MKVToolNix: baixar versions anteriors

New features and enhancements
- mkvmerge: AVC/H.264: the stereo mode is now set from the frame packing arrangement SEI message in the video stream if neither the command line nor the container specifies one. This works for MP4, Matroska, AVC elementary stream and MPEG transport stream input and is already known during file identification. Implements the AVC part of #6309.
- mkvmerge: HEVC/H.265: the stereo mode is now set from the frame packing arrangement SEI message in the video stream if neither the command line nor the container specifies one. This works for MP4, Matroska, HEVC elementary stream and MPEG transport stream input and is already known during file identification. Implements the HEVC part of #6309.
- MKVToolNix GUI: multiplexer: added new actions to the tracks context menu for enabling/disabling all items belonging to the same source file as the selected item. Implements #6318.

Bug fixes
- mkvmerge: MP4 reader: fixed losing video frames at the end of the file due to flushing the packetizers too early (when the first track ends instead of only when all tracks in the file have ended). Another byproduct is that BlockDuration attributes aren't set for the last frame when they aren't needed anymore. Fixes #6320.
- MKVToolNix GUI: multiplexer: when identification fails due to an unrecognized or unsupported format, clicking the "Cancel" button in the error dialog shown no longer locks up the GUI in the state of "identification is still running", which disabled most elements. Fixes #6298.
- MKVToolNix GUI: chapter editor: when adding chapters mandatory elements set to their default values are removed in the underlying data structures. This restores consistency to how the chapter editor worked when copying values from the UI into them for the selected chapter. The result is that those elements won't show up in saved XML/Matroska files even if they have never been selected in the UI. Fixes #6294.
- macOS: GUI: fixed check boxes in lists such as the multiplexer's track list being invisible on macOS 27 by patching the Qt bundled with the app. Patch by corticalcode, based on the fix J.D. Purcell proposed in QTBUG-150017. Fixes #6307.

Bug fixes
- MKVToolNix GUI: executing actions, type "execute a program": all the variables (<MTX_…>) will now be replaced again in the argument list to the program to be executed. This was broken in v100. Fixes #6306.

Security fixes
- CVE-2026-90783: avilib: fixed potential heap overflows/invalid memory access in the ODML index handling due to unsiged integer multiplication wrapping around (colloquially known as "overflowing") with specifically crafted AVI files. Affects only mkvmerge as the other tools do not read AVIs. Reported by Tristan Madani TristanInSec@gmail.com.

New features and enhancements
- translations: substantial extension of the Czech translation by Michal Várady.

Bug fixes
- mkvmerge: TrueHD parser: fixed mkvmerge dropping the last TrueHD frame if its size was smaller than 12 bytes. Fixes #6296.
- MKVToolNix GUI: job runner: the variable <MTX_INSTALLATION_DIRECTORY> will be replaed in the executable position of the command-line for the program to execute again. Fixes #6299.
- Windows: fixed converting the scalable SVG icons into the bitmap .ico ones used on Windows so that the grey background remains uniform & doesn't get garbled. Fixes #6280.

Build system changes
- The bundled libraries libEBML & libMatroska were updated to v1.4.7 & v1.7.2 respectively. Those versions fix various possible invalid memory accesses when reading data broken in certain, very specific ways, making them security sensitive.
- libEBML v1.4.7 & libMatroska v1.7.2 are now required.
- The meta info file org.bunkus.mkvtoolnix-gui.appdata.xml was renamed to org.bunkus.mkvtoolnix-gui.metainfo.xml.

New features and enhancements
- all: added new scalable (SVG) application icons for all applications, replacing the existing pixmap (PNG, ICO) icons. Icons from Sarreq Teryx. Implements #6253.
- mkvmerge: MP4 reader: track names are now read from the track's user-data atoms (trak → udta → name) if present. Implements #6274.
- MKVToolNix GUI: executing actions configuration, type "play audio file": added a slider to make configuration more intuitive. Implemented by #6267.
- MKVToolNix GUI: executing actions: macOS only: the GUI will now use bundled audio files for "play audio file" actions that Qt can play instead of using macOS's system sounds. Implemented by #6268. Fixes #6264.
- MKVToolNix GUI: executing actions: Windows only: added a new type: executing a PowerShell script. Either an existing script file can be selected or custom PowerShell script code entered in a small editor. The executed script has access to all MTX_… variables through the environment, e.g. $env:MTX_DESTINATION_FILE_BASE_NAME. Workaround for the problems talked about in #6254.
- MKVToolNix GUI: job queue: added a context menu for opening copies of the selected queue jobs in the multiplexer as new settings there without removing the queue jobs. Implements #6255.
- MKVToolNix GUI: job queue: added a search functionality for jobs that searches in job descriptions, outputs, warnings & errors. Implements #6256.

Bug fixes
- command-line tools: Windows: switched to Boost's UTF-8 code-conversion facet (boost::locale::utf8_codecvt) from std::utf8_codecvt included in MingW. This seems to fix an issue with converting certain high code point from wchar_t to char (from UTF-32/16 to UTF-8), preventing interesting exceptions from being thrown. Fixes #6257.
- mkvmerge: AAC: fixed mis-detection of ADTS streams not starting on a frame boundary. Fixes regression starting with v87 when fixing AAC LATM config not being parsed if it wasn't present in the first AAC frame. Patch by Corticalcode. Fixes #6196.
- mkvmerge: MPEG TS reader: under certain rare conditions mkvmerge was skipping a certain amount of content at the start of the main M2TS file when reading MPLS playlists. The amount of content skipped proportional to the probe range percentage. This only happened when the source Blu-ray contains HDMV TextST subtitles. Fixes #6269.
- MKVToolNix GUI: executing actions configuration, type "play audio file": fixed audio volume not working since switching to Qt 6 due to its interface taking a float in range 0.0–1.0 instead of the old interface taking an int in range 0–100. Implemented by #6267. Fixes #6266.
- MKVToolNix GUI: executing actions: fix backslash handling when parsing a Unix-shell escaped string into separate arguments. The user-visible fix is that the command-line in the "executing actions" dialog will not have the quoting changed in wrong ways by the GUI when the GUI adds another variable upon user request, a regression introduced in v99. Fixes #6253.

Build system changes
- all: when building for Windows the programs ImageMagick (executable magick) & Inkscape (executable inkscape) are required in order to build ICOs from SVGs.
- macOS: include the app's supported platform(s) in Info.plist to correctly resolve the app's Kind as Apple Silicon in System Information. Detected during discussion of #6260.
- macOS: updated Qt to 6.11.1. The patch that made building Qt from source possible on macOS 26.4 (by Touchstone64) has been removed as Qt 6.11.1 includes the fix upstream. See #6276.

New features and enhancements
- MKVToolNix GUI: the GUI will now remember the last used directory for selecting audio files for playback in "play audio file" program runners separately from any other "open file"-type situations. This directory will also default to /System/Library/Sounds on macOS now. Implemented by #6213.
- MKVToolNix GUI: executing actions → running programs: added new variables: MTX_DESTINATION_FILE_BASE_NAME (the name without the drive letter, path or the suffix; e.b. /movies/A.new.hope.mkv → A.new.hope) and MTX_DESTINATION_FILE_SUFFIX (only the letters after the last ., e.g. /movies/A.new.hope.mkv → mkv). Added examples to all the destination file variables in the popup menu when adding variables in the preferences. Implements parts of #6220.
- MKVToolNix GUI: executing actions → running programs: the command-line input widget will now receive focus again after using the popup menu for adding a variable. Implements parts of #6220.
- MKVToolNix GUI: executing actions → running programs: the variables will now also be set as environment variables when running a program after a job completes.
- MKVToolNix GUI: executing actions → running programs: when using the "Execute now" button for testing the MTX_… variables will be set to the current multiplexer tab's values for easier testing. Implements parts of #6220.

Bug fixes
- mkvmerge: if using legacy font MIME types is off mkvmerge will now remap legacy font MIME types present in source files into the current ones. Patch by corticalcode via #6249.
- mkvmerge, mkvpropedit, MKVToolNix GUI's multiplexer & header editor: on Windows & macOS the MIME type detection will now use the FreeDesktop.org MIME database instead of falling back to file extension-based guesses. This matches how it works on other operating systems. This fixes e.g. OpenType fonts being detected as the legacy type application/vnd.ms-opentype instead of the current IETF RFC, font/otf, no matter what the "use legacy font MIME types" settings in the preferences was set to. Fixes #6240 for Windows; fixes #6248 for macOS. Implemented by corticalcode for macOS in #6250.
- MKVToolNix GUI: update checker: fixed a potential attempt to read from an invalid memory address if an error occurred when parsing the XML file retrieved from the official MKVToolNix server.
- macOS: GUI: the default audio file for program runners of type "play audio file" has been changed to an AIFF file as Qt's Multimedia backend routes through Core Audio which doesn't support WebM/VP8/Vorbis/Opus. Existing configurations will be updated if they point to the prior default WebM audio file. Fixes #6209.

Build system changes
- macOS: build.sh: the Qt installation is now done via cmake --install instead of using classic make as the classic Makefiles produced by Qt's build system are incomplete. Patch by corticalcode. Fixes #6205.
- macOS: build.sh: the binaries in the DMG are now stripped of debug symbols. Patch by corticalcode. Fixes #6206.
- macOS: build.sh: enabled release build optimizations for dependencies. Patch by corticalcode. Fixes #6207.
- macOS: build.sh: disabled use of pkg-config for Qt to prevent linking against installed non-OS libraries such as from Homebrew. Patch by corticalcode. Fixes #6208.
- macOS: added support for notarization of a macOS disk image by an Apple developer account. Implementation of #6212 by Touchstone64.
- macOS: patch added to make building Qt 6.11 from source possible on macOS 26.4. Patch by Touchstone64.
- macOS: additions to DMG package naming including the machine type it targets (arm64 or x86_64) and a revision number (to support re-packaging of an existing MKVToolnix release). For example, MKVToolNix-98.0-1-arm64.dmg would represent the first revision of a DMG package for an Apple Silicon Mac, containing MKVToolNix release 98.0. Implementation by Touchstone64.
- macOS: the packaging process now verifies the MKVToolNix source release using the author's GPG key before packaging. Implementatio

New features and enhancements
- all: huge update to the Japanese translations which had been not worked on for several years. The program translation is now complete again, the man page translation has been extended as well. Both were reworked in most places. Translations by coolvitto.
- GUI: chapter editor: added an option in the "additional modifications" dialog that toggles applying the selected modifications to all currently open chapter editor tabs. Implements #6189.
- GUI: macOS: added dock icon progress bar for job queue. Patch by Miklos Juhasz.

Bug fixes
- GUI: chapter editor: when renumbering chapters limiting the number of chapters to renumber did not work. Fixes #6199.
- GUI: macOS: fixed refreshing widgets after system switches between dark & light modes. Patch by Miklos Juhasz.

Build system changes
- The bundled fmt library was updated to v12.1.0, fixing a build issue on FreeBSD. Fixes #6191.

New features and enhancements
- mkvmerge: MP4 reader: added support for TrueHD in MP4 with FourCC mlpa. Implements #6178.
- installer: the Windows installer will request admin permissions again, as it did before release 96.0.

New features and enhancements
- all programs: added a command-line parameter --no-bom that disables writing byte order marks to text files encoded with one of the UTF variants. Implements #6166.
- MKVToolNix GUI: multiplexer: added variable <MTX_CHAPTERS_FILE_NAME> to the "run program after job completion" mechanism containing the absolute path to the chapters file name. Implements #6172.

Bug fixes
- mkvmerge: OBU reader: fixed probing files in which the first frame ends after the 1MB mark, which is how big the memory buffer used for probing content is. Fixes #6165.
- mkvmerge: VobSub reader: VobSub .idx files that start with a byte-order mark (BOM) are now read again correctly. Fixes #6162.
- mkvextract: AV1/IVF: fixed inserting a temporal delimiter OBU at the start of each frame if there is none. Mostly fixes #6120.
- mkvextract: AV1/IVF: fixed a potential calculation error when deriving frame rate numerator & denominator from Matroska's default duration. Part of the fix of #6120.
- mkvextract: AV1/IVF: fixed calculation of IVF frame number calculation from Matroska's frame timestamps by rounding instead of truncating. Part of the fix of #6120.

New features and enhancements
- mkvmerge, MKVToolNix GUI: new chapter generation feature: a new placeholder has been introduced when generating chapters for appended files, <TITLE>, which will be replaced by the appended file's title metadata. Implements #6151. Implementation by Jason Donenfeld.
- mkvmerge: the display matrix from MP4 files are now translated into appropriate roll and yaw values for output MKV files. Implements #6150. Implementation by Jason Donenfeld.
- mkvmerge: add --date argument to set the date metadata. Implements #6155. Implementation by Jason Donenfeld.

Bug fixes
- build system: fixed building with the upcoming Boost v1.89.0 by only requiring the header part of the Boost.System library as it's been header-only since v1.69.0. Fixes #6143.
- mkvmerge: PCM packetizer: mkvmerge will now always write frames with 40ms of samples, no matter how long or short the frames in the source files were. Part of the fix of #6149.
- mkvmerge: MP4/QuickTime reader: fix exorbitant memory usage when reading PCM audio tracks. Part of the fix of #6149.

Build system changes
- Boost v1.74.0 or newer is now required.

New features and enhancements
- MKVToolNix GUI: multiplexer: the "delete source files after multiplexing" job runner will now delete both files of an .idx/.sub VobSub file pair. Implements #6133.

Bug fixes
- all: fix compilation without FLAC. Fixes #6128.

New features and enhancements
- all: updated the various lists that go into IETF/BCP 47 language tags: ISO 639 languages; ISO 3166 countries; ISO 15924 regions; IANA subtag registries.
- translations: added a Hungarian translation of the programs & man pages by Viktor György, John Fowler & Attila Zsigus (see AUTHORS).
- mkvextract: tags extraction: added an option --no-track-tags (short: -T) for not extracting tags associated with tracks.
- MKVToolNix GUI: multiplexer: the default regular expression for deriving the "forced display" track flag from file names for subtitles was extended to also match on the term signs. Implements #6094.
- MKVToolNix GUI: preferences: the revert buttons for the various "default regex for…" will only be enabled when the current text differs from the default, in other words: when reverting would actually change the text. Part of the implementation of #6099.
- MKVToolNix GUI: preferences: the GUI will now auto-upgrade the "default regex for…" to their respective current default values if they're still set to one of the previous default values. Part of the implementation of #6099.

New features and enhancements
- mkvmerge: FLAC reader: pictures embedded into the FLAC file were already handled as attachments, but they were left in the codec initialization data as well. They're now removed from the codec initialization data. See #6079.
- mkvmerge: FLAC reader: padding metadata blocks will now be removed from the codec initialization data. See #6079.
- mkvmerge: FLAC reader: embedded Vorbis comments will now be converted into Matroska comments or track/global header fields when available (e.g. TITLE will become the segment title & track's name, LANGUAGE will become the track's language). Copying of Vorbis comments that are converted into actual Matroska tags can be prevented with the usual options, e.g. --no-track-tags. The comments will also be removed from the codec initialization data. Implements #6079.
- mkvmerge, MKVToolNix GUI's chapter editor: when reading simple (OGM-style) chapter files & no character set is given for the file, mkvmerge will try UTF-8 first before falling back to the system's default encoding. Implements #6084.
- MKVToolNix GUI: multiplexer: the special drag & drop zones added in v91 are now shown by default in new installations.
- MKVToolNix GUI: in new installations the main window will now be sized at 75% of the screen's resolution initially with a certain minimum initial size. This improves initial readability on high DPI screens that use screen scaling factors such as 150%.

Bug fixes
- mkvmerge: Ogg reader: during identification the track tags are now reported properly.
- MKVToolNix GUI: multiplexer: within the "additional options", both track-specific ones & the global ones on the "Output" tab, it wasn't possible to specify empty (zero-length) arguments. With the intended syntax of two consecutive single or double quotation marks the empty arguments were simply skipped. This was fixed, and it is now possible to specify e.g. --title "" in the global "Additional options" in order to force no title to be written ever. Fixes #6087.

Build system changes
- Windows build: the packaging/windows/populate_installer_dir.sh now expects the user to pass the Saxon-HE's JAR file name to be passed with the -s or --saxon-jar parameter instead of the base directory for Saxon-HE. This allows newer versions of Saxon-HE to be used.

Important notes
- The MKVToolNix project's source code repository, bug tracker and wiki have been moved to Codeberg.
- The customized MXE repository used for building the Windows variants has been moved from Gitlab to Codeberg.

New features and enhancements
- MKVToolNix GUI: multiplexer: added actions in the "Multiplexer" menu for saving all currently open multiplexer tabs to a single .mtxcfg file. Loading this file later will restore all tabs. Implements #3797.
- MKVToolNix GUI: multiplexer: when adding files the GUI can automatically enable the "commentary" flag for audio and subtitle tracks if the file name contains the word "comments" or "commentary" delimited by certain characters (configurable). This feature is turned on by default. Part of the implementation of #3798.
- MKVToolNix GUI: multiplexer: when adding files the GUI can automatically enable the "original language" flag for audio and subtitle tracks if the track's language matches one configured by the user (configurable). This feature is turned off by default. Part of the implementation of #3798.
- MKVToolNix GUI: multiplexer: when adding files the GUI can automatically set several track flags based on the file name. It can now look for the same patters in the track names, too (configurable). This feature is turned on by default. Part of the implementation of #3798.
- MKVToolNix GUI: multiplexer: added special drag & drop zones where users can drop files to circumvent the preferences wrt. what to do with multiple dropped files. Each drop zone corresponds to one of the three possible choices (add all to current settings; create one new settings & add all there; add new settings for each file & add one file to each). This feature is turned off by default. Implements #3796.
- MKVToolNix GUI: multiplexer: added additional special drag & drop zones where users can drop files to add them as attachments. One of the zones will automatically set up the dropped file to function as a cover image. Implements #3794.
- MKVToolNix GUI: multiplexer: when making destination file names unique by suffixing them with a running number the GUI will now also consider the destination file names of multiplex jobs currently in the queue that are currently running or still waiting for execution. Implements #3801.

Bug fixes
- mkvmerge: timestamps format v3: fixed the parser; it was completely broken for the lines containing the duration & an optional number of frames per second. Fixes #2285.
- mkvmerge: DTS parser: if the X96 extension is present in a DTS-HD High Resolution stream, the sampling frequency will be set to 96kHz. This was broken when reading DTS from elementary streams & from Matroska files. Fixes #3288.
- mkvpropedit, MKVToolNix GUI's chapter & header editors: fixed a bug leading to a segmentation fault when trying to replace an element at the end of the file that's followed by only void elements (at least one). Fixes #3802.

Build system changes
- The bundled nlohmann-json library was updated to v3.11.3.

New features and enhancements
- MKVToolNix GUI: header editor: double-clicking on one of the three flag indicators ("Default track", "Forced display", "Enabled") for a track in the tree view will now toggle the corresponding flag. Implements #3773.

Bug fixes
- mkvmerge: AAC parser: LOAS/LATM streams: fixed use of uninitialized data when the StreamMuxConfig element doesn't contain the audioMuxVersion element; version 0 must be assumed in such a case. The result was that sometimes certain valid AAC packets were dropped. Fix by Stefan Pöschel.
- mkvmerge: HEVC/H.265 parser: fixed calculation of picture order count calculation that was triggered under rare circumstances. Fixes #3775.
- mkvmerge: Matroska reader: enabled limits for how much data a single Matroksa reader instance might buffer when the muxing core looks for packets for specific tracks, avoiding huge memory consumption in cases where tracks have huge gaps between packets. This might happen when appending files containing forced-only subtitle tracks, for example. Fixes #3771.
- mkvmerge: TrueHD reader: increased the probe range for TrueHD sync frames from 128 KB to 512 KB to avoid mis-detection with certain files with a lot of data between sync frames. Fixes #3783.
- mkvmerge: MP4/QuickTime reader: fixed detection of Big Endian LPCM audio. Fixes #3788.

Build system changes
- The bundled fmt library was updated to v11.1.2.
- added a new option to configure called --disable-dbus to disable looking for & using QtDBus even if it's present on the system. Default remains to probe for its existence. Patch by Anthony Ryan.

New features and enhancements
- mkvmerge: AC-3 writer: mkvmerge will now use the codec ID A_AC3 even for streams with bitstream IDs 9 or 10 instead of the deprecated codec IDs A_AC3/BSID9 & A_AC3/BSID10. Fixes #2387.
- MKVToolNix GUI: multiplexer: the mechanism for setting track languages to specific values upon adding a file has gotten a new option to always set the language, no matter whether or not the source container provided a track language or what it was set to.
- all command-line tools: implemented an escape mechanism for when you want to use the @ sign as the first character in an argument to an option such as --title. To escape it the @ sign has to be doubled as in --title @@midnight. Implements #3768.

Bug fixes
- mkvmerge, mkvpropedit, MKVToolNix GUI's multiplexer & header editor: the MIME type for TrueType & OpenType fonts will be set properly to either the current MIME types font/ttf & font/otf or to the legacy MIME types application/x-truetype-font & application/vnd.ms-opentype depending on whether the "use legacy font MIME types" option is disabled or enabled, even if the MIME database used by Qt returns the wrong one or even other MIME types such as application/x-font-ttf & application/x-font-otf. This was the case on Windows due to Qt 6.7.3 switching to a different embedded MIME database. Partially fixes #3751.
- MKVToolNix GUI's multiplexer & header editor: ensured that both the legacy & the current font MIME types are always present in the MIME type combo boxes of attachments, no matter what Qt's MIME type database contains. Partially fixes #3751.
- MKVToolNix GUI: the "disable tooltips" option in the preference will now disable the tooltip for the status bar, too.

New features and enhancements
- mkvmerge, MKVToolNix GUI's chapter editor: added support for reading chapters from PotPlayer bookmark files.

Bug fixes
- configure: fixed setting HAVE_QTDBUS properly if the QtDbus module is found. Fixes #3744.
- mkvmerge: MP4 reader: mkvmerge will no longer warn when multiple identical FourCCs are present within the same track headers. Fixes #3748.
- mkvmerge man page: removed the wrong statement that an attachment's MIME type must be set before use of the --attach-file & --attach-file-once options. If not given, mkvmerge auto-detects the MIME type.

New features and enhancements
- mkvmerge: chapters: added support for specifying MPLS files with --chapters, too, not just as regular source files. The documentation stated this was possible already, but that wasn't actually the case. Implements/fixes #3735.
- MKVToolNix GUI: multiplexer: added a progress dialog that is shown during file identification.
- MKVToolNix GUI: jobs: the status bar now differentiates between numbers of warnings/errors that occurred in the current session and those that occurred before the current session. Implements #3732.

Bug fixes
- mkvmerge: AAC parser: LOAS/LATM streams: if the first AudioSpecificConfig element is not found within the first LOAS/LATM frame, mkvmerge will no longer discard the frames before it but defer parsing them until after it has found the AudioSpecificConfig element. Fixes #3727.
- MKVToolNix GUI: job queue: fixed the GUI crashing when re-ordering the jobs in the job queue. This regression was introduced while fixing #3720. Fixes #3729.

Build system changes
- The bundled fmt library was updated to v10.2.1.

New features and enhancements
- mkvmerge: Matroska reader: track statistics tags are included in the JSON identification output just like other tags had already been included: as part of the track properties, prefixed with tag_. Implements #3714.
- mkvmerge: MPEG TS reader: mkvmerge will now detect teletext subtitle tracks even if they're not listed in the PMT as long as it can find teletext pages flagged as subtitles in the header within the probed ranged of the file. Implements #3650.
- MKVToolNix GUI: multiplexer: the default mode for escaping the arguments in the "Show command line" dialog can now be set in the preferences. Partially implements #3709.
- MKVToolNix GUI: multiplexer: the "Show command line" dialog now includes the command lines for all currently open multiplex settings, switchable with a combo box. Partially implements #3709.
- MKVToolNix GUI: multiplexer: some users add the option --regenerate-track-uids to the "additional options", even though --regenerate-track-uids is a file-specific option, and you can only use global options in the "additional options". However, the GUI currently doesn't have an option for specifying additional file-specific options. The GUI now detects the use of this option in the "additional options" & adds it for each of the source files instead. Implements #3707.
- MKVToolNix GUI: multiplexer: the option --regenerate-track-uids has been added to the "additional command line options" dialog. See #3703.
- translations: added a Norwegian Bokmål translation of the man pages by Roger Knutsen (see AUTHORS).

Bug fixes
- mkvmerge: when using timestamp files for subtitle tracks, mkvmerge will no longer set a default duration for the track. Partially fixes #3711.
- mkvmerge: when using timestamp files for subtitle tracks, mkvmerge will no longer queue frames longer than necessary, which resulted in the frames sometimes being written much later than they should have been according to their timestamps. Partially fixes #3711.
- mkvmerge: when using timestamp files for subtitle tracks, mkvmerge will now write the packets' duration properly. Partially fixes #3711.
- MKVToolNix GUI: job queue: the shortcut from the "Job queue" menu are now enabled correctly whenever the number of jobs in the queue changes (e.g. by adding new jobs). Fixes #3720.

Bug fixes
- fixed compilation of src/common/sorting.h with certain compilers due to the deprecation & removal of std::result_of<> in C++20. Fixes #3695.
- fixed compilation with the gtest library when gtest requires additional libraries by querying pkg-config for the correct flags & libraries to build with. See #3696.
- MKVToolNix GUI: multiplexer: restored the keyboard shortcut for switching to the "Attachments" tab (Alt+C for the English interface). Fixes #3702.
- MKVToolNix GUI: multiplexer: fixed several cases when the keyboard shortcuts for copying the first source file's name/the destination file's name to the title (Ctrl+F & Ctrl+D) and the one for copying the title to the destination file name (Ctrl+T) were not enabled. Fixes #3705.

New features and enhancements
- mkvmerge: added a new file-specific option --regenerate-track-uids. When used for Matroska files, mkvmerge will generate new random track UIDs instead of keeping existing track UIDs. This is done automatically when a Matroska file was created by MakeMKV.
- mkvmerge: MP4 reader: added support for FLAC in MP4. Implements #3692.
- MKVToolNix GUI: multiplexer: the "Attachments" tab's title will now include the total number of attachments (both from source files & to newly attach). Implements #3693.
- translations: added a Norwegian Bokmål translation of the programs by Roger Knutsen (see AUTHORS).

