Openshot-qt: Video preview is too slow - but it worked before!

[exaveal]

I installed "openshot-qt" for the first time. before I was running only "openshot" on my Ubuntu machine.
When I open my "old" projects which I have created with "openshot", it's impossible to go on working because the preview is so slow. Much too slow.
It's so laggy, that even video and sound are not synchronous.

I started openshot on the terminal to check if any error messages according the speed issues come up - but nothing. please help!

[edvaessen]

Same to me. It is a complete riddle.
For the time being I'll have to fall back to Cinelerra-CV.

[exaveal]

It's a RAM problem. The computer is out of memory within seconds. 8GB are fully used after several seconds of preview or moving the position marker. see attached screenshot.

[exaveal]

Same project file in preview mode with openshot 1.4.3. No memory-leak-problem!

[exaveal]

I reported the bug in launchpad and tried to describe it as best as possible (for me 😄 ): https://bugs.launchpad.net/openshot/+bug/1653241
Please support a fix of the problems via "This bug affects you" and/or add more details.

[DylanC]

Dup of #411

[DylanC]

Try OpenShot v2.4. The preview is much better and no lag detected in my testing.

[fabrixx]

Same problem for me in v2.4 also with low res profiles (16Gb ram core i7 preview work only 3 seconds, after is slow and lagging)

[N3WWN]

Check out the discussion, and particularly what works for me, here: https://github.com/OpenShot/openshot-qt/issues/960#issuecomment-337678019

In short, reducing the quality and resolution of the preview cache may help...

[fabrixx]

I setted resolution 640px and at minimal settings, but ram go at 90% of use after 4-5 sec
With only mp4 work well, i notice that have this problem with .mts clips.
I switched to kdenlive for now waiting for a solution.

[N3WWN]

@fabrixx Instead of changing the resolution of the project, the discussion in 960 is about changing the preview cache settings.

I am using .mts clips, also, but I convert them to .mp4 with ffmpeg at the command line before importing into OpenShot (I do that to gain video stabilization and force integer frame rates, but you can just convert them).

[fabrixx]

There must be something weird. After completing my project with kdenlive I read your cache response, I wanted to test. I've taken 15 .mts clips and some .mp4 clips but the problem does not reappear. I suspect that the problem is when I load in the project a large number of clips as I did. At the moment i can not verify in that situation as i should download more than 200 clips on the desktop and import them but suspect that the bug has a very high number of imported clips..

[fabrixx]

ok, after some test setting quality to 40 is only way for me for 60 fps (extreme pixellated)

[rcwtech]

I have the solution for this issue.

The memory leaks are caused by the preview needing RAM to cache, yet not having the ability to due to default settings.

Go to edit -> preferences -> Cache -> Cache Limit (MB) **Default Set to 250MB - THIS IS THE CAUSE OF LEAKS

I set this to 1000, which works perfectly. You could go higher if need be.