Bug 435653

Summary:	Huge performance penalty when using "Cut edge"
Product:	[Applications] kdenlive	Reporter:	postix <postix>
Component:	Video Effects & Transitions	Assignee:	Vincent PINON <vpinon>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	berndmj, postix
Priority:	NOR	Keywords:	triaged
Version First Reported In:	20.12.3
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description postix 2021-04-12 12:43:48 UTC

SUMMARY

I'd like to cut away 100px of a 4k@30 video using the "cut edge" effect.
With it KDEnlive uses around 14% of CPU resulting in roughly 27 fps.

If I activate the checkbox "Automatic central cut", which however reverts my aim to cut the lower 100px, I see around 40% of CPU usage resulting in roughly 114 fps.

Command for rendering:

f=mp4 movflags=+faststart vcodec=libx264 progressive=1 g=15 bf=2 crf=%quality acodec=aac ab=%audiobitrate+'k'

The encoding slider is set to the far right (maximum) and #threads to 24, using the parallel processing feature.

Is there a some bottleneck in the effect's code respectively could it be speed up?


SOFTWARE/OS VERSIONS
Operating System: Manjaro Linux
KDE Plasma Version: 5.21.3
KDE Frameworks Version: 5.80.0
Qt Version: 5.15.2
Kernel Version: 5.12.0-1-MANJARO
OS Type: 64-bit
Graphics Platform: X11
Processors: 24 × AMD Ryzen 9 5900X 12-Core Processor
Memory: 31.3 GiB of RAM
Graphics Processor: Radeon RX 580 Series

Comment 1 Bernd 2024-12-23 19:50:48 UTC

Hi and thank you for your patience.

Can you please check whether this issue still exists in the latest version 24.12.0?

If yes, please update this report to reflect the new version.

If it works now like you expect it would, you may change the status of this report to RESOLVED - FIXED.

At any rate, this report will be closed if there is no activity for the next 30 days.

Comment 2 postix 2024-12-23 20:10:13 UTC

> Hi and thank you for your patience.
I've totally forgotten about it. :-) 

I've tested playback of a mp4, h264, FullHD, 60 fps:
* Without Cut Away: 120% CPU 
* With Cut Away: 160% CPU utilization in htop
averaged roughly over 10 seconds, whereby Cut Away was set to 0 pixels on each edge, meaning essentially do nothing.

Rendering seems to be equally slow or fast for both cases. I'd say, works for me! Happy holidays!