Playback issues possibly related to audio - Firestick 4k max gen2

Plex Players
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Server Version#: 1.43.1.10611
Player Version#:10.30.9.4262 (067590FF)

I have a Firestick 4k max gen2 plugged directly into a Denon X3700h AV receiver (with the included hdmi extender that came in the box).

I have been experiencing issues primarily with HEVC videos but it also to a lesser degree affects H264 videos. A lot of media I watch are 4K HDR or Dolby Vision, many of these have multi channel EAC3 audio with dolby atmos. I’ve experienced patchy behaviour on both .mkv and .mp4 containers.

Behaviour 1: If the media is 4K HEVC has EAC3 and has a subtitle track enabled (most commonly .srt) then it will often display error message “Unable to play media”. However on the odd occasion it will direct play fine with no issue.

Behavior 2: If the media is 4K HEVC has EAC3 audio with no subtitle track selected, then it will sometimes display “An Error occurred while attempting to play this video. Please check your connection and try again.” Now when this happens often the TV has triggered dolby vision mode, spam clicking the “OK” button to try again quickly will often make the video direct play but PLEX will use the c2.dolby.eac3.decoder on the audio which seems to decode the audio to stereo and you lose the atmos information.
Now sometimes it will transcode, it will say that direct play was attempted but failed and it is falling back to transcoding. Sometimes it will say copy(hevc), copy(eac3), but sometimes it will do a hevc → h264 transcode. Fixing this is relatively simple - you enable subtitles (or flick it on an off) and it will magically direct play without needing to exit the player.
On the odd occasion it will direct play fine with no issues. However I will point out that I also get this error with 4K HEVC with AC3 audio too with same behaviours exhibited.

Behaviour 3: on very rare occasions I’ve found direct playing constantly drop frames or subtitles not displaying which required a restart of the firestick, I’ve only had to do this twice.

Now TRUEHD audio seems to be a bit better behaved, it won’t fail out right but video may fall back to transcoding and may need the quick fix of enabling or disabling or switching subtitles. The same goes for DTS audio. However other formats like FLAC and OPUS will direct play with no issues, I’ve never encountered falling back to transcoding or an error message with other audio formats with or without subtitles enabled. I also created a 4K HEVC file with subs but no audio and this also direct played with no issues, with or without subs enabled.

Things also seem much better behaved when switching directly between episodes or using the continue watching screen at the end of an episode to watch the next one.

I have tried HEVC video with EAC3 stereo audio, I’ve never seen it fail outright but it will often fall back to transcoding before fixing itself if you flick the subtitles.

HEVC files have a risk of failing to play outright but when playing back h264 files with eac3 audio I also sometimes find it falls back to transcoding and requires enabling or disabling or switching sub tracks to fix it and make it direct play.

2

I’ve also had trouble with some videos with subtitles in the mkv files. My firetv had random troubles and my brother had many issues with his apple tv as well. We also saw some playback issues with different audio formats as well.

I wrote a script to take all the subtitles out of the .mkv file and put them in the folder as external files and I have had no issues since. Strangely enough, removing the subtitles from the mkv file seemed to also help with the truehd audio issues I was having.

No idea if it would help you, but it would be easy to extract them on one causing issues and see if it helps.

3

Not exactly the same issue but there is definitely some weirdness going on with audio since I’ve updated to the new experience. I have my firestick plugged directly into a vizio soundbar and have no issues with any audio formats on the old app. Since the update I am unable to hear anything for any DTS-HD audio that should be playing as DCA and played fine on the old app. Normal just DTS tracks work fine on the new experience still. Nerd statistics show passthrough and DCA but just no audio at all for any dts-hd/dts-hd-ma ive tested so far. I even tried changing from passthrough to disabled in the settings but that didnt work either and im not sure the setting changed anything even though it showed disabled in my settings — nerd statistics still showed passthrough DCA.

4

Just a small update to this.

Instead of plugging into my receiver I plugged directly in my LG CX. While the behaviour was better it wasn’t completely solved.

Dolby vision mp4s with mov_text subtitles played flawlessly more often than not. The odd time it may transcode which is fixable by switching subtitles.

MKVs with .srt subs selected has mixed behaviour. It will sometimes do a h264 transcode and sometimes it will direct play. This is fixable by flicking the subtitles. The odd occasion it will have error message of “unable to play media” same as before.

MKVs without a subtitles track selected will play, sometimes it may “transcode” with copy(video) copy(audio) and sometimes it will direct play. Transcoding is fixable by flicking subtitles. The error that used to plague this (An Error occurred while attempting to play this video. Please check your connection and try again.) has seemed to have gone away.

I would prefer to keep it plugged into my receiver especially since the issue isn’t completely solved by plugging into my TV and there is still wonky behaviour.

I have created a file with no eac3 audio track and they direct play every time. I have created file with no subtitles tracks in the file but with eac3 and I still got the error message while plugged into the receiver.

I tried installing Kodi with PM4K and all the files there play perfectly fine even with the firestick plugged into my receiver. Preferably I still want to use the Plex client since I don’t want to go through the pain of fine tuning Kodi settings.