Abstract: The invention concerns a method for coding an original mesh representing a three-dimensional object, which consist in determining a simple meshing having a reduced number of defined faces each defined by vertices and edges, then coefficients in a wavelet base of a function whereof said source mesh is the image defined on said simple mesh, so as to supply successive refined meshes. The method is characterized in that each of the faces of said meshes is subdivided into a limited number of facets to form the higher level mesh, the subdivisions of said surface corresponding only to those required for observing an affinity condition of said function of said face. The invention also concerns the corresponding method for reconstructing the mesh.

Abstract: The video component(s) of a digital audio-visual first program are switched onto the video components of a second digital, audio-visual program by (1) switching onto the video component of the second program, subsequent to the switch command and to the end of a picture of the first program, and (2) replacing, as seen in the order of transmission, each non Intra picture of the component of a second program, with a picture having coding performed independently of (a) the picture data of the replaced picture and (b) of the contents of the pictures to which it refers until the beginning of the next Intra picture of the component of the second program.

Abstract: A data signal for modifying a graphic scene displayed on at least one terminal, the graphic scene mode of a set of graphic objects and each object defined by at least one field. The data signal includes frames containing information for updating the graphic scene. Some of the frames also contain a command to completely replace the graphic scene with a new scene. Further, a method of transmitting a data signal to modify a graphic scene displayed on a terminal. Also, a terminal for displaying a graphic scene, the terminal processing a signal for modifying the graphic scene.

Abstract: The invention concerns a method for synchronising a video image (IM) spatial position to find the position of an initial digital coding grid (GI), by said image (IM) coding blocks, characterised in that it consists in the following steps: a) moving along the direction of the image (IM) lines and/or along the direction perpendicular to the image (IM) lines, an analysis grid (GA) consisting of coding blocks and corresponding to at least part of the image (IM); b) determining for each position of the analysis grid (GA), the transformed coefficients Fu,v of each block of the analysis grid (GA), using a discrete cosine transform (TCD); and computing for each analysis grid (GA) position, an activity parameter (AM, ES) representing the image activity; c) determining the analysis grid (GA) position for which said activity parameter (AM, ES) has a minimal value.

Abstract: The quality of service in a digital television link is monitored cyclically by means of an analyzer which analyzes the transport stream packets to deduce therefrom many standardized analysis parameters which are complex to interpret. The invention minimizes the number of measurements of these parameters by preselecting first and second analysis parameters and periodically determining a first maximum for variations from the first selected parameters and a second maximum for variations from the second parameters selected to deduce therefrom, respectively, a first parameter which is representative of the synchronization relative to the equipment units in the link and at least one second parameter which is representative of a degradation in a link.

Abstract: The invention concerns a metrological device (200) for monitoring an upline broadcast signal comprising a main component and upline control data. The metrological device (200) includes an extraction circuit (220) for extracting the upline control data from the upline broadcast signal and delivering an upline instruction, and a measuring circuit (230) for measuring a parameter of the upline broadcast signal according to the upline instruction and delivering a measurement result. In accordance with the invention, the metrological device (200) also includes: a control circuit (250) for producing a downline instruction from the measurement results and an upline result produced by the extraction circuit (220) from the upline control data, an insertion circuit (240) for producing a downline signal to broadcast comprising firstly the main component of the upline broadcast signal and secondly the downline control data containing the downline instruction.

Abstract: First digital audio-visual program video component(s) are switched on a second digital audio-visual program video component(s) by switching on the beginning of the first set of images including an Intra-coded picture of the second program video component encountered after the switching command. In the transmission order of images, each bidirectionally predictive-coded picture of the first set of images referring to the set of images pertaining to the set of images preceding it before switching, is substituted for a bidirectionally predictive-coded picture of the video coding which is produced independently of (1) the substituted image content and (2) the contents of the images to which it refers.

Abstract: The invention relates to a signal intended to be transmitted towards a plurality of receivers, of the type comprising at least two source signals and consisting of a plurality of independently modulated substantially orthogonal carrier frequencies distributed over a predetermined frequency band. According to the invention, the frequency band is divided into at least two frequency sub-bands each comprising a set of the substantially orthogonal carrier frequencies, and to each of the sub-bands is allocated one of the source signals, so that a receiver may retrieve from the transmitted signal, by filtration, at least one of the sub-bands and perform demodulation processing only on the carrier frequencies contained in the retrieved sub-bands. The invention also relates to a transmission process as well as to a receiver of such signal.

Abstract: The invention concerns a method for continuously controlling the quality of distributed digital sounds broadcast by radio or television on a digital channel. The method consists in temporally breaking down the digital signal into sequences of samples; carrying out a spectral analysis of each sequence to observe the variations in energy and envelope of the digital signal and calculating a global quality index; and in calculating on the basis of the global quality index, a final gated and continuous quality index representing the quality of the digital signals. The invention is applicable to the continuous control of the quality of distributed sounds.

Abstract: A method for encoding a digital image for producing a bit stream representing the image, the bit stream length depending on the quality of the desired representation, consisting in: a) defining, on the domain of the image to be encoded, a hierarchical meshing comprising a plurality of nested meshes whereof the mesh peaks are the image pixels; b) determining for each mesh of the hierarchical meshing, a brightness variation between the image to be encoded and an interpolated image obtained from the nested meshing peaks whereto pertains the mesh concerned; and c) inserting in the bit stream position, brightness and chrominance values of the peaks of meshes whereof the brightness variation is higher than a threshold variation useful for encoding fixed or animated images with speed reduction.

