Since tvOS 18 update Apple TV 4K and Apple TV HD output only stereo despite 5.1 selected

As a developer I have found that the SDK API function AudioConverterFillComplexBuffer has stopped working for EAC3 in tvOS 18. This means it is not decoding EAC3 streams that use this API. The same function worked correctly on tvOS 17, and continues to work correctly on macOS.

Perhaps this is related, perhaps it isn't.

I've reported this via the developer Feedback Assistant.

Apple Support followed up to tell me that the engineers believe it most definitely a software problem, not a hardware problem (as it worked perfectly before). Expect it to be fixed the next update.

This happened to me as well! I tried everything from turning off my ATV, factory reset, unplugged and plugged both power and HDMI, etc. YouTube TV works fine with DD 5.1 PCM but not Netflix, Paramount+, ATV+. I tried with my PS5 and all streaming services flawlessly switch to DD 5.1 PCM.

I spoke with Apple Support which escalated to the engineering team. The guy mentioned that they've had multiple reports of the same issue. I had to send in a video, photo of my settings and system diagnostics to Apple Support. He's going to get back to me by Wednesday with an answer, hopefully.

Updated the tvOS 18.1 beta and it's finally fixed! Hallelujah!!

I've chatted with support now. They'll call me tomorrow.. not sure how that will help.. this needs a patch, nothing else.

Anyways, the guy confirmed that others have reported the issue.

Confirmed tvOS 18.0 has also broken the "Change Audio Format to Dolby Digital 5.1" for me.

Dolby setting only outputs stereo like others mentioned. Thanks Tim Apple.

I’m having the exact same issue, just wanted to stick some 💩 on while I relax after putting my son to bed, no visual at all on any streaming apps just sound and then the whole lot shuts off and tells me there’s an issue with the hdmi cables but I’ve tried 4 cables and gone into settings to run the hdmi checks which were all fine too

Good thing, the more people contacting them the more they'll work on it..

However, I don't think there's any fix for this besides another update of the tvOS... (Not counting hot-fixes that requires other Apple hardware products...)

I am also experiencing this issue any streaming app I use on my Apple TV 4K only sent stereo PCM to my Sonos beam. If I use my Xbox or other game consoles it can get Dolby 5.1 just fine so I think this has to be a tvOS issue right!

same here, the setting i used forever was to force 5.1 but with tvos18 the apple app audio streams only in stereo.

interresting is that when using the remote play app (don’t know the real name, the app the lets you stream video from your home network, in this case a mac mini) the video’s are in 5.1, so it’s not a hardware connection problem

Glad to have found this thread this morning before wasting more time on this today.

discovered last night I was only getting stereo when watching a movie. Ps5 still works in 5.1, it’s just the Apple TV. Hoping that fix is just around the corner.

I don't know - it may be that what I am seeing is another symptom of the issue you guys are seeing rather than the cause. Or it may be completely unrelated. But there are enough similarities for me to smell a rat.

All I know is that in the streaming app I am developing I have found that before upgrading to tvOS 18 a DD+ 5.1 stream was being decoded perfectly fine but post tvOS 18 the decoder just stops without any errors. In technical terms, the decoder is meant to ask for more data to decode; it asks for the first packet, which I give it, but never asks for any more after that, so no output data is ever produced. This has nothing to do with HDMI or anything else, at this stage it simply doesn't decode the data to PCM, so it never gets as far as sending it to the TV (or re-encoding as Dolby MAT, or whatever Apple TV does these days).

It's the same story on iOS 18, by the way. However, latest macOS (Sequoia) continues to decode the same stream, with the same code just fine.

As I say, I've logged it in the developer feedback section, so let's see.