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I know Blender does not yet support interpolating frames using any sort of motion detection etc., but is there a simple interpolation routine that uses say alpha blending of adjacent frames to generate new frames, governed by the exact time of the new frame compared to the old frames.

The other way round, if I have footage from a high-speed camera, can I compress the source frames into less output frames using a similar blending routine, something like what games do to simulate motion blur?

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  • $\begingroup$ Do you have simulations you want to avoid re-baking? You could increase your total number of frames, scale the location of your keyframes, and increase the scene's framerate. $\endgroup$ – ajwood Apr 21 '16 at 11:41
  • $\begingroup$ It is actually the output of an engineering simulation where an even more complicated question will be how to deal with frames whose time stamps are not evenly distributed in time. It would be the ultimate application for this kind of interpolation routine, to be able to take engineering simulation time step images and make true-speed and true slow-motion or fast-motion videos. $\endgroup$ – J Collins Apr 21 '16 at 11:56
  • $\begingroup$ There is a workaround using AviSynth for Frame Blending. However, the function existed until Blender 2.49 and hasn't been implemented again after the huge overhaul 2.5 project. And there's a recent tutorial on Cloth Slow Motion rendering, but be careful, it's got annoying sound and colors... $\endgroup$ – Samoth Apr 22 '16 at 8:47
  • $\begingroup$ Another workaround is to use the -blend or -dissolve options of imagemagick. With a wrapper script to shift the percentages as need, that's probably a convenient option. $\endgroup$ – squarespiral Dec 16 '16 at 14:40
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For simple results the VSE has a speed control effect strip.

With your strip selected ⇧ ShiftA->Effect Strip->Speed Control, you can then adjust the rate in the properties region N. This will alter the playback speed of the specific strip in the VSE.

speed options

To adjust the entire video speed you also have the time remapping settings.

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  • $\begingroup$ Thanks @sambler, that looks almost exactly what I want, though I'm noticing something potentially frustrating, that the 'Enable Frame Blending' functionality was removed in 2.50. Do you have any idea if it is back, where to find it or when to expect it? Backward steps in software are always hard to stomach... $\endgroup$ – J Collins Apr 22 '16 at 12:33
  • $\begingroup$ I didn't use the vse much before 2.50 so I'm not familiar with the old frame blending. 2.50 was a big coding change/refactor so some things were dropped. You might want to try adding a suggestion at rightclickselect $\endgroup$ – sambler Apr 23 '16 at 6:23
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Frame blending was removed and will not return. Only hack for that is baking with Dynamic paint (using a frame sequence or movie) OR using an image mapped to a plane (in 3D view) and turning on Motion blur in the Blender Internal renderer.

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  • $\begingroup$ It sounds like you might be an authority in the Blender development community, is there a rationale behind this decision? $\endgroup$ – J Collins May 4 '16 at 13:46
  • $\begingroup$ Haha, nope. Just been around long enough to see it go. Rationale (IIRC) is that Blender is strictly NOT 'temporaly' aware. That is to say that each frame is independent of the next. You want access to other frames then you bake. There is no correspondence between fames, even drivers are assessed in the moment. $\endgroup$ – 3pointedit May 5 '16 at 12:20
  • $\begingroup$ So in the ultimate case I'd like to use source frames whose timestamps are not uniformly distributed. With or without that, I wonder if you could update your answer with some more detail on how to bake using dynamic paint. Cheers! $\endgroup$ – J Collins May 6 '16 at 14:56

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