How to Join DVD VOB Files into an MKV with No Quality Loss

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 (losslessly).

How the VOBs are Joined Losslessly

In a typical DVD folder, you’ll find three kind 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. This 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 seconds to complete compared to converting.

NOTE:

  • If you want to understand more on how lossless conversions works, you can read here
  • Should you need 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 that’s achieves good quality at smaller sizes.
  • 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 quality and output size of the video.

Join VOBs Losslessly using MKVToolNix

First order of business is to simply join the VOB files into one VOB. The easiest way to do that is to use MKVToolNix.

MKVToolNix will not only join the VOB files but will also automatically “wrap” them in the MKV container. Another plus is that it automatically recognizes and adds VOB files from the same DVD – i.e. if you haven’t renamed their original file names (e.g. VTS_04_1.VOB, VTS_04_2.VOB).

STEPS

1. Get and install MKVToolNix from the tool’s homepage. 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.

load
VOB Parts Appended and Loaded

If you’ve renamed the VOBs, just drag and drop 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.

append
Append to Existing File

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.

add
Add and Append Video Files

3. 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.).

codecs
DVD Video and Audio Codecs

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.

4. Before finishing the process, you may want to edit some properties of the video though it’s not necessary. These includes 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.

properties
Add Properties

5. 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.

6. 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 of the 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.

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