Optical flow?

[Nukley]

I was wondering if you could implement optical flow kinda like adobe did with their video editor software, upon a quick google search it appears OpenCV is used for this. From my understanding, this gives a very clean frame doubling, better than most methods at least.

[Austin]

In the meantime, here is an alternative using FFmpeg command line:

30fps to 25fps

The command line given only does frame dropping or duplicating. To convert frame rate with more sophistication than dropping or duplicating, there has to be a motion vector tracker combined with a morph algorithm such as optical flow. Here is an example: ffmpeg -i Input.mp4 -filter:v minterpolate=fps=120:mi_mode=mci:mc_mode=aobmc:me_mode=bidir:me=epzs:vsbmc=1 Output.mp4 But there are lots of problems with these algorithms. Motion vectors are generated by finding common edges between video …

And here is why that filter isn’t in Shotcut already:

Filter Plugin Frontend set String Parameter for Framerate

Hi All, First of all many thanks to the Developer(s) and Contributor(s) of shotcut, this is a great opensource project. I have been trying to create a frontend for an existing mltservice filter and have problems on setting the value of a parameter that is supposed to be a string. Specifically I have been trying to create a frontend for the following filters. [ avfilter.framerate ] (https://www.mltframework.org/plugins/FilterAvfilter-framerate/) avfilter.minterpolate Both have the paramet…

For my personal workflow, I create slow-mo segments outside of my timeline. Optical flow can generate a lot of unsightly artefacts (even using Premiere), and I’d rather not be surprised by them in my final Shotcut export. Given how slow optical flow is to render, I like to pre-process segments outside of Shotcut, review it, tweak it, and when it’s acceptable, import it into my timeline. I also get real-time preview playback that way. But that’s just my personal preference.

For an example of optical flow artefacts generated by Premiere, see the screenshots in this thread:

Exported to 60 FPS but still the video is in 24 FPS

My second post provided numerous examples of why a no-impact rate change is desirable. Regarding the Marvel trailer, this is an example of optical flow interpolation. Adobe Premiere and DaVinci Resolve can do this, among others. Shotcut cannot. The idea behind interpolation is to take two frames, find edges in common between the two frames, and then mathematically bend the edges to generate in-between frames. The success of this method depends on edges in the two frames being properly dis…

[brian]

Architectural changes are in progress for Shotcut/MLT that will one day make this possible. But it is a long road. It is unlikely to be available this year.

I tend to agree with @Austin’s comments about performing CPU intensive operations outside of the Shotcut project.