One breaking change is that the property names in mkvmerge's JSON identification mode have also been changed to American English spelling. Both programs will continue to accept the British English spelling of their respective options indefinitely. This not only affects documentation and user interface controls, but also program options for mkvmerge & mkvpropedit. all: the spelling of 'colour' was changed to 'color' throughout all programs to match the use of American English spelling in MKVToolNix.Note that this build type isn't supported.

Several merge requests where accepted that improve compilation on MSYS2 on Windows.MKVToolNix GUI: multiplexer: color parameters that are floating point numbers (minimum/maximum luminance, projection pitch/roll/yaw) will only be set to a value during identification if the identification actually contains the property, and not to 0 anymore if it doesn't.MKVToolNix GUI: multiplexer: when reading color parameters from identified files that are floating point numbers (minimum/maximum luminance, projection pitch/roll/yaw) the numbers will be formatted in floating-point notation instead of scientific notation as mkvmerge only supports the former.mkvmerge: AV1 OBU parser: fixed identifying files that only contain single frame.MKVToolNix GUI: when adding directories via drag & drop/copy & paste the GUI will now offer the user the option to create one multiplex settings tab per directory & adding all files from that directory to the corresponding, newly created tab.If you only want to relocate the preferences INI file, you can store the desired file name for the INI file in MKVTOOLNIX_GUI_CONFIG_FILE. If set, the variable MKVTOOLNIX_GUI_STATE_DIR can point to a directory where the GUI stores both the job queue sub-directory and the preferences INI file. MKVToolNix GUI: the user can now control where the job queue files & the preferences INI file are stored via environment variables.

Mkvtoolnix 5.2.1