DCP glitches putting audio out of synch

[Skeletim]

Circling back on this since it has started happening again but now I'm having a secondary issue where there are dropped frames that cause the screen to go black.

The odd thing is that if there is a audio synch issue there is no black frame drop outs but if the audio stays synched all the way through the film then there are black dropped frames of various lengths between 1-5 seconds repeatedly throughout the film every 5-15 min at random intervals.

I have attempted changing out just about every variable that I can think of but I can't seem to get a single feature DCP to run without one of these two issues.

[Carsten]

What does DCP-o-matic player say about these DCPs?

[Skeletim]

I will say it's dropping numerous frames when playing through it. When the black drop outs happen they do not trigger it to say it dropped a frame which is strange. When I run a verification on a few of these it says 0 Errors, 2 Bv2.1 errors, and 0 Warnings. The 2 Bv2.1 errors are because I haven't set credit markers.

[carl]

It's possible that corruption is happening as the DCP is written to the drive. At the moment this is not detected. Are you writing to an external or network drive?

I do have a version of DCP-o-matic that checks for corruption like this, which you could test if you can remind me which platform you are using (mac/Windows/Linux)

[Skeletim]

I have now tried writing to multiple different external hard drives as well as directly to the desktop of 2 different computers. These were all using a Mac.

The oddest part of this is I have been making DCPs using DCP O MATIC for a few years and had never run into this until now. I'm willing to give anything a shot at this point since I program films weekly and often times need to make DCPs for them.

[carl]

Perhaps you could give this build of DCP-o-matic a try:

https://dcpomatic.com/build/2758-safe-write/fe9873f

and tick the "Check disk writes" in the advanced tab of preferences. That would tell us if something is going wrong as your DCPs are written to disk.

[JimTom]

Long-time user of D-O-M (I’m a big fan of it – thanks Carl!). I’m also a first time poster.

I had a recent problem with very similar symptoms – when making a feature DCP from an MKV, the audio would go significantly out of sync after a glitch a few minutes into the film. After some investigation, I finally was able to narrow down the problem.

The MKVs from Blu-rays I was making on my M1 Mac were now not being done cleanly by MakeMKV. When checking the MKVs through tsMuxeR, I found I was getting various errors.

After trying an alternative way to make MKVs, and checking that tsMuxeR did not report any errors, I was able to make good DCPs with no sync problems.

I hope this is useful! Thank you!