Sorry, I’m not familiar with eac3to. But, based on quick googling, wouldn’t that “fix” actually result in the removal of TrueHD? It seems to only convert TrueHD to other formats.
No, I see the same bug occur when using eac3to to fix the seamless branching. TSMuxer, DGDec and MakeMKV BTW also all fix the seamless branching (removing overlapping audio frames). The thing is every tool does it a little differently and its kind of unclear which processing is “correct”, because there were and still are playback issues with different players depending on the process.
icbaker has replied on the exoplayer bug report. Basically, it comes down to this, as I summarized there:
(to be clear, this is my summary, no icbaker’s)
It appears we’re at an impasse until either someone fixes the way these files are being formed, demonstrates beyond doubt that the files are not malformed, or submits code that fixes the issue regardless of whether the files are malformed.
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Sorry, I didn’t mean to imply that playback was flawless. Just that there shouldn’t be any obvious sync issues, in reply to the guy above me, who stated exactly that 
In other news, we are now 5 versions behind the latest ExoPlayer release…
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Based on this, I think Plex needs to have a good hard think about dropping Exoplayer… Although is there an alternative that they can use instead?
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I have discovered “The Natural” director’s cut reproduces these problems. To reproduce, append 00348.m2ts to 00364.m2ts (at the end of the scene where Hobbs is walking out of the judge’s office, after he flipped the light on, on the outside of the stadium and Mercy shows him his old cartoon… then Kim Basinger is tapping on a piano and that’s out of sync). Play this in file in Plex. Audio goes out of sync. I have tried numerous discs. Also DVDFab creates a “bad” MKV too. Also agree that most other players not bitsreaming the Atmos (Apple TV eg) do not experience out of sync audio. Shield is the only player that is “bad” which is a shame obviously!
I have ripped seamless branching Atmos to MP4 and M2TS. Playing an MP4 natively (HEVC/Atmos) reproduces the problem. For Plex I remuxed the M2TS into MKV. Again the problem was reproduced. Agree MKV is likely not a culprit.
For now I believe we have a few solutions.
Sometimes a DTS-MA track will be sidecarred next to the Atmos. This is usually a 5.1 track though; not ideal.
You could use eac3to to make a 7.1 .wav from the Atmos track and remux into the file. This makes the file several GB bigger than normal though. And you lose Atmos metadata/objects. But it sounds good, very sonically similar to the Atmos imho. Please turn off Dolby processing in the Shield to stream 7.1 PCM movies. Sometimes when starting playback of 7.1 PCM movies Shield reverts to stereo mode. Just skip the movie forward or back a second and 7.1 PCM bitstream should occur. This may be more of a problem if you are playing preroll trailers.
You could use DVDFab to convert the Atmos on the fly to 7.1 DTS-MA. This makes a pretty normal size audio track vs the Atmos track. You lose Atmos metadata/objects. But it sounds good, very sonically similar to the Atmos imho.
I have other workarounds I am working on. Again, MP4 containers don’t alleviate the problems and manually creating the MKV from m2ts files doesn’t work either. I also agree that seamless branching creates a kind of “lossless glitch” at the point where the branchings occur (at least in the eyes of certain decoders…).
Wish we had a “Use Old Exoplayer” option in settings or something.
You can use eac3to to make a “new” .thd file or a .thd+ac3 file. Remuxing these new (regenerated? I doubt it) back into the MKV container does not fix the audio sync. The only use as I mentioned above I have found for eac3to is to make a 7.1 WAV from the Atmos.
Note in the above: Plex used to “use our own implementation of True HD passthrough”. . . rather than relying on exoplayer’s.
Could they not do so again to potentially work around this issue? If exoplayer is unwilling to make modifications that could work around this issue (as hardware blu-ray players, and other file-based players have apparently done), it appears possible, based on the above, that plex could do it themselves.
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Previous very interesting thread. Seamless branching Atmos has been broken in Plex for a looooong time evidently.
Please fix someone 
Perhaps some tech media attention might help? Here’s my effort at such.
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Just came across this in a group NFO for one of the latest seamless branching discs, Avatar (2009):
“DGDemux due to seamless branching!”
This refers to DGDemux Blu-Ray/UHD Disk Demuxer. As to how they use this software exactly, I have no idea.
I tried that tool when it was mentioned earlier in this thread and replied in an earlier post that it has the same issues as MakeMKV and tsMuxeR when played on the Shield TV. It plays back correctly on my PC player (as do MakeMKV and tsMuxeR versions) but that player uses SW decoding and discards the Atmos.
I meant to point out that this tool is what, in this case, the biggest and most well known group uses currently to work around seamless branching issues. I have not tried this particular release yet, but I’m inclined to bet that it won’t have any playback issues on the Shield.
Yet it discards atmos?
It doesn’t.
Thanks. Good to know. But, alas, someone tried to use DGDemux to fix/work-around this issue here. Without success.
“Rocky” at the DGDemux forums seems to consider exoplayer’s stance a “cop out” (though he does use a question mark) and states that exoplayer needs to fix their player just as others had to do.
I’m very curious if these streams are actually valid.
I certainly agree that a player should be able to recover quickly even if they’re imperfect streams, but the whole “are the streams valid” question seems unanswered.
That’s honestly the only remaining question that is causing me to “keep my power dry” over on the bug report for exoplayer. If, in fact, all these other players have worked around an issue with how these streams are sometimes authored, then exoplayer team has a point that they shouldn’t be responsible for the shoddy streams.
On the other hand, if the streams are indeed faulty and all the players can/have fixed the issue, why should exoplayer be different? Should they not implement a fix if they can and prioritize the quality of their users’ experiences rather than planting their flag on the hill of “principle” that doesn’t help their users at all?
But, the fact that only exoplayer now has this issue makes it much less likely, circumstantially, that there is anything wrong with the streams. We can’t say for sure, but there is a preponderance of evidence.
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I tried DGDemux. Doesn’t work to fix issue. (And it keeps the Atmos.) FWIW latest eac3to doesn’t fix the stream either.
Still the best/cheapest user option right at the moment, imho, aside from using a sidecarred non-Atmos track on the disc, is to let DVDFab make a (48 kHz, 16 bit, admittedly) 7.1 DTS-MA of the Atmos track.
Obviously the BEST option would be for exoplayer as implemented within Plex to play the streams correctly. Of course
EDIT: Could not find issues with M3GAN (unrated edition, at least; see 1st post in thread). Is this because it’s DTS-MA?
The M3GAN Bluray I have (UK “Unseen Edition”) has 7.1 Dolby TrueHD (Atmos) audio track. Maybe you or someone else ripped the wrong track off disc?
Anyway in other related news… did anyone hear about the large layoffs that happened in PLEX recently letting go a lot of developers and others to save money (apparently lifetime pass is not a great way to make money long term)? I wonder if this will affect support for NVidia Shield and other less used devices. Possible that anyone that could have fixed this problem or spoke about it is now already let go from company since last time the bug was opened on their site.
I just wanted to point out that I noticed today this is happening with the directors cut of F9: The Fast Saga. Really frustrating that this isn’t resolved yet.
