* Add default entries to switch statements to catch programming errors
* Fix problem with high CPU usage when capturing live (the audio grabber
  is non-blocking for some reason). This is the stream_no_data stuff.
* Handle the video grabber getting behind in its work -- PKT_FLAG_DROPPED_FRAME


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@453 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b