Just FYI for anyone working with FLAC audio, MKVMerge won’t append FLAC tracks together, so you’ll have to do that in a separate tool. I haven’t had any success with that, so far.
You should report that to the developer of MKVtoolnix. He is pretty quick with fixes.
I’m pretty sure it’s known, or at least the error it throws makes it seem that way.
Yea, I got that same error with those Blue Rays. I tested out the merged file and didn’t have any problems. Would be nice to know what it’s complaining about though.
Does not work for me. The length of the movie is correct, and the first part of the movie plays fine, but the second part I appended shows a ton of video distortion and the audio is wrong. I think it might be the audio from the first half.
Sounds like you got 2 “parts” that don’t actually belong together (e.g. from different sources, different stream order / characteristics…).
Wow, thanks for the quick response. Everything seems to be the same except the resolution. Would that cause the problem?
This is not about only the video resolution… it’s about pretty much every characteristic of your files’s contents. If they’re not the same, you cannot simply stitch them together.
The video resolution is the only difference. I guess that is the problem. Appreciate the response.
My bad… I got confused by exact vs. except 
Yes… that’s the issue.
Was my mistake… glad I corrected my typo. I hate typos. 
It’s great software, just the same. Thanks again.
Any issues handling Dolby Vision tracks for MKV? I am using latest version of the tool.
Hey, tried merging LOTD EE UHD with Atmos/DV. It works fine. But then if I play it back on Plex comes the second part of the movie there is a clear audio sync issue. This issue doesn’t happen with media player classic.
a quick fast forward/backward seems to fix the issue, but I was wondering what could be causing it? A bug with mkvtoolnix?
LOTR EE UHD was my introduction to MKVtoolnix and merging multi-disc movies. I have the same exact issue and working on troubleshooting this. Fellowship of the Ring is the only one I have done so far, so waiting to try the other movies to see if they have the same problem before messing around with settings too much. Did you see the sync issue with all 3 movies? The forward/backward trick did work for me as well, so while annoying at least its a simple fix and better than dealing with multi-disc organization in Plex (and Emby as I use both).
Well, I also have that issue. I was splitting an ep from a TV show, I wanted to remove some parts and using mkvtoolnix, latest ver, I encountered the same issue. The parts are cut with mkvtoolnix from the same single file, and then rejoined. Individually, they play fine and for most of the rejoined file plays fine, but at some “joints” it displays artifacts when each individual part plays fine.
It sometimes helps if you do the cut/rejoin in a single step using the slightly more tricky split options — e.g. if using split by parts based on timestamp (?), using [start1]-[end1],+[start2]-[end2]
The respective options are described in the tool tips of the split details.
Yes, after figuring out the exact time stamps I’ve tried that too… same result on this particular joint. It just won’t work, neither does ffmpeg -f concat, so I’m curious what exactly goes wrong. Does mkvtoolnix do something the splits, since the original ffile works properly, but so do individual splits. It’s an odd one…
My issue is the file successfully (from what I can tell) joins the files together, but Plex still only sees “the first half” rather than the entire file. If I get to 95% watched, and then start to scrub backwards, the second file appears instead of what was just watched. A re-analysis accomplishes nothing, and Plex still sees the total runtime of 67 minutes, instead of roughly 120 minutes.
You might have accidentally merged the files instead of appending the streams… if so, you end up with a single file that contains 2 sets of all streams… you might even be able to pick the respective streams from within VLC – but they won’t play subsequently.
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This was exactly what I did. Thank you for the call out!
