360: Stabilize Video Filter

Stabilizes 360 footage. The plugin works in two phases - analysis and stabilization. When analyzing footage, it detects frame-to-frame rotation, and when stabilizing it tries to correct high-frequency motion (shake).

How to Stabilize Video

1. Disable Realtime (frame dropping) in the Settings menu. It is important that the filter sees all frames.
2. Add the 360 footage
3. Apply a Hemispherical to Equirectangular filter to it so it is in equirectangular format.
4. Apply a Transform 360 filter
5. Apply the Stabilize 360 filter.
6. Select a file to store stabilization data in.
7. Enable Analyze mode.
8. Use the Transform 360 filter to rotate the footage so that the point straight ahead is over the center cluster of track points.
9. Play the footage from start to finish. The FUD (Filter-Up Display) should show an increasing frame count.
10. When the footage has completed playing, switch off the Analyze mode.
11. You should now have stable 360 video.

The FUD (Filter-Up Display)

When you switch to analysis mode, the filter will overlay information on the video.

• In the top left is information about the file you use for storage and how many frames it has data for.

• The squares are the areas used for motion detection.

  • Red outline are the areas that were sampled.
  • Yellow outline is the search radius
  • Blue squares are fixed.
  • Green squares are where the sampled areas were found.

• When analyzing, the red, yellow and green squares are drawn first. Then the frame is transformed in such a way as to cancel the rotation from the previous frame, and the blue squares are drawn. If the detection and detected rotation are flawless, the blue and green squares should overlap completely and form cyan squares. Note: “Analysis: Apply Transform” must be enabled.

• The waveform drawn in the lower middle shows the detected motion. Red is yaw, green is pitch and blue is roll.

Parameters

• Mode: Toggle this checkbox to go from stabilization mode to analysis mode.

• File: Path to file that will be used to store the analysis data.

• Start Offset: The offset into the stabilization file that corresponds to the start of this clip. Press the Undo button to set it from Shotcut timeline. For example, if you have a 30 second clip, analyze it all, and then split it into three clips of 10 seconds each, then the start offsets should be 0s, 10s, and 20s.
  Added in Shotcut 20.11

• Interpolation: Output quality.

Analysis

• Apply Transform: When checked, the filter will apply the frame-to-frame transform in order to show the quality of the analysis (see the above section about the FUD). When you are satisfied with the analysis quality you can turn this off, as it adds approximately 50% to the analysis time.
  Added in Shotcut 20.11

• Sample Radius: The radius of the square that the stabilizer will sample.

• Search Radius: The maximum amount of motion the stabilizer will detect.

• Offset: The distance between the track points.

• Use backwards-facing track points: If set, six backwards-facing track points will also be used to detect pitch and yaw motion. Disable if, for example, you show up holding the camera there.

Yaw, Pitch & Roll

• Amount: The amount of stabilization to apply. 100% means that the stabilizer will make the camera as steady as it can. Smaller values reduce the amount of stabilization.

• Smoothing: The number of frames to use to smooth out the shakes. The higher the value, the slower the camera will follow any intended motion.

• Time Bias: Shift the frames used to smooth out the shakes relative to the stabilized frame. A value less than zero will give more weight to past frames, and the camera will seem to lag behind intended movement. A value greater than zero will give more weight to future frames, and the camera will appear to move ahead of the intended camera movement. A value of zero should make the camera follow the intended path.