I'm using Kdenlive to edit my first feature film. I managed to edit approximately 40 minutes without running into any instability issues, except the odd crash... until now.

I discovered that an entire two minute chunk of my timeline was now empty. There was a single-frame clip at the beginning and the end of this gap, but two days of editing a dialogue where completely lost.

Google Drive saved my **** here. I found a previous autosaved revision that had the missing two minutes (and immediately put the project file on git).

But getting these two minutes back into my "latest" clip was a pain in the ****. I tried to use the Library as the way to copy-paste between projects. Adding the library clip to the timeline froze my machine for a couple of minutes. But then expanding the clip into the timeline completely killed (158% CPU, 87% RAM the last time top, running in another window, managed to print anything...)

I gave up after a couple of reboots. I ended up manually copying and pasting between the project XMLs until I managed to get my project to a complete state. Phew!

I've been ranting so far. Trying to be more constructive -

• This is Kdenlive 17.12.0, the latest release AFAICT - is the refactoring branch stable enough to start using?
• I wasn't touching the timeline anywhere near the zone where the gap happened (which is why it took me two days to discover it!)
• Is the Library import algorithm horribly inefficient, or is there a bug?
• Is the Expand Clip algorithm horribly inefficient, or is there a bug? How can it eat 16 GB of RAM and not finish, when I can do something equivalent by copying and pasting a few lines of XML? I want to believe this is a bug.
• Is the Move tool really inefficient? With this 40-minute timeline, it takes a second or two after I start dragging for the UI to become responsive again.

At this point I'm wondering whether to try the refactoring branch / 18.04 when it's out; or try to fix the bugs myself (but I want to edit video in my free time, not doing more debugging!); or to switch to a different editing program (but it's difficult to export Kdenlive/MLT to anything else, so I may have to keep working on my exporter!)

Rant over. I'm sad

So... this happened again, and now I figured out what was the problem. Fair's fair: it was user error

What happened was that I had a timeline zone, and some times while trying to do Undo (Ctrl-Z), I must have accidentally done Lift Timeline (Z)

It's reassuring to know It's not a Kdenlive data loss bug, but... this is a dangerous feature that is too accessible I'll look for a way to change the shortcut to something else.