[mythtv] DVD playback Pause/Unpause problems

[John Harvey]

I am running into a problem with dvd playback where i can trigger
NuppelVideoPlayer::UnpauseVideo to loop forever, printing the message
"Waited too long to unpause video".

The problem is caused by OutputVideoLoop calling PauseVideo(false) whilst a
different thread is in the middle of doing an UnpauseVideo(true).

For some reason the calls to PauseVideo & UnpauseVideo in OutputVideoLoop
are not surrounded by locks on internalPauseLock. Is there a good reason for
this? 
Locking that from the OutputVideoLoop definitely seems to help but i wanted
to try to understand why they aren't there before submitting a patch.

I am also suspicious that calling PauseVideo(false) could break things for
the next call to UnpauseVideo if the video hasn't actually paused by the
time we call UnpauseVIdeo, though i have no proof of that yet. Is this
unfounded or is it worth investigating as well?

Thanks

Jon