[M4IF Technotes] Offscreen MVs

[the_ether]

Thank you Peter.
> Yes, it is possible for a motion vector to point off the screen. The off
> screen pixels are duplicated from the edge of the on screen pixels.

Just so I'm absolutely sure I understand, in my example which edge is
filled?
If I start with the following feature at (0,0):
1     1    1....1
2     2    2....2
3     3    3....3
16 16 16 ...16
and if this feature moves up by one pixel so that the motion vector is
(0,-1), what will the 1st and last rows of the corresponding macroblock look
like?
What I want to decribe to the decoder by sending a MV of (0,-1) is that the
first 2 rows should be
2222...
3333...
the fifteenth should be
16 16 16...
and the last row could be anything.
if instead the first two rows are
2222...
2222...
and the last row
16 16 16...
then only the first row would be correct. My guess is that the last is the
behaviour that would occur.