https://bugs.kde.org/show_bug.cgi?id=517497
Bug ID: 517497
Summary: Significant render quality regression between versions
23.08.1 and 25.12.3
Classification: Applications
Product: kdenlive
Version First 25.12.3
Reported In:
Platform: Microsoft Windows
OS: Microsoft Windows
Status: REPORTED
Severity: normal
Priority: NOR
Component: Rendering & Export
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 190625
--> https://bugs.kde.org/attachment.cgi?id=190625&action=edit
Project files, screen shot, rendered videos
A noticeable regression in render quality has been observed when comparing
Kdenlive versions 23.08.1 and 25.12.3. Rendering the exact same project file
with identical render settings produces a final video with visibly lower
quality in the newer version (25.12.3) compared to the older one (23.08.1).
Steps to Reproduce:
Open a specific Kdenlive project file in version 23.08.1.
Render the project using a specific preset or custom parameters (e.g., ab=192k
acodec=aac ar=48000 channels=2 f=mp4 pix_fmt=yuv444p real_time=-1 threads=0
vb=8M vcodec=h264_nvenc).
Open the same project file in version 25.12.3.
Render the project using the exact same render settings as in step 2.
Compare the two output video files.
Expected Result:
The rendered video from version 25.12.0-beta should have comparable or better
visual quality than the one from version 23.08.1, especially when using
identical high-quality settings like pix_fmt=yuv444p.
Actual Result:
The rendered video from version 25.12.3 exhibits significantly lower visual
quality. As shown in the screenshots provided in the forum post, details appear
softer or more compressed compared to the output from version 23.08.1.
Environment:
OS: Windows 11 (64-bit)
CPU: Intel i5-7300HQ @ 2.5 GHz
RAM: 8 GB
GPU: NVIDIA GeForce GTX 1050 Ti (and Intel HD Graphics 630)
Affected Kdenlive Version: 25.12.3
Working Kdenlive Version: 23.08.1
Additional Information:
The issue occurs with hardware encoding (h264_nvenc), but it should be tested
with software encoding (libx264) as well to isolate the cause.
The specific project file was attached to the forum post and should be used for
testing.
The chosen pixel format (pix_fmt=yuv444p) in the render settings might be a key
factor, as color subsampling can significantly impact quality.
This regression should be investigated to ensure rendering quality does not
degrade in future stable releases.
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