Just been doing a little test.
Place an .MTS clip on timeline, Video 2
Select a zone for rendering, missing off say ten to fifteen frames at both ends.
Render, in this case to .avi
Place new render on Video 1, lining up with start of zone.
The new rendered .avi is four frames longer than the selected zone.
Now this is weird:-
The first two frames are a copy of the first frame.
The last four extra frames are a copy of the last frame of the selected section.
Now, with the timeline cursor, cut off the first frame and delete it, any guesses as to what happens next?
No?, well, The next two leading frames are a copy of each other.
Drag the start of the clip to shorten it, then drag it back out fully.
Now the start frames move correctly, BUT (and that's a big 'but') Frames three and four are a copy of each other.
OK, I'm managing a workaround for this, but it all is a little strange.
No more hair pulling for me, it's all gone :-)
Latest sunab svn
Ubuntu 12.04 64bit