1. A method of pre-filtering video comprising: receiving an original video sequence comprising a set of video frames, each video frame having a set of pixels; pre-filtering each of a plurality of video frames to generate a pre-filtered video sequence, said pre-filtering comprising applying anisotropic diffusion filtering to each of a plurality of pixels in each of the plurality of video frames in order to reduce the differences between a plurality of neighboring pixels in the plurality of video frames, wherein the anisotropic diffusion filtering is performed for each pixel in the plurality of pixels in four horizontal and vertical directions comprising north, south, east and west and four diagonal directions comprising north-east, north-west, south-east, and south-west with respect to the pixel location of the pixel; and encoding the pre-filtered video sequence using an encoding method to produce a pre-filtered and encoded video sequence that has a smaller bit rate than an encoded video sequence that would result from encoding the original video sequence using the same encoding method.