Abstract: A method and a system for accelerating the calculation of a motion estimation metric are described. During a single clock cycle, a first word and a second word of packed unsigned bytes are provided. Each byte in the first word represents a pixel in an image to be encoded and each byte in the second word represents a pixel in previously encoded image. Each byte in the second word of packed unsigned bytes is paired with one of the bytes in the first word of packed unsigned bytes. An error measure is calculated for each pair of bytes to compute a portion of the motion estimation metric for multiple pixels during a single clock cycle.