Log Message:
mkvtoolnix: updated to 56.1.0

Version 56.1.0 "My Friend" 2021-04-09

New features and enhancements

* mkvmerge: AAC: added support for LOAS/LATM files with channel configuration
  indexes 9–21 (e.g. channel count 22.2 for index 13) according to Rec. ITU-R
  BS.1196-7 & ISO/IEC 23008-3:2019.

Bug fixes

* mkvmerge: HEVC/H.265 parser: fixed invalid memory access that could happen
  when reading certain types of HEVC data (e.g. with changing parameter sets
  mid-stream) from certain containers (e.g. Matroska). This bug was introduced
  in release 56.0.0.
* mkvextract: AAC: mkvextract will now abort with an useful error message when
  the user tries to extract a track whose 'audio-specific config' element in
  `CodecPrivate` signals a number of channels of 7 or greater than 8 as that
  isn't supported by the ADTS format.

Build system changes

* configure: the `--enable-ubsan` option hasn't actually enabled anything
  since release 39.0.0.