Hello,

This is my first post here. I've been using both Kdenlive for nearly 6 years now. I ran into a bit of a mystery with the release of Focal Fossa. Every LTS release, I do a full re-install from scratch. It usually takes me a week to get everything back up to snuff.

Previously, I was running Kubuntu 19.10 and Kdenlive 19. For a 1920x1080 "movie" with transparent overlays, and a little icon animation, over GoPro 4 video. Original frame-rate is 47.952fps, but I ... just realized I should probably change that, huh. Anyway, what I was going to say was ... but I render it to 23.976. I keep it at full resolution (both audio and video) - and it normally took about 2.5 hours of render time per 1 hour of rendered video (is that slow? it feels sorta slow).

But now - after the upgrade to Fossa and Kdenlive 20; good hell, it takes like 10 hours for 1.3 hours of video.

After re-installing Kdenlive, I set all of my settings and parameters to what they were - but something is obviously taking a major toll on my render time.

Before you answer; just so you have a decent idea of where I stand as a user:
On an expertise scale from 1-10, I honestly sit at around 3-ish. 3.5 maybe. I'm not an expert by any means; but I am proficient, and I know how to use it for my needs. I'm also a software engineer, so you can go nuts on the lingo without feeling like you have to explain everything (that's more meant to be a relief for you).

This is my podcast intro, maybe you can better gauge where I am with kdenlive: https://www.youtube.com/watch?v=N4rWhiH18so

By no means do I have all of the MLT flags and switches memorized, but I am familiar with like ... 10 of them, maybe. I know just enough to get by. I have a vague idea for how video encoding works; but I've never worked with them on any sort of level other than referencing them and vaguely understanding the major differences between them.

With all of this in mind - what do I need to look at here? Something has changed just enough to make a barely workable render into a scenario that is utterly impossible to deal with. Honestly - how many things could this be?

I really hope you say, "oh, 4 or 5 things could do this" and not, "any number of things could be causing this"

I believe Kdenlive normally coming with Focal is 19.12, if you have 20 do you use AppImage, Snap or PPA?
There has been a recent change in MLT, it doesn't handle image sequences (PNG etc) with the same default engine as before (QImage instead of AVFormat).
It seems the rendering changes (semi-transparents areas lost?) and speed is much poorer.
JB released a 20.04.0b which I believe includes a turnaround of this problem inside Kdenlive (don't use the default engine but specify AVFormat), maybe you should try this? (through AppImage; I'm updating the stable PPA right aways!)

Ah, alright - interesting.

I had first installed the snap version - but, AppArmor is apparently on a whole new level. I couldn't even render, it has been so utterly restricted and jailed-in.

So, I got rid of that; and thought I'd just use the deb package directly from Kdenlive's site.

It worked a whole lot better than the snap version (even the default icons were much crisper and cleaner looking). But, first off - it's apparent support for Nvidia hardware acceleration, I think is just a popup window with no functionality behind it. And second, the render time was horrendous.

I'll try out your suggestion, read the release notes a bit more carefully, and let you know how it worked out.

Thanks