Bug fixes
- configure: when called with --disable-gui the build system still ran the check for the GUI libraries & failed if they weren't found. This check is now skipped when the option is given. Fixes #3680.
- mkvmerge: several color-related track header properties were parsed into & stored as a wrong integer type internally. This could result in wrong values being copied when very large values were present in source files, or in error messages when very large values were used as command-line parameters.
- MKVToolNix GUI: multiplexer: the keyboard shortcuts from the "modify selected tracks" sub-menu didn't work right after opening a file. They only started working after opening the "multiplexer" menu. Fixes #3681.

Build system changes
- Release v8.0.0 of the fmt library is now required. If not found, the bundled copy will be used.
- A C20 compatible compiler is now required for several but certainly not all C20 features. g++ v10 & clang++ v10 should suffice.

New features and enhancements
- translations: added a Belarusian translation of the programs & the man pages by prydespar (see AUTHORS).
- mkvmerge, MKVToolNix GUI's chapter editor: added support for reading chapters from ffmpeg metadata files. Implements #3676.
- MKVToolNix GUI: added a new action type for execution after jobs or the queue finishes: quitting MKVToolNix. Implements #3677.

Build system changes
- The bundled fmt library was updated to v10.2.1.

Other changes
- Tons of changes were made to support the latest development versions of libEBML & libMatroska.

New features and enhancements
- mkvmerge: Matroska reader: the "video alpha mode" track header property will be copied to the output file if present. Part of the implementation of #3643.
- mkvmerge: Matroska reader: the "video alpha mode" track header property will be reported in JSON identification mode as the track property alpha_mode. Part of the implementation of #3643.
- mkvmerge: Matroska reader: the file's timestamp scaling factor will be reported in JSON identification mode as the container property timestamp_scale.
- mkvmerge: MPEG transport stream reader: teletext subtitles intended for hearing impaired people (type 0x05) are now marked as such via the appropriate flag in the track headers.
- mkvmerge: file identification: the JSON identification output schema version has been bumped to 19.
- mkvmerge: added a new hack always_write_block_add_ids that can be used as a workaround for players that don't support the handling of missing "Block Addition ID" sub-elements of "Block More" elements in block additions properly. These are used for e.g. alpha channel data in VP9 with a "Block Addition ID" value of 1, which is also its default value. Workaround for the player issues listed in #3643.
- mkvinfo: added support for the "video alpha mode" track header element. Part of the implementation of #3643.
- mkvpropedit, MKVToolNix GUI's header editor: added support for the "video alpha mode" track header property. In mkvpropedit it's called alpha-mode. Part of the implementation of #3643.
- MKVToolNix GUI: multiplexer: when adding files the GUI can automatically enable the "hearing impaired" flag for audio and subtitle tracks if the file name contains the word "cc" or "sdh" delimited by certain characters (configurable). This feature is turned on by default. Implements #3648.
- MKVToolNix GUI: multiplexer: when scanning for Blu-ray playlists the GUI will now ignore playlists that are likely meant for menus. Currently the GUI considers this to be the case when a playlist contains the same item at least five times. This behavior can be turned off in the preferences. Implements #3658.

Bug fixes
- mkvmerge: MPEG transport stream reader: fixed a crash introduced in v81 that occurred when there was at least one PCM track that wasn't copied from the transport stream file. Fixes #3645.
- mkvmerge: when reading data from Matroska files damaged in a specific way, mkvmerge ended up trying to write various types of elements that aren't allowed to be written (so-called EbmlDummy elements as well as elements that don't have a value set) to the output file, which caused the underlying libebml library to abort. These types of broken elements are now filtered out.

Build system changes
- Qt 5 is no longer supported. Qt 6 is now required for building MKVToolNix. This implies that the options to configure revolving around configuring Qt 5 or choosing between the two have been removed (e.g. --disable-qt6).
- Qt 6 detection: if detection fails, error messages from qmake can now be found in config.log. See #3649.
- Qt 6 detection: configure will only consider Qt 6.2.0 or newer, not 6.0.x or 6.1.y anymore, due to the lack of support for the multimedia module.
- Qt 6 detection: configure will now fail to detect Qt 6 if the 'multimedia' module is not found by qmake (e.g. due to development packages not being installed). See #3649.
- The bundled fmt library was updated to v10.1.1.

New features and enhancements
- mkvmerge: MPEG transport stream reader: HEVC/H.265: added support for reading single-layer Dolby Vision from Annex B type bitstream read from MPEG transport streams. Partially implements #3113.
- mkvmerge: MPEG transport stream reader, HEVC/H.265 elementary stream reader: added support for reading dual-layer Dolby Vision with both the base & enhancement layers in the same track from Annex B type bitstreams in MPEG transport files & elementary stream files. Implements #3126.
- mkvmerge: MPEG transport stream reader: HEVC/H.265: implemented combining dual-layer Dolby Vision with base & enhancement layers in different tracks. Implements #3127.
- MKVToolNix GUI: multiplexer: added a new option in the preferences for always enabling 'forced' subtitle tracks. A subtitle track is considered to be 'forced' if: the corresponding property is set in the source file; the track's name contains the word 'forced' (in English); deriving the 'forced display' flag from file names is active & the file name matches the corresponding pattern. The option is disabled by default. Implements #3627.
- MKVToolNix GUI: multiplexer: the functionality for detecting file name sequences when adding files can now recognize the patterns used by GoPro's cameras for chaptered video files. Implements #3633.
- xyzvc_dump: the end position of the current NALU will be output in non-portable format as well.
- xyzvc_dump: HEVC: the tool will now also output the inner NALU type of Dolby Vision NALUs (unspec62 and unspec63).

Bug fixes
- mkvmerge: when the user requests processing be stopped after the video ends mkvmerge will now take appending files into account properly. It won't stop processing unconditionally after the first file ends anymore. Fixes #3618.
- mkvmerge: AV1 handling in readers: the readers will now provide the pixel dimensions to the AV1 packetizer as early as possible, just like for other video packetizers. That way the pixel dimensions are available for calculating the display dimensions when command-line options such as --aspect-ratio & --aspect-ratio-factor are used. Before the change the calculation was done based on initial pixel dimension values of 0x0, resulting in display dimensions of 0x0, too. Fixes #3611.
- mkvmerge: HEVC/H.265 packetizer: when reading & appending HEVC/H.265 from Matroska, MP4/MOV or FLV files the first frame of all the appended files was sometimes dropped, resulting in broken video at the point where video is appended. Fixes #3479.
- mkvmerge: MPEG transport stream reader: when reading MPEG transport streams from Blu-rays the four-byte long TP_extra_header structure in front of the transport packets are now skipped properly. Before the fix a stray byte with value of 0x47 inside that TP_extra_header structure could have thrown off the detection of where the transport packets start, leading to mkvmerge dropping a few audio and/or video frames at the start of the file. Fixes #3632.
- mkvextract: AAC extractor: when an invalid program config element in the GA-specific config element is encountered, the program config element will be disregarded, which avoids mkvextract aborting with an exception. Fixes #3606.
- xyzvc_dump: fixed the tool aborting with an exception when the last NALU in an Annex B type file was shorter than four bytes.

Other changes
- AVC & HEVC dumper development tool: the tool has been renamed from xvc_dump to xyzvc_dump as xvc is an abbreviation for an existing video codec (Extreme Video Coding), and the tool has nothing to do with that codec.

New features and enhancements
- MKVToolNix GUI: if the system's locale uses one of the Han scripts, the GUI will force Arabic numerals to be used in spin boxes. This prevents Suzhou numerals from being used which seems to be the default on Windows systems sold in China. Implements #3624.

Bug fixes
- build system: fixed detection of Qt6 if clang is used for compilation on Linux. In that case Qt's qmake added a gcc-specific option that clang doesn't understand, -mno-direct-extern-access. configure will now pass the parameter -spec linux-clang to qmake so that it uses the correct compiler flags.
- build system: fixed the use of mktemp to be more portable to e.g. macOS. Fixes #3608.
- mkvmerge: if a video aspect ratio was given with --aspect-ratio-factor, the code would apply a second factor based on the pixel resolution, resulting in much too large values for the DisplayWidth element. For example, with a pixel resolution of 720x520 & an aspect ratio factor of 1/1 the result should be 720x520, but instead it was 900x520. Up until release 76.0 this has only happened when a track order was given (which unfortunately includes all invocations with MKVToolNix GUI as it always includes the track order). Starting with release 77.0 this has always happened due to the automatic sorting of tracks implicitly creating a track order, even if none was given.

New features and enhancements
- mkvmerge: AV1: added support for reading Dolby Vision from AV1 IVF & OBU streams. Patches by Quietvoid.
- mkvmerge: MPEG TS reader: added support for colors in teletext subtitles. Patch by Angela Schmid.
- MKVToolNix GUI: multiplexer: when adding files the GUI can automatically enable the "forced display" flag for subtitle tracks if the file name contains the word "forced" delimited by certain characters (configurable). This feature is turned on by default. Implements #3586.
- MKVToolNix GUI: multiplexer: added the option --stop-after-video-ends to the dialog for additional command line options. Implements #3594.
- MKVToolNix GUI: multiplexer: when adding Blu-ray playlists the dialog allowing the user to select the playlist to add will now show audio & video track properties as well (pixel dimensions for video; sampling frequency, channels for audio). Implements #3597.
- MKVToolNix GUI: header editor: in order to reduce confusion with users non that versed in Matroska elements, the naming of the two "language" track properties has been changed: the old element is now titled "Language (obsolete)" & the current, IETF BCP 47 based one is simply called "Language".
- MKVToolNix GUI: preferences: you can now use the "delete" key to remove entries from simple list widgets for strings (e.g. the list of recently used destination directories).

Bug fixes
- mkvmerge: DTS reader: if a DTS stream doesn't start with a DTS core but a sub-stream element (EXSS), the reader will now look for a core. If found, it'll start processing from there instead of from the start. This fixes the timestamp calculation if the sampling frequency in the core & in the extensions are different. Fixes #3602.
- MKVToolNix GUI: multiplexer: the "emphasis" and "stereoscopy" combo-boxes now have a much smaller minimum width, allowing to make the whole "properties" pane much smaller again. Fixes #3581.
- MKVToolNix GUI: macOS: when you install the application from the DMG it'll no longer register itself as an alternate handler for its supported file types. It seems like this overrode existing associations, forcing people to change them manually to whatever they wanted them to be. Additionally this forced the associated file to always be shown with an MKVToolNix icon. The GUI's own .mtxcfg files will still be registered. Fixes #3588.

New features and enhancements
- MKVToolNix GUI: header editor: for files that only contain legacy track language elements but no IETF language elements the header editor will now derive the IETF language elements from the legacy elements. See #3557.
- AppImage: the AppImage is now built on AlmaLinux 8 with Qt 6.5.1. This means that the minimum glibc version this AppImage is compatible with has also been bumped, to v2.28. The oldest Debian coming with this version is Debian 10 "Buster"; for Ubuntu it's 18.10 "Cosmic Cuttlefish".
- Windows installer: the installer will now remove the file dataportable-app if it's present in the installation directory as its presence would signal to the app to run in portable mode, requiring write access to its base directory. This fixes some installation issues that could occur when a user extracted a portable app archive into a folder like C:Program FilesMKVToolNix. Also added an installation check for the same issue. See #3558.

Bug fixes
- all: Linux: if initializing the locale system based on the system's settings fails, e.g. if environment variables such as LC_ALL have been set to fr_FR.UTF-8 but the locale for fr_FR.UTF-8 hasn't been built, MKVToolNix will try to fall back to en_US.UTF-8 first & C.UTF-8 second. If neither of the three succeeds, an error message will be shown, and the program will abort. This fixes the programs not catching an exception from the boost::filesystem library which doesn't cope with mis-configured locale systems well. Workaround for #3574.
- mkvmerge: sorting tracks by type did not work properly when some tracks weren't copied. Part of the fix of #3567.
- mkvmerge: track numbers in the destination file were assigned out-of-order when the track order in the source files differs from the one in the destination file. Now they're assigned sequentially in the order the tracks appear in the destination file again. Part of the fix of #3567.
- MKVToolNix GUI: under certain circumstances the GUI would try to display error messages from a secondary thread, which isn't allowed in Qt, causing to program to either hang or outright crash. Part of the fix of #3556 & #3561.
- MKVToolNix GUI: the GUI will check for several potential installation issues wrt. to having write access to certain directories (system's temporary directory, MKVToolNix's file identification cache directory and others) & display proper error messages if not. Part of the fix of #3556 & #3561.
- MKVToolNix GUI: header editor: fixed the application crashing whenever you change a property below the "segment information" node. This bug was introduced in v77. Fixes #3556.
- MKVToolNix GUI: header editor: when reading files that only contain legacy track language elements but no IETF track language elements, the header editor was showing all tracks as having "English" as the language. This bug was introduced in v77. Fixes #3557.
- MKVToolNix GUI: header editor: when a legacy track language element contains a country code (e.g. fr-CA), the header editor was wrongfully using und = "undetermined" as the language for that element. Now it'll use the language from the language/country pair, which would be fr in the earlier example. Part of the fix of #3557.
- MKVToolNix GUI: header editor: the keyboard shortcuts from the "modify selected track" sub-menu didn't work right after opening a file. They only started working after opening the "header editor" menu. Fixes #3573.
- AppImage: fixed the GUI resources (e.g. icons) not being found.
- AppImage: the Qt plugins required for using compose key/dead keys are now included. Fixes #3577.

