Does the ATV 4K pass DD+ over ARC?

[steve62388]

I have a LG B7 tv that supports passing DD+ over ARC. I have a Yamaha YSP-2700 sound bar.

When I use the internal apps of the TV it passes DD+ over ARC and my 2700 shows DD+.

But I can’t seem to get my ATV 4K to pass anything other than DD.

 

[Audit13]

The apple tv uses the TV's edid to determine the audio signal to be passed to the TV and, in this case, the TV's edid indicates dd only. Same thing happens with my lg c7.

 

[priitv8]

The apple tv uses the TV's edid to determine the audio signal to be passed to the TV and, in this case, the TV's edid indicates dd only. Same thing happens with my lg c7.

Not exactly.
Current tvOS on aTV never outputs genuine DD+ signal. That is the problem.
It will decode all audio into PCM (multichannel if possible) and manages to include Atmos metadata in the same stream.
Multichannel PCM is too much for current ARC (same capabilities as optical TOSLink : stereo PCM, DD5.1, DTS5.1).
However, aTV is able to internally re-encode audio output to DD5.1 (for compatibility) if you tell it to, in Audio Options.
That's why DD5.1 is the only Dolby bitstream, that can emanate from it's HDMI and TV-s are able to pass it through to ARC.

Source of my information: https://developer.dolby.com/blog/dolby-audio-support-on-apple-tv/

 

[steve62388]

The apple tv uses the TV's edid to determine the audio signal to be passed to the TV and, in this case, the TV's edid indicates dd only. Same thing happens with my lg c7.

Hmmm... Why wouldn't LG change this when they updated the firmware to pass DD+ over ARC?
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Not exactly.
Current tvOS on aTV never outputs genuine DD+ signal. That is the problem.
It will decode all audio into PCM (multichannel if possible) and manages to include Atmos metadata in the same stream.
Multichannel PCM is too much for current ARC (same capabilities as optical TOSLink : stereo PCM, DD5.1, DTS5.1).
However, aTV is able to internally re-encode audio output to DD5.1 (for compatibility) if you tell it to, in Audio Options.
That's why DD5.1 is the only Dolby bitstream, that can emanate from it's HDMI and TV-s are able to pass it through to ARC.

Source of my information: https://developer.dolby.com/blog/dolby-audio-support-on-apple-tv/

So plugging my ATV > 2700 >B7 should get me DD+? I was hoping to avoid this. Thank goodness the 2700 supports DV pass through.

 

[priitv8]

So plugging my ATV > 2700 >B7 should get me DD+? I was hoping to avoid this. Thank goodness the 2700 supports DV pass through.

Yes.
I have all my sources connected to AVR and only single wire goes to TV from there.

 

[steve62388]

Yes.
I have all my sources connected to AVR and only single wire goes to TV from there.

How do you cope with different display setting profiles for different devices since it's all on one input?

 

[Audit13]

How do you cope with different display setting profiles for different devices since it's all on one input?

One input can have a unique display profile for SDR, HDR, and DV.

 

[Sakurambo-kun]

This is one of my major peeves with the ATV. If it can internally decode a DD+ stream, why can't it send it over HDMI? Forcing it into PCM completely breaks ARC. How can Apple not have known this?

 

[priitv8]

How do you cope with different display setting profiles for different devices since it's all on one input?

I don't. I have Cinema Pro for all my sources. For visuals, I only have 3: IPTV set-top-box, aTV and bluray player.
HDR and DoVi adjustments are stored & remembered separately, as Audit13 mentions.

This is one of my major peeves with the ATV. If it can internally decode a DD+ stream, why can't it send it over HDMI? Forcing it into PCM completely breaks ARC. How can Apple not have known this?

ARC (the current one) is a sad artefact anyway, so why bother?
Official explanation as to why not pass through the bitstream - they want to add Siri and system sounds into the mix.
Also, the DRC that they do, demands decoding. Otherwise you'd need to fiddle controls on AVR.
Although I don't think, Siri even talks on tvOS.

 

[steve62388]

Right. So can I use pass through and ARC?

I'm thinking pass through for Apple TV because I want the best sound for my films. But ARC for my games console so I can use different display settings. Or will that confuse the system?

 

[cynics]

This is one of my major peeves with the ATV. If it can internally decode a DD+ stream, why can't it send it over HDMI? Forcing it into PCM completely breaks ARC. How can Apple not have known this?

With certain exceptions ARC in general does not support DD+, at least not at its full potential.

Audio passed through is encrypted. The ATV needs an unencrypted audio track to add system sounds that certain functions and features require. For example Siri responding needs to be injected into the audio.

 

[Michelasso]

This is one of my major peeves with the ATV. If it can internally decode a DD+ stream, why can't it send it over HDMI? Forcing it into PCM completely breaks ARC. How can Apple not have known this?

I never tested it but I was quite sure it did. In the ATV audio setting you can choose to send out the audio signal as Digital Dolby 5.1. I believe that carries the DD+ format as well. Or maybe not... I see now that this Apple technote makes me think otherwise, only DD 5.1 apparently. But at least you'll get real surround, the ARC may limit the LPCM, sending out only stereo.

