Apple TV 4 with tvOS 14.3 no longer able to passthrough AC3 Audio

Hi folks. I too can confirm this is a bug introduced in tvOS 14.0, and still exists in 14.3.

The more people can report the bug using the feedback tool below, the more likely it will get fixed since Apple don’t monitor these community forums.

https://www.apple.com/feedback/appletv.html

As others here have already mentioned, it mainly affects the Computers app but also some third party apps like “Surround Sound Check” app which the dev himself confirmed here: https://forums.macrumors.com/threads/tvos-14-3-apple-tv-4k-home-sharing-surround-sound-broken.2278178/

Very frustrating for those of us who use Home Sharing extensively :(

It’s not just Home Sharing.

tvOS 14.3 is unable to play surround sound... in Netflix, the Apple TV app, everything.

I’ve notice a moment’s delay when playing any movie with AC3.

Try downloading an app... Surround Speaker Check.

Or download this...

3MB Video

...originally from this web site...

Fraunhofer

I've converted the sound to AC3. Add the 3MB movie to the TV app on your Mac and stream it to your Apple TV 4K.

It may be challenging to tell what's wrong. Listen for the subwoofer... it's not there. One can't hear it at all. In addition, sound should play through each speaker individually, not all of them at once.

Surround sound is broken.

Here’s something else, too. The Language menu in Home Sharing’s Audio menu is missing.

Before I went back to tvOS 13 (replacement units) I found Plex still worked fine with DD5.1 in tvOS 14.2 on my Apple TV 4K.

So that could be an option, but admittedly not as straightforward as iTunes home sharing.

(Or Infuse? It would be simpler to setup than Plex but I only had the free version so never tested it’s DD5.1. They do free trials though of the full version)

The video and the checker app both provide 5.1 sound again including LFE.

The audio format setting is set to the default „automatically“ and the ATV either outputs Dolby Digital 5.1 or PCM stereo depending on the source.

Just enable to install beta releases and test yourself.

Hey quick question folks: If you’re having the issue, is your Apple TV still under warranty?

If so ... tvOS 13.4.8 is still being signed by Apple so if you get a replacement unit from Apple and you’re lucky enough that it’s only tvOS 12 or 13 you can still update it as far as 13.4.8 and you’re back to surround sound.

(It can be a little tricky with the Apple TV 4K as you can’t do the update via USB and have to avoid 14.3 being offered OTA. But it’s still possible to do if you block internet access after initial setup, and then quickly search for updates immediately after reconnecting)

That’s what I did so just putting it out there as a possibility :)

There hasn’t been audio passthrough options in many versions tvOS now (tvOS 10 if memory serves). This hasn’t suddenly changed with tvOS 14.3. All audio gets decoded to Multichannel, and optionally downmixed/re-encoded to DD 5.1 or Stereo, as set by the user, as with previous versions.

The LED indicator on your receiver isn’t thought of that important. PCM Multichannel (for 5.1) is the same quality as the source AC3 (for 5.1). The decoding is lossless for the same number of channels.

Video files with multiple audio tracks are a bit tricky, especially a mix of AAC and AC3, as Home Sharing might not see all tracks.

> I wonder if Netflix and other streaming apps output 5.1 surround; it's very difficult to tell without a video like the one I posted in which each speaker is played individually.

I'm confident that I can tell:

1. For the Apple TV 4K that is connected to the AV Receiver, the Receiver is indicating that it's getting a Dolby Digital 5.1 or Dolby Atmos signal when playing appropriate content. It also sounds like proper surround with properly separated channels and subwoofer being triggered. In addition, when looking at the the audio stream info in the TV's system setting, it's indicated as a DD 5.1 or Dolby Atmos.
2. For the Apple TV's that are connected directly to TV's, the TV's info indicates a DD 5.1 signal received (for Netflix, Disney+, etc.) which is inline with the audio stream info in the TVs systems setting. It also sounds like proper surround with properly separated channels. For Home Sharing files encoded with DD5.1 the audio stream info only shows Stereo as the received signal.

The above is true for my setup, but I wouldn't rule out that this is actually NOT working for others. Maybe the TV/Soundbar that the Apple TV is hooked up plays a role in how audio is output.

I've also tried setting the "Change Audio Output" to "On...Dolby Digital 5.1" and setting "Audio Mode" to "16-bit" (and combinations of both) and it made zero difference for me.

From what I’ve seen, the scrubbing/hanging problem can be caused by the tvOS 14 issues when there’s an AC3 track, which obviously is going to be most movie files..

But to answer your question the correct format for Home Sharing is normally:

• video track
• a stereo AAC track
• a surround AC3 track (with fallback set to the stereo AAC track)*

The order of the tracks isn’t important, and you can have other tracks that will be recognized (like subtitles and chapters)

*If you have a Mac then Subler is a great tool for making sure the .mp4 / .m4v file is compliant and optimized.

BTW we all should submit this here: Apple Feedback

That's correct. But if you have a slow internet connection you might prefer to let iTunes download the full movie and then stream it locally. And then there is no 5.1 anymore.

BTW everybody should submit this to Apple Feedback or Feedback Assistant for developers. At the moment Feedback Assistant shows to me that there are no other bug reports about this issue except mine.

I purchased an Apple TV 4K at Costco today; it came with tvOS 13.4.8.

Settings --> Video & Audio --> Audio Format --> Change Format --> On --> Dolby Digital 5.1

I now have surround sound again. It works perfectly.

If you haven’t already done so, please report this issue to Apple!

Ask to speak to an Apple TV specialist!

I spent an hour last week Saturday with a specialist… I submitted Apple TV diagnostic logs and videos.

When I called today for an update, everything has been lost!

I had to start all over again…

Have I contacted my television manufacturer?

Have a contact to my receiver manufacturer?

Have I tried connecting another television?

And on it went!

The more people report this, the sooner a solution will be found!

I know this isn’t the exact question you asked and not relevant for anyone who wants to stick with Home Sharing... but on a related note I’ve tested both your AC3 version and the original HE-AAC version in Plex on Apple TV 4K and both worked perfectly in tvOS 14.2, 14.3 & 14.4. Full channel separation and Dolby Digital 5.1 playback, with “Change Format” both on and off 👍

(Edit: oops, accidentally replied to OP.)

Same here. All home sharing streaming movies get down mixed to stereo only. Even movies that only contain a single Dolby Digital 5.1 AC3 track are just played back in stereo. Before tvOS 14.3 everything worked fine and AC3 was passed through.

And this is not only related to self-created home movies. The same happens to purchased iTunes movies that I stream from my iTunes to the ATV.

And there is another bug related to home sharing streaming: When you scroll around in a movie by pausing it and then move the cursor to some other time of the movie, everything freezes. Video playback never suspends again and nothing reacts to the remote anymore.

This is getting a bit more mysterious... I have 4 Apple TV 4K's in the house. One of them is hooked up to a Audio/Video receiver, the other 3 directly to TVs who then pass the audio back to soundbars (2 via optical, 1 via HDMI ARC).

The Apple TV that is hooked up to the Audio/Video receiver is playing 5.1 DD via Home Sharing just fine and the Surround Sound tester works. The Apple TV's that are hooked up to the TVs (all TVs are different brands) are all playing 5.1 files via Home Sharing in Stereo - doesn't matter if the soundbars are connected or not (verified by looking at the audio stream details that the TVs provide).

DD 5.1 content from streaming apps (Netflix, Disney+ etc.) works fine on all 4 TVs.