Dolby Atmos® FAQ

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HomerJAU

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What Is Dolby Atmos?
Dolby Atmos is an Object Based audio surround system (similar to competing DTS:X and Auro 3D systems). Object based systems are a combination of raw audio channels and metadata that describes the spatial position (in 3D space) and other properties of audio objects. Atmos (and DTS:X & Auro) add height speakers to create a true 3D sound field (5.1 is a 2D sound field).

So Atmos objects are not always locked to a specific channel (speaker), for example, an object can be set to appear in a 'phantom position' (between speakers), or can appear to move between any speakers in the speaker array in any direction. Atmos supports up to 128 simultaneous independent audio objects in a mix.

Furthermore, the intended spatial position can be rendered fairly accurately regardless of the actual speaker positions based on the actual Atmos speaker setup during installation, which will include a microphone and software in the AVR to measure speaker distances and gain (volume). The actual individual amplifier output is created during playback based on a combination of encoded mix and the speaker configuration (installation). However, more speakers will provide a better resolution of sound movement.

Dolby Atmos for Home, as delivered on Blu-ray and streaming services, are limited to 16 amplifier channels (similar an 'old' system 15.1 - However, as stated above, unlike traditional multichannel audio systems each channel is not sent to a separate speaker).

ObjectAudio.jpg


Dolby intro from their website:
http://download.dolby.com/us/en/technology/dolby-atmos-core-explainer.mp4
Dolby Atmos Objects explained:
https://drive.google.com/file/d/1Tb4uZQ6KwER_kOaH6bDoWxKLtLQWA4Eu/view?usp=sharing

Why was Atmos created?
The three competing Object Based audio systems were primarily created to add rich, realistic sound for movies. With Atmos an audio engineer can ensure a sound can follow an object on the screen, a helicopter circling overhead etc. Hundreds of movies are now available on Blu-ray and 4K UHD blu-ray with Atmos and DTS:X soundtracks. Many movie theaters have one of these systems installed.

Obviously, there are many surround music enthusiasts around the world. So the natural progression is to release Atmos music too. There are already several concerts and audio albums with Atmos mixes, with more coming.


Is Atmos backward compatible with existing equipment?
Atmos content does not require a new codec. It is implemented as an extension within the original Dolby TrueHD (lossless) and Dolby Digital Plus (lossy) codecs. Much like how DTS-HD was an extension to DTS.

Atmos can be delivered along with Dolby TrueHD, typically on blu-ray (BDV and BDA) at around 4000 to 7000kbps or along with Dolby Digital Plus, typically at 768kbps or less for streaming by Netflix, Apple, Tidal, Prime and similar services.

If your AVR does not have an Atmos decoder: If it has a Dolby TrueHD decoder it will decode the TrueHD 'core' to provide 5.1 or 7.1 channels (depending on your setup). In this situation you can playback an Atmos track, but its played back as 5.1 or 7.1 TrueHD. You will not hear the Atmos mix objects in their intended positions and will not hear any 3D immersion.

Although you need a new AVR to decode these Atmos extensions (older models will simply play the base TrueHD/Digital Plus content), Blu-ray players that fully conform to the Blu-ray specification will support
Atmos without requiring a firmware update.

Modern Media Players with HDMI will also playback Atmos tracks via HDMI pass-through to an Atmos, TrueHD or Dolby Digital Plus compatible AVR.


Do I lose anything by listening to an Atmos mix on a non-Atmos system in 5.1?
The raw musical information is sent to the 5.1 or 7.1 channels from the TrueHD or Dolby Digital Plus mix during Atmos track decoding, so you won't lose the base/core mix. However, the spatial information (location is 3D space) and will be ignored. You may not hear movement/panning or positioning as intended by the Atmos audio mixer but no music is lost.

Edit Sept 2020: Tests show if you have an Atmos decoder (AVR or BD Player), height channels get downmixed into front and/or side channels in a 5.1 system, so the height channels are reproduced in 5.1, merged with fixed floor channels. You don’t lose height information, just the height spacial/immersion experience.

