Bug 364891 - title clip rendering is broken in mlt-6.2
Summary: title clip rendering is broken in mlt-6.2
Status: RESOLVED LATER
Alias: None
Product: kdenlive
Classification: Applications
Component: Rendering & Export (show other bugs)
Version: 16.04.0
Platform: Gentoo Packages Linux
: NOR grave
Target Milestone: ---
Assignee: Jean-Baptiste Mardelle
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2016-06-29 07:42 UTC by Nikita Melnichenko
Modified: 2016-07-29 06:33 UTC (History)
1 user (show)

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Description Nikita Melnichenko 2016-06-29 07:42:54 UTC
Title text is looking very ugly in rendered video. I've uploaded repro examples to the bug #362385, but there was no response for several days and the bug is shown stroked, so I guess we need to reopen it for visibility and close this bug as a duplicate... Let me know if I can help more.

Reproducible: Always




Sorry for the dup.
Comment 1 Jean-Baptiste Mardelle 2016-07-15 22:17:48 UTC
Sorry for the delay. This is in fact not really a bug but a problem in the way Kdenlive (and MLT) handles alpha transparency and transitions. Title clips use antialiasing to provide smooth edges.

However, currently to be displayed correctly in Kdenlive / MLT, an image with alpha transparency must have a transition attached to it. In your project, the title has a composite transition, which is correct.

Now the problem here is that transitions in Kdenlive cannot be applied on an empty track. In your project, you have the title clip on top track, and the transition is applied with the track below, which is empty - reason why it does not work.

So to solve your problem, you must either:
* put a clip on the track below your title
* change the transition parameters (the track parameter) to apply transition on the background black track (in the "track" combobox, select "black"). this will make the transition work and text will look fine.

I am well aware that this behavior is confusing and problematic and have been working on a solution to make transparency correctly handled by default. I hope to introduce that for the 16.08 release in august.
Comment 2 Nikita Melnichenko 2016-07-26 07:45:58 UTC
This workaround works well, thank you!

Looking forward to better transparency handling! I wonder if it's possible to make transparency as intuitive as in GIMP layers...
Comment 3 Jean-Baptiste Mardelle 2016-07-26 08:35:44 UTC
Yes, this is currently fixed using MLT and Kdenlive from git master, should be available with Kdenlive 16.08 and MLT 6.4.0.
Comment 4 Wegwerf 2016-07-26 19:24:09 UTC
Nikita, can you please be so kind as to close this bug if the answer works for you? Thank you very much for you cooperation!

If you like to see what's upcoming, that is, the improved easy of use Jean-Baptiste is talking about:
* http://thediveo-e.blogspot.de/2016/07/new-kdenlive-transition-composite-and.html
* http://thediveo-e.blogspot.de/2016/07/kdenlive-easy-compositing-with.html
Comment 5 Nikita Melnichenko 2016-07-29 06:33:24 UTC
Closed. Thanks for the articles!