I just upgraded to Ubuntu 10.04 Lucid, and mythtv now has an audio/video sync issue. Specifically, the audio is consistently about half a second ahead of the video. This is a playback issue, rather than recording, because it occurs on old recordings that were previously fine, as well as on Live TV and on recordings made since the upgrade. In the in-playback menu (press M) there is an option to adjust the audio/video sync, and adjusting it 500ms to the right solves the problem, but this setting does not persist.
How can I either make that setting persist or correct the root cause of this desynchronisation?
MythTV version: 0.23.0+fixes24158-0ubuntu2
Audio output: ALSA:default
PulseAudio is running and shows mythtv as a client, but setting audio output to ALSA:plughw:0 does not help and, in fact, seems to cause video to play at about half speed and keep abruptly catching up to real time.
I've tried toggling the options "Extra audio buffering", "Agressive audio buffering", "Use OpenGL VSync for timing", "Upmix audio to 5.1" all with no effect.
...and I don't want to downgrade MythTV. :-) (database schema has changed and there might not even be a downward migration script)