1. A method, comprising: forming a difference frame comprising differences between pixel values of a first video frame and a second video frame of a video stream; calculating, using a processor, a variance for blocks of the difference frame; forming a variance histogram using at least some of the calculated variances; determining a threshold variance value to separate static or low motion areas from fast motion areas wherein a portion of the blocks of the variance histogram representing static or low motion areas have variances less than or equal to the threshold variance value; selecting at least one encoding parameter for a block of the first video frame based on a comparison of a variance of a spatially-correspondent block in the difference frame with the threshold variance value; and encoding the block of the first video frame using the at least one encoding parameter.