Bug 500623

Summary:	Transform: unreasonably low resolution when preview resolution is set lower than 1:1 and proxy is used
Product:	[Applications] kdenlive	Reporter:	Andrey <megester>
Component:	Video Effects & Transitions	Assignee:	Jean-Baptiste Mardelle <jb>
Status:	RESOLVED FIXED
Severity:	normal	CC:	fritzibaby, poracoppa75, snd.noise
Priority:	NOR	Keywords:	triaged
Version First Reported In:	24.12.2
Target Milestone:	---
Platform:	Microsoft Windows
OS:	Microsoft Windows
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Example

Description Andrey 2025-02-23 13:58:28 UTC

Created attachment 178773 [details]
Example

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SUMMARY


STEPS TO REPRODUCE
1. Make a 2160p project
2. Insert a 2160p H264 clip
3. Make a proxy of the clip
4. Insert the clip into the timeline
5. Add transform to the clip
6. Switch preview resolution to 720p

OBSERVED RESULT

Preview resolution is unreasonably low. Once Transform is disabled the resolution becomes normal.

EXPECTED RESULT

Adequate preview resolution when using the Transform effect.

SOFTWARE/OS VERSIONS

Kdenlive: 24.12.2
MLT: 7.30.0
FFmpeg
KDE Frameworks: 6.11.0
Qt: Using 6.8.2 and built against 6.8.2
KDE Flatpak runtime (Xcb)
Build ABI: x86_64-little_endian-lp64
Kernel: linux 6.11.10+bpo-amd64

Comment 1 Andrey 2025-02-23 14:00:01 UTC

I think it's not "quarter of the resolution" but more like a thumbnail resolution.

Comment 2 Andrey 2025-03-18 10:52:18 UTC

The issue is still present in 24.12.3.

Comment 3 emohr 2025-03-22 17:02:59 UTC

Thank you for reporting. I can confirm the issue. Following your steps. 
I tried with different proxy sizes. As soon as the transform effect is enabled on the timeline clip or on the bin clip it gets blurry.

Comment 4 Jean-Baptiste Mardelle 2025-03-25 10:06:58 UTC

Fixed in commit:
https://github.com/mltframework/mlt/commit/11023db52a8a4d80095e13212aabb1d13bdcafe4

Comment 5 editwithmyfeet 2025-03-26 17:18:21 UTC

Version 24.12.2 (installed version)
Os Windows 11

Hi, 
For Windows users (if this can help) : Since i have no skill to compile, i proceeded with a solution that's a bit tricky.
I switched libmltqt6.dll between two kdenlive versions. I took libmltqt6.dll from 24.12.0 and placed it to C:\Program Files\kdenlive\lib\mlt\ 
in 24.12.2 version.
Now i get a decent preview when using transform filter. 
Keep up the good work to make kdenlive even more reliable! Waiting for 25.04 to be released.

(In reply to Jean-Baptiste Mardelle from comment #4)
> Fixed in commit:
> https://github.com/mltframework/mlt/commit/
> 11023db52a8a4d80095e13212aabb1d13bdcafe4

Comment 6 Andrey 2025-03-26 17:57:32 UTC

Thank you very much for fixing this! Waiting for the next release to test it out (I'm on Linux).

Comment 7 Andrey 2025-04-30 07:01:13 UTC

This bug is fixed in v25.04.0 AppImage version only. The Flatpak version still has the issue, probably because of the outdated MLT framework. Is it possible to fix the Flatpak as well?

Comment 8 farid 2025-04-30 15:15:55 UTC

Updated upstream, it will update once merged. https://github.com/flathub/org.kde.kdenlive/pull/537

Comment 9 Andrey 2025-05-13 09:18:05 UTC

Confirmed as fixed in the Flatpak release 25.04.1. Thank you very much!