Dolby Atmos not working with update to TVOS 15

Thank you for your kind response. I did a cold boot of the entire LAN as per your suggestion, including un-plugging all relevant devices; unfortunately the issue remains.

What I have additionally noticed is that in Apple TV settings/apps/music app/Dolby Atmos, that if I toggle the Dolby atmos setting between Automatic and off (there is no 'always on' setting as before with tvOS 14.7) - the sound will sometimes give me full Dolby Atmos for part of the duration of a particular track.

However when a new track starts, I can hear atmos surround for perhaps a second, and then the sound collapses mainly to the left front channel, and at a lower loudness level, to the right. No sound at all from centre or rears - so two channel only - but at a low volume on both fronts.

I wonder if with the tvOS 15, something might have changed with it that does not 'fit' with my hardware setup. My TV is HDMI 1.4 - mostly likely B, as it dates from 2012. It does have ARC as part of the HDMI 1.4b specs, but not eARC - whether there is something different there in tvOS 15 I am unsure.

My limited understanding of this is that Apples implementation of Dolby Atmos uses Dolby Digital plus 5.1 lossy compression, with Dolby MAT 2.0; as such there is no passthrough and the Apple TV converts to multi channel PCM which it then sends to the TV. Certainly the TV which has an integral surround sound processor, reports that the incoming stream is PCM.

I'd also mention that my Apple TV 4K 64gb is version one - purchased not quite 3 years ago - whether an 'upgrade' to the latest version which makes mention of supporting eARC would make any difference I am unsure.

I should also mention that I am having no issues with 2 channel sources, or multi channel surround sound sources through the Apple TV 4K, which includes movies purchased from the Apple TV store - all of which play flawlessly in multi-channel surround sound, streamed online from Apples servers.

Additionally, nothing has changed re my hardware setup - the issue is only occurring in the Apple Music app, and with Dolby Atmos sources only.

If any one is able to shed light on the issue It would be greatly appreciated - or perhaps if I should raise the issue with Apple?

Many thanks again for your thoughts and kind response - much appreciated

Jonboi. :-)

Thanks so much for sharing your experience - am glad to hear I'm not alone on this, as its so frustrating to lose Dolby Atmos, or more to the point, discrete multi-channel surround sound on Apple music streaming services.

Given that apps like Netflix and Amazon Prime, along with Apple movies all work perfectly fine with surround sound, I cannot help but feel it may be a bug in tvOS 15 as regards the music app and Dolby Atmos.

In particular I've done some further reading on the purpose of ARC and eARC as it applies to Dolby ATmos.

Effectively, as best I understand it, this should not matter in my setup, as ARC/eARC is data that is sent upstream of the TV to say a receiver.

In the case of the Apple TV 4K in my setup, it is sending data downstream to the TV - which has an integrated surround sound module - signal from the SS processor in the TV then being sent to active speakers and the centre channel speaker system in the TV is also fully active and doubles as the centre channel in a surround sound role - so ARC is not used as regards sending on info to a receiver, as there isn't one.

My understanding also, is that the Apple TV decodes the Dolby Atmos signal and sends it on as multi-channel PCM via Dolby MAT.

Certainly it worked before and I would hope that it will work again - I wonder if apple are aware of the problem - they certainly need to be!

Thanks again for your comments - am very relived I'm not the only one experiencing this..

Jonboi.. :-)

Thanks so much for your response and information.

Sounds as if everyone needs to raise a bug report with Apple.

If they're not aware of it, they won't look in to it and fix it.

Thanks again!

Cheers

Jonboi.

Double post - apologies