Compression of motion vectors

A process according to any of the above claims, where the channel is a fixed data channel, comprising the further step of determining the current available capacity of the channel, and transmitting the lower significance part where permitted by the current available capacity.

A process for reducing the data rate of motion vector information, in which the components of the motion vectors are quantised, the quantised values are compressed and transmitted and the quantisation errors are additionally transmitted, whenever sufficient channel capacity is available.

A process according to any of the above claims, in which the motion vectors are compressed using run length coding.

A process according to any of the above claims, in which the motion vectors are scanned using a scanning pattern designed:

• to increase the expected run lengths of quantised motion vectors.

A process according to any of the above claims, in which the quantised vectors are transmitted by run-length encoding in descending order of frequency of occurrence.

A process for reducing the data rate of motion vector information, in which the motion vectors are run length coded using a scanning pattern designed to increase the expected run lengths.

A process for reducing the date rate of motion vector information, in which the motion vectors are labelled in descending order of frequency of occurrence and run length encoded.

A process for reducing the average data rate of motion vector information, in which the components of the motion vectors are separately or in combination compressed losslessly using a spatial transform followed by, a variablelength encoder.

A process for reducing the average data rate of motion vector information, wherein each region of each picture in a received picture signal has a plurality of motion vectors, each vector associated with a different coding mode, comprising transforming the vectors to equivalent velocity measures and applying a linear transform to the velocity measures.

A process according to any of the preceding claims, in which the motion vector information input is the difference between a motion vector and a selected representative vector and in which the representative vectors are separately encoded.

A method of compressing motion vectors which derive from a process of motion measurement which comprises the identification of a number of candidate vectors and the preliminary assignment of one or more of said candidate vectors to specific picture elements, the method of compressing comprising the steps of defining said candidate vectors as a set of representative values and quantizing the assigned vectors with reference to said set of representative values.

A video signal processor comprising an input for receiving a picture signal, a generator for generating from the picture signal an information signal for use in subsequent encoding of the picture signals, the information signal comprising at least motion vectors, a quantiser for quantising the motion vectors, means for dividing each of the quantised values into a part having higher significance and a part having lower significance, and means for transmitting the values such that at a low transmission channel capacity, only the higher significance parts are transmitted.