Dolby Atmos for Headphones not working correctly on Xbox One.
I should preface this by saying that I have run Atmos 7.1.4 in my home for over a year now. My current headset is the Astro A50 Gen3, which uses Dolby Headphone (virtual 7.1 from a 5.1 bitstream via stereo). I set my Astros to stereo-only and then enabled Dolby Atmos for Headphones using the Dolby Access application.
Comparing the sound of the two (Dolby Headphone vs. DAfH), something seemed off about the way Atmos for Headphone sounded. Listening to the Amaze and Leaf clips, which I am intimately familiar with in my 7.1.4 home setup, the sounds for the front soundstage were not imaging correctly in FRONT of the listener. To verify this, I used Dolby's CEDIA 2015 Dolby Atmos demo Blu-ray, which has test tones for 5.1.2, 5.1.4, 7.1.2, 7.1.4, etc. I then ran these test tones in the Blu-ray app on the Xbox One to see where each test tone imaged in virtual space around me.
1. Using Dolby Headphone on the Astros: Left main images at 45 degrees to left of center, right main images 45 degrees to right of center and center images in front of the listener. The important thing to note here is that the LCR channels were imaging virtually in FRONT of the listener, NOT in between the listener's ears as sounds do in straight stereo. Left surround images at 90 degrees to left of listener, right surround at 90 degrees to right of listener, left rear surround at about 110-120 degrees to left and same for right rear on right. The LFE test tone plays a deep bass note. These angles are roughly where Dolby dictates they should image in space given their speaker placement guidelines.
2. Using Dolby Atmos for Headphones with the Astros in stereo mode: Left main tone images at 90 degrees to the left, right main images at 90 degrees to the right, and center channel tone images in between the listener's ears as if these front three channels were still being sent in stereo rather than virtualized in front as they should. Left surround images behind the listener slightly rather than directly 90 degrees to the side, left rear maybe slightly further back, etc. And the LFE tone doesn't play any bass at all - just a midrange white noise tone - leading me to believe that channel is not being sent to the DAfH renderer for playback at all.
To confirm these findings, I played the Amaze and Leaf clips in both the Dolby Access app and off the Atmos demo Blu-ray using both Dolby Headphone via the Astros and Dolby Atmos for Headphones via stereo. What I'm hearing in the test tones bears out in the demo clips - with DAfH, none of the sound meant to be in the front three channels seems to come from in front of the listener. So basically, instead of the sphere of sound around the listener that Atmos is known for, you're only getting a hemisphere of sound from 90 degrees to either side and behind. I'm assuming that something is off in the implementation here, since it doesn't seem like the LCR channel output is being fed to Dolby Atmos for Headphone so that it is virtualized at all. It seems like those three channels are being output as straight stereo, with only the surround channels receiving virtualization, which is then summed with the LCR output. I don't believe that this is how Dolby intends it to work, as it doesn't even function as the older Dolby Headphone algorithm does.
I ruled out the Astro headset as the problem by running these same tests with earbuds connected to my Elite controller. The results are the same. DAfH is NOT properly steering audio meant to be in the front soundstage and is placing surround channels too far behind the listener. Double-checked with my Turtle Beach 500X headset, using its stereo-only mode and flat equalization. The TB's DTS:X Headphone properly steers audio in the front soundstage, whereas Atmos for Headphones gives the incorrect results described previously. THIS IS CONCLUSIVELY NOT AN ASTRO-RELATED ISSUE.
I also checked Windows Sonic to see if it exhibits a similar behavior. It does not. Test tones meant to be in front of the listener are properly imaging in front of the listener as they should, as are tones from the surround channels. This could explain why people are finding Windows Sonic to have a more spacious sound. Unrelated note: Windows Sonic doesn't pass the LFE channel either. This may be intentional behavior since it is for headsets, where this deep bass may not be ideal. This was tested on the Astros, the Turtle Beaches, and on the earbuds, and Windows Sonic works correctly on all three.
NOTE: I did not focus on height-channel test tones, as the tones when played back from the CEDIA 2015 Blu-ray did not seem to be placed overhead in any way. They seemed to image at 90 degrees to either side in the same way that the L/R channels did. I'm assuming that the Blu-ray app on the Xbox One has not been updated to provide the DAfH renderer with the object metadata from Blu-ray discs. However, that should NOT affect the bed-level speaker channel results that I've described above.
I've posted this in the Xbox Ambassador forums, Reddit as well as in an e-mail to Dolby, as I don't believe this is working as they meant it to. Hopefully, they can get this sorted out (or at least tell me whether this was by design, which I can't imagine as it seems like only a partial implementation of the Atmos for Headphone audio renderer). I'm going to test to see if I get the same results on Windows 10 CU, using Dolby 7.1.4 downloadable test tones from their website. I'm betting that the results will be the same, since they're likely using the same codebase on both.
If you were considering spending the $15 for a license for Dolby Atmos for Headphones on the Xbox One, I would strongly advise waiting to see if they fix this issue. If they don't, then you're better off using Windows Sonic, as it at least steers audio for the front soundstage correctly.
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