Bug 452429

Summary: Reversing clips lag and stutter
Product: [Applications] kdenlive Reporter: alkaris <shadwolf16>
Component: Monitors & PlaybackAssignee: Jean-Baptiste Mardelle <jb>
Status: CONFIRMED ---    
Severity: normal CC: fritzibaby
Priority: NOR Keywords: triaged
Version First Reported In: 21.12.3   
Target Milestone: ---   
Platform: Manjaro   
OS: Linux   
Latest Commit: Version Fixed In:
Sentry Crash Report:

Description alkaris 2022-04-09 12:35:54 UTC 
SUMMARY

When using Kdenlive I wanted to create a clip that's played in reverse, but when it's been created, Kdenlive likes to lag out and stutter on playback of that reversed clip, this should not even be a problem, why is this even a thing? it should reference the original clip in the project bin and playback at it's normal speed, and at least hand it off to the GPU to play back, or automatically create a proxy clip profile of the video clip that it's based on.


STEPS TO REPRODUCE
1. Select a clip and reverse clip.
2. 
3. 

OBSERVED RESULT

Reversed Clip will lag and stutter on playback making it impossible to work with.

EXPECTED RESULT

It should just play back as normal as if it weren't reversed.

SOFTWARE/OS VERSIONS

Linux: Manjaro Linux
Qt Version: 5.15.3
Comment 1 emohr 2022-04-10 09:33:56 UTC 
I reversed a clip in the timeline with change speed -> reverse clip. And yes the playback is slow and stutters. 

You can make preview more smooth using the preview settings: https://docs.kdenlive.org/de/glossary/useful_information/timeline-preview-rendering.html?highlight=preview
Comment 2 alkaris 2022-04-12 18:16:43 UTC 
(In reply to emohr from comment #1)
> I reversed a clip in the timeline with change speed -> reverse clip. And yes
> the playback is slow and stutters. 
> 
> You can make preview more smooth using the preview settings:
> https://docs.kdenlive.org/de/glossary/useful_information/timeline-preview-
> rendering.html?highlight=preview

While this is a useful feature, there's still significant lag and stuttering even when you've rendered a preview zone. I feel this is something that should be passed to GPU for playback rendering, instead of tasking the CPU to play it back.