So I modified the tvOS.xml profile to have the server feed Dolby Digital Plus (eac3) to the Apple TV. And it mostly just works…in some cases!
Cases where it works:
1. Direct Playing. If the video is 8bit h264 with a single eAC3 5.1 track, I have gotten it to reliably work with multiple files.
Cases where it doesn't:
1. Direct Streaming both Video and Audio (i.e. remuxing from mkv to a container Apple TV likes).
2. If the server has to transcode the video and attempts to direct stream the audio: video plays as expected, but audio remains silent. Cases where the video track has to be transcoded: hevc, 10bit, ssa/ass subtitle display.
3. If the server has to transcode the audio (from flac, dts-hd, truehd, etc), it prefers to do so in ac3, even though eac3 has replaced it the tvOS.xml profile.
Basically if Plex needs to do anything to the file to get it to play, eAC3 playback fails.
I know that this is unsupported, but are any of the devs able to tell me why it is failing? Are there plans to address this/fully support Dolby Digital Plus? DD+ is more efficient, allows for more channels, and a higher bitrate so I am eager to be able to switch over to it for my ripping workflow. Since it seems mostly feasible and decoding is supported by both Apple TV's native AVPlayer stack and my AVR, I don't see why this shouldn't be implemented. I can only assume time was the limiting factor here since you had to ship this excellent 1.0 in such a short amount of time.
Thanks for your time!