Made video_test working again.
Disabled VA-API Intel vaAssociateSubpicture workaround.
Fix bug: Must release lock for VideoPollEvent.
Allow faster video and audio sync.
Fix bug: Software decoder use vaPutImage with Intel backend.
Fix bug: Artefacts are shown after mpeg2 channel switch.
Fix bug: VideoReleaseSurface called after VideoExit.
Pass PTS to video codec.
Flush audio buffer on channel change.
Sync audio + video stream.
Add workaround for Intel VA-API driver that forgets OSD position/size.
Made audio thread cancelable.
Calculate audio PTS.
Disable alsa message to stderr.
Better buffer flush with threaded play.
Prepared audio resample, for unsupported number of audio channels.