Abstract: A method of deriving replacement block information, such as a replacement motion vector, for a lost or damaged image block in scalable video coding comprises combining information about neighbouring block information in at least the current layer and the corresponding and/or neighbouring blocks in at least one other layer, to derive said replacement block information.

Abstract: A method of approximating a motion vector for an image block, the method comprising retrieving motion vectors for neighbouring blocks, identifying a predominant value of at least one motion vector characteristic from the motion vectors for the neighbouring blocks, selecting those motion vectors for the neighbouring blocks which have a value which is the same or similar to said predominant value to form a group, and deriving an approximation for the motion vector for the image block from the selected group of motion vectors.

Abstract: A method of encoding a sequence of frames using 3-D decomposition, the method comprising dividing the frames into blocks and coding the blocks, wherein coding a current block comprises evaluating at least one neighbouring block in the same frame and making a determination about whether to code data in the region of the current block corresponding to a neighbouring block depending on the evaluation of said at least one neighbouring block.

Abstract: A method of encoding a sequence of frames for transmission comprises encoding a sequence of frames under different conditions to produce a plurality of encoded bit streams each representing the sequence of frames, for transmission at different bit rates, and storing each of the encoded bit streams in a respective buffer, and outputting a bit stream from a buffer for transmission, and the method further comprises switching between buffers to change the bit rate of the data for transmission, wherein at least one frame to be stored in one buffer is encoded with reference to a frame stored in another buffer.

Abstract: A method of encoding a sequence of frames using 3-D decomposition including temporal filtering and using intra-frame prediction/interpolation, comprises (a) a first stage of intra-prediction/interpolation in which any neighbouring blocks may be used; (b) evaluating the intra-prediction/interpolation of step (a) for each block to identify blocks for intra-frame prediction; (c) a second stage of intra-prediction/interpolation wherein blocks identified in step (b) are not used for intra-prediction/interpolation of other blocks.

Abstract: A method of approximating a motion vector for an image block comprises deriving a first set of vectors from motion vectors of neighbouring blocks in the same frame and the corresponding block and its neighbouring blocks in one or more preceding and/or subsequent frames, deriving a set of candidate vectors from one or more of motion vectors of neighbouring blocks in the same frame and the corresponding block and its neighbouring blocks in one or more preceding and/or subsequent frames, analysing said first set of vectors, and selecting one of the candidate vectors on the basis of the analysis.

Abstract: A method of approximating a motion vector for an image block, the method comprising retrieving motion vectors for neighbouring blocks, identifying a predominant value of at least one motion vector characteristic from the motion vectors for the neighbouring blocks, selecting those motion vectors for the neighbouring blocks which have a value which is the same or similar to said predominant value to form a group, and deriving an approximation for the motion vector for the image block from the selected group of motion vectors.