Understanding split parts definition

After downloading MKVToolNix for the first time this evening, I’m trying it out on an mpeg video recorded on a Humax set top box. I previously used VideoRedo to split or remove commercial breaks from this type of recording but this is app no longer usable, so I was interested when Computeractive magazine issue 670 featured MKVToolNix in their Workshop series. The article contains some outline steps for splitting files into multiple parts, but I hit a snag when trying the Split Mode “By parts based on timestamps”. I had logged the timestamps of interest by reviewing the video in VLC and tried entering text in the Parts box as follows:

  • 0:0:18,1:29:56,3:40:35 (format h:m:s, expecting 4 output files)
  • 0:0:0,0:0:18,1:29:56,3:40:35,4:30:38 (format as above, including start and end)
  • 0:0:0:0,0:0:0:18,0:1:29:56,0:3:40:35,0:4:30:38 (format d:h:m:s, expecting 4 output files)

In each case, hitting “Start multiplexing” resulted in the error “Invalid start/end specification for ‘–split’ in '–split parts:”

Maybe decimal s is expected, but what is the expected format?

It could be there’s a more fundamental issue for this novice user. Could you enlighten me?



The a “part” wrt. splitting is a range consisting of a start & and an end position. “By timestamps” then means that both the start & the end are timestamps, not frame numbers.

A range looks like this: start-end

You can leave out either the start or the end but not both. If you leave out the start, either the start of the file (if this is the first range) or the end of the previous range is used. Leaving out the end means everything up to the end of the source files.

This type of splitting syntax is useful if you’re only interested in certain parts of the file (e.g. everything from 00:02:00 until 00:10:00), or if you want to leave out a part in the middle (by specifying two ranges: one from the start of the file up to the start of the part you want to leave out, one from the end of the part you want to leave out until the end of the file).

If you want to keep all the content & only distribute it over a set out smaller files, the mode “splitting by timestamps” (no “parts” here) is more appropriate.

Read up some more on it in the documentation.

Thanks for your help. I included the start and three subsequent timestamps and generated four files named -001 to -004. I spotted a lip-sync issue in two of the files where the presenter is talking to camera. Can this be rectified in the output files, or prevented prior to multiplexing?


Usually desync shouldn’t occur. If it happens during appending, then you’re often simply out of luck.