Reconstruct MKVs (post-MakeMKV) for better compatibility?

[Asterra]

I make occasional use of MakeMKV to move the contents of my Blurays to a media player. An issue I have encountered is that the media player in question (Popcorn Hour A-300) seems to have a subtle flaw with MKV playback. It loses sync between audio and video, the further along the timeline the video is playing (skipping to specific spots does not re-sync). The discrepancy is roughly 7ms per hour. By the end of a special-edition Lord of the Rings movie, things are so bad (almost a third of a second) that even casual observers begin to wonder whether something is amiss.

I recall reading a rumor that this may be at least partly the blame of MakeMKV, which is apparently known to utilize aspects of the container which push the boundaries of compatibility. (Don't ask me for details; I know nothing.) Even though they may play fine in one player - such as anything on a PC - there might be issues on other players. I also seem to recall reading that one person's solution to this was to take whatever MakeMKV spits out and pass it through some other muxer or similar program, so that one finally ends up with something that shouldn't cause compatibility problems on anything.

That's more or less what I'm after. Something I can sift MakeMKV's output through, in order to hopefully cure the sync issue with this A-300 player, as it is now painfully clear that it will never be acknowledged, let alone fixed.

[hello_hello]

MKVMergeGUI. It's part of MKVToolNix.

Also, before remuxing the video, go into MKVMergeGUI's options and tick the "disable header removal compression" checkbox. Header removal compression has been known to cause problems with some devices.

[jagabo]

Also, before remuxing the video, go into MKVMergeGUI's options and tick the "disable header removal compression" checkbox. Header removal compression has been known to cause problems with some devices.

Be sure to exit MMG and restart it after making that change. The change doesn't take effect until the next time the program is run.

Also try specifying the frame rate in mmg. Use 24000/1001 or 30000/1001, whichever is appropriate. The difference between those and 23.076 or 29.97 is about 3.6 milliseconds per hour.