+2017-03-xx - xxxxxxx - lavf 57.68.100 - avformat.h
+ Deprecate that demuxers export the stream rotation angle in AVStream.metadata
+ (via an entry named "rotate"). Use av_stream_get_side_data() with
+ AV_PKT_DATA_DISPLAYMATRIX instead, and read the rotation angle with
+ av_display_rotation_get(). The same is done for muxing. Instead of adding a
+ "rotate" entry to AVStream.metadata, AV_PKT_DATA_DISPLAYMATRIX side data has
+ to be added to the AVStream.
+