How do you cope with different display setting profiles for different devices since it's all on one input?

I don't know about the LG, but my Sony Bravia has different profiles for each device connected to my AVR, which has the HDMI OUT/ARC connected to the TV (so when watching from an app in the TV it returns to my AVR up to DD+ 5.1). It doesn't always work because the OS is a piece of junk (Android and quite bugged), but usually I have my PS3 and PS4 on Game Mode and the ATV 4K on normal (automatically switching to Cinema Home when the video is at 23.9xyz fps). Also the picture mode for the two Game Modes settings are different between the two consoles (because I chose so). It's just that sometimes it goes banana and gets the wrong profiles.. Unplugging the TV (hard reboot) usually helps.

In any case, if a sound bar/AVR has more than 1 HDMI port I strongly suggest to use one HDMI IN for the ATV. Passing through the TV causes many of these issues. That's why I spent a bit more and got an AVR with 4+1 HDMI ports (for that and for the real satellites).

 

[RomanEmpire]

Hi, I have a similar Question: I have an appleTV 4k connected to an LGE7n - which supports Dolby Atmos (internal speaker).
Will I be able to watch iTunes movies with Atmos support or is there any limitation through HDMI 2.0?

 

[steve62388]

Hi, I have a similar Question: I have an appleTV 4k connected to an LGE7n - which supports Dolby Atmos (internal speaker).
Will I be able to watch iTunes movies with Atmos support or is there any limitation through HDMI 2.0?

There really won't be any point using the internal speakers for Atmos.

 

[RomanEmpire]

There really won't be any point using the internal speakers for Atmos.

Can you please explain why?

 

[priitv8]

Can you please explain why?

There are too few of them. Does this TV have any upfiring or ceiling speakers?
Height channel is the main thing Atmos brings to DD+ 7.1 setup.
How does your TV provide surround channels? Some sort of virtualisation?

 

[RomanEmpire]

There are too few of them. Does this TV have any upfiring or ceiling speakers?
Height channel is the main thing Atmos brings to DD+ 7.1 setup.
How does your TV provide surround channels? Some sort of virtualisation?

it‘s def. virtualisation, since there‘s only a single soundbar under the tv

 

[Sakurambo-kun]

I never tested it but I was quite sure it did. In the ATV audio setting you can choose to send out the audio signal as Digital Dolby 5.1. I believe that carries the DD+ format as well. Or maybe not... I see now that this Apple technote makes me think otherwise, only DD 5.1 apparently. But at least you'll get real surround, the ARC may limit the LPCM, sending out only stereo.

If the ATV is set to output DD5.1 then that's all you get. DD+ streams are downgraded to regular DD, and they sound pretty crappy.
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With certain exceptions ARC in general does not support DD+, at least not at its full potential.

Audio passed through is encrypted. The ATV needs an unencrypted audio track to add system sounds that certain functions and features require. For example Siri responding needs to be injected into the audio.

If they're crippling bitstream output just so they can add system beeps that really is beyond ridiculous. Siri is completly silent on TVOS so there'd be nothing lost there.

 

[cynics]

If they're crippling bitstream output just so they can add system beeps that really is beyond ridiculous. Siri is completly silent on TVOS so there'd be nothing lost there.

Sorry you are correct about Siri. And I was incorrect saying DD+ isn't supported over ARC. DD TrueHD isn't supported over ARC is what I meant to say.

Regardless its not just system sounds but things that require audio adjustments/enhancements like any audio syncing or reduce loud sounds or AirPlaying audio to other devices like headphones, HomePods, etc etc. Plus other apps like games, or an app that doesn't use Apples player like youtube.

I wouldn't say Apple is crippling anything, keep in mind its a streaming box. Atmos sources are coming from an already lossy DD+ stream. I don't have the beta nor does it seem "ready" by most accounts however you'll find on Dolby's page.....

If the stream is transcoded (not sure how that is possible however DD differs quite a bit from DD+ in the way audio is handled) I would imagine we would need to ditch ARC. However DD+ over ARC is possible with a TV that supports it.

Currently Netflix doesn't support Atmos for the AppleTV so its not an option if you go looking. I believe Atmos in iTunes is like HDR, if you don't have the hardware you can't see the option. This is an image from someone with Atmos on tvOS Beta 12.

 

[priitv8]

This whole ARC vs DD+ Atmos story is irrelevant as long as tvOS decodes Atmos into PCM. For multichannel PCM bandwidth requirements eARC will be needed.
Also EDID of the TV will need to declare Atmos capability for tvOS to enable Atmos option in A&V Settings.
Finally, modern flat TVs in general don’t have good audio systems anyway, so you’ll be much better off with a Atmos and HDR capable audio system and passing aTV through audio system to display, not vice versa.

 

[jetjaguar]

on my receiver it always says multi channel in when playing anything thru apple tv .. on shield however it says truehd .. etc