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Oct 10, 2021 Last updated


Older Versions

# Change Log

# Version 62.0.0 "Apollo" 2021-10-10

## 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


* 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


* 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. The `install` target still doesn't

install them, though.


MKVToolNix is a small collection of tools (mkvmerge, mkvinfo, mkvextract, mkvpropedit and mmg) that allows you to manipulate Matroska (MKV) files in several ways.

You can use MKVToolNix to create, split, edit, mux, demux, merge, extract or inspect Matroska files. The program will also work with other video formats (AVI, MPEG, MP4, MPEG, Ogg/OGM, RealVideo, MPEG1/2, h264/AVC, Dirac, VC1) including some video codecs (such as VP9 video codec support - reading from IVF/Matroska/WebM files, extract to IVF files). Audio formats (AAC, FLAC, MP2, MP3, (E)AC3, DTS/DTS-HD, Vorbis, RealAudio) and also most subtitle formats (SRT, PGS/SUP, VobSub, ASS, SSA, etc.). MKVToolNix is a cross-platform application that will work on Windows® (both 32 and 64-bit versions), Mac® OS X® and Linux. Please note that from this page you can download the Windows® (installer and portable) and Mac® OS X® versions. If you're looking for a Linux version, you can download one from MKVToolNix homepage.

Trademark Note 1: Microsoft®, Windows® and other product names are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries.

Trademark Note 2: Mac and OS X are trademarks of Apple Inc., registered in the U.S. and other countries.

MKVToolNix Review

Note: I tested MKVToolNix on Windows® 7 Ultimate 32-bit using mkvmerge GUI and several other tools opened from the Command Prompt such as mkvinfo. Therefore, if you're looking for more information on how to compile MKVToolNix yourself, check the README file (online). I wanted to test two things: the mkvmerge GUI (software interface) and see how easy or hard is to use the command line for all the other tools such as "mkvinfo."

The software interface (mkvmerge GUI)

As soon as the setup finished, I opened the "mkvmerge GUI" shortcut from my desktop. At a first look, the interface seems quite intuitive, so my first action was to open an MKV file, select an option and see the result. I went to program interface at the "Input" tab and used the "Add" button (it also works using the "drag and drop" method. 

I selected a 710 MB MKV file and I wanted to split this (from "Global" tab - select "Split Mode" - "split after size" and then I specified the size - in this case 50M = 50MB) in smaller files with a size of 50 MB for each. Finally, I clicked on "Start Muxing" button. 

The program required just 45 seconds for this operation, and the result was 14 smaller MKV files. After this, I wanted to mux the content of an AVI file in MKV format. Again, I went to "Input" tab and used the "Add" button, I selected an AVI file from my computer, and I noticed that the program displayed the Output filename automatically with the name of the same file but this time in MKV (Matroska) format. 

Again, the same button called "Start Muxing" was doing all the magic. This time the process was even faster - at the end I could read the following message "Muxing took 34 seconds".

Other command line tools (example: mkvinfo)

To use all the other command line tools in Windows®, open a Command Prompt window. Just hit the "Start" button, click on "Search programs and files" (Windows® 7 and Vista) or "Run" (Windows® XP and others) and type either "cmd" or "command prompt" (without the quotes). 

In the command prompt, you can try each program (mkvmerge, mkvinfo, mkvextract, mkvpropedit) by typing its name and the usage parameters. An example would be: "mkvinfo --help" that will display a list with all the commands available. I tried mkvinfo using this command: "mkvinfo -g" and the result was a small interface that allowed me to open an MKV file and see all kind of technical details about it. I was also able to save the results in the TXT format.


You can launch an instance of mkvmerge GUI (software interface) directly from the command prompt. Just type "mmg" and hit "Enter."

Besides of the usual standard documentation from the command prompt (I hate it because it's hard to read) you can find and read the online documentation available on MKVToolNix documentation homepage here: (use the blue links for mkvmerge, mkvinfo, mkvextract, mkvpropedit and mmg to access the online help).

Final Conclusion

You can learn how to use several main features in minutes but to master the program, it does require more time. Your best bet is to experiment all of his options and whenever you need some help, check the FAQ section (filled with great answers to common issues), start with the guide of mkvmerge GUI here and check the documentation for all the other tools - here (provided once again). MKVToolNix is a "must-have" software if you work with MKV files. It has an incredible amount of features that are not listed on the homepage. Ultimately, if you appreciate this tool, please consider a DONATION to support the work of Mr. Moritz Bunkus, the author of MKVToolNix.

Found this software useful? Please consider a donation to the author.