8.21

• Update windows libav* dlls.

  • ffmpeg 5.1 -> 6.1
  • libpng 1.3.9 -> 1.4.0
  • opus 1.3.1 -> 1.4
  • libsndfile 1.2.0 -> 1.2.2
  • libxml2 2.10.3 -> 2.12.0
  • dav1d 1.0.0 -> 1.3.0
  • libaribcaption 1.1.1 (new!)

• Avoid crush from VCEEnc 8.17 on systems which does not support AVX2.

• Improved progress display when --seek is used.

• Fix --option-file error when target file is empty.

• Changed --audio-delay to allow passing in decimal points.

• Improve AAC copy handling when muxing into mpegts.

• Remove --caption2ass.
  Equivalent processing can be done by --sub-codec ass#sub_type=ass,ass_single_rect=true.