Atmos playback on 5.1 system tests/results here:
https://www.quadraphonicquad.com/fo...ults-questions-experiences.29057/#post-514693

What is the minimum system requirement to hear a 'real' Atmos mix?
Requirements:
1. An AVR or Surround Processor that has a Dolby Atmos decoder. (All Atmos AVRs I've seen also have DTS:X decoders too. Many also include Auro 3D decoders)
2. A traditional 5.1 or 7.1 speaker layout PLUS at least 2 ceiling or height enabled speakers. Preferably 4.
3. Having enough amplifier channels to drive all the above speakers. Most Atmos AVRs will have 9 or more channels (The Denon AVR-8500 has independent 13 amplifiers).
4. A playback device (e.g. Blu-ray Player, PC or Media player) with HDMI output.

If your existing 5.1 AVR has analog inputs, its also possible to buy a new AVR with 11 or 13 channel pre-amp outs and use that to drive your old 5.1 AVR as an amp only, thus limiting the size/cost of the new AVR.


What are my Atmos Speaker Options?
Dolby Atmos Speaker Configuration Options for Home are listed below, but first, here's the Object audio naming convention:

AtmosConfigNaming.jpg


Typical Object Speaker configurations:
  • 5.1.2: A standard 5.1 setup with a pair of “middle” in-ceiling/ceiling-mounted speakers.
  • 5.1.4: A standard 5.1 setup with a front and rear pairs of in-ceiling/ceiling-mounted speakers.
  • 7.1.2: A standard 7.1 setup with a pair of “middle” in-ceiling/ceiling-mounted speakers.
  • 7.1.4: A standard 7.1 setup with a front and rear pairs of in-ceiling/ceiling-mounted speakers.
  • 9.1.2: A 9.1 setup utilizing front wide channels and a pair of “middle” in-ceiling/ceiling-mounted speakers.
A typical 5.1.4 system floor plan (from the Dolby website):
Amos5.1.4.png

1. Seating position
2. Left and right speakers*
3. Center speaker*
4. Subwoofer*
5. Left and right surround speakers*
6. Left and right top front overhead speakers
7. Left and right top rear overhead speakers

* Denotes traditional 5.1 floor speakers

In addition to the number of channels, there’s also two options for additional height speakers: Discrete in-ceiling/ceiling-mounted speakers or 'Dolby Atmos-enabled' speakers utilizing what they call 'reflective speaker technology':

1. Traditional speakers - Advantages: Better sound Disadvantages: Need to run new cabling within ceiling (and up walls)

2. Dolby patented 'Dolby Atmos Enabled' speakers. These are upward-firing drivers positioned on the front and/or rear speakers, they bounce the sound off the ceiling of your living room, giving the impression
that sounds are coming from above you. Advantages: Easier installation Disadvantages: Only suitable for Dolby Atmos, Sound is compromised vs traditional speakers

Typical Atmos Enabled/Upfiring system (from the Dolby website):
UpFiringSpeakers.jpg


Typical Atmos system with ceiling speakers:
CeilingSpeakers.jpg



Do Atmos Enabled Speakers Really Work?
Here's an interesting article:
https://www.audioholics.com/frequent-questions/atmos-enabled-speakers

What music is available in Atmos now?
There have been several Atmos music releases as of August 2019, both concerts and albums:

Notable Concerts on Blu-ray:
Imagine Dragons - Smoke & Mirrors Live
KISS - Kiss Rocks Vegas
Michael Schenker's Temple of Rock: On a Mission - Live in Madrid 4K
Mumford & Sons - Dust and Thunder
Roger Waters - The Wall

Notable Albums on Blu-ray:
Booka Shade - Galvany Street
INXS - Kick: 30th Anniversary Edition (includes some Music Videos in Atmos)
Kraftwerk - 3D The Catalogue (Includes Concert and Video in Atmos)
R.E.M. - Automatic For The People (25th Anniversary Edition)
Schiller - Morgenstund
The Beatles - Abbey Road (Sept. 2019 - 50th Anniversary Super Deluxe)

Here's the offical Dolby Atmos Music list (it's not a complete list):
https://www.dolby.com/us/en/experience/dolby-atmos/dolby-atmos-music-titles.html

What music will be available in Atmos soon?
Dolby have recently teamed up Universal Music Group and announced 'several hundred' songs will be mixed and released in Atmos (soon).
https://www.billboard.com/articles/business/8512853/universal-music-group-dolby-atmos-sound-mixing
As of August 2019 it is unclear how the UMG Atmos songs will be distributed, although it seems there will be at least a streaming/download option. Expect more information soon.

