Blackmagic Forum

I'm looking for a way to add motion blur after retiming. It seems that the way motion blur is set up to work, it applies the blur pre-retime. Because of this, if there is say a speed ramp on a clip, the amount of motion blur stays constant even though the speed of the motion changes. The logical way to deal with this is to create a compound clip so that the motion blur operates after the retime process. However, it seems like it is deliberately disabled on compound clips, Fusion clips, or any other way to make it happen post retime. It would be great to have a way to adjust whether motion blur works before or after retime, or at least get it to work on compound clips.

Has anyone found a workaround for this?

John Meyer wrote:Has anyone found a workaround for this?

The only workaround I know is to use new "Render in Place" function of Resolve 17 and then apply motion blur

panos_mts wrote:

John Meyer wrote:Has anyone found a workaround for this?

The only workaround I know is to use new "Render in Place" function of Resolve 17 and then apply motion blur

do the retime and compound clip? but I saw oddities with motion effects and compound clips....

panos_mts wrote:

John Meyer wrote:Has anyone found a workaround for this?

The only workaround I know is to use new "Render in Place" function of Resolve 17 and then apply motion blur

That's an idea, although I don't like having to render and I'm not sure how that would work in the final export.

waltervolpatto wrote:

panos_mts wrote:

John Meyer wrote:Has anyone found a workaround for this?

The only workaround I know is to use new "Render in Place" function of Resolve 17 and then apply motion blur

do the retime and compound clip? but I saw oddities with motion effects and compound clips....

That's what I wish I could do!! The only problem is that motion blur is disabled on compound clips. If they could just fix that it would be great.

Another workaround is to add motion blur on fusion page (but it's painfully slow)
Create a compound clip, go fusion page and add an optical flow and vector motion blur node.

I tried rendering in place and that actually does work. The only issue is that it is throwing away frames when you render a portion with increased speed which doesn't give the motion blur algorithm enough data to work with to create a smooth motion blur. What we really need is an implementation that will use the data from all the frames to create a smooth motion blur on sections/clips with increased speed. Other software can do this so it shoudn't be too hard to implement.

panos_mts wrote:Another workaround is to add motion blur on fusion page (but it's painfully slow)
Create a compound clip, go fusion page and add an optical flow and vector motion blur node.

I'll have to give that a shot, although it'll probably be too slugish for my liking.

So I figured out a way to essentially get the result I want, although it's not really a solution to the problem. I just keyframe the motion blur to along with the speed ramp. Not ideal, but probably the best quick fix until BM decides to fix it.

John Meyer wrote:So I figured out a way to essentially get the result I want, although it's not really a solution to the problem. I just keyframe the motion blur to along with the speed ramp. Not ideal, but probably the best quick fix until BM decides to fix it.

I was just about to post about this exact issue and I cam across your thread. Are you still using this method? Also, are you using just the motion blur in the color tab? I never find that it actually creates much blur.

What I really wanted to do was create the speed ramp in Fusion, and then add motion blur there, but I can't figure it out. In After Effects, I would do my speed ramp there, then add "CC Force Motion Blur", which is similar to vector motion blur in Fusion. Do you know how to speed ramp right in Fusion?

hopkins802 wrote:

John Meyer wrote:So I figured out a way to essentially get the result I want, although it's not really a solution to the problem. I just keyframe the motion blur to along with the speed ramp. Not ideal, but probably the best quick fix until BM decides to fix it.

I was just about to post about this exact issue and I cam across your thread. Are you still using this method? Also, are you using just the motion blur in the color tab? I never find that it actually creates much blur.

What I really wanted to do was create the speed ramp in Fusion, and then add motion blur there, but I can't figure it out. In After Effects, I would do my speed ramp there, then add "CC Force Motion Blur", which is similar to vector motion blur in Fusion. Do you know how to speed ramp right in Fusion?

Yes this is still what I do. You are right, for extreme speed ramps the motion blur in the color tab (what I use) isn't enough. It's fine for smaller speed changes though.

As far as Fusion, I've only done speed ramps in the editor. I think there might be a way to do it in Fusion though. IDK. Google it.

John Meyer wrote:

hopkins802 wrote:

John Meyer wrote:So I figured out a way to essentially get the result I want, although it's not really a solution to the problem. I just keyframe the motion blur to along with the speed ramp. Not ideal, but probably the best quick fix until BM decides to fix it.

I was just about to post about this exact issue and I cam across your thread. Are you still using this method? Also, are you using just the motion blur in the color tab? I never find that it actually creates much blur.

What I really wanted to do was create the speed ramp in Fusion, and then add motion blur there, but I can't figure it out. In After Effects, I would do my speed ramp there, then add "CC Force Motion Blur", which is similar to vector motion blur in Fusion. Do you know how to speed ramp right in Fusion?

Yes this is still what I do. You are right, for extreme speed ramps the motion blur in the color tab (what I use) isn't enough. It's fine for smaller speed changes though.

As far as Fusion, I've only done speed ramps in the editor. I think there might be a way to do it in Fusion though. IDK. Google it.

Hey man,

I finally figured out how to do this...You create a speed ramp right in the edit page, then create a fusion clip from that. Then in Fusion, you'll add an "Optical Flow" node, and then right after that a "Vector Motion Blur" node. You keyframe the "Blend" of the Vector Motion Blur node to go from 0-100 during that part that is sped up. You could also keyframe the Size to go from 0-1.

The playback kinda blows, so I just Render in Place after on the Edit page and i'm golden!

hopkins802 wrote:Hey man,

I finally figured out how to do this...You create a speed ramp right in the edit page, then create a fusion clip from that. Then in Fusion, you'll add an "Optical Flow" node, and then right after that a "Vector Motion Blur" node. You keyframe the "Blend" of the Vector Motion Blur node to go from 0-100 during that part that is sped up. You could also keyframe the Size to go from 0-1.

The playback kinda blows, so I just Render in Place after on the Edit page and i'm golden!

Hey, thanks I'll have to try that out. Sounds like it might be a good fix!