Handle files with sample rate changes correctly.

For example concatenated MP3 files.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36465 b3059339-0415-0410-9bf9-f77b7e298cf2
Set skip_alpha, we currently have no use for alpha values.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36466 b3059339-0415-0410-9bf9-f77b7e298cf2
vo_vdpau: Initialize variables before, not after setup code.

Fixes possible crashes when playing multiple videos without
-fixed-vo.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@36467 b3059339-0415-0410-9bf9-f77b7e298cf2