Abstract: The present invention relates to a device and a method for the preparation of data to be sent as a continuous stream via a communication network. The device comprises means for obtainment of the data originating from a database, which contains at least two data stream entities for data associated respectively with different transmission throughputs, means of transfer of these data to a sending system, means of connection to one of these entities, and means of switching of the means of connection from one of the entities to another. The preparation device also comprises means of regular addition to the data transferred, of error correction codes.

Abstract: The method, for the determination of the coding mode of a macroblock constituted of picture blocks, carries out a pre-selection of intra directional predictive coding modes of macroblock blocks according to the following steps: calculation of the activities gradient of a block in the prediction directions, pre-selection of intra directional coding modes of a block for which the directions correspond to the activity or activities gradient of minimum value.

Abstract: The method comprises the following steps: calculation of the spatial activity of each macroblock and of the temporal activity between the macroblocks constituting a group of macroblocks in field mode, calculation of an activity index relating to the group that is an increasing function of the temporal activity and a decreasing function of the spatial activity of the group, comparison of the activity index relating to the group, to a predefined threshold, to define it as a group having activity, coding of the picture in field or frame mode according to the number of macroblock groups detected having activity with respect to the number of groups of macroblocks in the picture. The application relate to data compression, particularly the H 264 standard.

Abstract: The invention relates to a method for coding a video content comprising a sequence of pictures and at least one logo. It comprises the following steps: —coding the sequence of pictures by a first coding method, this step generating coded data relating to the sequence of pictures; —coding the logo by a second coding method and additional information relating to the logo, the additional information comprising at least information relating to the positioning of the logo in the pictures of the sequence, this step generating coded data relating to the logo; and —generating a single data stream comprising separately the coded data relating to the logo and the coded data relating to the sequence of pictures.

Abstract: The invention relates to a method of locally adjusting a quantization step for each region of an image in a sequence of n images. The method comprises the following steps: calculating, for each image of the sequence, a first difference of bits saved on the potential masking region when quantizing it with a first quantization step and a second difference of bits required by the region of interest when quantizing it with a second quantization step; and in each image of the sequence, assigning to the potential masking region the first quantization step and if the sum of the n first differences of bits is higher than the sum of the n second differences of bits, assigning said second quantization step to said region of interest and otherwise assigning a third quantization step such that the sum of said n first differences of bits is distributed between the regions of interest according to a reconstruction quality criterion.

Abstract: The present invention relates to a device and a method for the preparation of data to be sent as a continuous stream via a communication network. The device comprises means for obtainment of the data originating from a database, which contains at least two data stream entities for data associated respectively with different transmission throughputs, means of transfer of these data to a sending system, means of connection to one of these entities, and means of switching of the means of connection from one of the entities to another. The preparation device also comprises means of regular addition to the data transferred, of error correction codes.

Abstract: The invention relates to a method for generating from a sequence of at least one source image, called source sequence, a sequence of at least one reduced image, called reduced sequence, the at least one reduced image having a size smaller or equal to the size of the at least one source image. The at least one reduced image is generated by extracting from the at least one source image at least one image part whose size and position depend on the perceptual interest of the pixels comprised in the at least one image part.

Abstract: Constant-bitrate rate control is very useful for real-time video transmission. However, it is difficult to realize a good CBR rate control in an MPEG4-AVC video codec. According to the invention, an adapted ?-domain rate control processing for real-time rate control is applied, whereby ? is the percentage of zero amplitude transform coefficients following quantisation. A couple of tables are used for mapping between the quantization parameters and ?. A detailed analysis at transform-level is carried out in order to get the slope of the relationship between the bitrate and ?. The slope of the linear model is constrained by a look-ahead procedure with respect to the neighbour frames or blocks.

Abstract: Device and method for inserting error correcting codes and for reconstructing data streams, and corresponding products The present invention relates to a device (1) for inserting error correcting codes into data streams (11) intended to be sent in packets in a network (8), a device (9) for reconstructing data streams (13), and corresponding methods and products. The insertion device comprises a unit (3) for identifying resynchronization indicators dispersed in the data streams and a unit (4) for determining successive segments in these streams, the segments forming partitions of the data lying between two consecutive resynchronization indicators. It also comprises a unit (6) for allocating a set of error correcting codes to each of these segments, these sets of codes having decreasing sizes between any two of the consecutive resynchronization indicators. Preferably, the device also comprises a data interleaving unit (7).

Abstract: The present invention relates to a device and a process for adjusting the bit rate of a stream of contents as a function of processing capabilities of at least one receiver. These contents are transmitted by a sender to the receiver according to a communication protocol providing for a return transmission of reception data of the contents by the receiver to the sender, including at least one parameter relating to conditions of communication of these contents in the network. The device comprises a module for estimating a required level for the bit rate as a function of information relating to these capabilities and a writing module modifying this parameter, to transmit, in return, to the sender stream adjustment cues capable of bringing about a modification of the bit rate in relation to the required level. Application to streaming.

