This feature applies image stabilization algorithms to the clip which can reduce the shakiness of a bit of footage.
Based on the tooltips from this screen and the docs here, this is what all the options mean:
Accuracy of shakiness detection. Should be >= shakiness factor. 1: low (fast processing). 15: high (slow processing). Default: 4. Recommended: 8.
How shaky is the video? And how quick is the camera? 1: little (fast processing). 10: very strong/quick (slow processing). Default = 4. Note: large values may also reduce the accuracy. This is due to the internals of the movement-detection. Typically you don’t need a value greater than 7.
Step size of search process. Region around minimum is scanned with 1 pixel resolution. Default = 6.
- Min. contrast
Below this contrast, the field is discarded. Range 0-1. Default = 0.3. You may want to use a smaller value for a really low contrast clip.
Controls the amount of smoothing/stabilization. The larger the value for smoothing, the more camera movements are compensated. The resulting clip has a lower change in camera speed. Technically it is the number of frames for lowpass filtering = (smoothing * 2) + 1.
For example, with a with 25 fps clip, a value of 12 for the smoothing factor means we would smooth over one second - 12 frames behind the current frame + the current frame (1) + 12 frames after the current frame. Default = 10.
Demo of the difference here (top:3, bottom: 30).
- Max shift
Maximal number of pixels to translate image. Default = -1. No limit.
- Max angle
Maximum angle to rotate in radians. Default = -1, which means no limit.
Unchecked means the border of the transformed frames contains the pixels from previous frames. Checked = black background. Default = unchecked.
Additional zoom during transform. Percentage to zoom > 0 = zoom in, < 0 = zoom out. The zoom specified here is in addition to the optimum zoom calculated by the program when optzoom is checked. Default = 0.
- Optimal Zoom
Use optimal zoom (calculated from transforms). Causes video to zoom until 90% of transformations are hidden. Default is checked. Hint: You can further zoom in with the zoom option.
- Optimal Zoom
Zoom per frame (used when “Optimal Zoom” = 2)
Sharpen transformed image. Amount of sharpening: 0: no sharpening. Uses filter unsharp with 5x5 matrix. Default = 0.8.
- Show fields
0 = draw nothing, 1 or 2 = show fields and transforms. Use 1 or 2 to preview what the process is going to do. Example. Default = 0. Non-zero values of this parameter are not relevant in the Kdenlive implementation - use zero.
Example of the effect of running stabilize - transcode from the original author - Georg Martius.
Side by side https://youtu.be/HYE3KAl8RAQ