mkvpropedit, GUI's chapter & header editors bug fix: in certain situations the modified file would not contain a seek head before the first cluster anymore resulting in most players not finding elements such as attachments or the index located at the end of the file anymore. Fixes #1513.
mkvmerge: bug fix: the change to do a deeper file analysis if no seek head was found was causing huge increases in file type detection time as popular tools like x264 don't write seek heads. The way elements at the end are searched has been changed to only scan the last 5 MB of the file instead of iterating over every level 1 element from the beginning of the file.
all: change: none of the tools will write a byte-order mark (BOM) to text files encoded any of the UTF-* schemes anymore.
mkvmerge: Matroska reader bug fix: the info about which packetizer is used was output twice for each HEVC track. Fixes #1522.
MKVToolNix GUI: bug fix: implemented a workaround for a bug in Qt which caused the GUI not to start anymore due to failing to detect a stale lock file if the GUI had crashed before on a computer with a host name that included non-ASCII characters. See https://bugreports.qt.io/browse/QTBUG-49640
mkvmerge: bug fix: a track's number of bits per audio sample wasn't output in verbose identification mode even if it was present in the file.
mkvmerge: enhancement: if no seek head is found before the first cluster when reading Matroska files then mkvmerge will attempt a deeper scan of all elements in the file in order to find track headers, attachments, chapters and tags located at the end of the file. See #1513 for the rationale.
MKVToolNix GUI: header editor bug fix: the "status" description wasn't adjusting its height properly resulting in its text being cut off. Fixes #1517.
MKVToolNix GUI: bug fix: the program changes its working directory to the user's profile/home directory on startup allowing the removal of its installation folder even if a program started by the GUI (e.g. a web browser) is still running. Fixes #1518.
ebml_validator: bug fix: elements with an unknown size weren't handled correctly.
mkvpropedit, MKVToolNix GUI's chapter and header editors: the tools were unable to update elements in files without a seek head present. Fixes #1516.
mkvmerge: bug fix: fixed two issues causing mkvmerge to write invalid data when updating track headers caused by the fix for "Re-rendering track headers: data_size != 0 not implemented yet". Fixes #1498.
MKVToolNix GUI: bug fix: the options for linking to the next/previous segment UID were wrong. Fixes #1511.
mkvmerge: enhancement: added JSON as an output format for file type identification. It can be activated with "--identification-format json --identify yourfile.ext" (or their short counterparts "-F json -i yourfile.ext").
mkvmerge: bug fix: the VC-1 handlig code was duplicating the first sequence headers with each mux. Fixes #1503.