Abstract: A process for evaluating the quality of coded images (e.g., two video sequences) uses a homogeneous motion vector field and psychovisual filtering to take into account Human Visual System (HVS) characteristics to calculate the error between the two video sequences.

Abstract: The method of distributing encrypted portions of an audiovisual programme to user terminals, in which the successive portions of the programme are encrypted with the aid of different keys, consists, on initiation, from a user terminal, of a telephone communication with a call centre, in transmitting in sequence from this call centre and during the telephone communication the keys to the user terminal, doing so in a manner synchronized with the distribution of the successive encrypted portions of the programme.

Abstract: The present invention relates to a device for compressing a source image by means of a base layer, coding a base image, and of an enhancement layer, coding a residual existing between the source image and the base image, the source image and the base image being structured as blocks of pixels. According to the invention, such a device is characterized in that it comprises means for generating the enhancement layer of a block as a function of the quality of restitution of this block, determined by comparing the coding of this block in the source image with the coding of this block in the base image, and/or as a function of information coded by this block of pixels.

Abstract: The present invention relates to a system and a method of security for a firewall. The system comprises means of communication with an application provided to make connections via the firewall, means of identifying at least one delegation parameter supplied by this application, provided to recognize this application as capable of establishing connections when the delegation parameter complies with at least one reference parameter and command means for establishing connections, based on requests originating from this application. The security system also comprises means of producing the reference parameter, including means of automatic generation and/or command means for automatic distribution, to a list of permitted users, of the reference parameter. It is thus possible to communicate in advance to users the reference parameter to be supplied as the delegation parameter.

Abstract: A process and device for coding video images using a non object-based coding standard that extracts at least one video object from an image originating from a sequence of images, by the construction of a segmentation key defining the contours of the object in the image. The video object is coded according to the MPEG 2 standard so as to form an elementary stream (ES). The segmentation key relating to the video object is coded according to the MPEG 2 standard, so as to form an elementary stream. A background image into which the object is to be inserted is coded according to the MPEG 2 standard, so as to form an elementary stream. The elementary streams relating to one or more objects and to the background image are multiplexed so as to provide a program stream (PS) or transport stream (TS) according to the MPEG 2 standard.

Abstract: The method is characterized in that it comprises: a step of reducing the binary train (2) consisting in deleting one or more video packets from the binary train so as to provide a reduced binary train, a step of implementing an error masking algorithm on the reduced binary train (3) so as to calculate a corrected degraded local decoded image which is the image reconstructed on the basis of the reduced binary train and of the masking algorithm, a step of validation (4) for validating or not the reduction in the binary train as a function of the quality of the corrected degraded local decoded image, a step of selection (2) of the reduced binary train or of the binary train, depending on whether or not there is validation.

Abstract: Device and method for inserting error correcting codes and for reconstructing data streams, and corresponding products

Abstract: The invention relates to a process for compressing digital data of a sequence of synthesis images describing a scene which is the subject of a script, comprising a processing step for modelling the scene on the basis of mathematical data, a step of image rendering for creating a synthesis image from this modelling and a partitioning of this synthesis image into image blocks, differential coding of the current image block on the basis of a block of at least one synthesis image, this block being defined on the basis of at least one motion vector, so as to provide a residual block, characterized in that the motion vector is calculated from mathematical data emanating from the synthesis script and defining the apparent motion of the various objects constituting the scene which is the subject of the sequence. Applications are image synthesis in production. For video games, these are for example interactivity or virtual reality applications.

Abstract: The invention relates to a method of image compression, especially of the MPEG2 type, in which the images are coded according to groups (GOPs) each of which comprises N images, with an I image coded in intra mode, P images predicted as a function of the intra image I or of the preceding P image, each P image being preceded and followed by n bidirectionally predicted B images, n possibly being zero. The number M=n+1 represents the structure of the group. At least one parameter characterizing the source images which are to be coded according to a group is determined using a test coding (70), and the numbers N and M are made to depend on this parameter or these parameters. In the course of the test coding, defined values are conferred on N, M, and on the quantisation interval Q.

Abstract: This process to convert frames into frames with a larger format is characterized in that it carries out a motion estimation (5) of the current frame relatively to a previous extended view, it compensates in motion (6) the previous extended view relatively to the current frame, it updates the previous extended view (7) by taking into account data from the current frame to give an updated extended view becoming the previous extended view for the motion estimation of the next current frame, it completes the current frame (8) with data from the up-dated extended view to provide the frame with a larger format. The applications concern the 4/3 to 16/9 TV format conversion for 16/9 TV sets.