Tl;dr: Unless I force stop Plex and clear cache, soundbar only plays in stereo. If I jump through hoops first, the soundbar indicates it is playing EAC 3, DTS, etc.
I have a Mi Box S connected to a Sony ht-st5000 feeding an LG B7 via ARC. The soundbar has two HDMI ports to support both the TV and the Mi Box.
I am running the latest PMS for Windows and the latest version of Plex for Android. Plex is set to pass through compatible audio via HDMI. The Mi Box is set to spdif output. I’m not sure if it makes a difference if the Mi Box is set to Auto or if the audio formats are selected manually.
CEC is also giving me trouble. Once all 3 devices are turned on, the LG remote will control Android TV and Plex. However, if I use the tv remote to power on, the soundbar doesn’t also turn on. But if I wake the Mi Box from sleep with the Xiaomi remote, all 3 devices turn on correctly. And usually if I put the Mi Box to sleep first, the tv and the soundbar also shut down. But CEC has been almost more trouble than it’s worth.
Any tips on how to get this setup to work more consistently? FWIW, I also have a Mi Box 3 I could use if it makes any difference.
Why is the Mi Box set to SPDIF output when it is connected to the soundbar via HDMI?
What are the configuration choices for the Mi Box?
SPDIF supports playback of AC3 & dts up to 5.1 channels and PCM 2.0. It does not support EAC3. Configuring the Mi Box for SPDIF compatibility may restrict what audio formats the Plex app can direct play.
What happens if you use the Plex app on the LG B7?
It should direct play AC3/EAC3/dts audio up to 5.1 channels, including EAC3 + Atmos. TrueHD will transcode, as it cannot be sent via HDMI-ARC.
Test with subtitles disabled. The Plex LG app has limited subtitle support. Enabling subtitles can result in a video transcode.
You can monitor playback via Plex Dashboard → Now Playing. It will show if the video or audio is direct playing, direct streaming, or transcoding.
