n5.1.7
tests/ref: Remove unused reference files
avformat/movenc: fix writing reserved bits in EC3SpecificBox
avformat/matroskaenc: Don't waste bytes to Write Tag length fields
fftools/ffmpeg_enc: apply -top to individual encoded frames
fate/pixfmt: test xyz12le
avcodec/snowenc: Fix visual weight calculation
avcodec/j2kenc: Fix funky bpno errors on decoding