Abstract: A method of pre-processing a sequence of video picture data comprising I pictures, P pictures and B pictures, where the pictures are arranged as a plurality of Group Of Pictures (GOP) and each of the Group Of Pictures has a first picture and a plurality of Sub Group of Pictures (Sub-GOP). The method uses an analysis of the sequence of video picture data to determine a position of a scene change relative to a position of a start of a new GOP within the sequence of video picture data and then moves the start of the new GOP to coincide with the scene change by extending or decreasing a current GOP length according to whether the scene change and the start of a new GOP are within a predetermined number of pictures of each other. An apparatus for carrying out the method is also provided.

Abstract: There is provided a method of encoding video data, comprising estimating the spatio-temporal homogeneity of at least one portion of the video data, providing spatio-temporal homogeneity flags dependent upon the estimated spatio-temporal homogeneity of the at least one portion of the video data, and guiding the encoding process dependent on the spatio-temporal homogeneity flags. There is also provided an apparatus for carrying out the method, and a computer readable product carrying instructions which when executed carry out the method.

Abstract: A method of pre-processing a sequence of video picture data comprising I pictures, P pictures and B pictures, where the pictures are arranged as a plurality of Group Of Pictures (GOP) and each of the Group Of Pictures has a first picture and a plurality of Sub Group of Pictures (Sub-GOP). The method uses an analysis of the sequence of video picture data to determine a position of a scene change relative to a position of a start of a new GOP within the sequence of video picture data and then moves the start of the new GOP to coincide with the scene change by extending or decreasing a current GOP length according to whether the scene change and the start of a new GOP are within a predetermined number of pictures of each other. An apparatus for carrying out the method is also provided.

Abstract: A method and system for detecting and replacing spurious motion vectors in video signal compression includes determining whether a motion vector of a current macroblock is spurious by comparing the motion vector with motion vectors of motion vectors of neighbouring macroblocks; and replacing the motion vector as spurious if the difference exceeds a predetermined threshold. In particular, the method and system seeks to determine (72, 73) whether at least one cluster of motion vectors of neighbouring macroblocks can be formed; and if not, leaves (80) the motion vector of the current macroblock unchanged but if so determining (74) whether the motion vector falls within a cluster. The motion vector may be replaced (81) under certain criteria if the motion vector does not fall within a cluster of motion vectors of neighbouring macroblocks.