https://bugs.kde.org/show_bug.cgi?id=510531
Bug ID: 510531
Summary: avfilter.fieldorder auto-loaded in Kdenlive/MLT with
interlaced files, causes errors and rendering issues
Classification: Applications
Product: kdenlive
Version First 25.08.2
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Rendering & Export
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
When opening or working with interlaced video files in Kdenlive, the
avfilter.fieldorder filter is automatically added to the timeline, even if it
was never manually applied in the project.
STEPS TO REPRODUCE
Always – with:
• Interlaced video sources
• New or existing Kdenlive projects
• MLT 7.32.0 + FFmpeg 8.0
OBSERVED RESULT
1. Error message in the Effect Stack / Console:
[filter avfilter.fieldorder] Unexpected return format
2. The Project Monitor stays blank (white) until the project is switched to
a progressive profile
3. Rendering (e.g. with hevc_vaapi) fails with hardware filter errors,
like:
A hardware device reference is required to upload frames to.
Failed to setup hwfilter: -22
This behavior also affects older project files, which previously worked fine
(e.g. in Kdenlive 23.x or older MLT versions).
EXPECTED RESULT
• The avfilter.fieldorder filter should not be applied automatically unless
the user adds it manually
• Alternatively, there should be a way to disable or blacklist this filter
(per project or globally)
• There is no documentation about this automatic behavior or any filter
blacklisting functionality
SOFTWARE/OS VERSIONS
• Kdenlive: 25.08.2
• MLT: 7.32.0
• FFmpeg: 8.0
• GPU: Mesa Intel® UHD Graphics 630
• VAAPI: enabled
• Operating System: Arch Linux
• KDE Plasma Version: 6.4.5
• KDE Frameworks Version: 6.18.0
• Qt Version: 6.10.0
• Kernel Version: 6.17.1-arch1-1 (64-bit)
• Graphics Platform: X11
ADDITIONAL INFORMATION
What was tested:
• Switching project profile to "progressive" → temporarily hides the issue,
but is not a solution
• Tried to blacklist the filter using:
◦ /etc/mlt-7/avformat/blacklist.txt
◦ ~/.local/share/mlt-7/avformat/blacklist.txt
• These files are not evaluated at all
• Manually adding fieldorder to /usr/lib/mlt/avfilter//blacklist.txt does
work
Suggestions:
1. Prevent automatic insertion of avfilter.fieldorder, unless explicitly
added
2. Provide a user-controllable blacklist mechanism for AVFilters (e.g.
config file)
3. Improve fallback behavior: don't show a blank Project Monitor if filter
fails
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