# MKVToolNix Canonical URL: https://encode.wiki/tools/utilities/mkvtoolnix/ Content version: ca42e61ede0a24f789d7287a0001244ad22f4abf Status: current License: CC BY-SA 4.0 Checksum (SHA-256): 0176ed798b2042580225909a3324110b8c53d3775a82415ff09a92403b1b47f9 > **Repository:** [mbunkus/mkvtoolnix](https://codeberg.org/mbunkus/mkvtoolnix). Creating and working with Matroska files. Latest tag: [release-102.0](https://codeberg.org/mbunkus/mkvtoolnix/src/tag/release-102.0), Sep 14, 2026. Last commit: Sep 28, 2026. Stars: 98. MKVToolNix, by Moritz Bunkus, is the reference toolkit for [Matroska](/containers/matroska/) and [WebM](/containers/webm/). It is what most encoders use for the last step of a job: putting the encoded video, audio, subtitles, fonts and chapters together into one `.mkv`. It never re-encodes anything, so every operation is lossless and fast. | Tool | Does | | ---------------- | --------------------------------------------------------------------------------------- | | MKVToolNix GUI | Front end for all of the below; most people use its multiplexer and header editor tabs. | | `mkvmerge` | Muxes, remuxes, splits and appends files. Reads MKV, MP4, raw streams, IVF, Blu-ray playlists and more. | | `mkvextract` | Extracts tracks, attachments, chapters, tags and timestamps. | | `mkvpropedit` | Edits titles, track languages, names and flags in place, without remuxing. | | `mkvinfo` | Shows the element structure of a file. | ## Install it The [downloads page](https://mkvtoolnix.download/downloads.html) has a Windows installer and portable archive, macOS disk images, an AppImage, and repositories for Debian, Ubuntu, Fedora and other distributions. It is also on [Flathub](https://flathub.org/apps/org.bunkus.mkvtoolnix-gui) and in most distribution repositories. Releases are frequent; distribution packages may trail by a few versions. ## Using the GUI MKVToolNix GUI multiplexer tab Drag files into the **Multiplexer** tab, untick the tracks you do not want, set language, name and the default/forced flags for each track, choose the output file and click **Start multiplexing**. Useful features: - Open a Blu-ray playlist (`.mpls`) or `index.bdmv` from an unencrypted disc folder to import a title with all its segments. - **Output → Splitting** cuts by duration, size, timestamps, chapters or frame ranges without re-encoding. - The **Output** tab's "Create WebM compliant file" option restricts the output to WebM. - The **Header editor** tab changes titles, languages and flags in an existing file instantly, without remuxing. - The **Multiplexer** menu can show the equivalent `mkvmerge` command line, handy for scripting. ## mkvmerge List the tracks and their IDs first. mkvmerge numbers tracks from 0 within each file; these IDs are not FFmpeg's stream indexes. ```sh mkvmerge -i input.mkv mkvmerge -J input.mkv ``` `-J` prints full details as JSON. Options before a file name apply to that file only. This muxes an encoded video, an Opus track and ASS subtitles with a font: ```sh mkvmerge -o output.mkv video.ivf --language 0:ja audio.opus --language 0:en --track-name 0:"English" subs.ass --attach-file font.ttf ``` Keep or drop tracks from a source with `-d`/`-a`/`-s` (video/audio/subtitle IDs to keep) or `-D`/`-A`/`-S` (drop all of that type). For example, to keep the video, only audio track 2 and no subtitles: ```sh mkvmerge -o output.mkv -a 2 -S input.mkv ``` The most-used options: | Option | Use | | ----------------------------------------- | ----------------------------------------------------------------------------------------- | | `--language ID:LANG` | Track language as a BCP 47 tag (`en`, `ja`, `pt-BR`). | | `--track-name ID:NAME` | Track title shown by players. | | `--default-track-flag ID:0` / `:1` | Whether players pick this track by default. | | `--forced-display-flag ID:1` | Marks a subtitle track as forced (for example, signs and foreign-language dialogue only). | | `--sync ID:MS` | Delays (positive) or advances (negative) a track by milliseconds. | | `--default-duration ID:24000/1001fps` | Overrides the frame rate of a raw video stream with no timing of its own. | | `--attach-file FILE` | Attaches a file, typically a font used by ASS subtitles. | | `--chapters FILE` | Adds chapters from an XML or simple `CHAPTER01=` text file. | | `--split ...` | Splits the output (see below). | | `--webm` | Produces a WebM file and rejects codecs WebM does not allow. | | `--title TEXT` | Sets the file's title. | ### Split and join ```sh mkvmerge -o part.mkv --split duration:00:20:00 input.mkv mkvmerge -o clip.mkv --split parts:00:01:00-00:02:30 input.mkv mkvmerge -o episode.mkv --split chapters:all input.mkv mkvmerge -o joined.mkv part1.mkv + part2.mkv ``` A split can only happen right before a keyframe, so each cut moves to the first keyframe at or after the point you asked for: clean, but not frame-exact; numbered files (`part-001.mkv`, …) are created when there is more than one part. A `+` before a file appends it to the previous one, which requires matching codecs and parameters. ## mkvextract ```sh mkvextract input.mkv tracks 0:video.ivf 1:audio.opus 2:subs.ass mkvextract input.mkv attachments 1:font.ttf mkvextract input.mkv chapters chapters.xml mkvextract input.mkv timestamps_v2 0:timestamps.txt ``` Tracks come out as their raw bitstream; pick an extension that matches the codec. Add `--simple` to the `chapters` mode for the plain `CHAPTER01=` format. ## mkvpropedit Edits are written into the file in place and take seconds even on large files: ```sh mkvpropedit input.mkv --edit info --set "title=My encode" mkvpropedit input.mkv --edit track:a1 --set language=ja --set flag-default=1 --edit track:s1 --set flag-forced=1 ``` `track:a1` is the first audio track, `track:s1` the first subtitle track and `track:v1` the first video track; these selectors count from 1 per type, unlike mkvmerge's IDs. mkvpropedit can also add, replace and delete attachments and chapters. The GUI's header editor does the same thing interactively. ## Related pages - [Matroska](/containers/matroska/) and [WebM](/containers/webm/) - [FFmpeg](/tools/utilities/ffmpeg/), [MP4Box](/tools/utilities/mp4box/) for MP4 - [Handle audio and subtitles](/guides/audio-and-subtitles/)