Fixed async video playback without audio.
Fixed async video playback without audio.

svn path=/trunk/libavg/; revision=2745

hoodie/libavg,yyd01245/libavg,yyd01245/libavg,libavg/libavg,hoodie/libavg,th3infinity/libavg,yyd01245/libavg,libavg/libavg,hoodie/libavg,hoodie/libavg,libavg/libavg,scotty007/libavg,libavg/libavg,th3infinity/libavg,th3infinity/libavg,scotty007/libavg,th3infinity/libavg,scotty007/libavg,yyd01245/libavg,scotty007/libavg