I read this in other topics and it is not accurate, at least in my testing.
Example:
- I put a movie on my server.
- The movie file includes two audio tracks: a 5.1 AC-3 track and 7.1 TrueHD Atmos track.
- I use FFMPEG to downmix the 5.1 track into a 2.0 Stereo AAC track with metadata tags marking it as the default track.
- In mkvtoolnix, I add the new Stereo track and set the track order to have the new 2.0 AAC track as the first audio track, with the “Default” flag set to Yes.
- I include the 5.1 and 7.1 tracks as the 2nd and 3rd audio tracks, and set their default flags to No.
- On playback, the Plex client automatically selects the 7.1 TrueHD track, causing Transcoding, unless the user manually selects the first audio track, which is the Stereo AAC track.
The first audio track that matches my language selections is the Stereo AAC track (Audio track 00 / first audio track). But Plex skips over this, and the second audio track, to default to the third audio track. It does so in clients on Roku TV, PS4, Web player, and Apple TV. My server version is updated and current. I can reproduce the error if necessary.
I started a thread that no one has replied to for this exact issue: Default Audio Track - Player Defaults to Surround Sound track! - #4 by Scoot
