Add logging for error message (for debugging).
Add mkvmuxer.cpp and mkvmuxer.hpp for modification.
Avoid crash anyway (though not show movie when crash occurs…)
Encode fail problem Fix!

When path bound is outside of screen, invalRegion becomes outside of viewBmp and getPixels throw Exceptions.
It will stop scheduleAtFixedRate task.
Change log tag to WhiteBoardCast.
Wrongly used newSingleThreadExecutor for animator.
Use synchronised instead of ad-hock synchronise logic.