Build system changes
- The compilation database (compile_commands.json) is now always built. The variable BUILD_COMPILATION_DATABASE is not evaluated anymore.

New features and enhancements
- mkvmerge: tracks in the destination file will now be sorted by their type automatically unless the track order is specified with the --track-order option. The order is as follows: video tracks first followed by audio & subtitle tracks with other rarely used types of tracks last. Tracks of the same type will be sorted in the same order as their source files occur in the command-line arguments. Note that this doesn't affect file identification. Implements #3545.
- MKVToolNix GUI: multiplexer: the default list colors used for distinguishing source files does not include the darkest tier anymore (the ones where one or two components are set to the value 0x3f) as they're hard to distinguish from each other. Only affects new installations, or when the user presses the "reset to default colors" button. Implements #3533.
- MKVToolNix GUI: multiplexer: the GUI will now check the state of the 'track enabled' flag of all video, audio & subtitle tracks when starting to multiplex or adding a job to the job queue. If there's no track with its flag turned on for a type, the GUI will turn on the flag for the first track of the type. This behavior can be turned off in the preferences. Implements #3535.
- MKVToolNix GUI: header editor: the columns in the tracks/attachments view and the values on the "track type" page will now be updated each time a corresponding property is changed (e.g. when a track's name is changed) instead of showing what's in the file on disk. Implements #3554.
- MKVToolNix GUI: macOS: when you install the application from the DMG it'll register itself as an alternate handler for its supported file types. This allows the use of the "Open with" context menu action in Finder.
- MKVToolNix GUI: Windows: a new settings in the preferences lets the user chose whether to use the light or the dark color palette, or to follow the system settings. Part of the fix for #3528.

Bug fixes
- Fixed compilation with fmt v10.0.0.
- mkvmerge: fixed several instances of wrong format strings for fmt::format used in debug messages. Fixes #3548.
- mkvmerge: AV1 packetizer: the packetizer did not honor the aspect ratio (factor) given on the command-line via the --aspect-ratio or --aspect-ratio-factor options.
- mkvmerge: JSON identification: cropping parameters are reported again even if some of the four values are not present in the file or set to 0. Fixes #3534.
- mkvmerge: Windows: when writing to a network share connected via SMB1 mkvmerge was aborting with a error about create_directory() failed with existing directories. This was due to a bug in recent versions of the Boost.Filesystem library. The Windows version of MKVToolNix will be built with Boost 1.82.0 from now on which includes the fix. Fixes #3547.
- MKVToolNix GUI: the defunct "disable the dark mode" checkbox was removed from the preferences.
- MKVToolNix GUI: language dialog: under certain conditions the controls for the individual components remained disabled when the dialog is opened even though editing of individual components is selected. Part of the fix of #3532.
- MKVToolNix GUI: language dialog: the controls for the individual components weren't re-initialized properly after opening the dialog for the second & all following times, potentially leaving previously selected/entered entries intact, primarily when editing multiple tracks at once. Part of the fix of #3532.
- MKVToolNix GUI: header editor: using the actions from the "modify selected track" context menu only worked if the user right-clicked on the first column in the view. They now work for clicks on any of the columns. See also #3554.
- MKVToolNix GUI: header editor: some of the actions toggling specific flags from the "modify selected track" did not work correctly if the flag wasn't currently present in the file, especially if the underlying value has a default value in the Matroska specs.
- MKVToolNix GUI: Windows: the GUI will now always use its own implementation of light & dark 

Important notes
- mkvmerge: removed the option --blockadd. Removing block additional data is not possible anymore, as it is often required for proper decoding. Part of the implementation of #3511.

New features and enhancements
- mkvmerge: JSON file identification: added a child element called num_index_entries to the properties track element containing the number of index entries found for a track. Currently only implemented for Matroska files where it contains the number of cue points. See #3510.
- mkvmerge: the maximum block addition ID track header value is now calculated automatically from both the existing mappings & the actually used block additions in the block groups. Part of the implementation of #3511.
- mkvmerge: Matroska reader: when reading WebM files that use block additions with ID 4 (HDR for VP9) an appropriate block addition mapping will be created automatically. Part of the implementation of #3511.
- mkvmerge: MP4 reader: the title/movie name meta data (content of the udta.meta.ilst.©nam atom) will now be copied over as the segment title track header attribute. Part of the implementation of #3475.
- mkvmerge: MP4 reader: the comment & encoder meta data (content of the udta.meta.ilst.©cmt & ….©too atoms) will now be copied over as global tags COMMENT & ENCODER respectively. Part of the implementation of #3475.
- mkvmerge, MKVToolNix GUI's multiplexer: added an option to stop processing after the primary video track ends called --stop-after-video-ends. This discards any remaining packets of other tracks. Part of the implementation #3506.
- MKVToolNix GUI: only on Windows: the GUI now uses Qt's "Fusion" style instead of the deprecated "Windows Vista" style. The advantage is that as of Qt 6.5 the "Fusion" style properly supports Windows 10's & 11's dark application mode. The Windows binaries are now built with said Qt version. Therefore the option to disable the dark mode has been removed. Fixes #3264 and likely others.
- MKVToolNix GUI: multiplexer: automatically setting the destination file name: added an option in the preferences for using the first source file's directory name instead of its file name as the basis for the destination file name. Implements #3512.
- MKVToolNix GUI: multiplexer: double-clicking on certain columns in the "tracks" view will now toggle them directly (columns "Default track" & "Forced track") or activate the corresponding control (columns "Language", "Name" & "Delay"). Double-clicks on other columns will do what they've done before, too: toggling the "Copy item" state. Implements #3513 & others.
- MKVToolNix GUI: the dialog for editing language tags is now created only the first time the user wants to edit a language tag & cached afterwards instead of creating a new instance each time. This makes subsequent uses instant.

Bug fixes
- mkvmerge: mkvmerge will now only try to probe for VobSubs if the name of the file to identify ends in either .idx or .sub, preventing mis-identification of other file types if VobSubs with the same base name exist in the same directory. Fixes #3508.
- mkvmerge: AC-3: mkvmerge will now skip certain types of garbage data (16 bytes starting with 0x01 0x10) that can occur before each sync frame, fixing the file not being identified as AC-3. Fixes #3484.
- mkvmerge: Matroska reader: when reading files that use block additions with IDs other than 1 (e.g. 4 for HDR for VP9) the IDs will now be kept & written to the output file. Before no ID would be written, effectively using 1 as that's the default value for the corresponding element. Part of the implementation of #3511.
- mkvmerge: mkvmerge will no longer write block addition mappings or the max block addition ID track header elements when creating a WebM file as those elements aren't supported there. Part of the implementation of #3511.
- mkvpropedit: fixed replacing chapters & tags in files that don't contain tracks. Fixes #3498.

New features and enhancements
- mkvmerge: MP4 reader: mkvmerge will now read Timed Text (FourCC tx3g) subtitle tracks & convert them on the fly to Matroska's simple text subtitle format (S_TEXT/UTF8; text only, no styles). Implements #2208, #2242, #2613, #3000, #3243, #3418 and possibly others.

Bug fixes
- all: switched back to using boost::filesystem functions for creating directories instead of the ones introduced to work around bugs in std::filesystem. The latter didn't work correctly with UNC paths after the switch to boost::filesystem::path in v74. Fixes #3483.
- mkvmerge: VobSub reader: mkvmerge will now probe the .idx file during VobSub identification even if the .sub file is passed as the source. Avoids mis-detection of the .sub as MPEG program streams. Fixes #3489.
- MKVToolNix GUI: the GUI could abort with an exception on startup while looking for the mkvmerge or mediainfo executables due to inaccessible folders. Fixes #3481.
- MKVToolNix GUI: preferences: when opening the preferences the first time the UI might pre-select the first entry in the list of interface languages if the operating system's language is not available for MKVToolNix. This might also happen on Linux if e.g. en_GB is set, even though en_US is available. Now English (en_US) will be selected instead. Fixes #3486.
- MKVToolNix GUI: multiplexer: when adding files the GUI has special handling for chapter/tags/segment info files. This is done by comparing their content to certain patterns. This recognition could wrongfully be triggered if any such file was embedded in another file verbatim, e.g. with a chapter XML file attachment in a Matroska file. When trying to add that Matroska file, the GUI would treat it as a chapter file instead of a regular one. This content-based detection was fixed. Fixes #3487.

Other changes
- mkvpropedit, GUI's header editor: removed support for the deprecated "minimum cache" & "maximum cache" track header elements.

New features and enhancements
- mkvmerge: SRT handling: added a hack called --engage keep_whitespaces_in_text_subtitles which disables stripping whitespaces from the start & end of each line of SRT entries during muxing. Part of the implementation of #3470.

Bug fixes
- all: Windows: UNC paths of type \?C:\… are supported again by switching back to Boost's file system library instead of using C++17's file system library. Fixes #3058.
- mkvmerge: AVC/H.264 & HEVC/H.265 packetizers: when appending tracks the pixel dimensions will be checked & muxing will be aborted if they don't match. Fixes #3480.
- mkvmerge: file type detection: file types that can be detected unambiguously by their content (e.g. Matroska, MP4, WAV…) will now preferred in the detection order over file types based on their extension. Prevents certain cases of mis-detection, e.g. DTS in WAV but with a file name extension of .dts being detected as the wrong type of DTS. Fixes #3462.
- mkvmerge: SRT handling: whitespaces will now be stripped from the start & the end of each line of each entry, not just from the end of the last line. Part of the fix of #3470.
- mkvextract: SRT extraction: whitespaces will not be stripped from the start & end of the whole entry anymore. Part of the fix of #3470.
- MKVToolNix GUI: multiplexer: when adding multiple files that include certain file types (chapters, segment info and tag files) and when the choice where to add them is "all files to a single new tab", these certain file types will now be added in the newly added tab as well instead of the current tab that had already been open. Fixes #3469.
- build system: fixed compatibility with Ruby 3.2.0 by using FileTest.exist? instead of File.exists?, Dir.exists? & FileTest.exists? which were removed in that release.

Build system changes
- MKVToolNix is now using & requiring Boost's "file system" and "system" libraries again instead of C++17's file system library. This is due to gcc's library not supporting UNC paths of types \?C:dirfile.ext.

New features and enhancements
- mkvmerge: greatly enhanced the speed of Base64 decoding which is used used e.g. when reading pictures embedded in Ogg or FLAC files or for binary data inside XML chapter & tag files. Even small blocks of data could take unreasonably long.
- mkvmerge: added support for reading HEVC/H.265 video from FLV containers. Implements #3466.

Bug fixes
- mkvmerge: splitting: fixed a typo in the string output in GUI mode regarding the timestamps before which splitting was done. See #3421.
- MKVToolNix GUI: job output: after having run multiple jobs the "Clear output" functionality only reset the visible parts. However, using the "save output" function would also save the output generated before the user used "clear output". Now only the output after the last use of "clear output" is saved. Fixes #3438.
- build system: when probing for the FLAC library the Ogg libraries will be linked with the compiled test program as well. This fixes detection if the pkg-config settings for FLAC don't list Ogg & the linker doesn't find the library automatically (e.g. for my macOS builds). Fixes #3439.

New features and enhancements
- mkvmerge: AV1 parser: the variable-width OBU size field will be re-written with minimal length if it's encoded longer than necessary.
- mkvmerge: when splitting is active the program will output the timestamps actually used for making the decision when to split. If GUI mode is active, a specially formatted line #GUI#splitting_before_timestamp <timestamp> is output as well. Lines prefixed with#GUI# are suitable for machine parsing, won't be translated and are guaranteed not to change in format. Implements #3421.
- MKVToolNix GUI: multiplexer: when dragging & dropping directories to the "attachments" tab, the files contained in those directories will be attached. Implements #3410.
- MKVToolNix GUI: info tool: added information about the file (directory, size, modification timestamp) at the top of each tab. Implements #3407.

