instance, a traditional 5.1 surround setup has three speakers on the front, two on the sides (or back), and one subwoofer. Add two height speakers to this system, and it’ll be described as a 5.1.2 setup instead.

How is Atmos different from Dolby Digital?

In order to learn the differences between Dolby Atmos and Dolby Digital, first, you need to understand how sound designers mix audio tracks for movies and shows.

Everything you hear in a film, whether it’s the music, SFX, or voices, mix into different audio “channels.” Suppose these channels, as in a conventional surround sound setup, are left front (L), right front (R), center (C), left surround (LS), and right surround (RS). More advanced setups also have “surround back” channels on either side. The subwoofer channel(s) handle the lower frequencies.

If multiple actors on the same screen are having a conversation, the voices mix to the center channel. And when the music ramps up in a climactic moment, it comes from the front left and right channels. The surround speakers handle all the other sounds from the third-person perspective.

So those who have a 5.1-ch Dolby Digital speaker system should be able to hear this particular mix of channels, right? It’s a bit more complicated than that, as all this heavily depends on the placement of your speakers and how much loudness and range they can provide.

On the other hand, Dolby Atmos doesn’t treat sounds as channels but rather as individual “objects.” In a conventional Atmos setup, filmmakers get the freedom to pinpoint where they want sounds to appear, in just about anywhere in the room, as long as there’s a speaker present. It provides greater scalability, making audio significantly more immersive in cinemas and home theaters.

Atmos is the current highest standard for multi-channel surround sound configurations. As we mentioned before, sound mixing has pinpoint accuracy, and the decoding process is different. Unlike Dolby Digital 5.1, Atmos setups can have in-ceiling or up-firing speakers to output sounds over your head. It produces a more convincing, natural, and immersive surround sound than all the previous Dolby formats.

What about the hardware?

Of course, you’ll need modern hardware to experience Dolby Atmos. Dolby Digital has existed for nearly two decades now, so your existing audio gear already supports it. Assuming you don’t need Atmos, your Dolby Digital-enabled devices should do the job.

Furthermore, if you buy, let’s say, a 4K streaming media player, you can still use it with your old receiver even if it isn’t Atmos-ready. It’ll simply decode the Dolby Digital or Dolby Digital Plus mix.

But if you want Atmos for your home theater audio, you’ll need to get height speakers. In-ceiling speakers are the best option, but speakers or soundbars with up-firing drivers are reasonable for regular living room setups. Such upward-firing speaker models bounce sound off the ceiling to create a surprisingly convincing effect. Plus, they’re far easier to install.

As we mentioned before, a Dolby Digital sound system requires 5 full-range speakers and a single subwoofer. Atmos allows for a higher number of speakers. You can install up to 34 (24 standard + 10 height speakers) if you want. Obviously, you don’t need that many speakers, but there’s room for future upgrades.

However, that’s not the only upgrade you require for Atmos. You must also have a receiver (or a soundbar) capable of decoding Atmos signals and a compatible source device. It can be one of those newer streaming boxes, 4K Blu-ray players, or game consoles.

And lastly, you need Atmos-enabled content. 4K Blu-ray discs generally feature Atmos tracks, though you should double-check before buying. If you’re into streaming, Netflix, Disney+, Prime Video, HBO Max, and Vudu offer extensive libraries of Atmos movies and shows. For those wondering, the following streaming services also offer Dolby Digital content.

Dolby Atmos vs Dolby Digital: Side-by-Side Comparison

As you may have already noticed, Dolby Atmos is far superior to Dolby Digital in nearly every aspect. So, to sum up this guide, we’ll compare their main characteristics side by side below.

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Dolby Digital Dolby Atmos
Dolby Digital is mainly used in 5.1 surround sound setups. Atmos supports up to a 24.1.10 channel system.
It’s primarily a two-dimensional surround sound format. It’s a 3D surround sound format that feels more realistic.
Bandwidth is too limited to drive height channels. It has sufficient bandwidth for up to ten height channels.
5.1-ch Dolby Digital audio has a typical bitrate of 384 to 650 kbit/s. With Dolby TrueHD, the bitrate for Atmos averages around 6 Mbit/s at a 48 kHz sampling rate.
It’s a channel-based surround sound technology. Atmos is object-based, which means more convincing surround sound.
Dolby Digital-enabled equipment is readily available and generally more affordable. Atmos-ready audio products can get expensive.

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Wrapping Up

That brings us to the end of this comparison guide of Dolby Atmos vs Dolby Digital. We’ve provided pretty much everything you need to know about Dolby Digital and Dolby Atmos. If you were to choose between the two, the latter is undoubtedly the better option for home theater surround sound setups. That said, all this depends on your existing audio gear and budget.

Dolby Atmos vs Dolby Digital (Comparison)

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