ADAPTIVE AND PROGRESSIVE VIDEO STREAM SCRAMBLING

摘要

The invention relates to a method of distributing digital video sequences according to a nominal stream format, said sequences consisting of a series of frames. Each of the aforementioned frames comprises at least one block containing numerous coefficients that correspond to simple digitally-encoded visual elements. The inventive method comprises a modification step, whereby at least one block of the original stream is modified. The invention is characterised in that, during the aforementioned modification step, the original stream is modified in an adaptive manner according to at least one part of the characteristics representative of the structure, contents and parameters of the original video stream, the profile of the recipient and external events. In one particular embodiment, the modification step consists in replacing one part of said coefficients in order to produce (i) a main video stream with the nominal format and (ii) complementary modification information which enables the original stream to be reconstructed by a decoder belonging to the recipient equipment. The range of said modifications is variable and determined by the above-mentioned representative characteristics. The invention also relates to a system which is used to implement the inventive method.