Hey Guys - I am out of guesses…
Running the latest OSMC on a Raspberry Pi 2 - wired connection to a VDR Server on a Pi 3. Live TV starts in Sync but gets out of sync after a random period of time. Sometimes I can watch for 40 minutes without problems, sometimes I have to restart the channel every 30 seconds (restarting Live TV solves the problem, at least for some time). I tried all the settings under Video -> Playback to keep Audio in Sync. The problem must be with OSMC and/or the Pi. If I open the stream with VLC on my Mac (wireless connected) Audio stays in Sync like forever…
What can I do? Would a Pi 3 help?
Thanks in Advance!
Have you purchased/entered your MPEG2 license key?
Yes vcgencmd codec_enabled MPG2 says enabled
I have the same issue with the same configuration. I also have a pi2 with up2date osmc and both video codec licenses installed and activated.
TV gets out of sync and nothing but restarting live tv or reboot fixes it. Sometimes switching channel and switch back helps 
german dvbt via usb
What exactly do u need and how can i collect?
To get a better understanding of the problem you are experiencing we need more information, including logs from you. Please see How to submit a useful support request - General - OSMC for advice on how to help us.
Ok I was just watching TV and it became out of sync quite fast … I enabled debug logging, did a reboot, startet TV and after 2 min it was out of sync. Then I created logs: http://paste.osmc.io/hizixuxoni
So, logs were clicked some times … any ideas?
Try to disable mmal and enable omxplayer in the video acceleration options.
Ok I had both (mmal and omxplayer) active. Now I disabled mmal. I will try.
How does disabling mmal influence watching movies not tv?
Still getting async i watched pro7 for about 4 or 5 minutes and then it went totally out of sync…
I am accessing the tv headend server on the raspberry2 also from my pc via vlc htsp plugin. Here everything is sync … 
Edit:
Tried today with another powerful dvbt antenna, same problem
If omxplayer and mmal are enabled, omxplayer will be used if possible. So disabling mmal will have no effect.
Try disabling omxplayer and leaving mmal enabled.
Tried to disable omxplayer, same problem.
But now this is REALLY weired:
For example watching Pro7: getting out of sync
Trying to watch Pro7 MAXX: TV Headend error: no signal
Doing the same on my PC:
Pro7 sync
Pro7 MAXX playing like a charme and also sync
the TV Headend server is in both cases the same, it is running on the raspberry 2 where I cant even watch pro7 maxx.
Now i am totally confused!
There is an update to tvheadend in the june update. Did you update already?
Yes I did, is the update for tv headend automatically applied?
At least the server seems to work, as I can use it with my VLC client on my pc without problems. Maybe it is the TV Headend client in osmc?!