Hi everyone!

First, I would like to sincerely thank everyone envolved and contributing to this program. I am a hobbyist/semi-professional video director and editor trying to go free software and Kdenlive is by far the most promising program that I've used so far (excluding the huge commercial options, anyway).

I have used Kdenlive on Ubuntu Studio now for a couple of months and edited/color-graded some short films and made some simple 2D-animations with great success, however I've also had some issues with stability along the way. Mainly three problems:

1. The program would just crash and not do anything at all (basically hang on importing any video file or when trying to playback a sequence/project).
2. The video and sound would be displayed out-of-sync and also exported that way, although the waveforms would visually match in the sequence.
3. The frames/cuts in the timeline would match my placements, but sometimes when playing back or exporting the sequence, other parts of the cut video would be shown, not where the cuts were intended to be. Then I'd have to redo the cutting and it might even change again (making frame-perfect cuts very difficult).

My problem is that while trying to solve these issues, I have now installed the newest version (17.xx) from the official PPA, switched back to the standard version of my distro (15.xx), enabled and disabled hardware acceleration and other settings so often that I don't know anymore what configuration works best and what doesn't. Sometimes, I am unable to edit a video file, because it won't load or play back correctly, then suddenly it will work and I can do everything with it and I can't tell if some setting was the issue or just divine intervention.

I would like to find out what the best workflow in Kdenlive is to be able to work as stable and predictable as possible.
What version should I use and what settings should I enable to make the program run most stable?
Can the hardware acceleration cause issues? Should I disable it?
Does Kdenlive favor certain file codecs/formats? Should I make sure to convert all of my files before importing them?
Are there known problems with certain frame rates, sample rates, file sizes, etc.?

If you have any info from your own experience or from what is officially known, it would definitely help me to get back on track.

Here's my system, in case it helps:
Ubuntu Studio 16.04 64-bit
AMD FX-8350
16 GB RAM
Nvidia Quadro K5000

Kind regards!

I have kubuntu 17 version, and i use the AppImage package ( not the ppa repo). KDENLIVE 17.12 or KDENLIVE 17.08.
I have no crash problem.

Hi jpasturel,

okay, I've definitely had some different experiences so far. Would you mind sharing your hardware and some settings for comparison? (MLT/OpenGL on, using Proxy-videos?)

aimanm wrote:1. The program would just crash and not do anything at all (basically hang on importing any video file or when trying to playback a sequence/project).

OpenGL and libmovit are switched on.

Synchronization problems and many more can be caused by compressed formats. Actually this is self-explanatory, keyword I-Frames. A video editor offers different options for transcoding. So, the material for video editing (video and audio) has to be basically uncompressed or a corresponding codec developed for video editing. If you don't want that, you can be lucky, but you shouldn't complain if it doesn't work. And that has nothing to do with the operating system, this is one of the basics of video editing.

Hi Stetsbequem,

Stetsbequem wrote:OpenGL and libmovit are switched on.

I've already suspected that while turning it on and off again, is this something driver-related or generally still unstable?

Stetsbequem wrote:Synchronization problems and many more can be caused by compressed formats. Actually this is self-explanatory, keyword I-Frames.

I actually did not know about that, thank you for bringing it up. I did a little bit of reading and I think I understand the problem. What I'm unsure about is if it would be a good idea to convert all media to something like DNxHD or a similar format with ffmpeg before importing it. I figured, since it's used for proxy videos, the support for it should be best. In an ideal world, I would only use those formats, but I get a lot of videos from different sources/people that are commonly in compressed formats, H264, Apple's formats, etc. and need to make it work somehow.

I don't want to be instructive, but a program or function that doesn't work as expected is called unstable (formulated politely).

I think we can agree that Kdenlive and his MLT engine are a bit far from an ideal world. As I said, it can work without transcoding. However, it is then necessary to develop a feeling for which sources can cause problems. And these problematic cases are best solved in advance, rather than after the integration into the project with all its tracks, cuts and filters. Look around, here are videos in circulation with missing frames. Even if the surface shows everything correctly, the video has to be rendered afterwards. You asked for a stable workflow. This also includes making the different formats suitable for your programs. Have a look at how the professionals work (in Germany e. g. SlashCAM). Kdenlive already offers a wide range of options for transcoding to DNxHD (slightly lossy, an alternative is FFmpeg's FFV1, which is lossless and also suitable as archive format). I would go one step further and choose Flac or Wave as the audio codec. The same applies to the container, which must also be suitable for cutting.

Something else about working with proxies, if it is actually unavoidable. Make sure that the quality and dimensions are not too small. Otherwise, things can happen on the cutting and editing stages that would not happen with normal resolution. And that's not because of technology, it's a human problem.