Bug fixes
- mkvmerge: AV1 parser: fixed the parser completely aborting when parsing the OBU size field fails due to there not being enough data to parse. Instead the parser will remember the last known-good position & restart from there after more data is available. Fixes #3431.
- mkvmerge: HDMV PGS subtitles: reverted the change that implemented a heuristic for detecting bogus timestamps & attempting to fix them. This was done to fix #3268. Unfortunately this affected valid subtitle files with intentional huge gaps in timestamps, e.g. forced subtitle tracks. The heuristic has simply been removed, fixing #3392.
- mkvmerge: Matroska reader: fixed reading files with EBML Void elements before the Matroska Segment element.
- mkvmerge: fixed reversed attachment selection: --attachments !4 would not copy any attachment instead of all attachments but the one with ID 4. Fixes #3427.
- mkvextract: IETF BCP 47/RFC 5646 language tags: mkvextract will now use & prefer IETF BCP 47 track language elements if they're present. Only affects the VobSub & USF subtitle extraction.
- mkvpropedit, MKVToolNix GUI's chapter & header editors: updated the list of deprecated Matroska elements. The applications will no longer try to write those elements, even if they're found in the file to be modified. The programs will no longer abort with error messages such as assertion "false" failed. Fixes #3416.
- mkvpropedit, MKVToolNix GUI's chapter & header editors: when the Matroska version numbers stored in the EBML Head element are updated, the updated EBML Head element might be smaller than the existing one. In that case the programs used to shrink the EBML Head & write a small EBML Void element between the updated EBML Head & the following element, usually a Matroska Segment element. This isn't widely supported by programs including MKVToolNix itself, causing them to declare such files as invalid. The programs will now create the EBML Void element inside the EBML Head element, making them a level 1 element instead of a level 0 element. Fixes #3355.
- mkvpropedit, MKVToolNix GUI's chapter & header editors: often the programs have to relocate the Master elements in which the modifications were done. In that case the Seek Head elements must also be updated to reflect to the Master elements' new positions. If a file contained a Seek Head element at the start already and if that Seek Head was too small to contain the updated positions, the programs would end up in an endless loop trying to write data to the end, creating ever-growing files. This is now handled properly by voiding this too-small Seek Head & finding a proper space for a new one instead. Fixes #3338.
- MKVToolNix GUI: header editor: fixed pixelated icons on higher display scaling values. Fixes #3420.

Build system changes
- bug fix: libFLAC detection is now done via pkg-config, and the corresponding compiler flags are honored. Fixes static compilation with newer versions of libFLAC with MXE where a compiler definition is required to signal that it libFLAC wasn't built as a DLL.

Bug fixes
- Chapters DTD: added the new edition & chapter elements from Matroska v5.
- Chapters DTD: fixed EditionUID being mandatory. mkvmerge can auto-generate it if it's missing from the XML file.
- Chapters DTD: fixed the example-chapters-1.xml not validating against the DTD.
- Chapters DTD: corrected the old name EditionManaged to EditionFlagOrdered.
- Chapters DTD: fixed ChapLanguageIETF missing its element declaration & ChapterLanguage being required.
- XML DTDs: fixed elements representing binary data not allowing the format attribute.

Build system changes
- bug fix: configure accidentally tested for libEBML ≥ 2.0.0 & libMatroska ≥ 2.0.0, even though the actual requirements are 1.4.4 & 1.7.1 respectively.

New features and enhancements
- mkvmerge, MKVToolNix GUI's multiplexer: added support for the Emphasis audio track header element via the --audio-emphasis option. It is also read from Matroska files.
- mkvmerge: the options --list-stereo-modes and --list-audio-emphasis have been added to list all support numerical & textual values for the --stereo-mode & --audio-emphasis options.
- mkvpropedit, MKVToolNix GUI's header editor: added support for the Emphasis audio track header element via the emphasis property.
- MKVToolNix GUI: multiplexer: when the track properties are configured to be displayed in a tab widget below the files & tracks in the "Input" tab, the "Color information" tab will be laid out in two columns. This reduces the minimum height the whole tab widget requires. Implements #3401.
- MKVToolNix GUI: greatly sped up closing the preferences dialog by only re-running certain initialization functions when their corresponding settings have changed. Also fixes issues such as #3406.
- mkvinfo, MKVToolNix GUI's info tool: added support for the following new elements from Matroska v5: Emphasis audio track header element; Chapter Skip Type; Edition Display; Edition String; Edition Language IETF.
- mkvmerge, mkvpropedit: added support for the following new chapter elements from Matroska v5: Chapter Skip Type; Edition Display; Edition String; Edition Language IETF. The GUI's chapter editor will receive support for them in the next release.

Bug fixes
- mkvmerge: Ogg/OGM reader: mkvmerge will now correctly skip tracks of unsupported types as well as tracks for which all track header pages haven't been found. Fixes #3394.

Build system changes
- libEBML 1.4.4 & libMatroska 1.7.1 are now required.
- The bundled libEBML & libMatroska libraries were updated to v1.4.4 & v1.7.1 respectively.
- The bundled fmt library was updated to v9.1.0.
- The bundled nlohmann-json library was updated to v3.11.2.

New features and enhancements
- MKVToolNix GUI: the user can now control where the job queue files & the preferences INI file are stored via environment variables. 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. 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. Implements #3382.
- 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. Implements #3371.

Bug fixes
- mkvmerge: AV1 OBU parser: fixed identifying files that only contain single frame. Fixes #3380.
- 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. Fixes #3368.
- 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.

Build system changes
- Several merge requests where accepted that improve compilation on MSYS2 on Windows. Note that this build type isn't supported.

Important notes
- all: the spelling of "colour" was changed to "color" throughout all programs to match the use of American English spelling in MKVToolNix. This not only affects documentation and user interface controls, but also program options for mkvmerge & mkvpropedit. Both programs will continue to accept the British English spelling of their respective options indefinitely. One breaking change is that the property names in mkvmerge's JSON identification mode have also been changed to American English spelling. As those properties have only been introduced in release v68, this seems like a small enough window to make such a change.

New features and enhancements
- MKVToolNix GUI: the number of recently used entries (e.g. destination directories) remembered by the GUI can now be configured in the preferences. Implements #3362.
- MKVToolNix GUI: multiplexer: when adding files the track properties regarding color information & color mastering meta information will be parsed & set in the corresponding GUI controls. Implements #3359.
- MKVToolNix GUI: job queue: the job queue can now be sorted by clicking on the column headers. Part of the implementation of #3365.
- MKVToolNix GUI: job queue: when loading jobs from the queue directory that weren't previously known to the program those jobs will be sorted by their "date added" timestamp instead of using the order the operating system returns them in. Part of the implementation of #3365.

Bug fixes
- build system: fixed compilation with fmt v9. Fixes #3366.
- mkvmerge: HEVC ES parser: the parser will now parse at least the first full access unit before reporting that it has found all the required headers. Otherwise parsing might stop in the middle of the access unit due to the source reader not providing more data in the first call, leading to the parser not finding the unspec62 and unspec63 NALUs required for Dolby Vision. Fixes #3363.
- MKVToolNix GUI: preferences: the default actions added to the "execute programs" section on new installations now default to use WebM file names instead of Ogg, matching the format of the included audio files.

Build system changes
- The bundled fmt library was updated to v9.0.0.

New features and enhancements
- mkvmerge: HDMV PGS subtitles: mkvmerge now tries to detect bogus timestamps (where the current timestamp is two hours or more after the previous timestamp) & correct them to something more sensible (1s after the previous timestamp). That way one bogus timestamp cannot cause the rest of the frames to not be interleaved properly with the other audio & video packets. Implemented for #3268.
- mkvmerge: added color information, color mastering meta information & video projection information properties to the JSON identification format. The properties are reported for container types for which mkvmerge supports reading them (Matroska & MP4). The JSON identification format version number has been bumped to v15.
- MKVToolNix GUI: multiplexer: added controls for all the video color information & the video projection information.

Bug fixes
- mkvmerge: SRT reader: entries with a duration of 0 or less will now be skipped. Fixes #3332.
- mkvpropedit, MKVToolNix GUI's chapter & header editors: fixed an invalid memory access when trying to update existing Matroska files whose EBML Head element had a "size" field length of eight bytes, and where rewriting said element would shrink the element by one byte. Files created by gstreamer fit the first part whereas the second depends on the changes requested by the user. Part of the fix of #3325.
- mkvpropedit, MKVToolNix GUI's chapter & header editors: fixed the programs not handling having to remove EBML void elements at the end of the file correctly and consequently aborting. Part of the fix of #3325.
- MKVToolNix GUI: the GUI now uses almost all SVG icons, allowing proper scaling even for scaling factors such as 125%. Fixes #3335.
- MKVToolNix GUI: when compiled with Qt 5 the character set of INI files is forced to UTF-8 in order to fix reading INI files written by a version compiled with Qt 6. Fixes #3346.

Build system changes
- Qt's SVG library is now required.

New features and enhancements
- all: IETF BCP 47/RFC 5646 language tags: when deriving the legacy language element codes to use a language tag's ISO 639 code is also potentially interpreted as an & its prefix is used as the legacy language code. For example, "Yue Chinese" = yue is not part of ISO 639-2. However, there is an extlang subtag yue with a valid prefix of zh ("Chinese"), and for "Chinese" there is an ISO 639-2 language code: chi. In this example the IETF language element would be set to yue and the corresponding legacy element to chi. Part of the implementation of #3307.
- all: IETF BCP 47/RFC 5646 language tags: grandfathered language tags are now supported. Part of the implementation of #3307.
- all: IETF BCP 47/RFC 5646 language tags: all deprecated subtags from the IANA language subtag registry are now supported. Part of the implementation of #3307.
- all: IETF BCP 47/RFC 5646 language tags: all lists of valid subtags have been updated from their respective authoritative sources. Part of the implementation of #3307.
- all: IETF BCP 47/RFC 5646 language tags: all in the IANA language subtag registry are now supported, even those marked as deprecated and of type 'grandfathered'. Part of the implementation of #3307.
- all: IETF BCP 47/RFC 5646 language tags: reduced the maximum number of extended language subtags that are present in a valid tag from 3 to 1 in compliance with RFC 5646 section 2.2.2. Part of the implementation of #3307.
- all: IETF BCP 47/RFC 5646 language tags: all language codes reserved for private/local use (qaa–qtz) are now supported. Part of the implementation of #3307.
- all: IETF BCP 47/RFC 5646 language tags: Digital Cinema Naming Convention language codes that fall into the IETF BCP 47 range of "private use" tags (qaa–qtz) are now replaced by their IETF BCP 47 equivalents during normalization (e.g. QMS → cmn-Hans). Part of the implementation of #3307.
- all: added a new translation to Chinese Simplified (Singapore) by Dian Li.
- mkvmerge, mkvpropedit: added a new command line option called --enable-legacy-font-mime-types. With this option on the two programs will use the same legacy MIME types for fonts whenever new attachments are added (both programs), when reading existing attachments (only mkvmerge) or when replacing existing ones (only mkvpropedit).
- mkvmerge, mkvpropedit: IETF BCP 47/RFC 5646 language tags: added a command line option --normalize-language-ietf <mode> which turns on normalization of IETF BCP 47 language tags to either their canonical (mode canonical) or extended language subtags form (mode extlang) or turns it off (mode off). If the option isn't given, language tags will now be normalized to the canonical form. Part of the implementation of #3307.
- MKVToolNix GUI: IETF BCP 47/RFC 5646 language tags: ISO 639-3 and 639-5 languages will now be used by default. Part of the implementation of #3307.
- MKVToolNix GUI: IETF BCP 47/RFC 5646 language tags: the language editor dialog will now show warnings in several cases: when deprecated tags are used; when the tag's canonical and/or extlang forms differ from the user input. Part of the implementation of #3307.
- MKVToolNix GUI: IETF BCP 47/RFC 5646 language tags: the language editor now has a button to replace the current tag with a normalized form (canonical or extlang) if those differ from the current tag. Part of the implementation of #3307.
- MKVToolNix GUI: IETF BCP 47/RFC 5646 language tags: added an option in the preferences to always normalize all language tags to their canonical or extlang forms or to turn normalization off. Can also be enabled from the language editor dialog. Part of the implementation of #3307.
- MKVToolNix GUI: IETF BCP 47/RFC 5646 language tags: the language dialog now shows a warning if a variant is used with a prefix that isn't in the variant's list of suitable prefixes. It'll also say if the corresponding canonical/extlang forms would have a suitable prefix. Part of the implementation of #3307

New features and enhancements
- mkvpropedit: added a new option --chapter-charset allowing the user to specify the character set to use when reading the following chapter file. Implements #3276.
- MKVToolNix GUI: each language shortcut can now be associated with an optional track name that is set along with the language when the shortcut is used. This is an alternative to the feature requested in #3283.

Bug fixes
- mkvmerge: Ogg/OGM reader: mkvmerge will no longer abort with an exception when it encounters Vorbis comments that contain data that isn't valid UTF-8. Fixes #3290.
- MKVToolNix GUI: multiplexer: fixed several issues with the tab order of elements in the "properties" pane and the "output" tab. Also fixed the language display widgets (e.g. "track language" in the "properties" pane) never receiving tab focus. Fixes #3274.
- MKVToolNix GUI: multiplexer: the chapter name template will now be passed to mkvmerge if a chapter file is selected on the "output" tab. Fixes #3295.

New features and enhancements
- mkvmerge: the options --default-track and --forced-track have been renamed to --default-track-flag and --forced-display-flag respectively for improved consistency with other option names & the wording used in the GUI. However, the old names will be supported and recognized indefinitely. What will remain unchanged is the property names for those flags in mkvmerge's identification output. Existing third-party programs will continue working as they are.
- mkvmerge: added a new option --track-enabled-flag to set or unset the "track enabled" track header flag.
- mkvmerge: MP4 reader: mkvmerge will now evaluate the flags field of the track header atom (tkhd) and set the track's "enabled" flag accordingly. Implements #3272.
- MKVToolNix GUI: multiplexer: added support for the "track enabled" track header flag.
- MKVToolNix GUI: multiplexer, header editor: added several menu entries & keyboard shortcuts for toggling various track flags of the currently selected tracks, e.g. Ctrl+Alt+F, D (that's Ctrl and Alt with F simultaneously followed by D without any other key pressed) for toggling the "default track" flag. Part of the implementation of #3253.
- MKVToolNix GUI: multiplexer, header editor: added menu entries & keyboard shortcuts for setting the language of the currently selected tracks to one from a configurable list of languages. The shortcuts used are Ctrl+Alt+A, 1 through Ctrl+Alt+A, 0 for the first ten entries of that list (that's Ctrl and Alt with A simultaneously followed by a digit without any other key pressed). Part of the implementation of #3253.
- MKVToolNix GUI: chapter editor: if the user enters commas in start or end timestamps they will automatically be changed to points as the decimal separator, allowing for easier copy & paste from other programs/sources. Implements #3273.
- MKVToolNix: header editor: the selected track or attached file can now be moved up & down with the keyboard shortcuts Ctrl+Up & Ctrl+Down respectively. Part of the implementation of #3253.

Bug fixes
- mkvmerge: Matroska reader: DVB subtitle tracks with a codec private data size of more than five bytes are accepted now, too. Fixes #3258.

New features and enhancements
- MKVToolNix GUI: language dialog: when the user switches between the two edit modes, the mode's corresponding first control is automatically focussed.

Bug fixes
- all: language lists: the entries for "Ancient Greek (to 1453)" and "Modern Greek (1453-)" have been renamed to "Greek (ancient, -1453)" and "Greek (modern, 1453-)" respectively in order to be easier to find.
- mkvmerge: VobSub reader: files containing id: -- lines to indicate that the track language isn't known were rejected by mkvmerge. Now they're accepted, and und (undetermined) is used as the language. Fixes #3246.
- MKVToolNix GUI: chapter editor: the "Save to Matroska or WebM file" function was using the wrong standard file dialog (the "open file" one instead of "save"), leading to confusing button names. Fixes #3242.
- MKVToolNix GUI: high DPI scaling: fixed the icons in the tool selector having the wrong size for scaling factors other than 100% or 200%. Fixes #3229.

Build system changes
- The bundled fmt library was updated to v8.0.1.
- The bundled nlohmann-json library was updated to v3.9.1.
- The bundled pugixml library was updated to v1.11 revision 6a76cac.
- The bundled utf8-cpp library was updated to v3.2 revision b85efd6.

New features and enhancements
- mkvmerge: AC-3 parser: E-AC-3 with BSID values > 10 and ≤ 15 are recognized now, too. Implements #3211.
- mkvmerge: when using language codes for track selection (e.g. -a und,en) all tracks that do not have a language property (due to their container not providing one, e.g. AVIs) will be treated as if they did have one set to und ("undetermined") as that is the language the track will have in the Matroska file anyway. Before this change it wasn't possible to match such tracks via language codes.
- MKVToolNix GUI: only on Windows: when compiled with Qt ≥ 5.14 and < 6 (which is the case for the officially provided binaries) fractional screen scaling will be enabled. This means that the GUI will be scaled appropriately if Windows is set to 125%, 150% or 175% instead of being too small or too large. Implements #3043.
- MKVToolNix GUI: the spinner in the bottom right corner will now be hidden when no jobs are currently running. Implements #3225.
- MKVToolNix GUI: header editor: a new column has been added to the tree view showing the status of the "track enabled" flag. The information is also shown on the track overview page on the right. Implements #3228.
- MKVToolNix GUI: header editor: users can now reorder tracks by dragging & dropping. Implements #3227.

Bug fixes
- mkvmerge: AVI reader: fixed reading AVI files that contain vprp video properties header chunks; reading aborted too early. Fixes #3209.

New features and enhancements
- all: IETF BCP 47/TFC 5646 language tags: all ISO 639 languages are now available, even the ones that aren't of types "Constructed", "Living" or "Special".
- mkvmerge, mkvpropedit: chapters: both programs will now write elements set to their default value, too (e.g. the legacy language element if it's set to eng). This is done to be more consistent with how MKVToolNix GUI writes chapters. Implements #3210.
- MKVToolNix GUI: multiplexer: when adding new files as attachments the GUI checks if there are other attachments with the same name. If so, the GUI would ask whether to skip the affected files or add them anyway. There's now an option in the preferences to always skip such files, and it's enabled by default. Implements #3213.
- MKVToolNix GUI: chapter editor: removed the support for explicitly setting the legacy country elements. Instead the legacy country elements are derived from the region parts of the IETF BCP 47 languages. Part of the implementation of #3193.

Bug fixes
- mkvmerge: fixed a crash when splitting by chapters is enabled but there are no chapters at all. Part of the fix of #3198.
- mkvmerge: the error message when trying to split by a chapter number that doesn't exist contained the wrong number of chapters that actually do exist. Part of the fix of #3198.
- mkvmerge: AVC ES parser: fixed mkvmerge aborting due to uncaught exception when encountering bad SPS data. Part of the fix of #3176.
- mkvmerge: AVC/H.264 parser: re-added the hack --engage all_i_slices_are_key_frames which was accidentally removed in release v61.
- mkvmerge: AVI reader: fixed a crash trying to allocate too big of a memory chunk due to an integer overflows in check conditions. Part of the fix of #3176.
- mkvmerge: HEVC ES parser: fixed another issue with frame type recognition. Certain frames were marked as B frames/discardable on the container level even though they could be reference pictures. Now only SLNR pictures (sub-layer non-reference) are marked that way. Fixes #3192.
- mkvmerge: HEVC ES reader: improved file content detection for HEVC ES files with wrong file name extensions (e.g. .mkv), which fixes them being mis-detected as something else, e.g. DTS. Fixes #3201.
- mkvmerge: HEVC ES parser: "end of sequence" NALUs are kept now, and no superfluous flushing will be done when one is found. This prevents splitting NALUs into two different Matroska blocks when they should really be part of a single one, also causing problems with erroneous timestamps. Mostly affects DoVi NALUs. Fixes #3202.
- mkvmerge: Matroska reader, TrueHD: mkvmerge will now probe much more TrueHD frames trying to find the first sync frame. This fixes track detection in situations when a TrueHD doesn't start with a sync frame, e.g. when the source file's the result of splitting between sync frames.
- mkvmerge, MKVToolNix GUI's chapter editor: IETF BCP 47/RFC 5646 language tags: when reading chapters from MPLS playlist files, the ChapLanguageIETF element will now be set to the configured default chapter language, not just the legacy ChapterLanguage element. Part of the fix of #3193.
- mkvmerge, mkvpropedit, MKVToolNix GUI's chapter editor: IETF BCP 47 elements will now always be created before writing chapters unless IETF BCP 47 elements are disabled. Part of the fix of #3193.
- mkvmerge, mkvpropedit, MKVToolNix GUI's chapter editor: when a chapter display element contains legacy language & country elements but no IETF BCP 47 elements and IETF BCP 47 elements aren't disabled, the IETF BCP 47 elements created will contain the region from the legacy element. Part of the fix of #3193.
- mkvmerge, mkvpropedit, MKVToolNix GUI's chapter editor: Legacy country elements are now created when IETF BCP 47 elements are present & contain a region code allowed in legacy country elements. Part of the fix of #3193.

Build system changes
- The tools sub-directory is now always built. The corresponding configure option --with-tools has been removed. 

New features and enhancements
- all: IETF BCP 47/RFC 5646 language tags: implemented support for officially registered IANA language tag extensions.
- mkvmerge: track selection: when using language tags for selecting which tracks to keep, mkvmerge will now use component-based language tag matching instead of comparing them verbatim. This means that only those components (language, region etc.) the user specified will be required to exist and be equal. For example, if a file contains three subtitle tracks with languages es (generic Spanish), es-MX (Spanish as spoken in Mexico) and es-ES (Spanish as spoken in Spain), the user can use --stracks es to match all three tracks or be more specific with e.g. --stracks es-MX which would only match one track. Similarly inverting the selection with e.g. --stracks !es would get rid of all three tracks, not just the one for the generic Spanish.
- MKVToolNix GUI: multiplexer: deriving track languages from file names: the GUI can now detect full BCP 47/RFC 5646 language tags in file names. Part of the implementation of #3173.
- MKVToolNix GUI: multiplexer: deriving track languages from file names: the default list of boundary characters now includes -. Part of the implementation of #3173.
- MKVToolNix GUI: multiplexer: the GUI now defaults to the "lower" process priority setting for new installations in order to leave more room for other applications, especially interactive ones. Up to and including v59 the default was the "normal" process priority. v60 changed that to "lowest", which turned out to be much slower on Windows for no real gain over "lower". The setting will be auto-corrected by the GUI if the settings file were saved last with a version between v60.0.0.0 & v60.0.0.17 & "lowest" & it is still set to "lowest".
- HEVC dumper development tool: the tool has been renamed to xvc_dump and extended to be able to dump AVC/H.264 bitstreams, too. It now also detects the type of bitstream framing (ISO 14496-15 vs. ITU-T H.264/H.265 Annex B).

Bug fixes
- all: IETF BCP 47/RFC 5646 language tags: fixed a corner case of wrongfully allowing scripts/variants not listed in any of the entries in the prefix list when the prefix list contains prefixes restricting scripts/variants and a prefix solely with the language at the same time (example: the variant ekavsk with its prefixes sr, sr-Cyrl and sr-Latn where e.g. sr-ekavsk and sr-Cyrl-ekavsk should be allowed but not sr-Bali-ekavsk).
- mkvmerge: HEVC/H.265: the frame type of B frames was often wrongfully signalled as P frames instead, both with BlockGroup (missing second references) and SimpleBlock ("discardable" flag not set) elements.
- mkvmerge: SSA/ASS packetizer: the frame numbers will now be re-calculated when appending SSA/ASS tracks so that frame numbers of appended tracks are always strictly higher than frame numbers of the track they're appended to.
- mkvmerge, MKVToolNix GUI's chapter editor: BCP 47/RFC 5646 language tags: when BCP 47 language tags are used with a language code that isn't part of ISO 639-2, the programs will now write a legacy language element set to und ("undetermined") instead of not writing such an element at all or writing one with an invalid code. Fixes #3174.
- mkvmerge, MKVToolNix GUI's chapter editor: BCP 47/RFC 5646 language tags: the programs will ensure that the legacy and IETF language elements written will be unique within the scope of the same "chapter display" element.
- mkvinfo, MKVToolNix GUI's info tool: in summary mode the frame type was reported wrong for BlockGroup elements in which the ReferenceBlock elements were located behind the Block element.

Build system changes
- all: std::codecvt_utf8 is now used instead of Boost's utf8_codecvt_facet. The bundled copy the latter in lib/boost has therefore been removed.

New features and enhancements
- all: IETF BCP 47/RFC 5646 language tags: added support for language families from ISO 639-5 that aren't part of 639-2.
- all: IETF BCP 47/RFC 5646 language tags: implemented support for Alpha 2 country codes of the "user-defined" category: AA, QM–QZ, XA–XZ and ZZ.
- all: IETF BCP 47/RFC 5646 language tags: updated the various lists of valid subtags from the official specs.
- MKVToolNix GUI: multiplexer: pressing the keyboard shortcut for the track's "Language" label (Alt+L for English) will now open the language dialog.
- MKVToolNix GUI: multiplexer: added an option in the preferences for turning off the colored boxes indicating which file each track belongs to.

Bug fixes
- all: IETF BCP 47/RFC 5646 language tags: fixed validating extended language & variant subtags against their allowed prefixes (e.g. a valid tag with a country code as in de-CH-1996 is recognized as valid while two generally known variants that aren't allowed together as in de-1901-1996 is recognized as invalid).
- all: IETF BCP 47/RFC 5646 language tags: when looking up a language for a two- or three-letter code, the programs will no longer compare that code with language names as that was unintended, ambiguous (e.g. the code "Ga" could be interpreted as the 639-2 alpha-2 code for "Irish" or as the name of the language called "Ga") and only worked with languages whose name was at most three letters long.
- mkvmerge: HEVC/H.265: appending Matroska files with HEVC tracks might lead to the loss of the first couple of frames from each of the second and all following files. Fixes #3170.
- mkvmerge, mkvextract: HEVC/H.265 parser: fixed the programs aborting when parsing VPS or SPS NALUs with invalid content due to unhandled exceptions. Fixes #3162.
- MKVToolNix GUI: multiplexer: when the option "use legacy MIME types for font attachments" is enabled, the GUI will now use application/x-truetype-font for font collection files.
- MKVToolNix GUI: multiplexer: fixed escaping the mkvmerge argument in the "Show command-line options" dialog for the "Windows (cmd.exe)" mode. Fixes #3164.
- MKVToolNix GUI: multiplexer: when adding multiple files at once, the GUI will sort file names with numbers the way a human would expect it to. For example, 1.mp4, 9.aac, 10.srt, 11.srt are now sorted exactly that order instead of 1.mp4, 10.srt, 11.srt, 9.aac.
- MKVToolNix GUI: header editor: the header editor will now honor the "use legacy MIME types when adding font attachments" setting when adding new attachments.