Artists mentioned as of August 2019 in various press releases:
Beck, R.E.M. LL Cool J, Wu-Tang Clan, R.E.M., Marvin Gaye, Public Enemy and Snoh Aalegra.

The Beatles’ Sgt Pepper has been mixed in Dolby Atmos for theatrical release to celebrate the groundbreaking album’s 50th anniversary. And more recently David Gilmour returned to Abbey Road Studios in 2017 for an Atmos mix of his Pompeii Live In Concert. Both mentioned here:
https://www.abbeyroad.com/news/abbey-roads-new-mix-stage-2243
Miles Davis’ - Kind of Blue mentioned here:
https://www.mixonline.com/the-wire/pmc-demonstrates-dolby-atmos-music-at-high-end-munich
INXS - Live Baby Live in 4K and Atmos for theatres here:
https://newmusicweekly.com/inxs-wembley-concert-to-hit-movie-theatres/
Atmos seems to be the market leader in object based audio, dominating the Movie space, there are also many DTS:X movies, Auro 3D has a few classical music only releases.


What about Atmos Upmixing stereo and quad music?
New AVRs with Atmos decoders also provide an onboard Atmos upmixer. This is more advanced than previous Dolby upmixer generations. The Atmos operates on stereo, quad, 5.1 and latest 7.1 Dolby TrueHD mix.

The system is capable of steering individual frequency bands from each channel to create up a matrixed Atmos environment based on your speaker configuration. Atmos upmixer will not send redirected content
to speakers between the front left, center, and right speakers in order to minimize the impact on the front stage.

These Atmos enables AVRs typically also do DTS Neural:X upmixing too.


Are there Atmos test files or Demos available?
Atmos Channel Test files in MKV format for the following:

5.1.2, 5.1.4, 7.1.2, 7.1.4 and 9.1.6

There is also a short Atmos demo from Dolby with an interesting couple of 3D graphics explaining the difference between 'conventional' 5.1 mixes and Object mixes)

Link: Atmos - Google Drive

The Kodi Wiki also has quite a few HD Audio samples, including Atmos/DTS:X:
Link: Samples - Official Kodi Wiki


Can I convert Atmos to FLAC to play in my car, on PC or Media Player?
FLAC is limited to 8 channels. It is possible to convert an Atmos track’s legacy TrueHD to 5.1 or 7.1 FLAC but this will not contain the Atmos extensions (height and spatial metadata) so it can never reproduce the true Atmos mix during playback. It will contain the music but in 2D plain only.

It is possible to copy the Atmos codec audio track (unconverted original) in its original container (m2ts for BDA) or into another container that supports TrueHD (MKV, MKA, MP4) to play back via HDMI Passthrough to an AVR for Atmos decoding. (Most content will have DRM so ripping/conversion software will be required, the usual suspects that support TrueHD will support Atmos).

There are no known Atmos decoders except for those within Atmos licensed AVRs and Surround Processors. So Atmos playback must always include HDMI from an external ‘player’ to bitstream to your Atmos AVR/Processor.

Atmos playback from a PC or Media Player is possible with HDMI bitstreaming using Kodi and Jriver software.

Playback of Atmos files in Kodi:
https://www.quadraphonicquad.com/fo...hd-and-dts-x-dts-hdma-audio-only-files.26799/

More Reading?
https://www.audioxpress.com/article/object-based-audio-and-sound-reproductionhttps://www.soundonsound.com/techniques/dolby-atmos-ministry-sound

DISCLAIMER: Fair use is claimed on all images and test files, as their purpose is only for the promotion of Dolby Atmos music, testing and technical evaluation for our members. QuadraphonicQuad is a non-profit, non-sponsored website.

