[EXPORT] Export takes too long and doesn't end

[gnolooo]

Commit Hash
10ce5fb

Platform
Windows 11; may aswell happen in Linux, but currently I can't even install it properly (see #2319 and #2320)

Summary
When exporting a few minutes clip (this one is 8 minutes long, with cut scenes from a movie), the export barely does anything (1% every ~3 minutes), while the the ETA goes up (in my case it arrived at 6 hours). At a certain point, the ETA stops increasing and begins decreasing, while the export barely speeds up (barely because after 10 minutes it's still at 6%). I don't think such video should take more than 2-3 minutes; in fact, in the past I've done the exact same thing (cutting movie scenes) on previous versions, and it worked flawlessly.

[gnolooo]

EDIT: no exporting actually worked. I tried multiple times but despite waiting for the long time, at a certain, random point, Olive crashes and I lose my export progress. So not only export takes too long, but at the end it doesn't even work.

[gnolooo]

Reporting the latest posts related to this issue, just to have a background and to continue discussing about it here:

I don't really see how, for instance, a different Windows runner could suddenly cause Olive's exports to fail, however. If it worked in an older version then that must have been in a significantly older version from before a related code change. Or the settings are simply different, like a higher resolution than before that cause out-of-memory crashes perhaps? Or the footage is different and somehow problematic...

About this, how could I troubleshoot it? My only 2 takes were: testing the same version on a different platform (e.g. Linux, but there I've the aforementioned problem with building and using Wayland), or using an older version on the same platform (not possible because I couldn't retrieve old download links).
The thing is, it's possible that the footage is problematic, but how would I know it, and what could be causing the problem? I exported a dozen clips from a ~100 min movie (Cars) without any problem for weeks; then I updated Olive and tried to export a single clip from its sequel (Cars 3, so similar duration, resolution etc) and I had the aforementioned export problems.

It's difficult to find the cause. You can try ffprobe and ffplay, preferably the version used in the AppImages (5.0), and check if any issues are reported for the media file. However, I remember Olive having trouble with a particular video file from a smartphone once whereas ffmpeg and video players had no issues at all to process/play it. Re-encoding the file with ffmpeg fixed it for me.

Does it already fail with a single short clip of the potentially problematic footage? If yes, then I think it's a general problem with that file. If it only starts causing issues in Olive if you have many clips, maybe watch the memory consumption and see if it eventually fails because it runs out of memory. There might be some mishandling of the file/ffmpeg, or a memory leak, or there might be an issue with the file that only manifests when seeking a lot (because of many clips) - sometimes there can be trouble determining the duration and might throw things off, and it's possible that handling these cases isn't implemented correctly in Olive's code (which I would say is likely if ffmpeg on its own has no trouble playing/transcoding the same file).

I've done a bit of testing and I've exluded the footage as possible cause. I tried to cut other clips from another movie, and few other videos, and the export didn't work in either case. At this point, I think the problem is either in this particular version, or in Windows itself. If the same version worked on Linux, I would test it there; but since I can't manage to build and/or launch it, I just can't.

[gnolooo]

After managing to build successfully olive in Linux and testing it, I can conclude this issue is only related to Windows. The same clip, among with many others, exports successfully in Linux taking around ~1 minute. So the problem is not the version itself, but the platform it runs on.