Article: How To Decode and Play Dolby TrueHD Atmos on Windows and macOS

[The Computer Audiophile]

I looked over some previous emails with Bert and I'm pretty sure he includes a lossless TrueHD binaural mix. I'll update as soon as I hear from him. 

[The Computer Audiophile]

OK, I heard back from Bert and an engineer working with him on the Atmos releases. 

 

Selecting the 2.0 channel playback in the Reference Player give you the stereo version. It will work on stereo speakers and give some semblance of spatialization, but it's mostly a fancy fold-down from the 5.1.

 

To get a binaural, it needs to be created either from the master file or with Dolby's new headphone format (which also takes into account the binaural metadata (which is specified by the mixer as 'Off' 'Near', 'Mid' or 'Far')) which is called AC-4 IMS (stands for Immersive Stereo). The AC-4 is better than DD+ in terms of compression, but not lossless.

 

[austinpop]

11 minutes ago, The Computer Audiophile said:

OK, I heard back from Bert and an engineer working with him on the Atmos releases. 

 

Selecting the 2.0 channel playback in the Reference Player give you the stereo version. It will work on stereo speakers and give some semblance of spatialization, but it's mostly a fancy fold-down from the 5.1.

 

To get a binaural, it needs to be created either from the master file or with Dolby's new headphone format (which also takes into account the binaural metadata (which is specified by the mixer as 'Off' 'Near', 'Mid' or 'Far')) which is called AC-4 IMS (stands for Immersive Stereo). The AC-4 is better than DD+ in terms of compression, but not lossless.

 

Thanks for getting this clarification, Chris. Too bad there isn’t a lossless version of this.

 

The only thing that still puzzles me is why their “9.1 Spatial Audio” page https://spiritofturtle.com/collections/9-1-binaural-headphone-dolby-atmos mentions binaural headphones. 🤔

[austinpop]

Inspired by @The Computer Audiophile's journey, I've been doing some exploration with immersive audio for headphones. It has not been smooth sailing, and I clearly have a lot more to learn about navigating this space. My intent with this initial foray was to just explore the potential of this experience on headphones. I decided to explore Apple Music, played back on an M2 Macbook Air, playing to Meze Empyrean headphones, both directly from the MB headphone out, or through an Audioquest Dragonfly Cobalt.

 

Even with this non-demanding setup, I was plagued by gotchas. Inexcusably, the Music app does not appear to use Exclusive Mode (or whatever the equivalent is in MacOS-speak)! I wanted to avoid sample rate conversions, but I don't know if I really succeeded. With Hi-Res tracks, you can at least see the sample rate of the track, but there is no sample rate view for Atmos. I made the assumption that all Atmos tracks were 24/48. Is that correct?

 

My patchwork solution to getting the best SQ for both the stereo and Atmos mixes of tracks was:

• only pick hi-res tracks up to 24/96, since the DF Cobalt does not do 24/192
  • Set the same sample rate in Audio Midi Setup before hitting play
• For Atmos, select "Always On" for Dolby Atmos in the Music app preferences
  • Set the sample rate to 24/48 in Audio Midi Setup before hitting play

Now to the punchline: my listening tests so far have not been very compelling. On the whole, the stereo tracks tend to sound better. Yes, I can hear the "immersive" aspect of Atmos, but it seems contrived, and comes at a noticeable drop in resolution and transparency. Will lossless Atmos (TrueHD) solve this? Possibly the resolution issue, but I suspect the true benefit of immersion comes from the physical separation of speakers in a 7.1.4 (and other) layout. Trying to simulate it with DSP for headphones seems to be a fraught endeavor, and I certainly did not have any Aha! moments.

 

Before I draw any conclusions from this, I need to ensure I have done everything right. I also need to understand exactly how and when Atmos mixes are decoded for headphones, and if there are any lossless (TrueHD?) mixes with headphone encoding. I'm not even sure I've got the terminology right!

 

Chris said this was a marathon, not a sprint. No kidding! Right now, I'm just looking over the trophy, and trying to decide if the race is worth running. 😁

[bbosler]

 

27 minutes ago, austinpop said:

but I suspect the true benefit of immersion comes from the physical separation of speakers in a 7.1.4 (and other) layout. Trying to simulate it with DSP for headphones seems to be a fraught endeavor, and I certainly did not have any Aha! moments

 

I think you nailed it.... 

 

It will take a tremendous amount of DSP to create all of the timing cues for 2 drivers that  our brain uses from 11 speakers to locate objects in space. Even if it can be done, hard to imagine this amount of processing won't have unintended consequences

 

I suggest you take the easy route. Buy > $100K worth of amps, speakers, cables, and processors to do it properly . 😉

 

 

 

[austinpop]

9 minutes ago, bbosler said:

I suggest you take the easy route. Buy > $100K worth of amps, speakers, cables, and processors to do it properly . 😉

 

🤦‍♂️ Of course. Why didn't I think of that. Thanks for the sage advice! 😂 

[phoenixdogfan]

13 minutes ago, bbosler said:

 

 

I think you nailed it.... 

 

It will take a tremendous amount of DSP to create all of the timing cues for 2 drivers that  our brain uses from 11 speakers to locate objects in space. Even if it can be done, hard to imagine this amount of processing won't have unintended consequences

 

I suggest you take the easy route. Buy > $100K worth of amps, speakers, cables, and processors to do it properly . 😉

 

 

 

Or buy a Smyth A16 Realizer and get an in person PRIR done in a studio by someone who know what they're doing.

[The Computer Audiophile]

14 minutes ago, phoenixdogfan said:

Or buy a Smyth A16 Realizer and get an in person PRIR done in a studio by someone who know what they're doing.

I’d love to compare an A16 to my 7.1.4 system. I’m a big fan of the power of DSP. 

[phoenixdogfan]

10 minutes ago, The Computer Audiophile said:

I’d love to compare an A16 to my 7.1.4 system. I’m a big fan of the power of DSP. 

Or in your case, your home, given what's already in your listening room.  

[austinpop]

27 minutes ago, phoenixdogfan said:

Or buy a Smyth A16 Realizer and get an in person PRIR done in a studio by someone who know what they're doing.

 

PRIR?

 

Google returns:

• Puerto Rico Immunization Registry
• Pacific Region Industrial Relations
• Pine Ridge Indian Reservation
• Primitive Irish.

I'm guessing none of the above? 😂

[phoenixdogfan]

10 minutes ago, austinpop said:

 

PRIR?

 

Google returns:

• Puerto Rico Immunization Registry
• Pacific Region Industrial Relations
• Pine Ridge Indian Reservation
• Primitive Irish.

I'm guessing none of the above? 😂

To quote the Smyth Research site:

 

"The best and easiest solution ... is to personalise the playback of the sounds through the headphones so that they recreate how our own ears hear each sound. We do this by measuring how sound propagates from an external source to each ear, and use this to create digital filters that mimic the normal analogue filtering action of each ear. During this measurement process we also determine the distance apart of the ears, and measure the acoustic impact (or reverberation) of the environment on what we hear.

The overall result is a personalised room impulse response (PRIR) that contains all the information needed to accurately recreate how an individual hears an external sound through their own ears. In combination with low-latency head-tracking personalisation ensures that the listener cannot tell whether the sounds through the headphones are real or virtual."

 

So a PRIR (a Personalized Room Impulse Response) measures how the transfer function of the room and your own anatomy (head shape and size, external ear, etc) alters a given digital signal before it comes to your ear canal as sound waves.  It then applies that measured transfer function to the output of your headphones to duplicate what you personally would have heard from speakers playing in the room where you were listening to them.

[retro]

@El Guapo, @The Computer Audiophile

You guys seen this?

A supposedly working, free DD+ Atmos to PCM decoder..!

http://cavern.sbence.hu/cavern/index.php

 

 

 

 

[retro]

VoidX, the creator, started posting on ASR:

https://www.audio “science” review/forum/index.php?threads/atmos-finally-decoded-in-pc-mac.32351/page-4

 

 

[The Computer Audiophile]

10 minutes ago, retro said:

@El Guapo, @The Computer Audiophile

You guys seen this?

A supposedly working, free DD+ Atmos to PCM decoder..!

http://cavern.sbence.hu/cavern/index.php

 

 

 

 

I hadn’t seen this but I’m struggling to see how / why anyone would use it with Dolby Digital + content. 
 

All music streaming in DD+  is decoded by the app already. 

[retro]

6 minutes ago, The Computer Audiophile said:

All music streaming in DD+  is decoded by the app already. 

You mean Apple Music on a Mac? But this opens up possibilities on a PC, doesn't it..?

I'll give it a test drive later..🙂

[The Computer Audiophile]

1 minute ago, retro said:

But this opens up possibilities on a PC, doesn't it..?

No because none of the services stream Atmos / DD+ to a PC.

[retro]

20 minutes ago, The Computer Audiophile said:

No because none of the services stream Atmos / DD+ to a PC.

Of course, but for downloaded DD+ Atmos files it has a use though.

[The Computer Audiophile]

1 minute ago, retro said:

Of course, but for downloaded DD+ Atmos files it has a use though.

