How to Split an MKV File: A Comprehensive Guide with Detailed Steps

MKV, or Matroska Video, is a popular container format known for its versatility and ability to hold multiple video, audio, and subtitle tracks within a single file. While this flexibility is advantageous, sometimes you need to split a large MKV file into smaller, more manageable parts. This could be for easier sharing, to create chapters, or to fit within the storage limitations of certain devices. This article provides a comprehensive guide on how to effectively split an MKV file, covering various methods and tools.

Why Split an MKV File?

Before diving into the ‘how,’ let’s explore the common reasons why you might want to split an MKV file:

• File Size Limitations: Large MKV files, especially those with high-resolution videos, can be difficult to share via email or upload to online platforms. Splitting the file into smaller segments can circumvent these limitations.
• Creating Chapters: For long movies or TV series, splitting the MKV into parts representing different chapters or episodes makes it easier to navigate and watch specific sections.
• Storage Space: If you have limited storage space on a device, splitting large MKV files into smaller segments can make them more manageable.
• Editing Purposes: Splitting a long video can simplify editing tasks, allowing you to work on smaller, more focused segments.
• Better Playback on Older Devices: Older devices or software might struggle to process very large files. Smaller segments might lead to smoother playback.

Methods for Splitting MKV Files

There are several ways to split MKV files, ranging from using specialized video editing software to simpler command-line tools. We’ll explore several methods, covering different skill levels and preferences. Each method will be explained in detail with step-by-step instructions.

Method 1: Using MKVToolNix (GUI)

MKVToolNix is a free, open-source suite of tools for creating, altering, and inspecting Matroska files. It’s a powerful and versatile program specifically designed for handling MKV files, making it an excellent choice for splitting them. It offers both a graphical user interface (GUI) for ease of use and command-line tools for more advanced users.

Step-by-Step Guide to Splitting with MKVToolNix GUI

1. Download and Install MKVToolNix:

   Visit the official MKVToolNix website (https://mkvtoolnix.download/) and download the appropriate version for your operating system (Windows, macOS, or Linux). Follow the installation instructions.

2. Open MKVToolNix GUI:

   Once installed, launch the MKVToolNix GUI (mkvmerge GUI).

3. Add the MKV File:

   Click on the “Add source files” button (usually a plus (+) icon) or drag and drop your MKV file into the “Source files” pane. You will see a list of all the tracks (video, audio, subtitles) contained within the MKV file.

4. Select the Splitting Mode:

   Navigate to the “Output” tab. Look for the “Splitting” section. You have several options here:

   • Split by size: Splits the output into files of a specified size (e.g., 1 GB, 500 MB).
   • Split after duration: Splits the output after a specified time duration (e.g., after 10 minutes, after 2 hours).
   • Split after timestamps: Splits the output at specific timecodes that you manually define.
   • Split before timestamps: Splits the output right before specific timecodes that you manually define.
   • Split into parts based on chapters: (If the MKV has chapter information, you can split at chapter boundaries).
5. Configure Split Settings:

   Depending on the mode you selected, configure the settings. For example:

   • Split by size: Enter the desired file size in megabytes (MB) or gigabytes (GB). You can also choose whether to split after the specified size or before the specified size.
   • Split after duration: Enter the duration for each part in the format hh:mm:ss (e.g., 00:10:00 for 10 minutes, 01:30:00 for 1 hour and 30 minutes).
   • Split after timestamps/ Split before timestamps: Enter the specific time codes at which you want to split the file, formatted as hh:mm:ss.milliseconds or hh:mm:ss. You can add multiple split points.
   • Split into parts based on chapters: The program will automatically create parts based on the existing chapters in the MKV file.
6. Set Output File Name and Location:

   In the “Output file name” section (usually at the top), select the location where you want to save the split files. You can also choose a base filename to be used by appending numbers or chapter names during splitting.

7. Start Splitting:

   Click the “Start muxing” button (usually a large button at the bottom). MKVToolNix will then split your file according to your specified settings. The time taken will vary depending on the size of your MKV file and your computer’s hardware.

