Apple Broke Dolby Digital 5.1 Output on Apple TV 4K

Mine stopped switching yesterday. It only output 2 ch PCM. Doesn’t matter whether the ATV 4k is attached directly to the TV with eARC or attached to my receiver. Other devices work just fine. TV is sending full digital signal back to the receiver.

Only Apple TV is stuck in stereo.

Same. I created a new thread on this and have submitted feedback to Apple but with iOS 18 launch yesterday they’ll be bug fixing for goodness knows how long 😥

Content that is flagged as Dolby Atmos plays as Atmos and is reported as such by the soundbar display. 5.1 used to show as Dolby Audio with sound coming from all channels. Now it reports PCM and sound only from the left and right front channels. Play the same content on the TVs on board ATV app and it plays as Dolby Audio complete with centre and rear channel sound.

I've just turned on my Apple 4K TV box 1st gen to watch something off Netflix.

I thought it was a Netflix problem but first but it's happening and every app that I have and any films that I purchased too in iTunes. Everything worked fine until this TV OS 18 update. Never turned on auto update.

I have a Denon AVRX2200 Receiver that displays what audio I am getting. I can change sound mode but I do not get the option of Dolby Digital anymore. Just plain old surround sound.

The Apple 4K TV first gen is part of my home cinema setup and I consider 5.1 sound crucial to watching anything.

If someone knows how to roll back to the latest version of OS 17 I would like to know how please.

Frustrating, isn’t it. But there’s a bit of me that’s relieved that it’s not just me and points to an Apple bug. Fingers crossed they get it sorted.

You have a valid point. PCM does not mean 2.0. I like your troubleshooting which makes sense. However, a lot of AVR's especially newer ones will upconvert a 2.0 signal automatically and indicate it is running through as many speakers/channels as the AVR can handle.

Example, AVRs could take a 5.1 and turn it into 7.4.2 (Atmos). Does your AVR have a "STRAIGHT," or "DIRECT" mode? What these modes will do is it passes the sounds through directly as the source puts out. I tested the same way you did, at first, I was like, "who cares if it displays PCM as long as it works correctly," until I realized it didn't work correctly. I did not put my AVR on "DIRECT." When I did, it indicates a 2.0 signal coming into the receiver (showing only the Front L/R was being used), and it was my AVR that upconverted into 7.4.2 when it wasn't in DIRECT. I came to this conclusion because I tested the AppleTV 4K box even when it showed all channels were active, it sounded funny, so I then used the native AppleTV application on my LG TV, the decoding was correct, and the sound was much, much fuller, even at the same volume, using the same movies. I have also tested with other services such as Netflix using AppleTV 4K box vs Apple TV application on the LG TV. When I switched both test to DIRECT, the ATV4K Box, was simply upconverting 2.0 lossless. (top photo is AppleTV Box, bottom is native AppleTV app on LG TV, 3rd photo is in DIRECT mode with the display set to indicate the channels used).

When I use my LG AppleTV application, it will pass through all channels indicated much like your screen shot (showing all the speakers being utilized, I apologize, to save time, I did not screen shot everything). When using "STRAIGHT," or "DIRECT" with the AppleTV 4K, it indicates only 2 channels. Please see screenshot. Please let me know if you have a DIRECT/STRAIGHT/PASSTHRU mode on your receiver and what your results are.

I will call Apple about this today

I fully agree with your post. When I bought the Apple TV 4k it was (I believe) on tvOS 17.2. Since 17.3, dolby digital has stopped working. Even though you select dolby digital in the settings, it just doesn't work. I've tested my setup with my Xbox and then it just works. Hopefully they will fix this soon!

Apple TV to AVR 5.1 Dolby decoding no longer available, just 2.1 PCM since the 18 iOS software update. I’m a United Kingdom customer, for what it’s worth. Apple Tech support, please do your thing…I’ve got movies to watch.

In a similar thread, developer @oviano reported "that the SDK API function AudioConverterFillComplexBuffer has stopped working for EAC3 in tvOS 18." That function apparently is not broken for macOS. It appears that only a software update is likely to provide a remedy.

I haven't found any solution yet. I have given Apple feedback through this form. Maybe it helps if more people use this form. Feedback form Apple TV

I have same problem in tvOS 17.5 with logitech z906,Netflix contents not showing 5.1 while my xbox series s play netflix content in 5.1 audio just fine.

Don't have this problem on a 2nd & 3rd gen Apple TV 4Ks running tvOS 17.5.1 through an AVR and 5.1 speaker system. Indicators for 5.1 playback light up on the AVR and sound is going to the correct speakers.

So apparently not affecting other setups?