Merge remote-tracking branch 'qatar/master'

* qatar/master:
  aacenc: Fix LONG_START windowing.
  aacenc: Fix a bug where deinterleaved samples were stored in the wrong place.
  avplay: use the correct array size for stride.
  lavc: extend doxy for avcodec_alloc_context3().
  APIchanges: mention avcodec_alloc_context()/2/3
  avcodec_align_dimensions2: set only 4 linesizes, not AV_NUM_DATA_POINTERS.
  aacsbr: ARM NEON optimised sbrdsp functions
  aacsbr: align some arrays
  aacsbr: move some simdable loops to function pointers
  cosmetics: Remove extra newlines at EOF

Conflicts:
	libavcodec/utils.c
	libavfilter/formats.c
	libavutil/mem.c

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

libavcodec/avcodec.h

@@ -3566,6 +3566,9 @@ AVCodecContext *avcodec_alloc_context2(enum AVMediaType);
  * @param codec if non-NULL, allocate private data and initialize defaults
  *              for the given codec. It is illegal to then call avcodec_open2()
  *              with a different codec.
+ *              If NULL, then the codec-specific defaults won't be initialized,
+ *              which may result in suboptimal default settings (this is
+ *              important mainly for encoders, e.g. libx264).
  *
  * @return An AVCodecContext filled with default values or NULL on failure.
  * @see avcodec_get_context_defaults