tvOS 14.3 & Apple TV 4K - Home Sharing Surround Sound Broken

[JeffPerrin]

Audit13, it is an Onkyo TX-NR646, and the ATV is connected directly to it via an HDMI 2.2 cable. The Onkyo is running the latest OS.

Try a different HDMI port? Different cable?

tvOS 14 has been a nightmare for a good many home theater enthusiasts (believe me, I've heard from them!). However, going direct to AVR has usually been the one set-up which has worked fine for most users.

Another option is to sign up for the tvOS beta program and see if the upcoming 14.5 update helps. Folks around here are saying this update fixes some of their issues.

 

[Mikecapeann]

Thanks, JeffPerrin. I was able to finally get the Onkyo receiver to output a Dolby Digital 5.1 signal from the ATV. However, I cannot seem to get a Dolby Atmos audio output to work from the ATV, even when an Amazon Video movie has the format. I know the Onkyo is compatible with Atmos, so I don't understand why it won't process the signal. I understood the ATV does the processing and sends the signal to the receiver, so selecting "Direct" should provide the Dolby Atmos audio. I can live with Dolby 5.1, but still frustrating.

 

[Mikecapeann]

priitv8, thanks. I was finally able to get the Onkyo receiver to output Dolby Digital 5.1 signal from the ATV (not not Dolby Atmos, even for movies in Amazon Video that use the format). The Dolby Atmos is definitely selected on the ATV, and not Dolby Digital 5.1. If you have any suggestions for why Dolby Atmos isn't being output on the receiver, I'd appreciate it.

 

[priitv8]

@Mikecapeann - if you turned on "Change Format" on aTV, then you will definitely lose the Atmos.
It is because aTV internally re-encodes the multichannel PCM into Dolby Digital (aka AC3) 5.1 signal and by definition, AC3 5.1 is not one of the three Atmos-carrier codecs (they are TrueHD, Dolby Digital Plus (aka E-AC3) and Dolby MAT).
You need to make sure, that your AVR and it's firmware are able to receive and decode PCM 7.1 with embedded Atmos metadata (aka Dolby MAT 2.0). I recall that some early Denon AVR-s needed firmware update to get the MAT2.0 support.

 

[Airsculpture]

I think this is a similar issue regarding surround sound and music playback I’ve noticed

Apple TV HD Audio Issues

I have my ATV feeding a Marantz 6012 receiver In settings on the ATV: If I have Audio set to auto, I get full multi channel audio from all speakers. Unfortunately when I play music, that is also output to the Marantz in 5.1 If I have Audio set to Change Format DD 5.1, I get my music back...

forums.macrumors.com

 

[Mikecapeann]

@Mikecapeann - if you turned on "Change Format" on aTV, then you will definitely lose the Atmos.
It is because aTV internally re-encodes the multichannel PCM into Dolby Digital (aka AC3) 5.1 signal and by definition, AC3 5.1 is not one of the three Atmos-carrier codecs (they are TrueHD, Dolby Digital Plus (aka E-AC3) and Dolby MAT).
You need to make sure, that your AVR and it's firmware are able to receive and decode PCM 7.1 with embedded Atmos metadata (aka Dolby MAT 2.0). I recall that some early Denon AVR-s needed firmware update to get the MAT2.0 support.

Thank, priitv8. I've checked those. The ATV is set to Dolby Atmos, and the receiver is capable of an Atmos signal and the OS is up to date.

 

[Mikecapeann]

I think this is a similar issue regarding surround sound and music playback I’ve noticed

Apple TV HD Audio Issues

I have my ATV feeding a Marantz 6012 receiver In settings on the ATV: If I have Audio set to auto, I get full multi channel audio from all speakers. Unfortunately when I play music, that is also output to the Marantz in 5.1 If I have Audio set to Change Format DD 5.1, I get my music back...

forums.macrumors.com

Theoretically, the ATV should send the signal to the receiver in the native audio format, but as a workaround try changing the audio output on the receiver to stereo/2-channel (assuming that's the output you want).

 

[Airsculpture]

The Marantz is set to auto and as you can see from the screenshot it is receiving multi channel while listening to a stereo music track

I can of course force the Receiver to output stereo but that doesn’t alter the fact that it is receiving multi channel and doesn’t solve the issue unfortunately

 

[priitv8]

The Marantz is set to auto and as you can see from the screenshot it is receiving multi channel while listening to a stereo music track

I can of course force the Receiver to output stereo but that doesn’t alter the fact that it is receiving multi channel and doesn’t solve the issue unfortunately

Something is not right there.
When you listen to stereo AAC stream, aTV will not create non-existing additional channels. Could it be that your source actually is multichannel? From Plex or something that is not Apple Music or your iTunes Library?
That is what I get when listening to music

Shared Photos

share.icloud.com

Theoretically, the ATV should send the signal to the receiver in the native audio format, but as a workaround try changing the audio output on the receiver to stereo/2-channel (assuming that's the output you want).

