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I have rendering issues.
  1. You may want to try a lower lambda value (5 or 10) in the rendering dialog.
  2. Alternatively you can manually fix the optical flow with slowmoFlowEdit, a short tutorial is here. This is often a good solution if you are sure that you want to use a clip of your video and need to remove some errors.

Black stripped frames output

Change to "_Farnback_" for _CPU, OpenCV_ in the Preferences settings. Close slowmoVideo. Delete project caches from project folders and temporary files.


I get flow builder errors.
  1. If the optical flow files cannot be built with flowBuilder: Are you running slowmoVideo in a VM? This usually does not work.
  2. If flowBuilder cannot be found, a) make sure that you compiled it (in the V3D directory), and b) make sure that the location to the binary is set correctly in the slowmoUI preferences.

If you have multiple video cards in your PC, one of them is the primary card. This one will be used by flowBuilder. If the primary card is an AMD card and the secondary an nVidia card, you will have to change them (physically), otherwise flowBuilder will not run.

Sometimes my mouse freezes. Why?

This is when your GPU is doing heavy work and does not have time for updating the screen. Nothing dangerous.

What are those QColor::fromRgbF error message?

If your debug output is flooded with messages saying QColor::fromRgbF: RGB parameters out of range then this is a result of tiniest floating point inaccuracy resulting in:

x + (1.0-x) > 1.0

These can be safely ignored.