8. Verify the Split Files:

   Once the process is complete, navigate to the output folder and check that the files have been split correctly. Play each file to ensure everything is as expected.

Tips for Using MKVToolNix GUI:

• Precise Timecodes: For precise splitting, note the timecodes from your video player while playing the MKV. Then enter the split points in the appropriate format.
• Preview Split Points: If you’re using the timestamps option, it’s a good idea to note a few seconds before and after your intended split points, as exact time codes might be slightly off due to how the video is encoded.
• Default settings are often good: MKVToolNix default settings for other aspects of the operation, like compression or audio handling, are usually very good and require no modification.
• Experiment with different settings: Try out different splitting modes and sizes to see what works best for your needs.

Method 2: Using FFmpeg (Command-Line)

FFmpeg is a powerful, open-source, command-line tool for handling multimedia files. While it lacks a graphical interface, its versatility and speed make it an excellent option for advanced users. Here’s how to split MKV files using FFmpeg:

Step-by-Step Guide to Splitting with FFmpeg

1. Download and Install FFmpeg:

   Download the appropriate version for your operating system from the official FFmpeg website (https://ffmpeg.org/). The installation process may vary depending on your OS; refer to the official documentation for detailed instructions. You’ll generally need to add the FFmpeg executable directory to your system’s PATH environment variable to access it from the command line.

2. Open Command Prompt/Terminal:

   Launch the command prompt (Windows) or terminal (macOS/Linux).

3. Navigate to the File Location (Optional):

   If your MKV file is not in your current working directory, use the `cd` command to navigate to the directory containing the MKV file. For example:

   cd /path/to/your/mkv/directory

4. Basic Splitting by Duration:

   The core command for splitting by duration is:

   ffmpeg -i input.mkv -c copy -map 0 -segment_time 00:10:00 -f segment output%03d.mkv

   Let’s break this down:

   • ffmpeg: The command-line executable.
   • -i input.mkv: Specifies the input MKV file (replace `input.mkv` with the actual name of your file).
   • -c copy: Tells FFmpeg to copy the streams (video, audio, subtitles) without re-encoding. This is faster and preserves quality.
   • -map 0: Specifies to use all streams from the input file.
   • -segment_time 00:10:00: Specifies the duration for each segment (10 minutes in this case, change to your desired time).
   • -f segment: Indicates that output should be split into segments.
   • output%03d.mkv: Specifies the output file name pattern. `%03d` creates numerical suffixes (output001.mkv, output002.mkv, etc.). You can adjust this pattern to match what you want to call the output files.

   To change the duration, simply replace `00:10:00` with the desired time. For example, to split the file every 20 minutes, use `00:20:00`.

5. Splitting by Specific Timecodes:

   To split at specific timestamps, you can use the following command:

   ffmpeg -i input.mkv -c copy -map 0 -ss 00:00:00 -to 00:15:00 output1.mkv -ss 00:15:00 -to 00:30:00 output2.mkv -ss 00:30:00 -to 01:00:00 output3.mkv

   Here’s what is different:

   • -ss start_time: specifies the starting time for an output segment.
   • -to end_time: specifies the ending time for an output segment.

   The output file naming pattern is done manually in this case. The above example will split the first 15 minutes into `output1.mkv`, the next 15 minutes in `output2.mkv` and the next 30 minutes into `output3.mkv`. You can extend this command to add as many specific splitting times as you need.

6. Execute the Command:

   Press Enter to execute the command. FFmpeg will split the MKV file based on the provided parameters.

7. Verify the Split Files:

   Check the output directory for the split files. Verify they are split correctly and that they play back as expected.

Tips for Using FFmpeg:

• No Re-encoding: Using `-c copy` ensures that FFmpeg does not re-encode the video and audio streams, making the splitting process faster and lossless.
• Accurate Timings: For splitting at specific points, use your media player to find the desired timecodes and copy them correctly to the command.
• Experiment: There are many options in FFmpeg. Research online for different functionalities to get the exact behavior you want.
• Batch Scripting: For large batches of splits, combine these commands into a script.

Method 3: Using LosslessCut (GUI)

LosslessCut is another free, open-source tool designed specifically for lossless trimming and splitting of video and audio files. It’s a great option if you need quick and precise splits without re-encoding.

Step-by-Step Guide to Splitting with LosslessCut

1. Download and Install LosslessCut:

   Download LosslessCut from its GitHub page (https://github.com/mifi/lossless-cut/releases). Select the installer for your operating system. It’s available for Windows, macOS, and Linux. Installation is usually straightforward.

2. Open LosslessCut:

   Launch the LosslessCut application.

3. Open the MKV File:

   Click on “Open” (typically in the File menu) or drag and drop your MKV file into the LosslessCut window.

4. Set Split Points:

   Use the timeline scrubber or the left and right arrow keys to navigate through the video. Press the `I` key to set the start point of a segment and the `O` key to set the end point. The highlighted region between the start and end point marks the clip that will be exported as a segment.

5. Export the Segment:

   Press the export button or the `E` key. LosslessCut will export a segment that matches your start and end point without re-encoding.

6. Repeat for Additional Segments:

   Repeat steps 4 and 5 for any additional segments you want to create. You’ll have to manually navigate through the timeline and set the new segment points to perform further splits.

7. Verify the Split Files:

   Check the output directory to confirm the segments were split as expected. Play back each file to verify they work correctly.

Tips for Using LosslessCut:

• No Encoding: LosslessCut does not re-encode video or audio, which means you will not lose any quality and the splitting process is extremely quick.
• Keyboard Shortcuts: Use keyboard shortcuts like `I`, `O`, and `E` to speed up the editing and splitting process.
• Visual Timeline: The visual timeline makes it easy to see where to perform the cuts and allows more precise splits.
• Multiple segments: Though you can create multiple segments using this method, it is not as straightforward or flexible as using MKVToolNix, since you have to set up one export at a time.

Choosing the Right Method

The best method for splitting MKV files depends on your specific needs and technical proficiency:

• MKVToolNix: Best for most users, offering a good balance of user-friendliness and features. It’s excellent for splitting by size, duration, or chapter, and it has many other capabilities for working with MKV files. It’s also suitable if you need a lot of control over the splitting process through specific timecode entries.
• FFmpeg: Best for advanced users comfortable with command-line interfaces. Provides great power and flexibility for batch processing and more complex splitting scenarios. If you need scripting capabilities or to do many splits in an automated fashion, this is the best option.
• LosslessCut: Best for quick, precise splits without re-encoding, with a visual timeline interface. Useful if you only need a couple of segments without too much pre-planning. Its focus is more geared towards editing (trimming) of video and audio instead of batch splitting.

Additional Considerations

• File Format: All of the programs mentioned above are capable of splitting more formats than just MKV. If you have video in a different container format, the principles are the same, and you can use the tools described in this article to split other types of video files as well.
• Hardware: Splitting video is not usually computationally intensive. However, if you’re dealing with large files or making use of re-encoding features (which is not part of this article), then having a relatively powerful computer with adequate processing power and RAM will make the process faster.
• Re-encoding: This article has focused on methods that preserve the quality of the input video, and all the examples avoid re-encoding the video streams. However, it is possible to re-encode the video at the time of splitting. This is often done to create segments that have smaller file sizes. However, re-encoding video will result in loss of quality and will be much slower than the methods described in this article.

Conclusion

Splitting MKV files is a straightforward process, especially when you use the right tool for the job. Whether you prefer the user-friendly interface of MKVToolNix, the flexibility of FFmpeg, or the rapid trimming capabilities of LosslessCut, you now have the knowledge and the tools to effectively split your MKV files into more manageable segments. Always remember to back up your original files before making any changes. By following the steps in this guide, you’ll be able to split your MKV files with ease and confidence.