slow audio-desync buildup on android/fire tv and dts-hd

[syxlox 0]

embyserver.txti run a debian 12 server with version 4.8.11.0.

my client is a Fire TV Cube (3. Gen); tried both apps "Emby" and "Emby for Fire TV", both had the same issue. i sent a report from "Emby for Fire TV" at 16:34 EDT. the logged in user was emby, the media played Shutter Island. playback was direct, no transcoding. connected via network-cable.

media info and playback info attached. server-log attached (there might a "Fringe" playback happening in there aswell).

i am not able to reproduce on chrome-web-player. (PC)
i am not able to reproduce on Kodi EmbyCon 1.11.37. (Cube)

 

during playback this evening i noticed a buildup of audio-desync over time (audio went faster than video, sound before motion). this was resolvable by either switching the audio tracks (dts-hd <-> ac-3; ac-3 is audio-description so i always "toggled") or skipping back and forth. (skipping introduced a new bug though; after a couple of seconds the video stopped, but audio not. after that i got a couple of frames running from time to time, then again video stopped playing, audio not).

did an explicit "test-run" after i finished the movie; around the time of the sent-in report (~16:30 edt). this did not happen playing ac-3, only dts-hd got out of sync.

im very sensitive when it comes to lip-audio-desync. i got around 10-15 minutes of playback until i noticed, after that the de-sync felt like growing faster. i cant put it in numbers, but i assume a few 100 ms at that point. "fixed" it and resumed watching. 

there were no error messages displayed.

this is the first time this has happened to me.

other medias played without these issues.
dts-hd had some playback issues from time to time though. never with Kodi EmbyCon.

 

 

embyserver.txt

 

 

Edited October 10, 2025 by syxlox

[Abobader 3464]

Hello syxlox,

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Emby Team

[visproduction 315]

Try removing the subtitles or finding another test file without pgssub.  These are graphic subtitles and cause more processing that text based subtitles.  They could be contributing to your issue of audio sync if these subtitles have to be transcoded.

[syxlox 0]

6 hours ago, visproduction said:

Try removing the subtitles or finding another test file without pgssub.  These are graphic subtitles and cause more processing that text based subtitles.  They could be contributing to your issue of audio sync if these subtitles have to be transcoded.

afaik no transcoding is happening for this media; at least i found no corresponding ffmpeg-log.

why isnt this happening with ac3?

will try anyway.

[visproduction 315]

Sy, 

Look closer at the logs.  I would guess that 49 mbps Dolby Vision just fails to get approved for direct playback and is transcoded.  That alone will take a lot of CPU power or hardware encoder and probably doesn't leave a lot of extra bandwidth to also covert or playback audio. DTS HD either has to play directly and every thing lines up to allow to do that, or it has to be transcoded.  I never use DTS-HD.  I think there are a lot of problems with that playback.  On my system I cannot play even AC3 wihtout transcoding.  You are at about 180 times the bandwidth I use for my media.  Maybe your combination hardware can handle this or direct playback works for both Dolby Digital and DTS-HD.  I know my setup would never be able to  play anything at all like this.

[Luke 42077]

Hi, we'll take a look at it. Thanks for reporting.