Merge remote-tracking branch 'qatar/master'

Merge remote-tracking branch 'qatar/master'

* qatar/master:
  libx264: only use ABR mode when the user explicitly set bitrate.
  libx264: use medium preset by default.
  mp2 encoder: make 128k the default bitrate.
  movenc: use libx264 by default when possible for mov, mp4 and psp
  avienc: saner default audio codec.
  matroskaenc: saner default codecs.
  avplay: add examples of how to specify size/pixel format through private options
  lavc: add A|E|D flags to "ac" and "ar" options

Conflicts:
	doc/ffplay.texi
	libavcodec/libx264.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>