Abstract: The invention concerns methods and devices for concealing artefacts induced by transmission errors in a video sequence transmitted over a network between a server and a client making it possible to avoid abrupt resynchronization following a transmission error. When an error is detected, a video stream is created from a first video stream not containing any error and data representing artefacts induced by that error. The influence of the data representing the artefacts diminishes with time such that the created video stream converges towards the video stream not containing any error. The creation of the video stream in which the effects due to a transmission error are progressively removed may be carried out by the server or by the client.

Abstract: The invention relates to a method of inserting a message in a sequence of digital images, characterized in that it comprises the insertion (S4), in the spatial domain, of at least one symbol of the message in at least one part of an image (In), said image being bounded between two images in which no symbol is inserted in their respective parts in spatial correspondence with said part.

Abstract: This method allows the transmission of coded data representing a sequence of digital images. A predetermined quantity of this data is stored in a buffer before transmission over a communication network. The method comprises a step of determining a subset of data in the buffer to be transcoded, as a function of at least one quantity representing the bandwidth available for the communication network.

Abstract: The method of sending at least one item of information relative to a multimedia data stream in a communication network is characterized in that it comprises the following steps carried out on a server device capable of sending the multimedia data stream over the network: obtaining at least one item of information relative to the data stream, said at least one item of information comprising an item of information on a visual quality of the multimedia data stream and an item of information on the bandwidth necessary for sending the stream with that visual quality, and sending said at least one obtained item of information over the communication network to a client device.

Abstract: A method of generating data representing a degree of importance of data blocks in a coded digital image of a digital video sequence coded in a hybrid predictive video coding format, said image being divided into a plurality of data blocks comprises, for the data blocks of the image, a step of determination of data representing the degree of importance of each of those data blocks on the basis of the coding or absence of coding of said data block, the determination also depending on the possible use of the data block considered for the coding of at least one data block of at least one other image of the video sequence. The invention also relates to a method of transmitting a coded video sequence.

Abstract: According to this method of temporal segmentation of a video sequence (200) containing one or more markers, the analysis of the content of these markers makes it possible to segment the video sequence into a plurality of video sub-sequences.

Abstract: A method for the prior monitoring of the detectability of a watermarking signal inserted by modulation in a set of coefficients representing for example a digital image. The method comprises the step of simulating a distortion on the set of modulated coefficients, the distortion corresponding to a given compression level of the set of coefficients before modulation, determined by optimisation of a ratio of transmission rate to distortion. The method further comprises the step of calculating a detectability test on the set of modulated coefficients after distortion, and a step of comparing the detectability test with a threshold detection value. The method is used notably for inserting a watermarking signal during the compression of a digital image.

Abstract: The method of verifying multimedia entities according to the invention to determine whether a first multimedia entity matches a second multimedia entity, is characterized in that it comprises a step of selecting from a plurality of second multimedia entities, by a content-based search, a set of second multimedia entities close to the first multimedia entity, and a step of deciding as to at least one match between the first multimedia entity and at least one second multimedia entity of the set of second multimedia entities, based on a comparison between the first multimedia entity and the second multimedia entities of the set.

Abstract: The invention concerns a method of inserting a message in an image, the message comprising binary symbols which are each referenced by an index, characterized in that it comprises, for a coefficient (Yn) of the image, the steps of:

Abstract: According to this method of temporal segmentation of a video sequence (200) containing one or more markers, the analysis of the content of these markers makes it possible to segment the video sequence into a plurality of video sub-sequences.

Abstract: The invention relates to a method of inserting a message in a sequence of digital images, characterized in that it comprises the insertion (S4), in the spatial domain, of at least one symbol of the message in at least one part of an image (In), said image being bounded between two images in which no symbol is inserted in their respective parts in spatial correspondence with said part.

Abstract: A method for the prior monitoring of the detectability of a watermarking signal inserted by modulation in a set of coefficients (b) representing for example a digital image (I), comprises a step (E44) of simulating a distortion on the set of modulated coefficients (Xjs), the distortion corresponding to a given compression level of the set of coefficients before modulation, determined by optimisation of a ratio of transmission rate to distortion; a step (E45) of calculating a detectability test (ts) on the set of modulated coefficients after distortion; and a step (E47) of comparing the detectability test with a threshold detection value (T).

Abstract: The invention relates to a method of inserting a message into digital data representative of physical quantities, the message including ordered symbols, including the steps of: