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Join DVD VOB Files into an MKV without Converting

The other day I was looking into my modest DVD collection, and I was surprised that I had some really good movies there that I could actually re-watch. Problem is, I no longer watch anything on the DVD player on account of the TV being in the most disturb-prone room in the house.

Now, I could easily watch them on my computer, but I hate the fact that playing a DVD disc gets in the way of what I can do with what is otherwise a powerful player.

So the simple solution to all this was just to convert the DVDs to a portable format like MKV that I could store locally on my hard drive, and while at it, avoid transcoding (conversion) as that would take too much time.

Consequently, I decided to settle for a “lossless conversion” which would join the individual DVD files (*.vob) into one single MKV file with no quality loss.

How the VOBs are Joined Losslessly

In a typical DVD folder, you’ll find three kinds of files: IFO, BUP and VOB. The VOB files are what hold the actual video and DVD menus/chapters, if present.

So all we need from a DVD folder are just the VOB files that have the actual video, the rest including menu/chapter segments can be discarded.

Now remember VOB, just like MKV, is a container format and not the actual video format (codec). In VOB, the video codec is MPEG-2 while the audio codec is usually AC3. These two are the standard formats found in all DVDs.

So all we need to do is just change the container with no need for transcoding (i.e converting). This will ensure that the original quality in the DVD is retained, but the overall video size remains unchanged.

Doing this will also take only a matter of minutes if not seconds to complete compared to converting.


  • Should you want to reduce the size of the DVD Video, it’s inevitable that you’ll have to convert the video, and this time with a better codec like H.264/MPEG-4 or HEVC that’s achieves good quality at a fraction of the DVD size. Most video converters will do this for you automatically. You’ll just have to select your output format (a container like MKV or MP4) and the desired bit rate which is what determines the quality and output size of the video.
  • If you want to understand more on how lossless conversions works, refer to my post on free tools that join video losslessly.

Join VOBs Losslessly using MKVToolNix

  1. Download and install MKVToolNix. It’s available for almost all platforms out there (Windows, Mac, Linux, BSD etc.). There’s also a portable version should you not want to use the installable one.
  2. Run MKVToolNix GUI then drag and drop the first VOB containing the main video (not the menus/chapters) into the Source file box. Doing that will automatically add the remaining VOBs and append them to the first VOB assuming you haven’t renamed them.
    A screenshot showing MKVToolNix main window with VOB files added.
  3. If you’ve renamed the VOBs, just drag and drop them in the order you wish to join them and then when prompted, select the Append to existing file option. This way, MKVToolNix will know the VOB files are from the same DVD.
    A screenshot showing MKVToolNix append dialog.
  4. Alternatively, you can add the VOB using the Add source files button at the bottom of the window. Likewise, the additional VOB files will be automatically added and appended. However, if you’ve renamed them, you’ll have to select the added VOB in the Source file box then go back to that button and from the arrow select append files to add the remaining parts.
    A screenshot showing MKVToolNix source fles menu..
  5. In the tracks, chapters and tags box, confirm that all the videos have the same codecs – the video (MPEG1/2) and audio (AC-3, MP3, DTS etc.).
    A screenshot showing video and audio codecs detected in MKVToolNix.
    If you have a different video or audio codecs listed there, the process will not work as the VOBs need to be in the same format for them to be joined. This should be the case if they all came from the same DVD.
  6. Before finishing the process, you may want to edit some properties of the video though it’s not necessary. These include properties such as the default languages, frame rate, aspect ratio, adjustment of time codes (delays or stretch) etc. To do that, just select the video or audio item in the tracks, chapters and tags box, then in the properties box adjust the properties as you wish.
    A screenshot showing MKVToolNix properties panel.
  7. Select the output folder and adjust the file name in the Destination file, otherwise leave it as it is to output the MKV in the source folder. To finish, just hit the Start multiplexing button or you can Add to job cue then add more jobs so that it does them in batch.
  8. Depending on the size of the video, the multiplexing (muxing) will take from a few seconds to a few minutes to finish the job.

The process may end with some warning and/or errors which you can look in the job output page. You can ignore the warnings though errors may mean that the job did not complete successfully.

Regardless, make sure to open the output video to verify it joined well (check the length and that the audio/video sync matches).

And that’s pretty much how you join VOB files into an MKV with no quality loss. If the joining does not work or the output video has sync and length problems, you may want to try some other free tools for joining videos losslessly.

If all fails, I think you have no choice but to join and convert the VOBs the usual way – with a Video Converter.



  1. Instructions for including subtitles would have been nice. Including subtitles wasn’t readily apparent to me, so I ended up using MakeMKV.

  2. MKVToolnix can transcode VOB into MKV but you simply can’t trust the result. While it might look good at first glance, there can be very many really horrible audio/video sync issues – you have to carefully scan through the movie to confirm how good a job it did. You’d be lucky getting a 50% success rate. The developers know about it and they’ve said VOB support hasn’t been touched in eons and there are no plans to improve that aspect. A much more reliable tool is MakeMKV, however it too has random audio/video sync issues to the extent that you can’t trust the result either. If you look at the generated log file you’ll get some sense if the sync issues are there or not. Sometimes it works, sometimes it doesn’t. For just transcoding VOB to MKV without compressing, I’m still looking for something reliable and haven’t found it.

    1. Kelvin Administrator

      I used to encounter the sync issues once in a while too. I rarely join VOBs nowadays but around the time I used to, I can recall Avidemux being more reliable. You could give it a try if you haven’t.

      1. I did also try AVIDemux when I was trying out MKVToolnix and MakeMKV, and it produced really messed up audio – it was so bad I abandoned it. However, I just tried it again and it prompted me for a new version (2.8, released 2 months ago on 2021.1228) which I subsequently downloaded and used. That worked this time – so apparently they fixed what was broken! However, when AVIDemux comes up against a time stamp error (which happens frequently when ripping DVDs that have some scratches) it just stops transcoding instead of being tolerant like MKVToolnix and MakeMKV (which keep going to the end).That means you need to check if every AVIDemux made it all the way, or you could end up with partial movies. In my experience, you’d be lucky to rip a full season of any TV series without ending up with at least one episode containing a time stamp error. The only movie I have that appear to play without issue are the VOB structures I ripped – I did those using MacDVDRipper Pro by ripping the main movie only.

        1. Kelvin Administrator

          How about a traditional video converter like Video to Video? It has a mux option that was less prone to errors compared to Avidemux & MKVToolnix. The only reason I didn’t use it nearly as much as the other tow was its interface, otherwise it worked just as good. You could perhaps give it a try too.

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    Kelvin Kathia

    Kelvin Kathia is a writer that's passionate about sharing solutions to everyday tech problems. He's the founder and editor of Journey Bytes, a tech blog and web design agency. Feel free to leave him comments or questions regarding this post, or by leaving him a message on the contact page. If you found his content helpful, a donation is much appreciated.