Reproduce: Media file should be AV1 video + AAC/OPUS (7.1 ch) audio. Plex will not play any audio (while falsely claiming it is). If any alternate audio track exists (5.1 ch or less), it will play this (while falsely stating it’s not). It is not possible to play the main 7.1 ch track with AV1 by any means, AFAIK. Direct Play is set to auto (forced will play no audio at all).
Notes: Obvious when alt track is very different (commentary, score only, etc). HEVC with 8 ch plays fine. All videos with 6 ch audio or stereo play fine. Will be testing more soon, more details will be edited in. Just wanted to get this topic started, as this problem endures.
Updates: It seems Roku was the problem. More here (Reddit, since this topic was closed). Jellyfin on Roku would not play either (actually reliably crashed it, lol). Finally switched back to Android (ONN Google TV 4K Pro 2024) and… amazingly Plex now plays all-the-things! (Almost: AV1 UHD HDR Direct Plays fine! Some others have issues for now.) Tips: Switch to Dolby Vision “low latency” mode (12 bit YCbCr 422), not “standard” (8 bit RGB 444). Check separate GTV volume (set low at 80% by default).
Bonus: I hate that topics are closed after only 90 days. Frustrating and unhelpful.
How do you know that a non 7.1 track is playing when Plex shows a 7.1 track playing? What does your dashboard (and receiver) say is being played?
What order are the audio tracks in? For example the Xbox has a BUG where if a DTS or Atmos track is not the first track there will not be any sound from that track. But other tracks would play just fine. It took me a long time to figure this out and even longer to rearrange everything to make it work.
Audio track is known because it is commentary, or something else obvious. Plex on Roku (and Plex Dash on Android) shows it playing main 7.1 track. No audio will play at all if it is the only audio track (but still states it is playing). It is first audio track (MKV).
Tested HEVC, plays fine with 7.1 track as expected. So this problem is only with AV1. It’s had a rough time with Plex on Roku, needed Direct Play on forced until very recently, never has played with 7.1 audio (I thought the cause was DP forced, apparently not).
