Impending doom: Shotcut is slowly destroying my work and it doesn't let me fix it back!

I feel like having to switch editing softwares, even if that will cost me the hours of progress I spent on Shotcut.

To anyone reading this post and they don’t have an answer, please like this post to make it more popular and also to let the Shotcut creators know about this problem, because I can’t imagine how bad it could actually be if it destroyed a more effortful part of my track, or another Shotcut user’s even more detailed track, because who knows if the bug will also affect you.

This bug should be top priority, because it can be a reason on why people quit Shotcut and also lose hours of progress.

So yesterday I installed Shotcut, and since then I always had one problem: Lag.
This lag, 99% of the time, would come from undoing. Everytime I did CTRL+Z or pressed the undo button on the screen, then Shotcut will freeze, lasting 10-60 seconds, which I’m pretty sure depends on how much detail you spend into making your video: The more detail you put into the video, the more time it will take for Shotcut to unfreeze. And I’ve reached a point where Shotcut would often times crash everytime I am trying to undo, and it doesn’t even say an after-response like “Shotcut has crashed blah blah blah etc.”. I was fine with waiting around 15 seconds everytime I did undo, but now it’s getting on my nerves because I feel like I am in quicksand and any move I make will worsen my position. Whenever I try to undo, there’s a very high chance that the app will crash, and when the app crashes and I re-open it, it asks me if I want to open my auto-save, to which I respond with yes, obviously. Now I am put back to where I previously was, but they still did not undo the mistake. And even worse, there isn’t undo history anymore because of the crash, so I am stuck with that mistake until I redo that entire part from scratch. So basically, my hours worth of progress is slowly getting destroyed due to Shotcut’s laggy app, and I see my progress disappear in front of my own eyes, which makes me really sad and annoyed, because I wanted to find a free editing software which could also help me with basic necessities for editing, and I put all my trust in this one app called Shotcut. What kind of bug just throws away your hours of work in front of your own eyes? I am keeping Shotcut closed and not opening my file again until this bug is fixed, and I hope that it gets fixed quickly, which the likelihood of that will probably be slim to none due to my message being hidden in a pile of many other messages because of its high chance of barely having any likes. And, by what I’ve seen on this forum, I saw many other people complaining about the same glitch but they haven’t gotten any response, not even any reply. I hate how now, because it’s so laggy, clicks done on my clips from the track will have like a 25% to turn it into a “Transition” which cannot even be deleted, and cannot be undone. I have over 100GB free space so the lag definitely isn’t because of my storage. And keep in mind that the only details I added to my Shotcut track were like just some Separations and like 6 different texts. This really reminds me of the time I used a trusted website, and that website deleted hours of my progress in the span of 3 seconds. I’m never using that website seriously again, and I might also never use Shotcut again if this bug isn’t fixed. To get the bug fixed is all I’m asking for, then I’ll be happy.

You did not answer the required questions in the bug report template about operating system and Shotcut version.

Did you notice that versions 23.09 and 23.11 both had some fixes for undo bugs?

Even if you are having problems with the latest version, this report is too vague to be actionable. There are thousands of possible permutations of undo operations. We need more specific steps to create the problem so that we can focus on the one specific operation that is causing your problem.

Can you start from a blank project and then give us specific steps to reproduce the issue you see?

Or, possibility provide us with an example project that easily exhibits the problem?

Sorry for being so angry in the last post, I was in a bad mood at that time.

But anyways, my Shotcut version is 23.12.15 and my previous project that first experienced the problems was a MKV file (like 1.5 hours long but it has been edited to be like 15 mins), and after trying it today with another file (WEBM and like 40 seconds long), as soon as I dropped the file in Shotcut, it froze and even my other softwares were crashing even after there was no running Shotcut software in the Task Manager, saying that there’s not enough memory. I had to force shut-down my laptop to actually get rid of it because even my laptop screen froze. So in conclusion, when I drop a WEBM file in Shotcut, it freezes and crashes after a few seconds, then my other softwares slowly start crashing too due to not enough memory, even though my laptop was completely fine before I dropped that file into Shotcut. And now when I tried to test it out with a MP3 audio, it works perfectly fine and the undo button isn’t laggy at all, same with the video files WMV, MOV, MP4, GIF.

After trying out the glitch with a different MKV file which is also smaller, I still see some lag but it’s not as bad and isn’t that noticable. But the most noticable part is when the entire track is deleted. If you delete the entire MKV track in Shotcut (while the tracks has lots of separations), then Shotcut will freeze for more time than compared to non-MKV or non-WEBM files (while those other files also have lots of separations).

I guess I’ll convert my file from MLT (the file type which Shotcut used to save my MKV file) to another file type, and start over from scratch at those destroyed parts. It was like 30 seconds anyways so it didn’t really affect my ~15min worth of video.

Edit: I converted the file from MLT to MP4 and there’s still lag when undoing, but there’s way less of it now thankfully. Even if it would start to lag out again, I can probably export the file into MP4 again and continue my work.

In conclusion, convert your laggy file to something else like WMV, MOV or MP4.

Hi @asdfqwerzxcv
Sounds to me like maybe your computer isn’t powerful enough to handle your project?

What are your computer specs?
What size are your files? 1080p? 2160p?
What frame rate is your project set at? 30fps? 60fps?

Have you tried Proxy editing and/or Preview Scaling?
Instead of one 15-minute project, have you tried to divise it in 5-minute long projects?

I highly doubt it’s about my device because it didn’t really lag out when the video didn’t have deleted clips. It depends on how many separations and edits I made on my video, like the last time I tried with another MKV file to see if the problem was also on any other file with the same file type.

And now I found out that my solution won’t even work properly because when exporting, the deinterlacing and interpolating is forced and I can’t find a way to disable it, which ruins my video quality on some frames because the interpolation will interpolate between two cut clips. I don’t know much about deinterlacing but I also would not want it on my video because my video is fine and doesn’t need any automatic detail improvements. These forced options are making my download take longer, which is pretty annoying. So if someone knows how to disable it, let me know. If there’s no way of disabling it, then it should be informed to the Shotcut developers and tell them to add such an option.

The lag has nothing to do with the file size, so any ways to make the file size smaller will not fix the problem. And dividing the project into smaller ones will still keep some lag because for some reason, Shotcut can’t handle MKV or WEBM files. Could you also upload a WEBM file to Shotcut to see if that memory crash thing will also occur to you? (If it does happen, then shut down your device using its hardware because the screen will be frozen and won’t react to any responses.) Or just try with a MKV file and give the file a couple of separations then delete some parts then undo it back to see if the screen will freeze for some seconds.

Preview Scaling does not decrease the lag at all.

I have no crashing problem with MKV (or WebM) files. And compared with files of other formats (MP4 for example) they do not add lagging while editing. None that I can notice at least.

After testing it out again with MP4 and MKV but with a blank screen this time, it seems like the screen freeze is equal in time, which is weird because I used the same duration and it still was the same amount of lag, even with the same file size. I didn’t believe that the file size mattered because my 10-15min project’s lag (and 25% chance of crashing upon undo) is way worse than its original 1.4 hour raw video with around 10 second lag on most undos. I don’t think it’s because I sped up the rest of the video to 5x faster (that’s why it’s around 10-15 mins) where I still deleted more than half an hour of other parts of the video though, so I don’t understand how the edited version is way laggier because there were only separations and 6 pieces of text. And during that time, I was still trying to shrink the project’s length and also wanted to put it back at 1X speed once it was finished, but sadly I couldn’t because of the rising amounts of lag. And if you’re thinking that maybe it’s because of the speed, it’s not. Even the raw video sped up 5X will still have way less lag than the edited project.

.I just don’t understand how my shorter length video is laggier than the longer length one, which is also what made me jump to the conclusion that the file size didn’t matter, which I now found out that it was incorrect.

Anyways this information might be useful: I use 11th Gen Intel(R) Core™ i7-11800H @ 2.30GHz and my installed RAM is 16GB (15.7GB usable).