New features and enhancements
- mkvmerge: WebVTT parser: the parser now follows the specs' rules for parsing timestamps more closely by being more lenient: it allows arbitrary number of spaces & tabs at the start of the line & around the arrow; it allows any number of digits for the hours. Part of #3139.
- MKVToolNix GUI: multiplexer: when adding a Blu-ray playlist without scanning for other playlists the GUI will now look for disc library information & let the user select which one to use if there's more than one entry. Implements #3143.
- MKVToolNix GUI: multiplexer: added an option for sorting files & tracks by track types when adding them to multiplex settings. The order is: video first followed by audio, subtitles and other types. Files & tracks can still be reordered manually later. The option is enabled by default & can be found in the preferences → "Multiplexer" page → "Adding files" section. Implements #2366.
- MKVToolNix GUI: multiplexer: added an option for recognizing file name sequences such as movie.001.mp4, movie.002.mp4, movie.003.mp4 when adding multiple files at once. If a sequence is detected, the only first file will be added while the second and following file names will be appended to the first one. The option is enabled by default & can be found in the preferences → "Multiplexer" page → "Adding files" section. Implements #2866.
- MKVToolNix GUI: multiplexer: added small colored boxes for each file & track in order to indicate from which file each track is read. The colors used can be configured in the preferences → "Multiplexer" page → "File & track colors" section.

Bug fixes
- build system: fixed compilation with fmt v8. Fixes #3151.
- mkvmerge: SRT subtitle reader: characters that aren't valid according to the assumed encoding of the file will now be replaced by the Unicode "Replacement Character" U+FFFD instead of keeping the invalid characters, potentially violating the Matroska specs.
- mkvmerge: WebVTT parser: the parser now accepts timestamps with hours larger than 99. Part of #3139.
- mkvextract: TTA extraction, only on Windows: fixed removing the temporary file created during extraction.
- mkvmerge, mkvpropedit, MKVToolNix GUI's multiplexer & header editor: MIME type detection is now done using Qt instead of the magic library. The main impact is the MIME types of TrueType & OpenType fonts are now detected correctly. Fixes #3137.
- mkvmerge, mkvinfo, MKVToolNix GUI's info tool: only on Windows: displaying dates before 1970-01-01 00:00:00 UTC or after 2038-01-19 03:14:08 UTC was broken. Note that the header editor was not affected. Fixes #3148.
- MKVToolNix GUI: only on 64-bit Windows: under certain conditions, the 64-bit Windows binaries crashed when opening dialog windows. Even though the underlying bug hasn't been identified, the investigation showed that building it with newer versions than 10.2.0 of the mingw/gcc cross-compiler enabled the crashes, while binaries built with 10.2.0 were fine. This affected v57 and v58 which were built with gcc versions 10.3.0 and 11.1.0 respectively. For the time being I've switched back to building Windows binaries with gcc 10.2.0. Fixes #3132 & #3133.
- MKVToolNix GUI: multiplexer: when adding files to the multiplexer by running the GUI's executable with file names as command line arguments, the source directory will be remembered as the "last open directory" again, causing subsequent uses of the "open file" dialog to start in the same directory.
- MKVToolNix GUI: multiplexer: the "default track flag" column in the track list was missing its icons. Additionally it contained text even for things that aren't regular tracks and therefore do not actually have that flag (e.g. chapters or tags). Fixes #3144.
- MKVToolNix GUI: multiplexer: the default for the dialog asking the user what to do with dragged & dropped files if they've never seen the dialog is back to adding the files to the current multiplex settings instead of "add as additional parts" which was an 

New features and enhancements
- mkvmerge, MKVToolNix GUI's multiplexer: the handling of the "default track" flag has been changed to match the recent changes to the Matroska specifications. The new semantics are that if it is set, it is supposed to signal to the player that this track is eligible for being played by default, potentially taking other factors such as user preferences regarding languages into account. This implies that more than one track of each type can have this flag set. For example, a Blu-ray disc with three audio tracks might have the main audio in both English and Japanese, whereas the third audio track contains the director's comments. In such a case the first two tracks should have the "default track" flag set, the third one shouldn't. Earlier mkvmerge was enforcing that only one track of each type could have the flag set. This restriction has been removed, both in mkvmerge and in the GUI's multiplexer. mkvpropedit and the GUI's header editor are unaffected as they've always allowed to set the flag on as many tracks as the user wanted.
- mkvmerge: AVC/H.264 & HEVC/H.265 identification: added the stream's pixel dimensions (AVC only; were present for HEVC already) & default duration. Implements #3116.
- mkvmerge, mkvextract: HEVC/H.265: added support for reading single-layer Dolby Vision from Annex B type bitstreams (elementary streams, MPEG transport streams). Patch by quietvoid. Implements #3113.
- mkvinfo: the option -X/--full-hexdump now affects all binary elements, not just the frame data in SimpleBlock and BlockGroup elements.
- MKVToolNix GUI: multiplexer: the "delay" and "sync" options can now be used for chapters in source files, too. Implements #3129.
- MKVToolNix GUI: when moving list entries up & down with the optional buttons or the keyboard shortcuts (instead of using drag & drop), the GUI ensures that the top-most selected entry remains visible after the move. Implements #3123.
- MKVToolNix GUI: added an option in the preference to use legacy MIME types for font attachments instead of the current standard ones (e.g. 'application/x-truetype-font' instead of 'font/sfnt' and 'font/ttf').

Bug fixes
- build system: fixed filtering out optimization options when compiling the file iso639_language_list.cpp (before only numeric optimization levels were filtered out and only if it wasn't the last option in the list of flags). See #3105 for context.
- build system: when libmagic was detected via pkg-config, MKVToolNix was actually compiled without support for libmagic due to a preprocessor symbol not being defined.
- mkvmerge: MP4 reader: fixed an issue with timestamps overflowing when the file's or the track's time scale is large. Fixes #3124.
- mkvmerge, mkvextract: fixed key frame handling for BlockGroup elements with a forward reference but no backward references. Patches by Tom Yan.
- mkvmerge, mkvpropedit, MKVToolNix GUI's chapter editor: the programs will no longer omit writing mandatory elements set to their default value if other elements of the same type are present in the same master. This affects mostly the "chapter language" element which may occur multiple times within the same "chapter display" master. If it does occur multiple times and one of them is set to "English" (which is that element's default value), that element will now be written, too. Part of the fix of #3120.
- mkvmerge, mkvpropedit, MKVToolNix GUI's chapter editor: when parsing chapter files IETF & legacy language elements as well as legacy country elements will now be properly generated depending on which exist already, especially when there's more than one language and/or country element in a "chapter display" element. Part of the fix of #3120.
- mkvmerge, mkvpropedit, MKVToolNix GUI's chapter editor: fixed reading OGM-style chapter files with timestamps that don't have exactly three decimal places. Any number of decimal places between one and nine is now supported for nanosecond precision. Fixes #3121.
- MKVToolNix GUI

New features and enhancements
- mkvmerge: MP4 reader: added support for reading Dolby Vision from MP4 files (FourCCs dvh1 and dvhe; configuration records dvcC, dvvC and hvcE will be converted into block addition mappings). Implements #2784.
- mkvmerge: SRT subtitles: mkvmerge now accepts empty text files with the extension .srt as SRT subtitle files, enabling the creation of empty SRT tracks. Implements #3089.
- mkvmerge, mkvextract: HEVC/H.265: access unit delimiter NALUs will no longer be discarded, neither during muxing nor during extraction.
- MKVToolNix GUI: preferences: switched the order & wording of controls in the "enabling items" panel to make it clearer that certain controls define exceptions. Inspired by 3086.

Bug fixes
- mkvmerge: HEVC/H.265 parser: several NALU types, notably the Dolby Vision-specific NALUs ("unspecified 62" and "unspecified 63") and suffix SEI NALUs, are now stored with the frame they belong to instead of with the next frame. Part of fixing & implementing #2784, #2818, #3093 and #3113.
- mkvmerge: HEVC/H.265 packetizer: fixed setting the track's default duration when reading HEVC/H.265 from Matroska files that don't have a default duration set.
- mkvmerge: HEVC/H.265 packetizer: fixed the calculation of the duration of frames so that SimpleBlock elements can be used again instead of BlockGroups with BlockDuration elements. Fixes #3114.
- mkvmerge, mkvextract: HEVC/H.265 parser: fixed issues with ordering & duplication of certain NALUs (parameter set & prefix SEI NALUs). Part of fixing & implementing of #2784, #2818, #3093 and #3113.
- MKVToolNix GUI: multiplexer: when dragging & dropping files to the multiplexer, the source directory will be remembered as the "last open directory" again, causing subsequent uses of the "open file" dialog to start in the same directory. Fixes #3110.
- mkvinfo: fixed the position of frames in block groups containing "block duration" elements in summary mode (e.g. for subtitle tracks).

Build system changes
- configure will now try to detect libmagic via pkg-config and fall back to including & linking directly if it cannot be found via pkg-config.

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. Fixes #3081.

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. Fixes #3083.
- 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.

Bug fixes
- all programs, only on Windows: fixed checking existence of & creating directories with UNC paths such as \\server\share\folder\file.mkv. Fixes #3041.
- all programs, only on Windows: implemented several workarounds for bugs in std::filesystem wrt. UNC paths. The effect of those bugs was that Blu-rays and DVDs couldn't be added from UNC paths. Fixes #3037.
- mkvmerge, only on Windows: fixed non-ASCII characters getting mangled in the destination file name when splitting is active.
- MKVToolNix GUI, only on Windows: fixed the GUI hanging when trying to browse for files on drives that don't actually exist. Fixes #3046.
- MKVToolNix GUI, only on Windows: the GUI did not remember UNC paths as the "most recently used source directory" properly.
- MKVToolNix GUI: only on Windows: when dragging & dropping files from other applications to MKVToolNix GUI the GUI will force the drop action to be a copy action, no matter which keys were pressed by the users. This prevents Windows Explorer from deleting the dragged file when the user presses shift while dropping the file onto MKVToolNix GUI.
- MKVToolNix GUI, only on Windows: when using the file dialog for selecting a file name to save to (e.g. when browsing for the destination file name in the multiplexer or saving an attachment in the header editor) non-ASCII characters in the default file name were mangled. Fixes #3049.
- MKVToolNix GUI: multiplexer: the user can now configure what to do when using the "Add source files" button independently of the setting for what happens when files are dragged & dropped onto the GUI. The same options are available, but they're distinct settings, allowing for different use cases. Fixes #3035.
- MKVToolNix GUI: multiplexer: deriving the track language from file names doesn't use one big regular expression of all enabled languages anymore. Instead, the file name is split into parts on a list of characters (such as . or ( and ); configurable in the preferences). This prevents the regular expression becoming too big for the regular expression library to handle when many languages are enabled. Fixes #3048.
- MKVToolNix GUI: preferences: the language lists for "deriving track languages" and "enabling items by language" always included all the ISO 639-3 languages, even if those weren't enabled in the "often-used languages" pane. Fixes #3047.

Other changes
- mkvmerge, MKVToolNix GUI multiplexer: the functionality for changing the length of the NALU "size" field for AVC/H.264 and HEVC/H.265 tracks has been removed. The corresponding command-line option will continue to be recognized by mkvmerge as not to break existing third-party applications, but it won't actually do anything.

New features and enhancements
- mkvmerge: added support for using ISO 639-3 language codes in IETF BF47 language tags. Part of the implementation of #3007.
- mkvmerge: AC-3 parser: added support for byte-swapped AC-3 data. Implements #3022.
- mkvmerge: Matroska reader: for audio tracks that have the bit depth track header set mkvmerge will now keep that header even for codecs that don't require it for decoding. Implements #3009.
- mkvmerge: MPEG transport stream reader, PCM audio tracks: mkvmerge will now re-order the channels for 5.1, 7.0 and 7.1 channel tracks from the Blu-ray layout to the WAVEFORMATEXTENSIBLE layout expected in Matroska. Patch by Tom Yan. Implements #2988.
- mkvmerge, mkvinfo, mkvpropedit, MKVToolNix GUI: added support for the following new track header elements: "hearing impaired" flag, "visual impaired" flag, "text descriptions" flag, "original" flag, "commentary" flag. Implements #3011.
- MKVToolNix GUI: added support for using ISO 639-3 language codes in IETF BF47 language tags. As there are several thousand of them, they're deactivated by default and must be activated in the preferences ("GUI" → "Often used selections" → "Languages"). Part of the implementation of #3007.
- MKVToolNix GUI: multiplexer: when adding Blu-rays the user can select multiple playlists to add simultaneously in the "select playlist to add" dialog. Implements #2961.
- MKVToolNix GUI: multiplexer: the file name extensions "eb3" and "ec3" were added for Dolby Digital Plus & "mpl" for Dolby TrueHD in the file dialogs. Part of the implementation of #3027.
- MKVToolNix GUI: multiplexer: when adding multiple files the dialog asking the user what to do with them has gained a new checkbox. If enabled, all files containing at least one video track will always be placed in newly created multiplex setting. Implements #2966.
- MKVToolNix GUI: multiplexer: added a menu entry in the "Multiplexer" for adding all files that are currently in the clipboard. Implements #3006.

