Patent ID: 8903087
Filing Date: 2014-12-02
Classification: H04L

Abstract:
1. A method for distributing a nominal audiovisual stream comprised of nominal coefficients to a recipient device comprising: Extracting and replacing, in the nominal audiovisual stream, at least one nominal coefficient among the nominal coefficients to generate a modified main stream having a same format as the nominal audiovisual steam; generating complementary information which forms a stream separate from the modified main stream; inserting the extracted nominal coefficient into the complementary information such that the nominal audiovisual stream may be reconstructed from the complementary information and the modified main stream; generating at least one copy of the complementary information; applying to each copy of the complementary information a different protection method to generate multiple sets of protected complementary information, each set of protected complementary information pertaining to a different conditional access method and each set enabling the nominal audiovisual stream to be reconstructed by substituting into the modified main stream the nominal coefficients contained in the complementary information upon application of an access method compatible with the protection method which has been used to protect the complementary information; and transmitting to the recipient device the modified main stream; determining the protection method pertaining to the recipient device, requesting the complementary information protected according to the determined protection method, and transmitting to the recipient device the protected complementary information pertaining to the recipient device.