Blender Git Loki

== FFMPEG ==

This is a fix for the following issues in ffmpeg movie reader:

* mpeg transport stream seeking (HDV) failed completely, since ffmpeg
doesn't want to seek by timestamp (those aren't guaranteed to be
strictly monotonic within those file formats)

We therefore seek by byte and use the bitrate in those cases.
This isn't a real fix,
I will add a seperate index building process, soon, so that we can
finally seek by timecode properly (optionally with "free run timecode"
on consumer video camcorders, stay tuned :) )

* Recent versions of ffmpeg do set the ALPHA channel to 0xff properly,
so we test the first pixel for proper ALPHA and then workaround
optionally.