Bug during export - always in the same place, but when exporting only part of the file it disappears


I’ve put my question in how to section and not in bug as I don’t have enough information to provide what is the reason of bug.

I have my project created in 22.01.30 shotcut version. It’s quite big not because of the lenght but because of many tracks and many different elements on tracks (short clips). When editing everything is fine. However when exporting I have quite strange situation. I also tried to export it 22.06.23 version but it didn’t solve the issue.

Let me describe what I noticed.

  1. When exporting from 22.01.30 or 22.06.23 full version, export fails exactly in the same place (the same output file size after fail so it seems to be deterministic).
  2. There is no error message, neither there is no red error icon. From user interface it looks like that the export finished with success (green icon marking export finished, 100% done). However when observing progress bar during export it goes to 9% and suddenly it jumps to 100%. The exit code is 11 so as I found on Internet, it means nothing.
  3. I have 32 GB RAM and a lot of free space on disk. I use ram monitor to see if there might be anything related with ram and it doesn’t look like that. Also job log doesn’t suggest any problems with RAM.
  4. Basing on 9% fail moment, I try to estimate moment of the file making problems. Next I add 1 minute less and 1 minute more and I try to export this 2 min part. I have different behaviour depending on the shotcut version.
    4a. On 22.01.30 it fails and the completeness percentage suggest that it’s exactly the same place. However there is no red icon and no error code (the same as with the whole project export).
    4b. On 22.01.30 if I divide the 2 minutes on 10 seconds parts (with some 1 sec overlapping so in practice 12 sec), each small part is exported successfully. So when dividing the 2 minutes part on 10 seconds part, I’m not able to find the place causing problem (I’m able to export the whole 2 minutes divided in 10 seconds clips).
    4b. On 22.06.23 both 2 minutes part and all 10 seconds parts are exported correctly. (However on 22.06.23 the export of the whole project fails as I wrote previously).

Concluding it looks like that the problem appears always in exactly the same moment. However when dividing the suspicious part of the video into smaller parts I’m able to export it successfully.

Btw, the only 2 a bit suspicious parts in the log I’ve found is the following

“[mp4 @ 0x7f7478200f00] Timestamps are unset in a packet for stream 1. This is deprecated and will stop working in the future. Fix your code to set the timestamps properly
[mp4 @ 0x7f7478200f00] Encoder did not produce proper pts, making some up.”

Failed with exit code 11
Export job failed; trying again without Parallel processing.
mlt_repository_init: failed to dlopen /media/VIDEO/shotcut-linux-x86_64-220623/Shotcut/Shotcut.app/lib/mlt-7/libmltmovit.so
/usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.26’ not found (required by /media/VIDEO/shotcut-linux-x86_64-220623/Shotcut/Shotcut.app/lib/libmovit.so.2))

Concerning the rest, it seems to be a normal log.

Any ideas how to find the reason of problems?

Edit: I’ve moved this to bug section.

One thing more.

Not sure, but these two threads might be helpfull here

Ok links I gave above didn’t help with my problem.

However after many attempts I’ve finally discovered what is the issue.

One of parts after the suspected part had problem with one filter. Thus my initial choice of suspected part of the video was wrong. It was few seconds later.

If I add NoSync filter with many keyframes with smooth type, it caused crash during export (but worked fine during preview in editing mode). Changing type from smooth to liner for all points made export possible.

Please have a look on part of keyframes view. It’s a bit strange as there is line returning left. I guess it could cause some problems.

I’m not only sure why previously selecting part of the firstly selected small part caused crash. But it could be that it was caused by sth else. Ex. so many attempts to make export.

Concluding it seems that there is sth wrong with NoSync filter during export (sometimes). And it’s also quite strange that export works in a different way than editing.

For me it’s a bug.

The export messages you show are not the cause of your problem. libmltmovit.so is only needed for when using the hidden, experimental, unsupported GPU Effects. Do you have that turned on? It appears at the top of the Settings menu when turned on. Even when turned off the engine still tries to load the library simply to register its plugins. But it fails gracefully and simply makes those plugins unavailable.

That is a cosmetic bug in the UI’s rendering of the curve that I have not yet solved. It has no bearing on the engine’s implementation of smooth keyframes, which uses Catmull-Rom spline.The UI toolkit only has Bezier spline and uses a conversion to try to depict it.

Yes, it is a bug in the No Sync filter that you got a crash when using it. Quite likely the curve is causing a value to go out-of-range and that situation not handled properly. I will try to reproduce and fix it.

Yeah, that was also my guessing. I’m only surprised that crash is only during export and not during editing…

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This was fixed in version 23.12