Apple TV 4K Direkt Stream DTS-HD MA & Dolby Atmos (Digital Plus 7.1)

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Why it is not possible to play movies with DTS-HD MA or Dolby Atmos audio track (mkv) with Direct Audio Stream? (Plex Dashboard shows Direct Stream)
Apple TV 4K always transcode it to PCM 5.1 (not at all 7.1)! If the movies has an audio track of Dolby Digital Plus 7.1 it also reduces it to 5.1!
Infuse plays the movies correctly and Apple TV 4K outputs the sound in DTS-HD MA and Dolby Atmos, why it does work with Infuse? For me this means that it is not the Apple TV but the Plex Player.

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The Apple TV does not natively support mkv files, so with Plex it has to be converted to an mp4 file. The Apple TV can only passthrough 7.1 audio when the file is being direct played, not when direct streamed. So because of these 2 issues, you cannot get 7.1 audio out of these files with Plex.

Remux your files to mp4 and it should work.

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@anon18523487 I had not noticed that MKV’s Direct Stream in Plex (on the ATV). I’ve learned something new!

As for DTS-HD MA and TrueHD, I’ll refer to a recent post I wrote:

So while Infuse plays TrueHD files, it does not play TrueHD Atmos. Apple will need to support Dolby MAT 2.0 in order for that to happen.

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Your post is correct. Infuse will decode the 7.1 audio locally using software so it doesn’t matter what the hardware supports.

Actually, I might be slightly wrong about the mkv thing. That ability might have been added with Plex’s enhanced player, I can’t remember. So maybe op just needs to turn that on? Maybe?

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I just tested a few MKV files with 7.1 audio. I currently only have my system set up for 5.1, so I cannot attest to the downmixing claim.

What I found:

  • When playing an MKV file with 7.1 TrueHD, the video Direct Streamed while the audio transcoded to FLAC.
  • When playing an MKV file with 7.1 DTS-HD MA, the file Direct Played (so while I only have 5.1, it still direct played the 7.1 track.)

The new enhanced player (which is now avaliable to everyone by default) adds support for MKV.

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I use the enhanced player, “Use old player” is turned off.
My Receiver is able to decode Dolby Atmos, True HD, DTS-HD MA, Dolby Digital Plus/Vision and so on. When I use the AppleTV+ app, the sound is Dolby Atmos 7.1 (EAC3), the same file downloaded & played in Plex is EAC3 5.1 (no Dolby Atmos), the same file with Infuse is Dolby Atmos 7.1 (EAC3) like the AppleTV+ app play it. So it seem to be a problem of the Plex player. The same is with DTS-HD MA 7.1, Dolby Digital Plus 7.1 on so on, the Plex app plays only 5.1. I know that Atmos True HD 7.1 doesn´t word, Infuse play it as PCM 7.1, Plex transcode it to FLAC.

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Yes, Infuse can pass through EAC3-Atmos. Plex app cannot yet.

Plex transcodes TrueHD to FLAC on the server, then on the AppleTV transcodes again to LPCM. But on my Denon, shows as receiving 7.1. TrueHD transcode is the only way to get 7.1. As you’ve noted DTS-HDMA plex only pulls the core 5.1, it’s probably licensing expense.

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TrueHD-Atmos 7.1:

  1. PlexServer discards Atmos metadata
  2. PlexServer transcodes to FLAC
  3. Plex Client/Player on AppleTV transcodes FLAC to LPCM 7.1
  4. My Denon receiver receives the LPCM 7.1, and downmixes to the 5.1 I have hooked up.

DTSHDMA 7.1

  1. PlexServer DirectPlays
  2. PlexPlayer converts to LPCM 5.1 (probably using the embedded DTS core)
  3. Denon receives the 5.1 LPCM.
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Yes, that’s what I also found out. I hope that, one time, PLEX player plays audio tracks as well as infuse, because the PLEX app interface is much user-friendly & I love it! :slight_smile:

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