AppleTV Audio Pass Through

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Level 1

11 points

AppleTV Audio Pass Through

Hello All,

I am hoping that posting to this question in the Apple forum will provide me some answers. I've been searching for an answer for sometime. First, here is my set up;

LG OLED 4K SmartTV, dolby vision capable
AppleTV 64GB
STR-DN1080 AVR
All connected with hi-speed HDMI compliant cables

Senario 1 Appletv through the Sony HDMI video out to the LG;

Netflix; atmos, dolby vision working, supporting shows on the AVR indicator and TV as such

Prime; same for many of the supporting movies

YouTube; only 4K video content is preserved, audio pass through as PCM (typically 2.0)

Senario 2 LG through the Sony via optical out for audio decoding, the LG proving the video of course;

Netflix; atmos, dolby vision working, all shows on the AVR indicator show Dolby Digital as streamed

Prime; same for supporting movies

YouTube; same for supporting videos, dolby digital test viseos, dolby videos, etc...

What is it that the AppleTV is blocking, preventing the AVR from receiving a similar audio stream other than "PCM" which seems to default down to PCM 2.0.

I have tried friends receivers, Firestick HD and it seems to be the AppleTV that is the issue.

Any help here would be greatly appreciated.

Apple TV 4K

Posted on Jun 30, 2019 6:10 AM

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Answer 1

Urquhart1244

Level 10

147,256 points

Jun 30, 2019 10:22 AM in response to nmincone

Apple TV can output audio in one of three formats: “Automatic” =best available =PCM Multichannel; Dolby Digital 5.1; Stereo (PCM 2.0). The latter two are fallback options in case Automatic doesn’t work satisfactory.

PCM can be multichannel; it doesn’t mean 2.0 per se.

There is no passthrough with Apple TV. The content is received compressed (AAC 7.1, DD 7.1, etc.), then decoded or re-encoded to one of the output formats.

I would advise to connect the Apple TV to the receiver, then connect the receiver to the TV using the HDMI ARC ports. No need for optical audio with two HDMI connections. Optical audio does not support PCM Multichannel. The optical audio may be the reason for 2.0 stereo output.

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Answer 2

Urquhart1244

Level 10

147,256 points

Jul 3, 2019 5:47 PM in response to nmincone

For example a Dolby Atmos Demo video played on YouTube through the AppleTV4K shows PCM 2.0 on the Sony AVR.

I haven’t seen confirmation that the tvOS YouTube app is capable of delivering Atmos or surround sound through Apple TV. It may be a deliberate app limitation.

Apple TV should always output according to its settings: Atmos (if available), or PCM Multichannel (up to 7.1), or Dolby Digital (up to 5.1), or Stereo.

But if a third party app gets a 2.0 stream from the internet, then the device can’t do anything about that.

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Answer 3

nmincone Author

Level 1

11 points

Jul 3, 2019 4:57 PM in response to Urquhart1244

Thanks for your reply. The AppleTV is connected directly to the AVR receiver through HDMI and I suppose depending on how the AppleTV4K (tvOS) is progamed to interpret and "decode" the digital audio signals it triggers the AVR respectively.

For example a Dolby Atmos Demo video played on YouTube through the AppleTV4K shows PCM 2.0 on the Sony AVR. The same video played from the LG through to the Sony AVR plays as Dolby Digital Atmos and lists on the AVR as well.

But... if I play a NetFlix Atmos movie, then the AVR (sometimes) shows DolbyD on the AVR...

Is the AppleTV decoding function taking "liberties" with the formats it interprets and decodes?

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Answer 4

nmincone Author

Level 1

11 points

Jul 3, 2019 7:48 PM in response to Urquhart1244

Ah, so if I understand your reply correctly the result I am seeing is not due to the AppleTV decoding programming but most likely the result of different YouTube app capabilities across different devices?

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Answer 5

rkaufmann87

Level 10

148,682 points

Jul 3, 2019 10:54 PM in response to nmincone

That is correct, your Apple TV appears to be functioning fine. I have a similar setup, Apple TV 4K, 2018 Onkyo receiver setup with a 5.1system and a 2018 Samsung 4K QLED TV. I connect my high speed HDMI from the Apple TV to the receiver's streaming box input and then connect the receivers ARC HDMI output to the TV's ARC input. It all works perfectly, audio is governed by what the provider is playing.

Ensure the receiver is setup correctly and you should be fine.

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Answer 6

Urquhart1244

Level 10

147,256 points

Jul 4, 2019 12:06 AM in response to nmincone

Yes, my interpretation of the current situation is that the app in this case gives the 2.0 stream. That and YouTube limitations on any platform. Even the official Dolby channel on YouTube features 2.0 audio.

Try ‘Universe Fury’ or ‘Shattered’ MP4s through Home Sharing for good Atmos sample files, that light up all the right identifiers on your receiver. Video Streams - Sample Media - Dolby Developer

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AppleTV Audio Pass Through

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