AppleTV 4 surround sound issue

No it is not as I stated in my post it is set to "full dynamic range".

I already have an open support ticket to apple with this problem there investigating the issue, I was escalated to a supervisor who said he can duplicate that the full dynamic range is not being output by the ATV 4

No it is not as I stated in my post it is set to "full dynamic range".

And as I previously asked, "What is your TV4 global 'Reduce Loud Sounds' setting?" I.e., the "Audio and Video > Reduce Loud Sounds" setting found immediately below the "Audio and Video > Surround Sound" setting. This setting is either "Off" or On."

For now I went back to previous settings with regards to my 7.2 home theater setup since no actual 7.1 content is availabe through Netflix and only one crappy movie throug iTunes.

ATV set to surround so the receiver sees Dolby Digital AC3. Then to make sure my surround back hannels get sound provisioned I set my receiver to: Dolby Digital + Dolby Prologic IIx.

For now I went back to previous settings with regards to my 7.2 home theater setup since no actual 7.1 content is availabe through Netflix and only one crappy movie throug iTunes.

Same here. In addition, I just posted product feedback and developer bug reports regarding the potential "sticking" of AC3 1.0 and 2.0 content output in the 2-ch PCM mode after using the "Auto" settings for such content. It appears the TV4 won't restore "passthrough" functionality in the "Dolby Surround" mode until a valid DD5.1 (or I assume a DD+7.1) signal is detected.

Then to make sure my surround back hannels get sound provisioned I set my receiver to: Dolby Digital + Dolby Prologic IIx.

I activate DD PL II manually in the "Auto" mode to restore AC3 mono center channel, 3-channel front, and "rear surround" audio if present since the tvOS v9.0.1 outputs the AC 1.0 and 2.0 audio as 2-channel PCM which now bypasses automatic Dolby decoding. The "Dolby Surround" mode seems to work fine on its own once I force it back into "passthrough" operation.

Not sure if the v9.0.1 change to "Auto" mode functionality was supposed to fix Dolby problems I never had or if it is to prevent the incidental tripping of Dolby decoding as reported by some users. In either case it sure has messed up my use of the "Auto" setting.

Regarding your issue re: AAC 2-ch Stereo vs AC3 5.1 Surround (Pass-thru), I have videos encoded the same way using Handbrake. Like you I have to make sure to switch which audio track is being used while playing the video. This is disappointing because the Apple TV 3 would automatically choose the better AC3 5.1 Surround when presented with both type of audio. I'm going to consider this a bug and submit it as such to Apple. Hopefully they will fix it and return the behaviour of previous Apple TVs.

As for outputting the "Full Dynamic Range," I believe it is in fact doing that but there is a audible difference in the loudness when switching between the 2-ch stereo track and the surround track, the 2-ch track is played louder. There is only a slight difference when switching between "Reduce Loud Sounds" and "Full Dynamic Range" in both the 2-ch and surround settings but it is there in both.

Exact same issue! This shouldn't even be a bug... hopefully Apple release update soon.

No again reduce loud sounds is not on in the audio menu and under the info menu it is set to full dynamic range. I have a ticket into apple on this issue they were able to duplicate it. I am waiting for a reply from there engineering group and have a call back scheduled for tomorrow.

The difference is when playing back AC3 5.1 tracks from the same movie and from the same sequence. I can switch back to my ATV 3 and play back the same AC3 5.1 track at the same part and the difference is dramatic. I have a ticket into apple which was escalated to there engineers, I am waiting for a call back scheduled for tomorrow. The person I talked to said this definitely sounds like a bug and would probably have to be fixed in an update to tvOS. He can duplicate it by the way.

Just finished some testing after emailing with programmer of 'Theater Test' application. Finally (after update) this app seems to work and proofing evidence of 8 channel playback via ATV 4. With both ATV4 and receiver set to 'auto' for decoding mode, the receiver receives a 7.1 LPCM stream NOT a DD stream. With that setup I am able to test ALL 8 channels of my surround system accordingly.

Via some research I found that LPCM is sent by the ATV after decoding the stream. If ATV4 was able to pass-trough the DD+ signal it would show DD+ at my receiver. This IS the case when setting ATV audio to 'surround'. In that case however only DD 5.1 is sent to the receiver (shows in the display).

This proofs that ATV4 for now is not supporting DD+ in pass through mode. I guess (hope) this is a software issue.

Too bad I do not understand all the tech-speak in this thread, but this is the text of a report I sent to Apple:

I have lots of Dolby Digital 5.1 surround movie content which has always played properly on previous versions of Apple TV 1, 2 and 3. By playing properly I mean that the A/V receiver shows 5 speakers active - center, left/right front, left/right rear and SW with LFE effects. But with ATV 4 All I get are left/right front (and possibly center, I actually do not recall as I type this).

The connections between ATV, the A/V receiver and the TV have not changed, and I can replicate the issue by simple swapping in and out an ATV 4 and an ATV 3: with ATV 3 all speakers “work” but with and ATV 4 in place I only get stereo (or as I mentioned, possible a center as well).

The setup is simple and has been in place for years:

. ATV connects to A/V receiver via HDMI

. TV connects to A/V receiver via HDMI

I see lots of comments on this issue. If I switch to a non-ATV source DD 5.1 works fine, it’s only ATV 4 that appears broken. I have gone into Setup and the only audio setting that seems relevant is to switch from Auto to Surround, but that does not appear to have an affect.

And yes, all the 5.1 content has AAC and AC3 passthru, if I am speaking the jargon correctly.

Steve Lidie wrote:

Too bad I do not understand all the tech-speak in this thread, but this is the text of a report I sent to Apple:

This is a known difference. It may be a bug or simply a poorly documented change. tvOS 9 selects the first soundtrack. iOS 8 on the ATV3 selects a 5.1 (AC-3) soundtrack if one is available (or is in the first n soundtracks).

If Apple feels that consumer sourced video content should stereo (say from your iPhone) or that such content should be flagged the same way Apple does it then it's poorly documented. If someone has a statement from Apple that the way the ATV3 works is the "right" way then it's a bug. I'm guessing that the previous behavior is like using a private API. When it stops working it's not a bug.

OK, that I understand, thanks. What I do not know how to do is ensure the 5.1 audio track is first .. does that mean, somehow, re-Handbrake every media item?

Steve Lidie wrote:

What I do not know how to do is ensure the 5.1 audio track is first

You could reconvert the original with Handbrake but I'm sure it would much faster to demultiplex the file and remultiplex the tracks in the desired order. I've never done this but perhaps subler or ffmpeg can remux without (re-)transcoding.

bodosom, thanks for pointing us in the right direction. Subler will fix this issue by changing the default audio source in the video file and it does it without transcoding.

First, for those who need it, Subler can be found here: https://bitbucket.org/galad87/subler/wiki/Home

Once you've downloaded and installed the app launch it and make some changes to the preferences (see screen capture below.) I do this because I don't want to convert any of the audio.

Next open a video file in Subler. You'll notice that the AAC 2-ch Stereo track is the default.

Deselect the 2-ch and select the surround track of your choice. In my case I chose the only one available, the AC3, 6-ch, which is the 5.1 channel Dolby Digital surround track.

Now save the video and test it on the Apple TV.

SOB. The Subler trick worked perfectly. Many thanks. I verified that you can simply have Subler Save the original in the iTunes Movies folder too, so it's (relatively) efficient to use this technique on all the media files. Still a PITA, but at least ATV 4 is no longer relegated to the dungeon of shame and non-use.