Playing Stereo MP3/FLAC Files Produces 5.1 Output With Empty Sub/Center/Surround Channels for AppleTV?

Plex Players Streaming Devices
,
1

Server Version#: 4.63.0
Player Version#: 7.24 (1284)

TL;DR: it seems the Plex for AppleTV app produces a 5.1ch output when playing stereo FLAC/MP3 files. Further, in this output, it seems the Center/Surround/Subwoofer channels are empty. Is there a way to request that Plex produce a 2.0ch output so that a receiver can process that signal and output to its subwoofer (or center/surround speakers) if configured by the user?

New Plex user here… generally working well so far, but I noticed something unexpected today - when I play (stereo) music via the Plex app on my AppleTV 4K Gen2 (which is connected to my 7.2 home theater receiver/speakers), I get no subwoofer output.

I’m confident that my receiver and speakers are capable of 7.1ch sound and that the speakers are properly connected to the receiver. My AppleTV is connected to my receiver via and HDMI cable, and then the receiver’s output is connected to my TV via another HDMI cable.

Here’s what I’ve been able to determine so far:

  • I’m able to play assorted movies in 5.1ch/7.1ch mode with Plex on my AppleTV and my receiver receives all expected channels. Expected sound is heard from all speakers. This works with DolbyDigital, DTS, etc.
  • When playing stereo FLAC/MP3 files, the Plex dashboard shows Audio FLAC (Stereo) or Audio MP3(Stereo)
  • The receiver indicates it’s receiving a 5.1ch input while playing music from Plex-AppleTV
  • The receiver indicates it’s receiving a 2.0ch input when scrolling around the Plex UI in the AppleTV app
  • When playing music via Plex on AppleTV, I’ve tried all the different sound modes on my receiver and I only ever get sound from the front left/right speakers.
  • My receiver has a Multi-Stereo option that will play stereo inputs via all all connected speakers - even in this mode, I only get sound through the front left/right speakers. This makes me wonder if Plex is telling the AppleTV to output 5.1ch sound with audio information only on the FR/FL channels.
  • I also tried the Plex app on my Xbox One X (also capable of 7.1 output to my receiver). It, too, only plays music through the FL/FR speakers, no matter sound setting I use on the receiver. Under these conditions, the receiver reports receiving a 7.1ch input from the Xbox.
  • When I use Plex or PlexAmp on my iPhone and cast to a Chromecast Audio or Chromecast Ultra as that’s connected to my receiver, it produces subwoofer output as expected.** The receiver indicates it’s receiving LPCM 2.0, and all the sound fields work as expected (Multi-Stereo, 2ch, Surround). The Plex dashboard still shows Audio Flac (stereo), but it has an additional line below that indicates Direct Play.

I found this article that discusses Plex Media Player having a configurable option for Direct/Passthrough modes, but I don’t see anything like that in the Plex for AppleTV player settings. Did I miss it somewhere?

Based on what I’m observing, it looks like the Plex app for AppleTV is producing 5.1ch output when playing stereo FLAC/MP3 files and just having empty Center/Surround/Sub channels. If this is correct, why would Plex not just output a 2.0ch signal and let the receiver decide what to do with it? Based on the 2.0ch output observed while navigating the Plex UI, it would seem that the AppleTV is capable of producing a 2.0ch output via Plex, so that doesn’t appear to be the limitation.

2

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.