Animation Scene Strip rendering slower than Animation Scene rendering #101269

New Issue

JC Cavadini · 2022-09-22T12:00:10+02:00

JC Cavadini commented

2022-09-22 12:00:10 +02:00

System Information
Operating system: Windows 10
Graphics card: NVidia RTX 2060

Blender Version
Broken: 3.3
Worked: N/A

Short description of error
Rendering an animation using Scene Strip resync / reevaluate every mesh each frame, resulting in slow rendering.
Rendering the same animation directly from the same Scene only does this process for the 1st frame, hence a quicker rendering.
(It doesn't seem to be related to the render engine, Eevee or Cycles same issue).

Additionally during Scene Strip rendering, on Windows, the memory doesn't seem to be cleaned correctly between each frame resulting in a crash at some point (depending on your memory size).

Exact steps for others to reproduce the error
Add 2 subdivision modifiers to the cube, with 6 and 4 render levels.
Create a new scene, go to the VSE, add a Scene Strip pointing to the 1st scene.
Render animation from VSE scene => slow rendering
Render animation from the scene => fast rendering

scene_strip.blend

**System Information** Operating system: Windows 10 Graphics card: NVidia RTX 2060 **Blender Version** Broken: 3.3 Worked: N/A **Short description of error** Rendering an animation using Scene Strip resync / reevaluate every mesh each frame, resulting in slow rendering. Rendering the same animation directly from the same Scene only does this process for the 1st frame, hence a quicker rendering. (It doesn't seem to be related to the render engine, Eevee or Cycles same issue). Additionally during Scene Strip rendering, on Windows, the memory doesn't seem to be cleaned correctly between each frame resulting in a crash at some point (depending on your memory size). **Exact steps for others to reproduce the error** Add 2 subdivision modifiers to the cube, with 6 and 4 render levels. Create a new scene, go to the VSE, add a Scene Strip pointing to the 1st scene. Render animation from VSE scene => slow rendering Render animation from the scene => fast rendering [scene_strip.blend](https://archive.blender.org/developer/F13553010/scene_strip.blend)

JC Cavadini commented

2022-09-22 12:00:10 +02:00

Added subscriber: @iWhiteRabbiT

JC Cavadini changed title from ~~Scene Strip rendering slower than Scene rendering~~ to Animation Scene Strip rendering slower than Animation Scene rendering

2022-09-22 12:10:43 +02:00

JC Cavadini commented

2022-09-22 12:10:43 +02:00

Added subscriber: @iss

Richard Antalik commented

2022-09-26 20:32:44 +02:00

It seems, that mesh caches are rebuilt for every frame, but have to dig deeper to see if this works as intended and if it could be optimized.

Pratik Borhade commented

2022-09-27 06:40:53 +02:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2022-09-27 06:40:53 +02:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Pratik Borhade commented

2022-09-27 06:40:53 +02:00

I'm able to replicate this. Changing status to Needs Information from Developers until further investigation. Feel free to revert the status :)

I'm able to replicate this. Changing status to `Needs Information from Developers` until further investigation. Feel free to revert the status :)

Sergey Sharybin commented

2022-11-11 15:24:52 +01:00

Added subscriber: @Sergey

Sergey Sharybin commented

2022-11-11 15:24:52 +01:00

/* Sorry, scratch the reply, i accidentally replied to the wrong report*/

Sergey Sharybin commented

2022-11-11 15:30:41 +01:00

If I understand this report correctly, then this is caused by the current design of render pipeline and sequencer.

The regular animation render keeps a lot of contexts alive throughout the render: dependency graphs, GPU resources etc. This is possible for this type of render because we can more easily predict resource usage.

This is not how sequencer works: sequencer creates dependency graph and all the render contexts and GPU resources for every frame it renders from the scene strip, and destroys them when the frame is rendered. This is because it is harder to predict what else will be happening in the sequencer, and we do not want the system to go out of RAM or VRAM when multiple scene strips are used.

If I understand this report correctly, then this is caused by the current design of render pipeline and sequencer. The regular animation render keeps a lot of contexts alive throughout the render: dependency graphs, GPU resources etc. This is possible for this type of render because we can more easily predict resource usage. This is not how sequencer works: sequencer creates dependency graph and all the render contexts and GPU resources for every frame it renders from the scene strip, and destroys them when the frame is rendered. This is because it is harder to predict what else will be happening in the sequencer, and we do not want the system to go out of RAM or VRAM when multiple scene strips are used.

Richard Antalik commented

2022-11-11 18:54:27 +01:00

Sorry, I forgot to re-check on this. I have forgot to put this report on TODO list and browser crashed.

Thanks for explanation, I guess this would be limitation of pipeline rather than VSE? Will check how compositor handles this. Because in VSE we can tell how much scenes and where in time are needed so it would be possible to keep depsgraph around for next frame.

Sorry, I forgot to re-check on this. I have forgot to put this report on TODO list and browser crashed. Thanks for explanation, I guess this would be limitation of pipeline rather than VSE? Will check how compositor handles this. Because in VSE we can tell how much scenes and where in time are needed so it would be possible to keep depsgraph around for next frame.

Aditia A. Pratama commented

2022-11-12 10:25:22 +01:00

Added subscriber: @AditiaA.Pratama

Trung Phạm commented

2022-11-12 21:29:24 +01:00

Added subscriber: @zNight

Sergey Sharybin commented

2022-11-14 09:41:45 +01:00

I am not sure we can put it as simple as whether this is on VSE side or on the render pipeline side. The OpenGL animation render uses special tricks to keep the dependency graph alive, since it knows that it renders single scene. The final F12 render with default configuration will re-create dependnecy graphs for every scene which renders, but with the Persistent Data option it is possible to reuse more data.

For the VSE strips rendering technically it is the scene strip renderer who takes care of the dependency graph creation and evaluation. So if we are to look into speed improvements here it does touch the sequencer code. But this needs somehow be done in a way that the memory usage during all kinds of rendering stays under control, so it is somehow to live within the render pipeline.

I am not sure we can put it as simple as whether this is on VSE side or on the render pipeline side. The OpenGL animation render uses special tricks to keep the dependency graph alive, since it knows that it renders single scene. The final F12 render with default configuration will re-create dependnecy graphs for every scene which renders, but with the Persistent Data option it is possible to reuse more data. For the VSE strips rendering technically it is the scene strip renderer who takes care of the dependency graph creation and evaluation. So if we are to look into speed improvements here it does touch the sequencer code. But this needs somehow be done in a way that the memory usage during all kinds of rendering stays under control, so it is somehow to live within the render pipeline.

Philipp Oeser removed the

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Animation Scene Strip rendering slower than Animation Scene rendering #101269