Maniphest T39057

VSE wipe (with transparent 2nd input ) broken in RC1 !
Closed, Archived
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Assigned To
Sergey Sharybin (sergey)
Authored By
David Salvo (slinkeepie)
Mar 8 2014, 10:51 PM
Tags
  • BF Blender
  • Video Sequencer
Subscribers
Bastien Montagne (mont29)
David Salvo (slinkeepie)
Sergey Sharybin (sergey)

Description

System Information
Mint Cinnamon 15 (3.8.0-19-generic)
NVIDIA G92 [GeForce 9800 GT]

Blender Version
Broken: 2.7 RC1 (19f7f9a)
Worked: 2.7 Testbuild (10f4c62)

Short description of error

This has broken my current project (yes I can render frames from older version but would like to get it fixed!), I used to be able to wipe from one image to another with a transparency, and the original image would show beneath it (with both the transparent image's blend mode and the wipe effect strip's blend mode set to alpha over). In RC1 it no longer works...

Exact steps for others to reproduce the error
Load one image(or video), then an image(or video?) with transparency.
Place the transparent image one channel higher and cross over.
Add wipe (so bottom opaque image wiping to top transparent image).
Set transparent image's mode to alpha over and the wipe effect stripe's mode to alpha over as well.
The top transparent image will not use its alpha channel to see through to the bottom strip.

Sorry I am running late for something and no time to attach a blend file! It's pretty easy to reproduce.

Thanks in advance.

Event Timeline

David Salvo (slinkeepie) created this task.Mar 8 2014, 10:51 PM
David Salvo (slinkeepie) raised the priority of this task from to 90.
David Salvo (slinkeepie) updated the task description.
David Salvo (slinkeepie) added a project: Video Sequencer.
David Salvo (slinkeepie) edited a custom field.
David Salvo (slinkeepie) added a subscriber: David Salvo (slinkeepie).
Bastien Montagne (mont29) lowered the priority of this task from 90 to 30.Mar 18 2014, 4:04 PM
Bastien Montagne (mont29) added a project: BF Blender.
Bastien Montagne (mont29) added a subscriber: Bastien Montagne (mont29).

Please do add a small demo .blend file, we have hundreds of reports to check each week, so saving even five mins on each is important for us!

David Salvo (slinkeepie) added a comment.Mar 18 2014, 5:26 PM

Hey there,

I've attached the files, I thought you could pack the images into the .blend itself, it didn't work?
Anyway:

transparent_wipe_blender_bug.tar.bz2444 KBDownload

Bastien Montagne (mont29) raised the priority of this task from 30 to 50.Mar 18 2014, 7:18 PM

Thanks for the file, issue confirmed. :/

(And no, packing files used by compositor does not work - sigh…)

Bastien Montagne (mont29) claimed this task.Mar 18 2014, 7:18 PM
Bastien Montagne (mont29) reassigned this task from Bastien Montagne (mont29) to Sergey Sharybin (sergey).Mar 18 2014, 8:12 PM

Hrrrmm… In fact, I would be tempt to call 2.69 behavior buggy…

Assigning to Sergey to get its advice, but imho an effect strip should always completely "replace" its operand ones, not allow to be overlayed over one of them…

Sergey Sharybin (sergey) changed the task status from Unknown Status to Unknown Status.Mar 19 2014, 5:48 AM

This is an intentional change to the sequencer stack renderer made in rBb3bc9e4 to address T38598.

If the effect mixes with it's inputs it gives really unpredictable results when blending images with alpha and i'm pretty much sure no other software would allow effect to blend together with it's inputs.

Even with your file you can see the buggy behavior in 2.69 -- last frame of wipe effect is different from first frame after that wipe effect, and there's no sane reason for this.

I'll document this in the release notes pages and call it a known change in the behavior.