With appleTV this is never the case. It always decodes incoming encoded audio into uncompressed PCM and outputs that.
That’s what is meant when you hear that appleTV does not bitstream audio.

 

[Airsculpture]

No. The files are either AAC or ALAC stereo music files local home sharing

Usually happens after watching a movie and then listening to music but not always.

Tried it today after watching The Godfather. Played a music track all 7 channels lit up and sound coming from all speakers.

Rebooted the ATV. Played the same track and I get correct 2.1 sound. So it’s not the tracks, it’s the way ATV is handling the audio.

 

[priitv8]

So it’s not the tracks, it’s the way ATV is handling the audio.

Must then be a combination of things. aTV + your TV + AVR.
I’m on my third hockey-puck appleTV (3, 4 and 4K), on second Bravia TV and third Sony AVR. Never had similar problem like yours.
First AVR was non-HDMI so I used optical and had to enable Dolby Digital 5.1 output on aTV, but stereo always played from 2 channels.

 

[Airsculpture]

It’s very weird. Only started on tvos 14, never happened on 13

Unfortunately I cannot go back to 13 as since January Netflix does not work on 13

 

[priitv8]

It’s very weird. Only started on tvos 14, never happened on 13

Unfortunately I cannot go back to 13 as since January Netflix does not work on 13

I wish I knew how to write a tvOS app, that checks the audio capabilities of the HDMI link it sees and displays it on screen.

 

[worldomination]

Home Sharing - Computers App

Settings --> Video and Audio --> Audio Format --> Change Format --> On --> New Format Dolby Digital 5.1


I grew tired of waiting for an official working update so I installed tvOS 14.5 Beta 6.

Both Dolby Digital Plus E-AC-3 and Dolby Digital AC-3 separate channels correctly.

Surround works as expected when movies are encoded with Dolby Digital Plus E-AC-3.

However, surround sound does not work with Dolby Digital AC-3. First, movies begin to crackle and pop. Next, audio falls out of sync with video. Last, sound ends altogether.

I use one of two FFMPEG scripts to convert AC-3 to E-AC-3...


ffmpeg -i input.ac3 output.eac3

ffmpeg -i input.m4v -vn output.eac3


I mux everything back together again with Subler.

 

[worldomination]

April 20, 2021

tvOS 14.5 (18L204)

Today's tvOS release candidate does not entirely fix the problem.

Again, both Dolby Digital Plus E-AC-3 and Dolby Digital AC-3 separate channels correctly.

AC-3 surround sound does not work; sound cuts out within a few minutes. Pause the movie or television program and surround sound returns for a brief moment before cutting out again.

E-AC-3 Dolby Digital Plus surround sound works as advertised.

 

[worldomination]

Here's another problem with tvOS 14.5 (18L204).

Stereo two channel sound ACC does not stay in sync with the picture.

 

[Atomic~]

AC-3 surround sound does not work; sound cuts out within a few minutes. Pause the movie or television program and surround sound returns for a brief moment before cutting out again.

This happens to me with the Computers app on Apple TV 4K.

Also AAC 2 or 6 channel: out of sync issues, sometimes even audio drop out after a while. Interesting thing about this is I can hear clipping with these movies with Quicklook on my iMac (21.5-inch, Late 2015 - Big Sur 11.3). If I hear that audio clipping, I know it will fail (go out of sync) through the Computers app on ATV.

Not all mp4s or m4vs (HEVC h.264) are effected by this bug(?).

If I extract the HEVC (or h.264 - I changed the bash script to work) and AAC and recompile twice (MP4BOX, then FFMPEG), it works fine.
https://community.firecore.com/t/problem-with-x265-playback/19514/23

I was using the above to fix over a year ago on certain HEVC movies that wouldn't play on Mac OS or Computers app. It seems to fix on any current movie since this new issue started to happen.

Why this works? I'm not geeky smart enough to know - maybe someone else here can tell me? Why is this creeping up on 14.5? Maybe the framerate fix (23.976fps and 24.000fps) on Apple tvOS broke something else?

We may see more comments of this issue with 14.5 and 11.3 (?)

 

[Atomic~]

No, Apple TV doesn't like AAC 5.1 audio tracks... which is why I convert them to AC3.

I've been doing the same for a couple of years but am now curious why. When did AAC 6 channel start working properly on the ATV?

https://www2.iis.fraunhofer.de/AAC/ChID-BLITS-EBU.mp4

I download this to my Mac, add to Home Videos and play through the Computers app on ATV. It is definitely 5.1 surround.

Audio format is Auto, Atmos Available.

 

[worldomination]

OMG, Atomic~!

I've more testing and trial-and-error to go through... but...

I believe you nailed it!

First... like you...

When did 6-channel AAC begin to work?

I've been remuxing for years. Now... suddenly... it doesn't seem necessary. Six-channel AAC works great with proper channel separation.

As to your solution to make audio work... well, perhaps I can offer an easier method.

Subler

I drag a movie file to a new window and save it. That's it. All the movies I've had trouble with are fixed.

