A method that is performed by a video encoding device is provided. The method includes identifying N image frames in a sliding window of an image frame sequence, the N image frames including N−1 encoded image frames and a to-be-encoded image frame; obtaining a motion amplitude difference of the N image frames in the sliding window, the motion amplitude difference indicating a difference between a corresponding image frame motion amplitude and a previous image frame motion amplitude; updating a static variable based on the motion amplitude difference of each of the N image frames in the sliding window, the static variable indicating a number of consecutive static image frames; and encoding the to-be-encoded image frame as an I frame based on the updated static variable not being less than a first preset threshold.