The invention provides a method of transcoding a video signal made up of an input bit stream representative of frames of a video, each frame being made up of blocks of pixels, there being a corresponding block of data within the input bit stream for each block of pixels, the method comprising: for the bit stream of a frame of the video signal, identifying the type of frame; and for certain types of frame, disregarding a configurable proportion of the data in respect of plural blocks within the frame, thereby taking into account local motion activity within the frame.