https://bugs.kde.org/show_bug.cgi?id=498263
Bug ID: 498263
Summary: Exporting with pix_fmt=yuv444p does not use 4:4:4
chroma subsampling
Classification: Applications
Product: kdenlive
Version: 24.12.0
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Rendering & Export
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 177114
--> https://bugs.kde.org/attachment.cgi?id=177114&action=edit
Source image, Kdenlive project file, Kdenlive render script, Kdenlive video,
FFmpeg video
SUMMARY
I have H.264 videos encoded in the yuv444p pixel format, and I would like to
edit them in Kdenlive and export them in yuv444p. I've tried creating a custom
render preset with the "pix_fmt=yuv444p" flag added, exporting with crf=0 which
is supposed to be lossless, and enabling "Render full color range", but the
exported video still shows subsampling artifacts, despite being in the yuv444p
format according to VLC and FFmpeg.
STEPS TO REPRODUCE
1. Add a PNG image or yuv444p video to the timeline
2. Use a custom render preset that has "pix_fmt=yuv444p"
3. Take a screenshot of the rendered video with VLC or FFmpeg
OBSERVED RESULT
Video is encoded in yuv444p format, but still shows chroma subsampling
artifacts
EXPECTED RESULT
Video is encoded in yuv444p format and has no chroma subsampling artifacts (and
is identical to the original if exported with crf=0)
SOFTWARE/OS VERSIONS
Arch Linux
Kernel Version: 6.12.7-arch1-1 (64-bit)
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.9.0
Qt Version: 6.8.1
ADDITIONAL INFORMATION
I've attached the project files used to demonstrate this issue, along with an
FFmpeg-rendered video that shows the correct behavior (has no chroma
subsampling artifacts).
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