Abstract: A method and device for monitoring the quality of distributed digital images coded by blocks of pixels in which a false contour phenomenon may be generated when the image is reproduced. An image average for pixels represented by at least one luminance respectively chrominance components is calculated and a false contour effect on the basis of a criterion for discriminating the luminance or chrominance component difference between adjacent pixels of adjacent groups of pixels is detected in at least one reference direction of each current image. A visibility coefficient of at least one current image is calculated from the value of the image average speed vector and psycho-visual criteria relating to the existence of the false contour effect in the reference direction.

Abstract: The invention relates to a method of controlling equipment for monitoring the quality of digital television signals comprising a data stream organized into frames. It comprises the following steps: a) selecting a reference time signal (PCR) in the data stream; b) on the basis of the reference time signal (PCR), generating a multibit digital clock signal (MTS) whose phase is servo-controlled from said reference time signal (PCR) and whose count is deduced unambiguously from the count of a time base (STC) generated during initial encoding of the digital television signals; and c) transmitting at least meaningful bits of the digital clock signal (MTS) to the measurement equipment synchronously with an analog video frame synchronizing signal (STV) as decoded from the data stream so as to generate a measurement triggering signal (MSTC).

Abstract: The invention relates to a data signal for animation of a graphic scene to be used by means for constructing images that can be displayed on at least one screen, a signal in which the scene is described in the form of a set of animation objects, each of which is associated with at least one characterization field defining a parameter of the object, comprising at least one quantization object, for which the characterization fields define the quantization rules for the characterization fields of the animation objects, each applicable to at least two distinct characterization fields, such that most or all of the characterization fields of the animation objects with a numeric value can be quantized. The invention also relates to the corresponding process and device.

Abstract: The invention concerns a method and a system for assessing the quality of a broadcast digital signal. A reference signal (sref) is generated (1001) from an initial signal (so) and jointly broadcast (1002) with a digital signal (sn). At reception level, the broadcast digital signal and reference signal received (snr, sref) are synchronized (2001) and a value D of the distance between the reference signal and the digital signal (snr, sref) is computed (2002) for assigning (2003) a quality value Q. The invention is applicable to the broadcast of audio and/or video digital signals.

Abstract: The invention concerns a graphic scene animation data signal, designed for means constructing images capable of being displayed on at least one screen, said graphic scene having probably been loaded in said means constructing images, in the form of a set of objects, some of said objects at least having its own particular identifier, said signal comprising: a single animation mask, delivered as preamble to said animation, and assigning at least one of said objects to an elementary mask comprising: said object identifier, as defined in said graphic scene to be animated; and the designation of at least one dynamic characterization field of said object, representing a characteristic of said object capable of being modified; animation frames, comprising, according to the order defined by said mask, data updating said object dynamic characterization fields, so as to modify them, said constructing means decoding said animation mask data, and initializing the animation of the basis thereof, and updating the scene on

Abstract: A method for estimating an interference phase shift when receiving a multicarrier signal formed of a time series of symbols modulating a plurality of carrier frequencies, at least some of the carrier frequencies of at least some of the symbols bearing reference elements, whereof the value at transmission level is known by the receiver carrying out the reception. The phase variation &dgr;n between at least two symbols bearing reference elements is estimated by analysing the reference elements. Each of the reference elements in the estimation is weighted by information representing the noise affecting the carrier frequency bearing the reference element.

Abstract: The quality of service in a digital television link is monitored cyclically by means of an analyzer which analyzes the transport stream packets to deduce therefrom many standardized analysis parameters which are complex to interpret. The invention minimizes the number of measurements of these parameters by preselecting first and second analysis parameters and periodically determining a first maximum for variations from the first selected parameters and a second maximum for variations from the second parameters selected to deduce therefrom, respectively, a first parameter which is representative of the synchronization relative to the equipment units in the link and at least one second parameter which is representative of a degradation in a link.

Abstract: A method for the time synchronization of a multi-carrier signal receiver consisting of a sequence of symbols each formed by a plurality of carrier frequencies. Each carrier frequency is modulated by a modulation coefficient. The position of some of said carrier frequencies in the time-frequency space is known to the receiver, and said frequencies are reference carrier frequencies. Each reference carrier frequency bears a reference coefficient with a value that is known to the receiver. The method includes a fine synchronization step, wherein the signal transmission channel impulse response is estimated on the basis of reference coefficients belonging to at least two received symbols. The beginning of the useful portion of each of the symbols is determined, and/or a receiver clock is controlled by analyzing the estimate of said impulse response.

Abstract: The invention relates to a method and to a system for measuring the quality of digital television signals comprising a data stream, the method including measuring quality and producing measurement signals that are representative of quality. The method comprises the following steps: a) selecting a reference time signal (PCR) from the data stream; b) generating a multibit digital clock signal (STC′) from the reference time signal, the phase of the clock signal being locked on the basis of the reference time signal (PCR) and its count being deduced unambiguously from the count of an initial time base (STC); and c) labelling the measurement signals with at least some of the bits (HDT) of the digital clock signal that are meaningful given the nature of the measurements performed.

Abstract: A method and an equipment for allocating to a television program, which is already conditionally accessed, a complementary conditional access. The television program is first received by means provided with access entitlements and the control words are restored. Complementary access control messages and complementary entitlement management messages corresponding to a complementary access control system are built up. The initial unmodified television program is rebroadcast, together with the complementary messages related to the complementary access control system.