Abstract: A method of determining the coding parameters of a variable-resolution video stream by a video coder, said video stream including multiple resolution layers and being compressed so as to be transmitted at a given rate or a given quality through a heterogeneous network to multiple users, said method including a classification step to associate each resolution level with a group of users and to determine the optimal coding parameters for each resolution level as a function of the requirements of each group of users.

Abstract: A method and interactive system for the on-line transmission of a high-resolution video sequence composed of a succession of T images includes a step of selecting relevant images comprising at least the following steps: split each image to be transmitted at the instant t into a number N of zones, for each zone n determined in the previous step, calculate a value representative of the content of said zone, for each image to be transmitted, generate a vector representative of the content of said image containing the values obtained in the previous step, calculate a normalized coefficient of correlation ? between the reference vector determined for a previously selected image and that calculated for the current image, make a decision on the selection (or not) of the current image as a function of the value of the normalized correlation coefficient ?.

Abstract: A method is provided for visually encrypting at least one part of an at least partially compressed video stream or video sequence, it being possible for said stream to be decomposed into a first type of objects and a second type of objects, the method being applied on each of the images contained in a video sequence, including at least the following steps: analyzing the sequence in the compressed domain so as to define for a given image N at least one first group of objects to be protected by visual encryption and a second group of objects, the transformed coefficients and the motion estimation vectors being transmitted directly to step d) of compression, predicting on the basis of the data arising from the analysis in the previous step of the compressed image N, the position of the objects for a following image N+1, determining the splitting into slices or into groups of slices of the image N+1, compressing the first group of objects of the image N+1 and ciphering at least one part thereof, transmitting t

Abstract: Method of determining the coding parameters of a variable-resolution video stream by a video coder, said video stream including multiple resolution layers and being compressed so as to be transmitted at a given rate or a given quality through a heterogeneous network to multiple users, said method including a classification step to associate each resolution level with a group of users and to determine the optimal coding parameters for each resolution level as a function of the requirements of each group of users.

Abstract: A method and interactive system for the on-line transmission of a high-resolution video sequence composed of a succession of T images includes a step of selecting relevant images comprising at least the following steps: split each image to be transmitted at the instant t into a number N of zones, for each zone n determined in the previous step, calculate a value representative of the content of said zone, for each image to be transmitted, generate a vector representative of the content of said image containing the values obtained in the previous step, calculate a normalized coefficient of correlation ? between the reference vector determined for a previously selected image and that calculated for the current image, make a decision on the selection (or not) of the current image as a function of the value of the normalized correlation coefficient ?.

Abstract: A method is provided for visually encrypting at least one part of an at least partially compressed video stream or video sequence, it being possible for said stream to be decomposed into a first type of objects and a second type of objects, the method being applied on each of the images contained in a video sequence, including at least the following steps: analyzing the sequence in the compressed domain so as to define for a given image N at least one first group of objects to be protected by visual encryption and a second group of objects, the transformed coefficients and the motion estimation vectors being transmitted directly to step d) of compression, predicting on the basis of the data arising from the analysis in the previous step of the compressed image N, the position of the objects for a following image N+1, determining the splitting into slices or into groups of slices of the image N+1, compressing the first group of objects of the image N+1 and ciphering at least one part thereof, transmitting t

Abstract: A method and system is provided of protecting at least one part of a video stream or of a compressed video sequence against a violation of the information contained in said stream, said stream being able to be broken down into at least one first type of objects and one second type of objects, the method being applied to a selection of images contained in said video sequence, characterized in that it comprises at least the following steps: analyzing the video sequence in the compressed domain so as to define for a given image N at least one first type of objects to be protected by encryption and one second type of objects, the analysis module which identifies the portions of the image belonging to the first type of objects to be protected sends the motion estimation vectors and the transformed coefficients to the encryption step; determining, according to the breakdown into portions or into groups of portions of the existing image N, those corresponding respectively to the first type of objects to be protected