 

[worldomination]

Atomic~!...

What do you use to extract and convert audio?

I used to use MP4Tools. However, something in tvOS has changed; movies remuxed with it don't play audio correctly.

Subler muxes movies properly but in my experience doesn't convert multi-channel AAC very well. Maybe I need to play with it more.

I've turned to FFMPEG and the command line to extract and convert audio.

 

[priitv8]

I used to use MP4Tools. However, something in tvOS has changed; movies remuxed with it don't play audio correctly.

IMHO Subler does all the muxing tasks MP4Tools did. You now need to set the fallback audio channel for the surround track. Subler handles it automatically for new muxes and allows you to manually fix them for already muxed files.
Handbrake does a good job of audio encoding.
For demuxing I tend to use TSMuxer, in more complex situations the eAC3to (windows only, thus inconvenient for me).

 

[Atomic~]

What do you use to extract and convert audio?

I used to use MP4Tools. However, something in tvOS has changed; movies remuxed with it don't play audio correctly.

Subler muxes movies properly but in my experience doesn't convert multi-channel AAC very well. Maybe I need to play with it more.

I was using MP4Tools to convert AAC 6 to AC3 5.1 as I could control the audio bitrate - I wanted a higher bitrate as this is a lossy conversion.

(edit): I use Subler on all for metatagging and some muxing (subtitles). I haven't used lately for re-encoding audio as I've no need to have 6 channel and 2 channel in the files (unless its different language, commentary tracks).

Pre tvOS 14.5, these mp4 or m4v files (aac 2, aac 6, ac3 5.1) worked great, most are only 1 video & 1 audio track. I did have to recompile some HEVC as they didn't work on MacOS (or tvOS) as noted above in the link.

Since tvOS 14.5, I started to see complete audio dropout (ac3 5.1) and out of sync (aac 6 & 2) as you noted.

Something changed in 14.5 (and 11.3). Even when converted from AAC to AC3, these files inherited something from the original mp4. The original mp4 has something in it that 14.5 doesn't read properly - is it just the hev1 video tag that needs to be hvc1 (x265), or missing ctts atom? - I'm not sure, I'm a novice. NOTE- not all mp4 or m4v have this issue - some have been compiled and are Mac friendly.

What ever is in the original file that 14.5 doesn't like, recompiling works (and it's not lossy) on x265 and h264 using the above. I don't know MP4BOX or FFMPEG enough to know what it removes (or adds) when recompiling. Could recompiling be done with MKVToolNix/mkvmerge and FFMPEG on the Mac?

Re: Fallback rate - tried, didn't fix.

 

[worldomination]

priitv8...​

I wish it were that simple.

I open a TV show or movie in Subler, select the audio track, and choose Fix Audio Fallbacks. It doesn't correct the problem.

AC3 surround audio still drops out and AAC 2-channel stereo audio eventually falls out of sync.

The only solution which works for me is to open a new Subler window, drag a movie to it, and re-save.

 

[worldomination]

Atomic~...​

Until a better solution presents itself I'll extract audio from an original movie file using FFMPEG...


ffmpeg -i input.m4v -vn output.eac3

...or...

ffmpeg -i input.m4v -vn output.ac3


...and assemble things using Subler.

For instance, drop an .mkv movie into a new Subler window and choose only the video track. Then drop the newly created audio track to the same window and, after adding metadata, subtitles, artwork, and chapters, save the new movie.

It plays properly in the Home Sharing app on my Apple TV.

 

[priitv8]

AC3 surround audio still drops out and AAC 2-channel stereo audio eventually falls out of sync.

The only solution which works for me is to open a new Subler window, drag a movie to it, and re-save.

I have muxed and converted from MKV-s a lot of files, and I have yet to experience the problem you describe.
Have you tried to Optimize the files?
I am thinking, that re-save as new file in Subler will first and foremost runs a new Optimization right after saving.
I am not sure, but it might also re-create some of the atoms and magic cookies.
For example, what I discovered - when you import pure ac3 or eac3 file - then Subler uses a macOS framework to create an audio track from it. And macOS will return a properly formatted MP4 track with all atoms and magic cookies set properly. Even the DD+ Atmos parameters are set correctly.
During import from MKV it parses the (E)AC3 track and builds the cookies by itself.

Until a better solution presents itself I'll extract audio from an original movie file using FFMPEG...


ffmpeg -i input.m4v -vn output.eac3

...or...

ffmpeg -i input.m4v -vn output.ac3


...and assemble things using Subler.

For instance, drop an .mkv movie into a new Subler window and choose only the video track. Then drop the newly created audio track to the same window and, after adding metadata, subtitles, artwork, and chapters, save the new movie.

It plays properly in the Home Sharing app on my Apple TV.

It is a lot of work.
I always just drop the whole MKV into Subler, select the tracks I need and let it save.
Never noticed a problem with them.
Then again, I also have not installed the 14.5 beta. I am waiting for the official release.