LAST EDITED: 2020-9-19
 
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Great job, Gary. Wow, what a wealth of information!
The only thing I'd add, right off the bat is:
don't bother with Michael Shencker's Live in Madrid. Great show, but nothing special going on in the Atmos (I've read the same about Kiss).
Do bother with Luca Turelli's Rhapsody: Atmos Experience, RPWL New Dawn, Metallica Through the Never and Hans Zimmer Live in Prague.
 
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Are there Atmos test files or Demos available?
Atmos Channel Test files in MKV format for the following:

5.1.2, 5.1.4, 7.1.2, 7.1.4 and 9.1.6

There is also a short Atmos demo from Dolby with an interesting couple of 3D graphics explaining the difference between 'conventional' 5.1 mixes and Object mixes)

Link: https://drive.google.com/drive/folders/1NjSmU8j-G7be_shGoT2L0yeikeHsfWhe?usp=sharing

The Kodi Wiki also has quite a few HD Audio samples, including Atmos/DTS:X:
Link: https://kodi.wiki/view/Samples

There are also many "demo discs" produced by Dolby available for Atmos since 2014 that are exceptional IMO

Here is the list: https://www.demo-world.eu/dolby-demo-discs/

You can find these discs for sale on ebay (the one's from China are most likely counterfeit (copies that look like real pressed discs but are copied, then pressed) so beware.

just an FYI, but those Kodi Wiki files:
are just files rips of the tracks on these demo discs from Dolby.

IMO the "Amaze" demo track is the best, it's actually "amazing".
 
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This is truly brilliant, @HomerJAU. Thank you! Nice to have some authoritative, fact-based info to help cut through all the noise (and cynicism--mine included). Like any technology, Atmos can be used for good or ill, I expect. Let's hope for more of the former.
 
Wow, what a fantastic job Garry @HomerJAU ; that's a lot of info to digest and is getting me excited to see what comes next!
I'll be buying Atmos titles for sure until the day I'm fortunate enough to actually get a legit system together and blow the dust outa my house:D
Let's all just hope enough folks in the market support it to keep it going.
My dream of a 3-D Geodesic dome listening room, may not be dead just yet;)
 
To hear one of the first (and best) examples of high-quality music to be given the full Dolby Atmos immersive/spatial treatment on a commercially released Bluray Audio (audio only) disc then Earth: One Amazing Day - The Immersive Experience remains the best place to start - especially given the 150 piece orchestra/choir and sounds of nature combined on a +74 channel mix at Abbey Road. The album certainly sets a high watermark in terms of state-of-the-art immersive Dolby Atmos audio/music - and worthy of debate. To add, the album holds the accolade for the world's first immersive music & effect album to be commercially released in both physical and digital formats.

EOADTIE - Key Art (low res).jpg


Link to EOADTIE Dolby Atmos BD on Amazon: click here

For those (many) who don't have a Dolby Atmos home sound system, there's a great immersive digital edition of the album (designed for headphones) also commercially available on Apple Music in a groundbreaking 29th Order encoded ambisonic binaural immersive mix. I strongly recommend A/B track-to-track comparison against the original soundtrack album by Alex Heffes from the feature film, even just for the psycho-acoustic experience demonstrating how much a great immersive spatial sound design/remix/remastering can substantially enhance what is already high-quality source music.
A. For the Immersive Binaural Edition: click here
B. For the OST Edition: click here
 
EOADTIE uses the basic orchestral music audio stems from the original theatrical (not BD-V) Atmos mix from the film but incorporates a completely re-imagined narrative, new/enhanced original foley effects and real-life nature sound audio minus the Robert Reford audio narration track.

The BD-A Atmos immersive mix is a fundamentally different audio experience from the OST, as you can gauge for yourself from the A (binaural) /B (OST) above, and quite independent from the 4K Dolby Vision/Atmos BD-V of the feature film (although noting, the latter audio-visual film version is well worth a watch!)
 
