France Telecom

Yann Bodo

Nathalie Laurent

Christophe Laurent

The invention relates in particular to a method of scrambling a video signal using an encryption key for controlling access to audiovisual information. The video signal is scrambled by applying a tattooing function to the video signal by using a marking key derived from the encryption key, the tattooing function including a parameter for regulating the amplitude of tattooing so as to enable the visibility of the tattooing in the video signal to be adjusted. The invention also provides a dual unscrambling method, and a system, an encoder, a decoder, a broadcast server, and a data medium for implementing said methods.

Methods of scrambling and unscrambling a video signal, a system, an encoder, a decoder, a broadcast server, and a data medium for implementing the methods

This method comprises the following steps of applying a watermarking function to motion vectors calculated by estimation of movement between images of a video signal, followed by a step of generating the watermarked video signal by compensating movement with the aid of the watermarked motion vectors. The watermarking function is applied by marking the coordinates of the selected motion vector in a reference space, certain portions of this space constituting a first zone and the other portions of this space constituting a second zone complementary to the first, assigning a binary value to each of the two zones, and, if necessary, modifying the coordinates of the selected motion vector so that it is in the zone whose binary value corresponds to a bit of a marking key associated with the selected motion vector.

System and method of watermarking a video signal and extracting the watermarking from a video signal

A method for the watermarking of a sequence of video images implements a step for the insertion of at least one watermarking bit into at least one motion vector obtained by motion estimation between two images of said sequence, so as to obtain at least one watermarked motion vector. The motion vector is identified by its coordinates in a reference space, partitioned into two types of complementary zones, each having a distinct binary value associated with it. The insertion step implements, if necessary, a modification of the coordinates of said motion vector so that it is located in a binary value zone corresponding to said watermarking bit to be inserted. During said modification, at least two potential watermarked motion vectors are determined and, from among said potential watermarked motion vectors, an optimal watermarked motion vector is selected according to at least one predetermined criterion, so that the modified coordinates of said motion vector are those of said optimal watermarked motion vector.

Method for the watermarking of a video sequence with adaptive selection of the watermark insertion zone, corresponding detection method, devices, data carrier and computer program

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Rennes, France

Yann Bodo