Seeming bug with Rolling Shutter Repair + Frame Blending

[jonah.c.l]

Hi there,

I have a 30fps video clip in Comp A, which is also 30fps. Comp A is in Comp B, which is 60fps. As long as both the video clip in Comp A, and Comp A (in the timeline of Comp B), have Frame Blending set to Pixel Motion, then the "in-between" frames are interpolated, and the video becomes 60fps.

However, if I apply Rolling Shutter Repair to the original clip (in the timeline of Comp A), suddenly, no matter what I do, some frames are duplicated (i.e. not interpolated) when I scrub through it in Comp B. The odd thing is, some of the frames still appear to be interpolated (warp artifacts are visible), as if Pixel Motion frame blending is still enabled, but it just won't give me the "in-between" frames - some frames repeat.

I can't apply Rolling Shutter Repair later, because it only works properly when applied to a clip at its original frame rate.

Any help would be greatly appreciated.

Thanks,

Jonah

[Rick Gerard]

Try applying Rolling Shutter repair to the original clip, then Pre-compose and move all attributes to the new comp. Make sure "Preserve Frame rate when nested..." is not turned on in the Pre-comp's Advanced settings. You should now be able to get the frame blending you want.

[jonah.c.l]

Thanks for the suggestion, but that was already what I was doing, and "Preserve Frame rate when nested" is turned off for all the comps. The problem is still happening where every other frame is a duplicate in the 60fps comp as long as rolling shutter repair is applied to the clip in the precomp.

[Rick Gerard]

Sorry, I forgot that Frame Blending is not available in a nested comp. It is only available on a footage layer. I interpreted some 59.97 fps footage as 10-fps and dropped it in a 60-fps comp. It had repeated frames, as expected. I turned on Pixel Motion frame blending (the second click in the frame blending options for footage layers, and the motion smoothed out. I then added Rolling Shutter repair to the footage and waited for a region of interest preview to render zoomed in to 400% so I could really take a look at the pixels. Everything seems fine. Frame Blending was not affected at all.

For. some reason, the forum is not allowing me to upload a video. Here's a Dropbox link to the file. https://www.dropbox.com/s/ad6y861v7o6z530/FrameBlend.mp4?dl=0

You should be able to see the effect of adding frame blending and then the change when I turned on Rolling Shutter Repair. There are no duplicated frames.

[jonah.c.l]

That seemed to do it! I should have increased the frame rate of Comp A (the one with the clip in it); I was only increasing the frame rate of Comp B (the one with Comp A in it). Now the frames are interpolated with no duplicates.

I still think the original behaviour is odd, and perhaps a bug - if you're interested, maybe try recreating what I did before, i.e. put the footage+rolling shutter repair in a comp matching the clip's frame rate and put that comp in a comp with an increased frame rate, and notice how frames are repeated only when rolling shutter repair is applied to the video clip in the inner comp.

Thanks for your help!

Jonah

[jonah.c.l]

Looks like I spoke too soon - I still have the issue, but only when I slow down the clip of the inner comp in the outer comp using time remapping. Then, frames are repeated, but only when Rolling Shutter Repair is applied to the video clip in the inner comp.

However, I can work around this by making the inner comp frame rate high enough. Nonetheless, I still think this is unexpected, perhaps buggy behavior.