https://bugs.kde.org/show_bug.cgi?id=520273
Bug ID: 520273
Summary: A variety of unintended behavior is caused by the
Transform effect forcing the project's resolution onto
media
Classification: Applications
Product: kdenlive
Version First 25.12.3
Reported In:
Platform: Ubuntu
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Video Effects & Transitions
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 192372
--> https://bugs.kde.org/attachment.cgi?id=192372&action=edit
Various issues caused by the transform effect, annotated
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Across a variety of projects, I've noticed that the Transform effect in
kdenlive causes a variety of unintended behavior when used on images and videos
with a different aspect ratio than the parent project. Anything with a
different resolution and especially aspect ratio than the project itself is
going to suffer from these issues. I've created a graphic that compiles these,
and believe that these all have the same root cause. Note also bugs 499371 and
456507 are most likely related, and perhaps also 455288.
There isn't an option to use the transform effect that respects the original
media's aspect ratio while preserving any effects: the distort option is the
closest, but it stretches the image to the project resolution, which is usually
not useful. Placing the transform effect below other effects on media will
cause the later effects to appear properly, but will distort the underlying
image, making later effects appear differently than they did, as though applied
with improper settings.
The last image should communicate the level of data loss that the method by
which the transform effect works causes. I also believe that Transform and
other effects that work in the same way are the only way to reliably move areas
of media that are off the frame into frame to be rendered, but the effect
simply ignores everything that isn't in the frame before it's applied.
If this is intended behavior, it's not obvious why it is. If it isn't, be aware
that rolling out a patch that simply replaces the old transform effect with one
that fixes these issues will certainly break older projects that account for
this bug.
I notice that the Composite and Transform composition works in that it can
transform media with effects without distorting them or causing data losses,
however it's a composition rather than an effect and thus works differently in
how it can be applied and its interchangeability with the transform effect
(shouldn't they work the same way?) If there was an effect that worked the same
way as Composite and Transform that superceded the existing Transform effect,
this issue could be sidelined entirely, though how the original Transform
effect would be handled then becomes an issue. In addition, I often stack
transform effects, and compositions can't be stacked in the version of kdenlive
I have installed.
STEPS TO REPRODUCE
1. Import media into a project. The media and project should have different
resolutions (for instance, a 640x640 square image added into a 1920x1080
project).
2. Add the media to the timeline, and apply an effect dependent on the
position of each pixel (i.e. pixelize, kaleidoscope, rotoscope, alpha shapes;
other effects such as those dealing with color won't be so noticeable).
3. Add a transform effect on top of the media.
OBSERVED RESULT
The image is distorted in a way that causes some form of data loss, with the
level depending on the specific effect used and the difference in aspect ratio
and resolution between the media and the project.
EXPECTED RESULT
A transform effect without any modifications to its stock settings should not
affect the media in any way by itself.
SOFTWARE/OS VERSIONS
Operating System (available in the Info Center app, or by running `kinfo` in a
terminal window):
KDE Plasma Version:
KDE Frameworks Version:
Qt Version:
ADDITIONAL INFORMATION
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