MKVToolnix

Create, edit, inspect and produce Matroska video files using this advanced app with numerous configuration settings for expert users.

• MKVToolnix
• License :GPL
• OS :Windows All
• Publisher :Moritz Bunkus

Download Now

MKVToolNix is a free, powerful set of tools to create, edit, split, mux, demux, and inspect Matroska (.MKV) video files. It’s most commonly used to:

• Combine video, audio, and subtitle tracks into a single MKV file (multiplexing)
• Remove or add subtitle/audio tracks
• Change default tracks or language metadata
• Split MKV files into parts
• Extract elements (demuxing)

🎬 How to Use MKVToolNix GUI

The main tool in the suite is MKVToolNix GUI. Here’s a step-by-step guide to the basics.

✅ 1. Download and Install

• Official site: https://mkvtoolnix.download
• Available for Windows, macOS, and Linux
• Download and install the version for your platform

✅ 2. Open MKVToolNix GUI

• Run the program: MKVToolNix GUI
• You’ll see several panels:
  • Source files
  • Tracks, chapters, and tags
  • Output
  • Multiplexer settings

✅ 3. Add Your MKV (or Media) Files

• Drag and drop a video file (MKV, MP4, etc.) into the window or
• Click “Add source files” and select a file

MKVToolNix will list all the tracks (video, audio, subtitles, chapters).

✅ 4. Choose Which Tracks to Keep or Remove

• ✅ Check the tracks you want
• ❌ Uncheck unwanted tracks (e.g., a language you don’t need)

Example:

• Keep: English audio + English subtitles
• Remove: Other audio/subtitle languages

✅ 5. Modify Track Properties (Optional)

• Click a track and tweak settings like:
  • Language (important for players to detect)
  • Default track (which audio/subtitle plays by default)
  • Compression (e.g., turn off header compression if needed)

✅ 6. Set Output File Name

• At the bottom, choose the destination file name and location
• Default: same folder, _new.mkv suffix

✅ 7. Start Multiplexing

• Click the “Start multiplexing” button (bottom right)
• Wait a few seconds to minutes, depending on file size

The new MKV file will be created with your selected tracks and settings.

🔧 Common Tasks You Can Do with MKVToolNix

🎯 Add Subtitles to a Video

1. Add the video file
2. Add the .srt, .ass, or .sub subtitle file
3. Set language (optional)
4. Start multiplexing

🔊 Change Default Audio Track

1. Add the MKV file
2. Select the audio track you want as default
3. Check “Default track flag” = Yes
4. Start multiplexing

✂️ Split MKV File into Parts

1. Add the file
2. Go to “Output” tab > Splitting
3. Choose:
   • By size (e.g., 100MB)
   • By duration (e.g., every 10 minutes)
   • By parts (e.g., 00:00:00-00:05:00,00:05:00-00:10:00)
4. Start multiplexing

📤 Extract Tracks (Demuxing)

Use MKVToolNix GUI or the command-line tool mkvextract.

In GUI:

• Add the MKV file
• Uncheck all tracks except the one you want to extract
• Click “Start multiplexing” to get a file with just that track

Or use:

mkvextract tracks myfile.mkv 1:audio.aac 2:subs.srt

🧠 Pro Tips

• MKVToolNix is lossless – it doesn’t re-encode, so it’s fast and keeps original quality
• You can batch process multiple files using the job queue
• Works great with downloaded subtitles or custom audio dubs