EAC5.1 Atmos won’t pass through on appletv 4k

Plex Players Streaming Devices
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Server Version#: 1.21.1.3795
Player Version#: 7.11

Did not find a solution for my problem searching the forum and related topics ste six month or older and closed so I hope my post is ok here.

I am running plex on my appletv. When I play any verified atmos eac5.1 title on plex through my appletv it does not pass through as atmos to my denon but is played as multichannel DD surround.

Direct play is on, Atmos is on in appltv 4k setting, subtitles are off (and they are not pgs but srt anyway) and still I get NO atmos. The same titles are immediately recognized as atmos when playing them in plex on my LG OLED.

So why isn’t plex passing this through on my appletv? Driving me nuts! Please help.

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Is your Apple TV connected to your TV or Receiver? It should be connected directly to your receiver. If it is connected to the TV, then the TV must support ATMOS and be able to pass it through to the receiver and this must be done using a eARC channel. Your receiver must also support eARCas well as ATMOS which I assume it does. You will also need to use a high speed HDMI cable.

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Hi, tx for chipping in. It is directly linked to the reciever. Cables are belkin 4k high speed cables as fiund in apple store.

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Check the stream from plex and make sure the audio is not transcoding. Also make sure that the receiver is setup for Atmos. Like on mine if I don’t use Atmos I can use the amp for that Atmos channel for a second output for like outdoor speakers.

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Hi, stream says it plays in original quality. Denon has no other zones assigned, only main zone. Plex server has direct stream and direct play enabled. Plex player 7.1.1 on appletv only has direct play option, which is enabled.

Like i said, appletv+ and amazone prime atmos movies pass sound through without a problem. The exact same tracks play fine on my oled with atmos detected.

Could somebody from plex please chip in?

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I was under the impression that Plex ATV can’t passthrough Atmos. This thread seems to confirm it. What's the status of Dolby Vision + Atmos on Plex? (re: LG WebOS, Nvidia Shield, Apple TV)

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I read that as well. But i was under the impression it did pass through the eac atmos track but not the truehd atmos track. Afteral, the itunes store itself passes through atmos snd so do the amazon prime snd netflix apps.

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Actually I think you are right. You should look through this post

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Tx. I read that as well, but I still don‘t know what else I can do to make it happen. All settings seem to be correct and the eac track is still not includibg atmos when it get‘s to the receiver.

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Did you try with a verified file? Go to https://thedigitaltheater.com/dolby-trailers/ and download the “Nature’s Fury (Dolby Digital Plus ATMOS)” clip. It should work on your setup. Are you using subtitles in your movie?

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The file is verifief in the sense that my LG OLED recognizes and plays it as atmos.

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I’m not an expert on this and frankly this whole subject confuses me. What I can say is for my setup, ATV4HD → Sony STR-DN1050, everything I play has only ever shown up as LPCM. It is my understanding that this is normal behavior and not necessarily wrong. The Dolby Apple TV support page mentions as much:

When a user plays media with stereo or multichannel audio (including Dolby Digital Plus and Dolby Digital audio), the audio soundtrack is decoded to two or more PCM channels (uncompressed digital audio) before it is sent to the AVR or other downstream device.

It is important to keep in mind that while the Apple TV supports Dolby Digital Plus, this does not mean the Apple TV is necessarily sending a Dolby Digital Plus bitstream over its HDMI® output. After it decodes the Dolby audio, the Apple TV sends the audio to your receiver via HDMI; how it sends the audio depends on the Apple TV settings as well as the capabilities of your HDMI-connected device.

Assuming that your AVR is capable of receiving 7.1 channels of audio, and assuming that the content that you are playing includes a 7.1-channel Dolby Digital Plus audio soundtrack, you will then see that your receiver is receiving multichannel PCM audio from the Apple TV, and the receiver should indicate that 7.1 channels are detected. This carries the 7.1-channel audio decoded from the Dolby Digital Plus audio track. The only difference is that it is being sent to your receiver as multichannel PCM audio and not as a Dolby Digital Plus bitstream.

Now how Atmos plays into all this I don’t know, but I assume it can be transferred over PCM too? So your avr showing PCM is not necessarily wrong?

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It is wrong. As I understand ftom fora atmos is only transmitted by EAC or truehd. PCm will not maintain the extra atmos metadata. My Denon AVC-X8500H shows atmos tracks as „Multichannel DD surround“.

Maybe Plex is not able to pass through EAC atmos yet. I know infuse is. So could somebody from plex please confirm whether or not it can output eac atmos on the appletv 4K over hdmi?

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Actually, Atmos metadata can be transmitted via LPCM, by using Dolby MAT 2.0. This is in fact the only way that the Apple TV transmits Atmos data. All DD+ content is decoded on device, the user interface sound effects are put over top and the final output it sent out as multichannel LPCM, with Dolby MAT 2.0 for Atmos content. The Xbox uses a similar method.

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