Bug 509841

Summary: Audio Spectrum Filter does not appear in rendered video for low values of Window Size
Product: [Applications] kdenlive Reporter: Niko Fox <niko>
Component: Audio Effects & TransitionsAssignee: Jean-Baptiste Mardelle <jb>
Status: REPORTED ---    
Severity: normal    
Priority: NOR    
Version First Reported In: 25.08.0   
Target Milestone: ---   
Platform: Other   
OS: Other   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Niko Fox 2025-09-23 18:28:04 UTC 
SUMMARY
When the Audio Spectrum Filter is applied to the On Master effects list with a low Window Size, the spectrum visualization appears in the timeline preview, but does not appear in the video when the project is rendered. I don't know where the exact threshold lies, but I found that 256 was low enough to trigger the bug and 512 was high enough not to.

STEPS TO REPRODUCE
1. Add an audio track to the timeline
2. Add an instance of Audio Spectrum Filter to the On Master effects list
3. Change the Window Size parameter to a low value (ex: 256)
4. Render the project

OBSERVED RESULT
The spectrum visualization is not present in the rendered video.

EXPECTED RESULT
The spectrum visualization is present in the rendered video.

SOFTWARE/OS VERSIONS
Windows: 10 Pro 22H2 19045.6332
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: 
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION
https://www.reddit.com/r/kdenlive/comments/1niq80b/help_audio_spectrum_filter_disappears_in_rendered/