Bug 513192

Summary: HSV Key effect not working.
Product: [Applications] kdenlive Reporter: Gabriel Gazzán <gabcorreo>
Component: Video Effects & TransitionsAssignee: Jean-Baptiste Mardelle <jb>
Status: CONFIRMED ---    
Severity: normal    
Priority: NOR    
Version First Reported In: unspecified   
Target Milestone: ---   
Platform: Other   
OS: Other   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: HSV Key effect malfunctioning

Description Gabriel Gazzán 2025-12-10 20:30:05 UTC
Created attachment 187501 [details]
HSV Key effect malfunctioning

This effect doesn't seem to be working properly.

Still, when the "Compare effect" option is active for the clip, it "kinda wanna work" 😅 (i.e. it shows the keyed area in black, while still failing to show the clip below in the keyed area), as showed in the attached screenshot.
Comment 1 Gabriel Gazzán 2025-12-10 20:30:57 UTC
(in the rendered video, the effect does nothing)
Comment 2 Gabriel Gazzán 2025-12-10 20:33:28 UTC
tried both in trunk and 25.12.0 RC
Comment 3 Jean-Baptiste Mardelle 2025-12-11 08:19:46 UTC
Thanks for your report, I can confirm the issue. Not exactly sure where is the problem though. I am not sure avfilters can add an alpha channel in MLT. Bernd, were you able to make it work at some point ?
Comment 4 Gabriel Gazzán 2025-12-11 17:54:05 UTC
I've just made some tests with past versions of Kdenlive...

I've found the effect worked fine from its introduction in 22.04.1, up until 24.05.2 (both in preview and final render).
Starting from 24.08.0 on, it didn't work.

The "Compare effect" black background in keyed areas was there all the time, though.