ADAPTIVE AND PROGRESSIVE AUDIO STREAM SCRAMBLING

PROBLEM TO BE SOLVED: To avoid fraudulent use of audio programs recorded in a memory or on a hard disk while preserving the auditory quality.SOLUTION: Audio sequences include a succession of frames, each of which includes at least one block grouping a plurality of coefficients corresponding to simple digitally coded audio elements. A process includes modifying at least one block of an original stream, in a manner adaptive to the original stream as a function of at least a part of characteristics representative of a structure, content and parameters of the original audio stream, a profile of recipient 8, and external events. The modification stage comprises replacing a part of the coefficients to produce on the one hand a main audio stream in nominal format and on the other hand complementary modification information that allows reconstruction of the original stream by a decoder of reception equipment.