# Optical Flow
This feature is very performance consuming and can cause video preview freezes. Many Android devices do not support this feautre, which may cause crashes, flash screens and other bugs.
After selecting any video layer, open the layer menu and select [Time Interpolation -> Optical Flow].
Then you will see the following panel, where you can choose the usage: Frame Mix or Motion Blur.
# Frame Mix
After turning on frame mix, you also need to slow down the video speed (stretch the video layer) to see the effect.
You can also change the video speed through [New Property -> Time -> TimeRemap].
In order to achieve the best result, please refer to the following suggestions.
- Use the original video (not a exported or downloaded video)
- Video resolution >= 1080P
- Video FPS = 60
# Motion Blur
When motion blur is turned on, moving pixels will be blurred.
- Length indicates the trailing length of pixels, the higher the value, the more blur.
- Feather can adjust the radius of the blur, increasing the value can reduce frame blending, but it may cause inaccurate optical flow.
- Dispersion can make RGB dispersion of blurred places to achieve cool effects.
Due to the limited computing power of the mobile device, frame blending is currently performed in areas where the movement is relatively fast. In order to achieve the best results, please refer to the following suggestions:
- Use 60 FPS videos and set the project FPS to 60
- For AMV editors, you can adjust the Length to a smaller size and maximize the Feather
- You can also export the video once, and then do the motion blur processing on the exported video again