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>
avcodec/mpegaudio_parser: fix off by 1 error in bitrate calculation

Fixes Ticket3918

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>