If you
So, if I already have a 7 speaker system with 4 speakers in the ceiling, will atmos work?

If you have an Atmos-capable AVR and you designate your speakers accordingly in your AVR's setup, then yeah.

Only...dumb question...do you mean you have 7 (7.1?) speakers at ear height + 4 additional ceiling speakers (in which case you could do Atmos 7.1.4), or 7 speakers total, with 4 of them in the ceiling? (The latter would be unusual, I guess, but everybody's different...)
 
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So, if I already have a 7 speaker system with 4 speakers in the ceiling, will atmos work?
Dobly has done a pretty good job of documenting the various speaker configuration guidelines online. Some of that information is quoted at the beginning of this thread. I started with my 7.2 system and had imagined where I'd place my 4 ceiling speakers out in the room in front of me on existing ceiling beams. After research, I found that the listeners should be inside the 4 speaker ceiling box and not outside of the ceiling box so I had to find the best sounding positions for the speakers.

Here's a link to the Dolby-atmos-home-theater-installation-guidelines.pdf

https://www.dolby.com/us/en/technol...tmos-home-theater-installation-guidelines.pdf
It should answer most of your questions....

David H
 
If you


If you have an Atmos-capable AVR and you designate your speakers accordingly in your AVR's setup, then yeah.

Only...dumb question...do you mean you have 7 (7.1?) speakers at ear height + 4 additional ceiling speakers (in which case you could do Atmos 7.1.4), or 7 speakers total, with 4 of them in the ceiling? (The latter would be unusual, I guess, but everybody's different...)
I have the fronts, center channel and sub with the 5.1 and 7.1 speakers in the ceiling. So, it appears I should get some kind of Atmos effect.
 
I have the fronts, center channel and sub with the 5.1 and 7.1 speakers in the ceiling. So, it appears I should get some kind of Atmos effect.
Atmos is built on top of a 5.1 or 7.1 system. They call the base 5.1/7.1 configuration as the "listener-level" speakers. They want a definite separation of the listener-level speakers and the over-head speakers. Originally, I had my rear surround speakers mounted up about 6 feet on the rear wall. When I added my over-head speakers for Atmos, I moved my rear surround speakers down to ear height to have the separation between the two levels. The linked pdf I posted earlier has this to say about using existing ceiling speakers for Atmos....

"Use of Existing Overhead Speakers
In some existing home theater systems, overhead speakers are employed to generate audio that would otherwise be created by listener-level speakers (for example, left/right surround speakers). When transitioning to Dolby Atmos, you should repurpose existing overhead speakers as overhead outputs only if you can add a corresponding listener-level speaker to assume the previous overhead speaker feed.

For example, if two overhead speakers located toward the rear of the room are currently used to reproduce left/right surround outputs, they should be used as overhead speakers only if replacement left/right surrounds can be added at the listener level. If this is not possible, the overhead speakers can continue to be used for left/right surround outputs, although not recommended.(4) In this case, overhead sound can be achieved by installing additional overhead speakers, Dolby Atmos enabled speakers, or add-on modules in the front speaker locations.

(4) To get the best Dolby Atmos experience, there must be separation between the listener-level speakers and overhead
speakers. Installing all of the speakers in the ceiling will not give the optimal experience and is not recommended."
 
It all sounds marvelous, however, I am curious about how it would integrate into my analog/ digital separate components system? Obviously I would have to use a home theater amp with all the necessary channels, but I would need analog inputs for my reel to reel, CD4, Audionics decoder, my DBX De-esser. My Sansui AX-7 mixers would take care of a lot of that, but not all. I rely on the input selectors on my 3 Sansui au717 amplifiers for that, with the phono inputs with the preamps internally bypassed so as to accommodate a CD-4 demodulator. (field mod). I kind of doubt that a home theater amp would have the switch around capabilities I have come to rely on. A lot of them don't even have tape monitors anymore. I guess I'm not really up on modern home theater gear. I think I might like to wait for a stand alone decoder. Maybe one with all the new immersive formats.
The Quadfather
 
Most higher end AVRs will have multichannel analog inputs (RCA) so you could use those from your quad decoder/switcher.

