rsndvd: avoid dvd playback freezing briefly after un-pausing while disc spins up again, add more buffering in playbin

Submitted by Mehmet Giritli

Link to original bug (#633894)

Description

If you are playing a dvd with totem via the resin-dvd plugin and you pause the movie for a while, you will get a brief freeze shortly after you resume the movie until the disc starts to spin-up again. I think it is a simple cache issue. This doesn't happen with windows media player for instance and perhaps this can be easily improved.