MKV file out of sync

[techmot]

Hi does anyone know why a file I have in MKV produces audio sync issues?. When the file is played on my PC the audio is fine, but when I play the file on my TV via a external HDD the audio is fine to begin with then goes out of sync. Is this down to the codec?. I've had similar files like this. And also when I try to remux the file in OBS I get a message saying "the file has been remuxed but may not play" and the outputted MP4 doesn't play because the file couldn't be remuxed. Looks like a dodgy file format.

[jagabo]

It may be that the file uses MKV metadata to make the audio play faster or slower. The player you're using on the computer follows those instructions, the player on your TV doesn't.

Not all codecs used in MKV are supported by MP4.

A MediaInfo text report may reveal these things.

[ProWo]

... or the video.
Is often recommended here in the forum to synchronize audio from a video with different FPS with another video stream without recoding, by simply changing the fps value in mkvtoolnix.
These problems are then the result.

[Ennio]

Is the video Dolby Vision? Posting MediaInfo data may be helpful.

[techmot]

... or the video.
Is often recommended here in the forum to synchronize audio from a video with different FPS with another video stream without recoding, by simply changing the fps value in mkvtoolnix.
These problems are then the result.

What about encoding the file in Handbrake to an MP4 file and setting it to 25fps, would that correct the sync?. Could the sync issue with due to break up/pixelation of the video half way through?. Reason I ask is that I was playing another video a few days ago and the picture broke for a few seconds and after that the audio became out of sync. Used to a happen alot years ago with ripped DVDs I used to have.

[ProWo]

My 5 cent: with synch issues recode the audio, never the video.

[jagabo]

What about encoding the file in Handbrake to an MP4 file and setting it to 25fps, would that correct the sync?.

No. Handbrake will add or remove frames to maintain the running time. There will be no change in A/V sync.

Could the sync issue with due to break up/pixelation of the video half way through?.

It's possible. But you can easily test for that. Is the audio in sync before the breakup? And out of sync after?