device for converting mpeg-2 multimedia and audiovideo content in secure content of the same type

摘要

The invention relates to method of distributing video sequences according to a nominal stream format, said sequences consisting of a succession of images with each image comprising a succession of blocks. At least one of the blocks of one of the images is calculated by predicting motion in relation to at least one reference image, said motion prediction being encoded in the stream with at least one motion vector. Before transmission to the client equipment, the aforementioned stream is analysed in order to generate (i) a first modified stream having the format of a nominal stream and comprising images modified by the substitution of certain data by data of the same type and (ii) a second stream having any format and comprising the substituted data and the digital information which can be used to reconstruct the modified stream. The two streams thus generated are then transmitted separately from the server towards the destination equipment. Moreover, a synthesis of a stream with the nominal format is calculated on the destination equipment, for the above-mentioned stream, as a function of the first stream and the second stream. The invention is characterised in that the modification consists in modifying at least one of said motion vectors.