VSE Scene Strip (in "Use Sequence" mode) Incompatible with certain Effect Strips
Open, ConfirmedPublic

Description

System Information
Windows 10, Quadro K2000

Blender Version
Broken: 2.77, 2.78

Short description of error
The Scene strip (in "Use Sequence" mode) doesn't handle certain types of strips within the referenced scene correctly. For Multicam Selector strip, the output is blank. For Adjustment strip, blender crashes!

Exact steps for others to reproduce the error

Using the attached blend file you can follow these steps:

  1. Scan through the short scene. Notice that it switches from black to white.
  2. Switch to scene 2: multicam scene
  3. Scan through the scene. Notice that it is not rendered as expected. It should be the same as the first scene but it's just blank.
  4. Switch to scene 3: adjustment. Notice that because of the adjustment. The output is a light grey.
  5. Switch to scene 4: adjustment scene. Blender crashes.

Finally, I've never worked on blender's code base before but I believe I have a solid attempt at a fix but I'm not sure what the best way to convey it is. I have my change committed locally in git. What would be the best way to go about trying to get this change reviewed?

Details

Type
Bug

@Matt (HyperSphere): didnt have a look at the issue yet, but you can post your diff here

Thanks for the info!

Here is the diff:
https://developer.blender.org/D2252

Thanks!

Matt

@Matt (HyperSphere): thanx for the patch!
Sequencer is not really a part of blender that I am very familiar with, at first glance I can confirm the patch seems to solve issues mentioned in the report. Hope I can spend some more time checking more in depth...

Philipp Oeser (lichtwerk) triaged this task as "Confirmed" priority.Sep 23 2016, 10:38 PM

btw: issues from report confirmed

I've committed D2252 now. Does it fix all the issues reported here?

Before I sent it out, I confirmed that the reported issues with the linked blend file don't occur when using blender built on Windows with the fix Diff you linked.

I can pull from head and reconfirm on Windows and check it on Linux (Ubuntu) as well if you would like.

Hi folks,

Is this related to keyframed changes on strips not being used correctly when the scene is inserted into another in "use sequence" mode?

In 2.78, if you keyframe some audio levels in a scene and then insert that scene into another some time after the start, the keyframed values happen at the wrong time - it seems like the time is measured from the start of the second scene, rather from the time the first scene's start position.

To reproduce:
scene 1) audio strip 10s long, volume at 1 at start, keyframe at 5s at volume 1, another keyframe at 6s at volume 0.
scene 2) insert scene 1 as sequence, at position 3s.

Render scene 2 as animation, audio will change volume at 5s from start (2s from start of scene 1), rather than at 8s.

Since I found that this applies to other strip types, I have made a blend file as an example. In the scene "sub" you can see the text count from 1 to 5. In the scene "master", "sub is inserted at 2s, and the numbers start counting from 3 instead of 1.

Hey Olly,

It's definitely conceptually similar. although it relates to the way strips reference the animation data as opposed to referencing other strips. I took a quick look and it looks like it's more complicated than I originally thought. I think this is a different enough issue to merit another task.

If you're interested in looking into the code you can look at the solution to the original issue which is here:

https://developer.blender.org/D2252#d494a504

Thanks,

Matt

Thanks Matt. I've created a new task (https://developer.blender.org/T49658), hope that's okay!

I've had a dig through with the debugger and don't see any data that could be used to correct the error at the point where the curves are being evaluated.