Abstract: A video encoding method, video encoding device, and image processing device are provided. The video encoding method is used to encode a video including multiple frames, and each frame includes multiple blocks. The video encoding method includes the following steps: reading multiple first characteristic data of a first frame from an external memory to a memory; reading multiple pixel data of a second frame from the external memory to the memory, the second frame being subsequent to the first frame; generating multiple second characteristic data of the second frame based on the pixel data in the memory; encoding, block by block, the pixel data of the second frame in the memory; calculating, block by block, a difference value between the first characteristic data and the second characteristic data; calculating motion information according to the difference values of the blocks; and determining an encoding bitrate based on the motion information.