FIELD: physics.
SUBSTANCE: said utility invention relates to systems and a method of partial scrambling of a data flow. A method of partial scrambling of data flow (6) including packets (7) of a transport stream having an overhead (8) and payload (9) is proposed; payloads carrying coded data elements being mapped to sections of network adaptation layer (NAL) (15). The method involves: selection of transport stream packets (7) forming a subpattern of the said pattern, and scrambling of at least part of payloads (9) of each transport stream packet (7) in the subpattern, monitoring of payloads (9) of some of transport stream packets (7) in the pattern, for the presence of data (22) showing the boundary between two subsequent NAL sections (15), and, for selected NAL sections (15), inclusion in the subpattern of at least one of transport stream packets (7) carrying data forming part of selected NAL section (15); while the subpattern is included up to some maximum number of the transport stream packets following the first transport stream packet that carries data forming part of selected NAL section (15).
EFFECT: provision of scrambling of payloads of several transport stream packets selected and maintaining efficient content protection.
10 cl, 5 dwg
