Crash on "show graph of audio levels" for merged MKVs

[chrusli]

Dear community,

I have a ripped MKV of my original “The Lord of the Rings: The Return of the King” Blu-ray. As the extended version comes on two discs, I have two MKVs. I merged the MKVs with MKVToolNix via “Append files”. This resulted in an 80 GB MKV. I added it to the DCP-o-matic project and then clicked on “Show graph of audio levels...”. It takes a very long time to do so and ultimately crashes (program closes without warning or information). I also tried to do the DCP via Jobs → Make DCP, which results in a crash too (I assume the same analyzing of audio takes place). I tried to remove all unneeded audio tracks and only keep the one I want. The result was a crash as well. I then tried to create the DCP with one piece of the original MKV, which worked fine.

It's unclear now, whether this is the result of the merge of the MKVs or is due to the size and length of the audio/file of the 80 GB version.

Is the merge a problem? Is there a better way, inside DCP-o-matic to make one DCP out of two MKVs?

I greatly appreciate your help.

[carl]

Hi,

It sounds like the merge is triggering some bug in DCP-o-matic. I doubt the size is causing the problem. It would be interesting to merge two much smaller MKVs using mkvtoolnix and see if the resulting file also crashes DCP-o-matic. If so I could try and find the problem.

You could just put both MKVs one after the other into the DCP-o-matic project. Would that work? Or indeed make two DCPs and play them back to back.

[chrusli]

Thank you for your input. I tried it now with two smaller MKVs that I merged and DCP-o-matic didn't have any issue. Obviously, the MKV is different in many ways, so it's hard to judge. If you like, I can privately provide you with the MKV that causes the crash.

Initially, I tried to put both MKVs in the project, that was no issue, but I couldn't find out how to append one to the other. I wasn't able to find anything about it in the documentation and forum. Is this possible to do?

[carl]

Hi, thanks for testing that out! If you can make the bad MKV available that would be amazing.

The DCP-o-matic project has a primitive "timeline", so if you add both MKVs using "Add file..." you can then either click "Timeline..." and drag them into place, or go into the "Timing" tab and position of the second accordingly.

That being said, I think if you just add two MKVs it should arrange them sequentially. You can check the "Timeline..." window to be sure.

[chrusli]

Hi Carl. Thank you for pointing that out. Indeed, if you have two videos, it just adds one after the other. I wonder how I missed that in the first place -

[carl]

Hi, I can see the crash on analysis but not the crash on making a DCP from your file. Was it the same sort of crash? DCP-o-matic just closed without any message?

[chrusli]

Hi Carl. I never skipped the analysis part when you click on "Make DCP", so I assume it is the same analysis that is happening and crashes therefore too. By crash I mean, that the program closed without any visible error message.