I have Kdenlive Version 18.08.2 running in Xubuntu 18.04

I have been using Kdenlive for almost two years now and rendered many videos, all in 1080p, many over 1 hour, some over 2 hours.

Today I tried to render a simple, barely edited 17 minute video with one source clip and found that about 50% of the way through, all my RAM was used up, the swap partition began to be used heavily, and the system slowed to a crawl. This is on an 8-core system with 16GB of RAM.

It makes no sense. I have rendered much longer, much more complicated videos, with multiple clips before now with no issue.

What is going on? Why have things suddenly turned to custard? Is this a bug?

There is a similar issue with timeline rendering in the refactoring version. Investigations are ongoing. Maybe version 18.08 is affected as well but in the render part.

Please try with the current Kdenlive AppImage version 18.12.0c
Run the Appimage from the terminal (press CTRL + ALT + T). Move to the AppImage folder and run the .AppImage: ./Kdenlive*.AppImage

If you run into problems:
deleting this: $home/.local/share/kxmlgui5/kdenlive (contains the toolbar configuration)
and this: $home/.config/kdenlive-appimagerc

Thanks for the reply. I'll give that a try if I can be sure I can reproduce the issue in 18.08.2.

I'm wondering now if it's only related to that specific project; I rendered a completely different video yesterday without problems. RAM usage was about 3.4GB the whole way through, and the rendering completed successfully.

It's also reminded me of something else which happened a few weeks ago - a video which took over twice as long as expected to render, as the render process seemed to sit around doing nothing for an hour or so. CPU usage dropped to an apparent idle state during that time and it was as if the process had failed, although it completed successfully, too, eventually. I'd just assumed that was because of the effects I'd used in that project, but perhaps it's a symptom of the same issue.

It looks like I found the problem.

I have two machines with Kdenlive installed. Both are running fairly fresh copies of Xubuntu 18.04, which I had upgraded to recently, and both (or so I thought) had the same 18.08.2 version of Kdenlive installed from the official kdenlive-stable PPA.

This, as it turns out, was not true. My editing machine (on which I had the PPA version installed) could render the project just fine. On my other machine, I had the standard Ubuntu repo version installed. Both version 18.08.2 - but clearly not the same! Thinking that must be the problem, I upgraded my render machine to the PPA version - only to find that I still had the exact same problem.

I then wondered if somehow the project or clips were corrupted. I recopied them from my editing machine. This made no difference, either.

I was about to try the latest Appimage version, but then noticed something odd in the render process command-line arguments.
I saw that the profile included the string "atsc_1080p_25" which made no sense, as I work with 1080p 30fps or 1080p 29.97fps video.


A moment of realisation dawned when I checked the Kdenlive settings on my render machine.

Since I had never done any actual editing on the render machine, I had never changed the Kdenlive settings - and the "Project Settings" were defaulted to 1080p 25fps. This wouldn't normally be an issue, as the projects created on my editing machine would have the profile set to 1080p 30fps, and that would override it.

BUT - with this specific project, the profile was set to something other than "1080p 30fps". It was using something called "1920x1080 30.00fps", which I now remembered, is what Kdenlive had suggested I choose when I imported the clip, and which I had, unusually, answered yes to, without thinking about.

This "1920x1080 30.00fps" does not seem to be a standard profile, and did not exist on my render machine, so Kdenlive just silently defaulted the render job to the unchanged factory-set "1080p 25fps" profile. This issue is reproducible.

By either changing my render machine's Kdenlive default profile to "1080p 30fps", OR changing the project's profile to "1080p 30fps", I can render the project normally.


I think this constitutes two bugs, in essence;
1) That Kdenlive should notify when opening a project with a profile that does not match any already-existing profile, and
2) That rendering a project at a different framerate than its source material should not lead to excessive RAM usage.

Both bugs/issues are also reproducible in the latest Kdenlive AppImage, version 18.12.0c.

Many thanks for the analysis.
This must be a problem in MLT we should report to them...
Would you do it or do you prefer I forward to them?

Well, of course I would prefer someone else to do it...

But in seriousness, I assume someone like yourself already has an account, knows the procedure for bug reporting, etc, so perhaps it makes more sense if you forward it on anyway?