The viewer playback used to rely primarily on the vsync, which was
extremely smooth, but had issues when there was only audio or the viewer
was hidden. This was bodged by attaching to the audio in these scenarios,
but still not perfect.
Now we run a timer in tandem with vsync for the best of both worlds.
Playback is no longer wholly reliant on vsync, yet the viewer can remain
as smooth as possible using vsync.
itsmattkc
550d30ed8f