The index must take into account the pre-roll time and must seek backwards,
not forwards.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit bd603494f905a7db92fc04eab9c0f6793b0ed7d1)
Conflicts:
tests/ref/lavf/asf
tests/ref/seek/lavf_asf
Fixes Ticket1563
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>