API changes, most recent first:
+2017-08-08 - xxxxxxx - lavu 55.74.100 - pixdesc.h
+ Add AV_PIX_FMT_FLAG_FLOAT pixel format flag.
+
+2017-08-08 - xxxxxxx - lavu 55.72.100 - imgutils.h
+ Add av_image_fill_black().
+
+2017-08-08 - xxxxxxx - lavu 55.71.100 - frame.h
+ Add av_frame_apply_cropping().
+
+2017-07-25 - 24de4fddca - lavu 55.69.100 - frame.h
+ Add AV_FRAME_DATA_ICC_PROFILE side data type.
+
+2017-xx-xx - xxxxxxx - lavc 57.100.100 - avcodec.h
+ DXVA2 and D3D11 hardware accelerated decoding now supports the new hwaccel API,
+ which can create the decoder context and allocate hardware frame automatically.
+ See AVCodecContext.hw_device_ctx and AVCodecContext.hw_frames_ctx. For D3D11,
+ the new AV_PIX_FMT_D3D11 pixfmt must be used with the new API.
+
+2017-xx-xx - xxxxxxx - lavu 56.67.100 - hwcontext.h
+ Add AV_HWDEVICE_TYPE_D3D11VA and AV_PIX_FMT_D3D11.
+
+2017-06-24 - xxxxxxx - lavf 57.75.100 - avio.h
+ Add AVIO_DATA_MARKER_FLUSH_POINT to signal preferred flush points to aviobuf.
+
+2017-06-14 - xxxxxxx - lavu 55.66.100 - hwcontext.h
+ av_hwframe_ctx_create_derived() now takes some AV_HWFRAME_MAP_* combination
+ as its flags argument (which was previously unused).
+
+2017-06-14 - xxxxxxx - lavc 57.99.100 - avcodec.h
+ Add AV_HWACCEL_FLAG_ALLOW_PROFILE_MISMATCH.
+
+2017-06-14 - xxxxxxx - lavu 55.65.100 - hwcontext.h
+ Add AV_HWDEVICE_TYPE_NONE, av_hwdevice_find_type_by_name(),
+ av_hwdevice_get_type_name() and av_hwdevice_iterate_types().
+
+2017-06-14 - xxxxxxx - lavu 55.64.100 - hwcontext.h
+ Add av_hwdevice_ctx_create_derived().
+
+2017-05-15 - xxxxxxxxxx - lavc 57.96.100 - avcodec.h
+ VideoToolbox hardware-accelerated decoding now supports the new hwaccel API,
+ which can create the decoder context and allocate hardware frames automatically.
+ See AVCodecContext.hw_device_ctx and AVCodecContext.hw_frames_ctx.
+
+2017-05-15 - xxxxxxxxxx - lavu 57.63.100 - hwcontext.h
+ Add AV_HWDEVICE_TYPE_VIDEOTOOLBOX and implementation.
+
+2017-xx-xx - xxxxxxx - lavc 57.95.100 / 57.31.0 - avcodec.h
+ Add AVCodecContext.apply_cropping to control whether cropping
+ is handled by libavcodec or the caller.
+
+2017-xx-xx - xxxxxxx - lavu 55.62.100 / 55.30.0 - frame.h
+ Add AVFrame.crop_left/right/top/bottom fields for attaching cropping
+ information to video frames.
+
+2017-xx-xx - xxxxxxxxxx
+ Change av_sha_update(), av_sha512_update() and av_md5_sum()/av_md5_update() length
+ parameter type to size_t at next major bump.
+
+2017-05-05 - xxxxxxxxxx - lavc 57.94.100 - avcodec.h
+ The cuvid decoders now support AVCodecContext.hw_device_ctx, which removes
+ the requirement to set an incomplete AVCodecContext.hw_frames_ctx only to
+ set the Cuda device handle.
+
2017-04-11 - 8378466507 - lavu 55.61.100 - avstring.h
Add av_strireplace().