Backport of "avwait: Allow setting start timecode after end timecode; protect propeties with mutex" into 1.16
Backport of !352 (merged) "avwait: Allow setting start timecode after end timecode; protect propeties with mutex".
Commits:
Backport of !352 (merged) "avwait: Allow setting start timecode after end timecode; protect propeties with mutex".
Commits: