Merging files with different subtitle counts

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So i have a video with two different languages and two different subtitles. I also have an mkv file that’s just a simple audio file and video file. It’s just a little intro I want to add. How can I add that intro to the existing file. Idk if MKVtoolnix can do this. The audio would be the same regardless of language track, and I just need subtitles to start with the old track in time, ignoring the added intro (or adding blank time) Can someone help me with this?

2

I would try the following approach (of course there is more than one way how this can be done):

  • Open the second (main) file in MKVToolNix and select the first subtitle track (deselect all the other tracks) and multiplex it into a file “subtitle1.mks”.
  • Now select the second subtitle track (deselect the other tracks) and multiplex it into a file “subtitle2.mks”.
  • Next, open the first (intro) file in MKVToolNix and select only the audio track (deselect all the other tracks) and multiplex it into a file “audio1.mka”.
  • Use MediaInfo to check if there is a time delay for the audio track in the first file. Should usually be 0 but could be greater than 0.
  • Use MKVToolNix and open the first (intro) file again. Add the file “audio1.mka” as additional file and if there was a time delay in the previous step, enter that value in milliseconds in the field “sync” for the audio track from “audio1.mka”.
  • Add the file “subtitle1.mks” as additional file and enter the value “-999999999” in the field “sync”, which effectively removes all subtitle entries from that track in the next step.
  • Add the file “subtitle2.mks” as additional file and enter the value “-999999999” in the field “sync” the same way you did in the previous step.
  • Mux the file into a new file “temp_intro.mkv”. Enable “stop after video ends“ just to be sure. You now have a new intro file with two equal audio tracks and two empty subtitle tracks.
  • Open the newly muxed intro file with MKVToolNix and then open your main file to append it to the first file. The numbers and types of the tracks in the two matches now and can be appended to each other.
  • Remux this to your final file with every track from the second file appended to one track from the first file.

But that only works if the video and audio tracks in your files have the exact same format (codec, resolution etc.). Otherwise MKVToolNix isn’t able to concatenate these files.

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