- Removal of the custom atomic API (5cc0057f49, see http://ffmpeg.org/pipermail/ffmpeg-devel/2017-March/209003.html)
- Use the new bitstream filter for extracting extradata (8e2ea69135 and 096a8effa3, see https://ffmpeg.org/pipermail/ffmpeg-devel/2017-March/209068.html)
- Read aac_adtstoasc extradata updates from packet side data on Matroska once mov and the bsf in question are fixed (See 13a211e632 and 5ef1959080)
+- new bistream reader (see http://ffmpeg.org/pipermail/ffmpeg-devel/2017-April/209609.html)
Collateral damage that needs work locally:
------------------------------------------