Hi,

Let me first explain my workflow:
I use 4k 25fps h264 source material. Which I render to 1080p 25fps.
In kdenlive I use a 4k timeline, since otherwise I get weird problems, among which the crop and zoom effects suddenly doubling or halving their percentages. (By the way: I don't really understand what the timeline resolution settings are for / affect?)
I use proxies (the default MJPEG profile).

When I play/scrub clips as they are, it works fine. But as soon as I put a title on top (transparent png made in gimp), apply an opacity composite or a zoom/rotate/crop effect, playing reduces to the effect of a frame per second or so.
I use a lot of crop/zoom/panning (which is the reason I film in 4k to render to 1080p), so that gets a little bothersome rather quickly.
I've tried using previews, but these render so slowly that they're useless for anything except checking a final cut before moving on. And then I can just as well set an in and out on the timeline and render to a file.

I'm currently working on a 2011 lenovo t420s laptop with a i5-2520M cpu (2 cores@2.5-3.2Ghz), 16GB ram and intel hd3000 gpu.
If necessary (and it will make my workflow better), I'm willing to buy a new laptop.
One big must is that the laptop stays portable as it'll be going on a 10 month trip with me, where we'll be moving every few days. For me that means max 365mm wide, and at most 2.2kg.

If I do need to get a new laptop, I don't know what hardware I should be focusing on.
If I were to use blackmagic resolve I'd know to get one of the new nvidia rtx 2070 max-q laptops, and I should be set, but I gather the gpu won't make all that much difference to kdenlive? Does it make any difference at all if I were to get a laptop with an intel HD620 vs nvidia gtx 1050ti max-q vs nvidia rtx 2070 max-q?
I've also read that the most important part is the cpu speed, and that more cores above four won't make much difference. What performance gain could I expect going from my i5-2520M 2 core max 3.2Ghz cpu to a i7-8550U 4 core max 4.0Ghz cpu? And what about a i7-8750H 6 core max 4.1Ghz cpu?

Some laptops I'm considering:
lenovo t480s with i7-8550u, 24gb ram, intel hd620
lenovo x1 extreme with i7-8750h, 32gb ram, nvidia gtx 1050i
lenovo legion y740 15 / msi gs65 stealth 8sf / gigabyte aero 15 x9 / razer blade 15 advanced / ... (one of the new light weight rtx 2070 max-q based gaming laptops)

Will a new laptop make a big performance difference? (Preferably to the point where everything starts playing/scrubbing smoothly?) Which laptop would suffice, or is best? And do I even need a new laptop (can I make it work smoothly on my current laptop by doing something differently?)

Thanks,
Bernard

GPU acceleration doesn’t work in Kdenlive so far. Switch it off. At the moment all is rendered by CPU.

We found some performance issue in MLT related to multithreading.

Don’t split video/audio. It seems that slows down timeline performance (https://bugs.kde.org/show_bug.cgi?id=385842) .

Please try with the current Kdenlive AppImage version 18.12.1b https://files.kde.org/kdenlive/release/ .

If you like you can have a look at the refactoing version which has a more optimized timeline performance. Kdenlive_Nightly_Appimage:
https://binary-factory.kde.org/job/Kden ... /artifact/ .
A developer is working on GPU acceleration for the refactoring version.

i5-2520m vs i7-8550U see here: https://cpu.userbenchmark.com/Compare/I ... 20742vsm29 .
16GB ram would be fine.

I wasn't using GPU acceleration, but was doing split video/audio in a few places. But I've just made a new project and put a few clips on without splitting audio, and it didn't seem any different, as soon as I do anything but simple cutting, it starts bogging down.

Both AppImages give me skippable "Could not create the video preview window. There is something wrong with your Kdenlive install or your driver settings, please fix it." errors on startup. In the console output I see "[consumer sdl2_audio] Failed to initialize SDL: Could not setup connection to PulseAudio" which makes sense, since I don't use PulseAudio.
When I try to change the playback to Alsa on the 18.12.1b AppImage it segfaults. On the 19.03.70-16a6318 AppImage the dropdown is grayed out. (I didn't need to do this on my installed version by the way, there it's working fine on "Automatic".)
When I try to load my project on the 18 image it seems to hang. On the 19 Image, after very slowly loading all clips (quite a bit slower than on the installed version), it segfaults.

I've also upgraded the kdenlive on my Arch Linux (it was at 18.12.0-1 and is now at 18.12.1-1), but that didn't seem any different from before.

I guess I'll hold out a bit until the 19 version arrives on Arch, and then re-evaluate.

If it's still too slow, in your opinion, would there be much difference running kdenlive on a i7-8550U versus a i7-8750H? Considering they're both about equally fast, but one is a U version with 4 cores, and the other an H version with 6 cores?

Thanks,
Bernard

PulseAudio is needed for Kdenlive. Run the Appimage from the terminal (press CTRL + ALT + T). Move to the AppImage folder and run the .AppImage: ./Kdenlive*.AppImage. If Pulse Audio still missing: https://docs.ubuntu.com/core/en/stacks/ ... pulseaudio.
You should be able to run the Kdenlive AppImage then everything is proper installed.

Your current notebook should play FullHD video on Kdenlive without problem. i7-8750H seems 30% faster than i7-8550U. But I'm not sure if Kdenlive can use all cores.