API changes, most recent first:
+2015-xx-xx - lavu 55.0.0
+ xxxxxxx - Change type of AVPixFmtDescriptor.flags from uint8_t to uint64_t.
+ xxxxxxx - Change type of AVComponentDescriptor fields from uint16_t to int
+ and drop bit packing.
+ xxxxxxx - Add step, offset, and depth to AVComponentDescriptor to replace
+ the deprecated step_minus1, offset_plus1, and depth_minus1.
+
2015-xx-xx - lavu 54.17.0
xxxxxxx - Add av_blowfish_alloc().
xxxxxxx - Add av_rc4_alloc().