Bug fixes
- all: Windows: fixed compatibility with gettext 0.21 and newer on mingw.
- all: Windows: fixed several of the programs having problems with certain Unicode characters (primarily emojis) in file names (e.g. mkvextract wrongfully complaining about an "invalid mode" or the GUI not being able to find parts of Blu-ray file structures).
- mkvextract: AAC: fixed wrong channel mask field in the ADTS headers for 7.1 channel layouts. Fix by Tom Yan. Fixes #2636.
- mkvextract: HEVC/H.265 extraction: if the first frame starts with the parameter sets (SPS, PPS & VPS), the ones from CodecPrivate aren't written and the ones from the first frame are kept. Fixes #3031.
- mkvmerge: fixed the calculation of chapter timestamps read from NTSC DVDs. Fix by Tom Yan.
- MKVToolNix GUI: IETF BCP 47 language widget: the language combo box will now always contain the language code the user enters in the free-form field, even if it isn't in the list of often-used languages the user configured in the preferences.
- MKVToolNix GUI: multiplexer: when browsing for the destination file name the default directory is now chosen according to the preferences regarding how the destination file name should be formed. For example, if the policy is set to "fixed output directory" then that output directory will be the one initially set when the directory selection dialog is opened. Fixes #3021.
- MKVToolNix GUI: multiplexer: fixed the removal of appended source files if the "delete source files" end-of-job action is enabled. Fixes #3029.
- MKVToolNix GUI: chapter editor: when importing chapters from DVDs the IETF BCP 47 language elements will be set, too, not just the legacy language elements.

Build system changes
- libEBML v1.4.2 and libMatroska v1.6.3 are now required. The optional, bundled copies of both libraries have been updated to those versions. This bump in requirements fixes several heap overflow bugs in libEBML.
- MKVToolNix is now using the C++17 library feature "file system library" instead 

New feature: IETF BCP 47 language tags
- I've written up a nice FAQ entry (https://gitlab.com/mbunkus/mkvtoolnix/-/wikis/Languages-in-Matroska-and-MKVToolNix) about the switch to using IETF BCP 47 language tags, how they interact with legacy language elements, how the programs actually behave and how to disable their use if necessary.
- mkvmerge: IETF BCP 47/RFC 5646 language tags: mkvmerge will now accept full BCP 47 language tags for all options taking a language. mkvmerge will always write "LanguageIETF" track header elements. If the language tag contains a valid ISO 639-2 language code it will also set the legacy "Language" track header element to the included ISO 639-2 code. Part of the implementation of #2419.
- mkvmerge: IETF BCP 47/RFC 5646 language tags: if present the "LanguageIETF" track header element will be reported as the language_ietf property in JSON identification mode. Part of the implementation of #2419.
- mkvmerge: IETF BCP 47/RFC 5646 language tags in chapters: mkvmerge will now write "ChapLanguageIETF" elements when creating chapter atoms, either when reading the simple chapter format or when generating chapters due to the --generate-chapters command line option. Part of the implementation of #2419.
- mkvmerge: IETF BCP 47/RFC 5646 language tags in tags: mkvmerge will now write "TagLanguageIETF" elements when creating "simple tag" elements, either when reading tag XML files or when generating them. Part of the implementation of #2419.
- mkvmerge: IETF BCP 47/RFC 5646 language tags: added an option --disable-language-ietf that causes mkvmerge to only write the legacy language elements.
- mkvmerge, mkvpropedit, MKVToolNix GUI's chapter editor: IETF BCP 47/RFC 5646 language tags in chapters: when reading XML chapter files the programs will now add "ChapLanguageIETF" elements for atoms that don't contain them. The values are derived from existing "ChapterLanguage" elements. Part of the implementation of #2419.
- mkvpropedit: IETF BCP 47/RFC 5646 language tags: setting/deleting the track language now acts on both the old language element as well as the "LanguageIETF" track header element. Part of the implementation of #2419.
- mkvpropedit: IETF BCP 47/RFC 5646 language tags: added an option --disable-language-ietf that causes mkvpropedit to apply changes to the language track header property only to the legacy language track header element.
- mkvinfo: IETF BCP 47/RFC 5646 language tags: added support for the "LanguageIETF" track header element. Part of the implementation of #2419.
- MKVToolNix GUI: multiplexer: added full support for IETF BCP 47/RFC 5646 language tags for both track and chapter languages. Part of the implementation of #2419.
- MKVToolNix GUI: chapter: added full support for IETF BCP 47/RFC 5646 language tags for chapter languages. Part of the implementation of #2419.
- MKVToolNix GUI: header editor: added full support for IETF BCP 47/RFC 5646 language tags for track header languages. The header editor allows editing of the legacy language elements and the IETF BCP 47 language elements independent of each other. Part of the implementation of #2419.

Other new features and enhancements
- mkvmerge: the chapter generation mode when-appending now also works with the splitting modes parts: & parts-frames: when using the …,+… syntax for appending other sections of the source file to the same destination file. Implements #2898.
- MKVToolNix GUI: multiplexer: the file selection dialogs now include the extension .dtsma for DTS files. Implements #2901.
- mkvmerge: MP4 reader: sped up parsing MP4 DASH files with a lot of segments (trun atoms) quite a bit. Part of the fix of #2900.
- The PCRE2 regular expression library is now used instead of std::regex for big performance improvements in all places where regular expressions are used for parsing big chunks of text, e.g. in the subtitle parsers. Part of the fix of #2899.
- all programs: Windows: all programs now support long file names on Windows 10 releas

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.
- Windows installer: the images are shown again. Fixes #2868.
- 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.

New features and enhancements
- mkvmerge: AC-3: file identification will report AC-3 tracks encoded in Dolby Surround EX as codec "AC-3 Dolby Surround EX". Implements #2740.
- MKVToolNix GUI: multiplexer: on new installations the GUI will now recognize all known ISO 639-2 language codes in file names by default instead of only the top 100 of languages by native speakers.
- MKVToolNix GUI: multiplexer: on new installations the list of "often used languages" will by default only contain certain agnostic ones ("multiple languages", "no linguistic content", "reserved for local use", "uncoded languages"), "English" and the default user interface language. The "list of spoken languages by native speaks" isn't used anymore. Also implements #2716.
- MKVToolNix GUI: header editor: added an option to remove all attachments to the tree context menu. Implements #2835.
- MKVToolNix GUI: while the GUI is running it will remember the last page that was selected when the preferences dialog is closed. Upon re-opening the preferences that page will be selected by default. Implements #2852.

Bug fixes
- mkvmerge: fixed a segmentation fault when exiting prematurely due to write errors such as the destination having run out of space. Fixes #2843.
- mkvmerge: DTS: fixed wrong channel count for DTS tracks with XCh extensions. Fixes #2715.
- mkvmerge: MPEG TS reader: fixed detecting AVC/H.264 and HEVC/H.265 tracks that consist of only a single frame. Part of the fix of #2849.
- mkvmerge: MPEG TS reader: fixed handling of unbounded PES sizes for tracks that consist of only a single PES packet. Part of the fix of #2849.
- mkvmerge: MPEG TS reader: PGS subtitle tracks are now exempt from the "detect bogus subtitle timestamps" heuristic which could lead to some PGS subtitles not being timestamped correctly. Symptoms were that they were shown at the wrong time or that they were shown indefinitely. Fixes #2736 and partially fixes #2824.
- mkvmerge: MPEG TS reader: when reading MPLS playlists the start timestamps of a play items were handled wrong: all the timestamps of packets read were compared to that start timestamp, dropping those packets whose timestamps were smaller than the play item's start timestamp. The correct behavior is to accept all packets as soon as the first one with a timestamp equal to or larger than the play item's start timestamp is encountered. This could result in PGS subtitle entries located right at the start of the play item being garbled/lost as they consist of multiple PES packets for which some timestamps are often slightly smaller. Part of the fix of #2824.
- mkvmerge: MPEG TS reader: when reading MPLS playlists mkvmerge will no longer read the whole M2TS files they reference, processing only the packets lying inside the timestamp range given by the playlists's play item's start & end timestamps. Instead mkvmerge will use the index information present in corresponding clip information (CLPI) files in order to seek to the nearest file position of the play item's start timestamp. Additionally mkvmerge will simply stop processing a file once the end timestamp is seen. This change greatly speeds up processing files from which only small portions must be read. Part of the fix of #2824.
- mkvmerge: WavPack: fixed support for files created by v5 of the program. Checksums, DSD audio data and non-standard sampling rates are handled correctly. Patch by David Bryant.
- MKVToolNix GUI: multiplexer: fixed the cursor being positioned wrong after entering or pasting characters that aren't allowed in file names into the "destination file" control. Fixes #2855.

Build system changes
- libEBML v1.4.0 and libMatroska v1.6.0 are now required.

Other changes
- The source code repository's main development branch was renamed to main.

New features and enhancements
- mkvmerge: chapters: mkvmerge can now read chapters from DVDs if the user specifies the path to a DVD folder structure via the --chapters … parameter. By default chapters from the first title will be imported. This can be changed by append :<title number> to the file/directory name in the --chapters … argument, e.g. --chapters /srv/dvds/BigBuckBunny/VIDEO_TS:3 This feature requires mkvmerge to have been built with the libdvdread library. Part of the implementation of #2808.
- mkvmerge: added --engage append_and_split_flac that enables mkvmerge to append and split FLAC tracks, restoring pre-v45 behavior. The resulting tracks will be broken: the official FLAC tools will not be able to decode them and seeking will not work as expected.
- MKVToolNix GUI: multiplexer: added support for mkvmerge's new support for reading chapters from DVDs if both have been built with the libdvdread library. Part of the implementation of #2808.
- MKVToolNix GUI: multiplexer: when deriving languages from file names the GUI will now look for simplified language names instead of the full ones (e.g. instead of looking for "Greek, Modern (1453-)" it would simply look for "Greek").
- MKVToolNix GUI: multiplexer: the options in the "additional command-line options" dialog are now sorted alphabetically. Additionally the --append-mode option has been added as one of the only missing global options.
- MKVToolNix GUI: chapter editor: the chapter editor can now read chapters from DVDs if MKVToolNix has been build with the libdvdread library. Part of the implementation of #2808.
- MKVToolNix GUI: header editor: added an option in the preferences for displaying all date & time values in UTC instead of the local time zone. Implements #2814.

Bug fixes
- all: fixed a crash when using the MTX_LOGGER=file syntax for logging debug messages without specifying a file name to log to. It will now log to a file called mkvtoolnix-debug.log in the system's default temporary directory, as initially intended.

Build system changes
- The libdvdread (https://www.videolan.org/developers/libdvdnav.html) library will be used if found via pkg-config. If it is found, support for reading chapters from DVDs will be enabled in mkvmerge and the MKVToolNix GUI. Part of the implementation of #2808.
- Boost's Date/Time, Lexical Cast, Range, Range Adaptors, Tri-Bool, Variant libraries are not used anymore.
- MKVToolNix now requires a C++ compiler & standard library that support the following features of the C++17 standard: "std::variant", "std::gcd". For the GNU Compiler Collection (gcc) this means v7 or newer; for clang it means v4 or newer — the same versions required by earlier MKVToolNix versions.
- MKVToolNix now requires version 6.1.0 of fmtlib or later for the fmt::to_string function and bugfixes to the formatting of floating point numbers. If a system-wide version is installed that's older, the bundled copy will be used.
- The bundled version of fmtlib has been updated to release 6.2.1.

New features and enhancements
- mkvmerge: when splitting, the placeholder %c can be used in the destination file name. It'll be replaced by the name of the first chapter in the file. Implements #2791.
- mkvmerge: when reading MPLS playlists mkvmerge will include a tag named SOURCE_ID in the track's statistics tags that conveys the fact that the source was a Blu-ray and what the track's ID was in the source container. When reading Matroska file existing SOURCE_ID tags will be kept. The format used is the same format MakeMKV uses. Implements #2774.
- mkvmerge: for audio-only files mkvmerge will now write a cue entry every 500ms instead of every 2s.
- MKVToolNix GUI: job actions: split up the option "execute when the job finishes successfully or with warnings" into two separate options: "…when finishes successfully" and "…when exits with warnings". Implements #2798.

Bug fixes
- mkvmerge: Matroska reader: when regenerating UIDs for chapters mkvmerge will now fix referencing tag chapter UID targets to have the same values. Fixes #2804.
- mkvmerge: MP4 reader: fixed a crash that could potentially happen while trying to identify HEVC/H.265 tracks.
- mkvmerge: MP4 reader: when reading HEVC/H.265 tracks without a frame offset table (ctts atom) present, mkvmerge did not parse the hevcC structure correctly in certain cases, causing no video frames to be output at all or the output not being playable. This fixes #2782, a bug introduced in v45.
- mkvmerge: MPLS handling/MPEG TS reader: timestamp restrictions as given in an MPLS file were only honored for the first play item, not for subsequent play items. For those play items the whole referenced file was always copied. Part of the fix of #2789.
- mkvmerge: MPLS handling/MPEG TS reader: under certain circumstances mkvmerge copied one frame too many before switching to the next play item. Part of the fix of #2789.
- mkvmerge: for audio-only files cues will only be created for I frames (important for e.g. TrueHD where decoding can only start on a sync frame). Fixes #2790.
- MKVToolNix GUI: fixed a crash that happened when closing the preferences after having closed at least one multiplexer tab. Fixes #2785.
- MKVToolNix GUI: macOS: changed the default of the "elide tab header labels" feature introduced in v45 from "no" to "yes" to mirror how versions before v45 behaved on macOS.