What it does: This highly-requested tool repairs common wobble and skew damage which affects many video cameras using CMOS sensors. CMOS cameras employ a "Rolling Shutter" that scans the image line by line instead of all at once. This can cause skew because a fast moving object or camera move appears in one position for the first scan line, but shifts to a different position by the time the last scan line captures it. To solve this, Rolling Shutter estimates the motion between the two points in time and shifts the image to compensate.
How to use it: Place Rolling Shutter on a clip that exhibits rolling shutter error. Next, calibrate by moving to a position in the clip where there is motion skew is apparent and adjust the Correction control to straighten the image, possibly adjusting Quality to help with accuracy. Once the Correction value is established, use it for all clips from the same camera at the current frame rate.
Note: If the video was shot at a different frame rate from the project settings, some video editors mix frames to scale between rates. This creates images that are harder for Rolling Shutter to track. If you are working with media in a different format from your project and experience difficulty, consider working in the original media format, fixing with Rolling Shutter and rendering to an intermediate corrected file, and then using that in your project.
- Correction sets the percent amount of rolling shutter error to correct. This directly correlates to the percentage of frame time the shutter is open. For example, if the shutter is open for 50% of the frame, then the correction should be also set to 50. A typical value is 20%. To calibrate Correction, move to a frame where motion skew is apparent and adjust to straighten the image.
- Quality sets the power of the rolling shutter analysis algorithm. A lower value runs faster because it requires less CPU resource, but it may have more difficulty with shaky or blurry video images.
- Set the Scanning Direction option to reflect whether the camera scans the image from top to bottom or bottom to top. Typically, this is Downwards.
- Border Fill determines what to do with the edges of the video image which the rolling shutter correction reveals in the process of shifting the image to compensate for rolling shutter error.