Having audio problems in Plex on Xiaomi Mi Box with Oreo

by vnenov

I’ve finally received the Android Oreo update on my Xiaomi Mi Box. My AV receiver is old, so I use the SPDIF output from the Mi Box to the SPDIF in on the receiver.

Before the Oreo upgrade DTS and Dolby Digital were not possible even with the Pass-through Auto option enabled in Plex and Mi Box set to output RAW on SPDIF. However, DTS and Dolby Digital worked in Kodi 17.6.

Now if I set the Mi Box to Sound -> Surround “Always” and Plex Pass-through to Auto to force the device to pass-through digital audio it works for both Dolby Digital and DTS without transcoding. However, I get no audio on regular programming with AAC sound.

If I switch Mi Box to Auto then AAC audio works, but no audio on Dolby Digital and DTS. Same if I turn off the Plex Pass-through Audio option to No. Neither Mi Box or Plex have detail settings what to pass-through and what not, like Kodi has.

Any idea if this is something that can be addressed by Plex update to add additional options instead of just “Auto” pass-through? Or this is something that should be fixed by a future Mi Box update?

BiggussDikkuss

Simple solutions:

Use Kodi and tick the transcode to AC3 audio option. Kodi also has a Plex for Kodi Addon.

Use the MrMC App that also had the transcode to AC3 option. That App had built in Plex (& Skin) support. Excellent FFWD and RWD capabilities as well.

GldRush98

Yeah, something is wrong. AAC 5.1 isn't playing the voice channel, even with transcoding it still isn't playing it. I can flip over to my Chromecast and it works fine. I tried several files with AAC 5.1 and they all exhibited the same behavior.

This is a problem with the Mi Box, not Plex.

cfoucher

Interested in this as well as I am facing the same issue.

svogon

What does your receiver accept? Usually it'll be Digital Dolby (AC3) and/or DTS. Any other format sent over SPDIF "raw" usually won't produce audio.

Bodycount9

yes i'm going through this also.

I had two options because I know Plex wouldn't bother with a fix and Xiaomi wouldn't bother with a fix:

  • Buy a new receiver that uses HDMI audio processing or can process AAC sound.
  • Convert all my movies and TV shows to AC3.

So I took the second method because I'm a cheap ass. Found the freeware program Xmedia Recode and I'm slowly converting all my AAC 5.1, DTS 5.1 and AC3 5.1 to AC3 5.1 640 kbps. This lets me hear digital audio on all my Plex media and it also helps my remote users so they have a better chance of direct playing my stuff. Apple TV doesn't like DTS. AAC 5.1 doesn't even work and Plex will always transcode it to 2.0 stereo.

I started on Tuesday and so far I have about half my movies done. It's also letting me edit out the foreign audio tracks which I don't need so I'm saving some hard drive space.

vnenov

Just an update and correction. There is no problem with regular AAC files, so I was mistaken.

The issue with no sound is with the EAC3 (Dolby Digital) files as my receiver does not support pass-through of EAC3. Still Plex client does not allow us to set transcoding of EAC3.

I have tried creating a custom Android xml profile to force the transcoding, but unsuccessful.
If somebody knows how to force Plex to transcode EAC3 to AAC, please let me know.

The workaround for now is to transcode EAC3 to AAC using ffmpeg and script and I would like to avoid that.

My Plex server is capable of transcoding, but I don’t know how to force that for EAC3.

AndreLuisOS

Same...