I've never seen a downloadable DD+ music file. Have you?

Oh wait, I have sen a couple MP4 DD+.

[retro]

8 minutes ago, The Computer Audiophile said:

I've never seen a downloadable DD+ music file. Have you?

Oh wait, I have sen a couple MP4 DD+.

Right, you're only into music, forgot..🙂

But as for myself, I'm also big into music concerts, as well as movies. Content is available from various sources..

 

BTW, I predict: Within a year, U will have a high-end projector and a retractable screen to complete your system..😉

[The Computer Audiophile]

On 4/23/2022 at 11:40 PM, El Guapo said:

You didn't miss anything. 😅 

 

Media players' capabilities and video format limitations are two major issues. 

• For Kodi, unfortunately the max output channel is 7.1. The JRiver can support many audio channels but it's just for audio. The video playback is still limited to 8 audio channels.
• Most of the video file formats are only support / contain 8 uncompressed audio channels.

So that's why I choose DaVinci Resolve as a solution on PC for editing and playback. Or use Resolve to export .mov with 16ch, 24/48 LPCM and playback from QuickTime for Windows.

1. Go Workspace: Switch to Page: Deliver 

 

2. Click video tab and select QuickTime + H.264

 

3. Click audio tab and select 24bit LPCM. Add all of the 16 buses. Check 'Render one track per channel' and 'Render as discrete audio track' then add to / start the render queue:

 

I don't know why JRiver didn't use the QuickTime engine for playback the video with 16ch LPCM audio...🤔

 

 

Di you see the JRiver 30.0.32 update for Windows?

 

 

30.0.32 (11/15/2022)

1. Fixed: The links toolbar could crop some buttons since the addition of Spotlight even when there was space for more.
2. Fixed: The option at the top of smartlists to expand links was not working properly.  Now it changes the visible files.
3. Changed: Links are expanded when adding files to a playlist (instead of when viewing since the view should map exactly to the actual files).
4. Changed: Pulled in the Modern Cards Dark updated frame borders from Marko (thanks!).
5. Changed: Updated German translation file (thanks Bytestar).
6. Fixed: (Possibly fixed) bda tuners could crash when recording is finished.
7. Changed: Play Doctor does not play a local file first when Include Files From Cloudplay option is set to 100%.
8. Fixed: Play Doctor would fail to get any Cloudplay files in some circumstances.
9. Changed: Updated LAV Filters to 0.77.1, for improved performance, compatibility, and bugfixes.
10. Fixed: Video files (and audio files using the video engine, eg. MKA) with more then 8 audio channels did not work.
 

[El Guapo]

7 hours ago, The Computer Audiophile said:

10. Fixed: Video files (and audio files using the video engine, eg. MKA) with more then 8 audio channels did not work.

Will try! Thanks for the info. I didn’t follow this issue for a while. 😅

[mkt]

Is there a Mac-only (or Mac + linux) way to go from a Blu-ray Disc to individual files that the Dolby Reference Player (DRP) can play?

 

I tried makemkv to make a backup of the blu-ray and then DVDAE to extract the truehd/mlp files but DRP did not like the way that they were split. MMH does a an unspilt mlp file it's unspilt and windows.

[The Computer Audiophile]

30 minutes ago, mkt said:

Is there a Mac-only (or Mac + linux) way to go from a Blu-ray Disc to individual files that the Dolby Reference Player (DRP) can play?

 

I tried makemkv to make a backup of the blu-ray and then DVDAE to extract the truehd/mlp files but DRP did not like the way that they were split. MMH does a an unspilt mlp file it's unspilt and windows.

I’ll see if I can make it work. 
 

what happened in DRP when you tried to play the mlp?

[mkt]

Opening individual files (except for the first one) gives

when the 16 channel option is set

They open without error if an option other than "16 channel" is selected. So opening with individual files with Auto works and I can then switch to 16 channel to get atmos, but playlists don't work.   

 

I might try with truehd downloads.

[The Computer Audiophile]

18 minutes ago, mkt said:

Opening individual files (except for the first one) gives

when the 16 channel option is set

They open without error if an option other than "16 channel" is selected. So opening with individual files with Auto works and I can then switch to 16 channel to get atmos, but playlists don't work.   

 

I might try with truehd downloads.

Ah yes. This is a known issue that the developer of mkvtoolnix refuses to fix. Even with a PC you will run into this issue. 
 

Many people play the extracted album as a whole, into Audacity and capture as WAV. Then split it with a cue sheet. Then you can play it in any app that supports WAV and multichannel. 
 

Music Media Helper on Windows will soon extract to Atmos WAV without needed to use DRP.