Bad cursor synchronization in timeline

After changing to a more recent PC (see characteristics in attached file + NVidia GE 6200) with lubuntu 22.04, I reinstalled version 24.01.28 from the snap on the shotcut site.

Overall no operating problems.
Except that I have poor synchronization of the timeline cursor with my keyboard.
At first, this cursor did not move linearly. I changed Setting>Display Mode>OpenGl to Software (Mesa) and it gave me a more linear cursor scroll.
However, the fact remains that this cursor is not synchronous with my keyboard command (space bar) and this is very annoying for the precision of the editing, mainly for the identification of the waves of the audio files…
This is not necessarily a bug, but rather a configuration fault that I cannot determine in shotcut (or a hardware problem or even the Bios ??).
I tested the shotcut parameters a lot, without being able to find a solution… Some tips from experts would be useful to me.
I am ready to answer any questions you have about my hardware configuration if necessary…
PC CSL 2024.pdf (12.0 KB)
journal 17-2-2024.txt (40.4 KB)

Your PDF says “AMD Radeon” but here you say NVIDIA GE 6200 from 2004.

Are you talking about the time for playback to start or stop when you press the space bar? How long do you guess that is? That is called latency or lag. It is normal for it to be up to a second, and it may be longer if Settings > Player > Realtime is turned off. It also depends on if your video file is edit-friendly (uses heavy compression), high resolution (>1080p), or on slow storage (WiFi, USB, etc). People use Proxy and Preview Scaling (see FAQ, Documentation, and Tutorials page) to reduce latency/lag.

Some things from your log

[Debug ] Mlt::Controller::setPreviewScale 1280 x 720

I see you are using preview scaling. If you do not make and use proxies at the same resolution, this can slow things as explained in Preview Scaling

[Debug ] MainWindow::setAudioChannels 1

Did you really mean to change your project to mono (using menu Settings > Audio Channels)?

“AMD Radeon” is the motherboard chip. My graphics card that I added is NVIDIA GE 6200

Thank you for this initial feedback which I understand quite well. Your proposals (Proxy, Realtime…) have been tried in a methodical manner without providing any improvement in latency when I stop reading (and not when starting playback).

My video editing is simple, and the audio quality in mono (24 kHz) is sufficient (and increases my bandwidth).

On the other hand, after further tests, I noticed that the latency problem disappears when I reduce the main window, while keeping the “maxi” size of the timeline on my second screen. I work with a dual screen (see attached screenshot).
This observation is recurring and confirmed by a series of tests on different .mlt. The more I enlarge the screen size 1, the more the latency increases.
But you understand that working on screen 1 then becomes difficult!!!

What do you think ?
journal 17-2-2024.txt (40.4 KB)

I think that is the problem; that GPU was launched in 2004. It is going to be slow by today’s standards. Shotcut uses OpenGL, which is a GPU technology, for screen drawing and video display. I do not understand why you would put that in a modern Ryzen 5 system. Making the Shotcut main window smaller makes the video preview smaller, which reduces the work for either the CPU on software OpenGL or for a very old GPU.

Simply to save money and to avoid waste…
Otherwise, I agree with your analysis which shifts the problem to the graphics card, even if it was effective with shotcut on my old motherboard dating back more than 10 years!

​Is it possible to detach the reduced preview, like you do with the timeline or playlist? I can’t find the trick! Which would allow me to have the whole thing in full screen and only the preview in reduced mode, at my correct size.

No, but you can detach everything else. I recommend to try the Radeon GPU on your motherboard.

I can’t detach filters or keyframes???
I am in the process of asking ASUS France, to find the right Radeon GPU settings, because I am having some difficulty getting the 2 screens to work directly on the motherboard…

I can, but it depends on the OpenGL compatibility on your system. With software OpenGL it will work. If you still have a problem then I guess you have not figured it out. It is not that difficult and very similar to the behavior of many similar multi-panel UIs.

It’s strange. I can manipulate the timeline and the playlist without any problem, but not the filters or the keyframes???