Merge remote-tracking branch 'cus/stable'

* cus/stable:
  ffplay: calculate audio diff threshold based on the actual settings
  ffplay: try more channel count combinations for SDL_OpenAudio
  ffplay: simplify audio_open, rename parameters to more explanatory names
  ffplay: remove VideoState from audio_open
  ffplay: put audio parameters to their own struct
  ffplay: put audio_open into a seperate function
Merged-by: Michael Niedermayer <michaelni@gmx.at>