Hi all,

I've been noticing a rare but annoying problem with kdenlive, and I'd like to get a sense of whether this is known, and if I'm doing something wrong. I can't find anything about it by searching, unfortunately.

I don't have specific repro steps, because it seems to happen randomly. Maybe there's a race condition in the code or something....

In my edits, I do a lot of slicing/dicing/copying/pasting, and I often apply speed changes to various clips (not sure if they're called clips or scenes... but I'm talking about what you drag around in the timeline, not the "source" videos).

Sometimes, in this process, things break, and if I'm lucky, I've saved recently and can recover from not too far back.

Here are the kinds of things I encounter sometimes.

* Clip suddenly becomes unavailable (not the source video, but rather, one clipping from the timeline). Like, it will still be visible on the timeline, but I won't be able to move it, and if I try to copy/paste it, it tells me it doesn't exist or something like that.
* Clip goes dark. Suddenly, some clipping on the timeline just becomes a black screen
* Clip contents move. I once had a timeline with a large number of short clips, all with speed change effects applied. I had to move them all to the right, so I selected them all, slid them to the right, and to my dismay, discovered their contents had changed to a seemingly random, other part of the video I cut them from.

Again, no specific repro steps because it happens randomly from time to time. It's reasonably rare, but can be infuriating when it happens.

Based on the behavior, I assume it's some kind of bug with memory allocation/management.

Does this happen to anyone else? Is there some obscure setting, like a memory optimization that speeds things up, but is actually buggy, that I can disable, to make things work more reliably? (e.g. Chrome has "hardware acceleration", and it's typically best to turn it off because it causes flickering and all kinds of silliness on some hardware).

Ah, I think some of these issues have already been reported:

https://bugs.kde.org/show_bug.cgi?id=371353 and https://bugs.kde.org/show_bug.cgi?id=369585

There's talk of refactoring the timeline, which should hopefully fix some of these things. There's also talk of deprecating the speed change effect, which... NOOOOO, that thing is awesome, I don't want to have to duplicate a 2 hour clip multiple times just so I can have a 5 second chunk at 70% and a different 5 second chunk at 50%.

Can confirm I've had this happen, and not necessarily with speed-change clips. Only solution is to save, exit, reload Kdenlive. Fortunately the timeline hasn't been permanently borked for me, although I might find two clips 'overlapping' on the same track, where they should have overwritten (obviously 2 clips can't existing in the same place).

This has been happening to me too-- specifically, I just tried the exact same maneuver of shifting a set of clips, all with speed change, to the right. Every single clip has it's contents moved around, and the speed change is gone, even though the effect is still on the clip. Honestly, stuff like this isn't just inconvenient bugs , it makes kdenlive almost completely unusable. This stuff happens constantly for me. Tasks that should take 5 minutes take a half hour because the timeline is so shockingly unreliable.

Further, after try to undo the move to recover my progress, then the timeline is really mangled. Clips come in and out even if it doesn't agree with the timeline, and color effects that are applied to clips that weren't even touched in any of this are broken.

Edit: After browsing various bur reports and the refactoring todos, it seems that pretty much all of this is known about. Thanks very much to the devs who are putting valuable time into this. Your work doesn't go unappreciated. Having said that, it surprises me that fixing the timeline corruption issues is step 3 in the refactoring, given that kdenlive cannot reasonably be used for production until that happens. Can priorities not be moved around? I have had several projects get utterly botched either when saving or shifting clips, and while I would greatly prefer to continue supporting the open-source community and devs, it's to the point that I have very little choice other than to move to Windows (from Ubuntu) so that I can use Premiere