libmatroska 1.6.2:

• KaxBlockAddIDValue class: this class is no longer marked as "mandatory" in order to coincide with the latest specification.

mkvtoolnix 49.0.0:

New features and enhancements

• mkvmerge: added support for copying the new track header elements BlockAddIDName, BlockAddIDType, BlockAddIDValue and BlockAddIDExtraData from Matroska files if they exist. Part of the implementation of #2887.
• mkvinfo: added support for the new track header elements BlockAdditionMapping, BlockAddIDName, BlockAddIDType, BlockAddIDValue and BlockAddIDExtraData. Part of the implementation of #2887.
• MKVToolNix GUI: multiplexer: the list of recent directories can now be edited in the preferences → "Multiplexer" → "Destination file name". Implements #2861.
• MKVToolNix GUI: preferences: the values in the various "predefined values" lists can now be re-ordered freely by dragging & dropping.

Bug fixes

• mkvmerge: Matroska reader: when reading tracks (e.g. a subtitle track) from Matroska files with their default track flag set to yes, and when overwriting those via the command line to no, mkvmerge would not promote additional tracks of the same type from other files (e.g. another subtitle track from an SRT file). Fixes #2863.
• mkvmerge: SRT reader: empty lines inside entries were doubled. Fixes #2888.
• mkvmerge: subtitles: when calculating the rounded duration of each entry the error from rounding the corresponding timestamp will be taken into account. Fixes #2890.
• mkvextract: SSA/ASS extraction: mkvextract is no longer inserting empty lines before the Dialogue: lines. Fixes #2876.
• mkvextract: USF subtitles: start & end timestamps were too high by a factor of 1.000.000. Fixes #2875.
• MKVToolNix: info tool: when saving to a text file the checkbox "Save as default for saving output to text files" did nothing. Fixes #2869.
• MKVToolNix: info tool: when saving to a text file in "all elements in a tree-like structure" mode, the GUI always stopped at the first cluster regardless of the setting of the "verbosity" option.
• MKVToolNix GUI: preferences: when tooltips were disabled the dialogs for adding new entries to the various "predefined values" lists were missing their texts.
• configure: fixed detection of QtDBus. Fixes #2886.

Build system changes

• libMatroska v1.6.1 is now required. The bundled version has been updated to that version.