Some also have multichannel analog outputs (RCA) allowing you to use existing high end amp(s) for your main channels, just use the AVRs internal decoders and additional surround/ceiling amps for Atmos and TrueHD/DTS-HDMA 7.1 releases.
 
Hi. I am a long-time multichannel fan, one of the original four charter members of NativeDSD dot com (I am the US Tech Director who puts in the metadata, etc), wrote the 2011 SACD ripping guide, and an all-around 5.1 fanboy/enthusiast. Ask Brian. :) I also started the hirez subforum on Audio Circle and have written several reviews on Computer Audiophile (now AudiophileStyle). BUT...I am a newbie ignorant Atmos guy. And wasn't going to do anything about it.......UNTIL....I read the Abbey Road Atmos thread!! Argh! I gotta go there! :)

I had a very state of the art 5.1 (music) and 7.1 (movies, different smaller sides and rears) man cave back in NE Ohio (pictures somewhere on this site) but we moved to the Denver area back in June 2018 and I've yet to start the build on the new audio room. It begins very very soon. So I am posting this to ask Atmos questions:
1) with my 5.1 setup I use the rule of "full range equidistant equivalent speakers" to a tee. My speakers are Aerials, with my mains being 20T version 2s, and the center and surrounds being timbre-matched closely. My surrounds will be around 100 degrees or so (plus minus 5 degrees). How closely do cieling-based Atmos speakers need to be timbre-wise? Frequency-wise?
2) if doing four ceiling-based speakers, how much better is the overall experience than two ceiling-based speakers? I realize this is slightly silly, but for now I NEED to own a total of one Atmos release (Abbey Road) so I am trying to understand how committed I should be.
3) My 5.1 multichannel music setup was always dac-direct (i.e multichannel dac to speakers, no receiver) and I used my Denon AVR for movie stuff. Now, with Atmos, I plan on upgrading to an Atmos-capable setup...I assume some AVRs or pre/pros are better at Atmos than others?

Thx in advance for spending my money,
Ted
 
Hi Ted,
1) I think you'll find that Dolby Atmos ceiling installations will vary greatly among home setups. I've repeated read the opinion that ceiling speakers do not need to be very nice or timbre matched to the rest of your speakers. I personally believe that you should match them as well as you can with your main speakers, especially if you are listening to music vs sound effects for movies. The Atmos audio disks that I have, Abbey Road, Automatic for the People, Kraftwerk Catalogue all have musical instruments and voices coming from the ceiling...

I would suggest that you read the Dolby-atmos-home-theater-installation-guidelines.pdf to get a good understanding of these installations.
https://www.dolby.com/us/en/technol...tmos-home-theater-installation-guidelines.pdf

From the above guidelines...
1572297724482.png

2) I also think that you should follow as closely as you can to the proper ceiling speaker placement that Dolby Labs have specified. Since you are attempting to create a 3 dimensional space around the listening area, I highly recommend the use of 4 ceiling speakers so the listening position will be centered in between the front and rear ceiling speakers.
1572297790231.png
1572297819620.png

1572297846680.png

I have wondered how much ceiling speaker quality and placement may have to do with various listeners opinions of the Atmos music they have heard... some people don't hear much from the ceiling, or hear one mix sounding better than another... Our amplifiers can adjust/correct for imperfect speaker placement for our base level speakers fairly well. But I believe that the ceiling placement could be fairly critical since the AVR is trying to place sounds within a 3D space around/above a listener.

3) I don't have any idea about which AVR may have better ATMOS capabilities/decoding...

David H
 
Thx so much David. It looks like I need to decide on 5.1.2 vs 5.1.4 early in the game in order to place the ceiling speakers correctly (in the dot four setup the fronts are further forward than when set up alone). I also need to read about any good movies in Atmos, to further the value add. Thx again.

Edit: I found some Andrew Jones-designed ELAC ceilng speakers, so they might do well. It looks like other than the requisite Atmos AVR and source player and material, the overal investment isn't too high.
 
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