vdpau_mpeg4: Do not fail on unknown profile.

This is a regression, previous code did not require
users to set the profile to use VDPAU.
In addition, ASP is a superset of SP, so there is not
even a good reason to require it.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
ffmpeg: init sub2video.last_pts.

Get the heartbeat working when the video has negative timestamps.

Fix trac ticket #4062.

Signed-off-by: Nicolas George <george@nsup.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>