Abstract: A method and device for transmitting data packets from a server to at least one client concerns i) estimating a time lapse between the transmission of a successive first and second packet, on the basis of information relating to the first packet, the information being representative of whether or not the first and second packets transport image data from the same image, and ii) triggering and defining retransmission of the second packet, on the basis of said time lapse. In one embodiment, the client estimates the time lapse on the basis of the type of the second packet and on the basis of statistical results concerning the type of the second packet and requests the retransmission of a packet awaited for a longer time than that time lapse.

Abstract: The invention relates to a method and to a device for determining the value of a delay to be applied between sending a first dataset and sending a second dataset, the data being representative of a sequence of coded images, the datasets consisting of data subsets, the coded images being coded according to a first level of resolution and at least a second level of resolution higher than the first level of resolution, the data subsets containing data of a first level of resolution. According to the invention: first and second datasets are obtained (E506); and the value of the delay is determined (E507), the value of the delay being dependent on the number of decoded images that can be formed from the data subsets of the first dataset which contain data of the second or of a second level of resolution.

Abstract: The method of scalable coding of moving images using at least one reference image for at least one image to code, comprises, at least on passing, for a so-called “current” image, from an initial quality level to an intended quality level different from the initial quality level: a step (705) of coding the current image as far as the intended quality level to provide a coded current image, a step (710) of reconstructing the current image at the intended quality level to provide a reconstructed current image of intended quality level, a step (715) of obtaining at least one reference image of the current image at the initial quality level, to provide a prediction image for the initial quality level, a step (720, 725) of determining a differential texture refinement depending on the prediction image for the initial quality level and on the reconstructed current image of intended quality level and a step (730) of coding the differential texture refinement.

Abstract: The present invention relates to a method of forming transport packets for transmitting, from a server device to at least two client devices, data representative of a coded image sequence, the coded data being encapsulated in transport packets comprising a first portion composed of a plurality of fields and a second portion. The method comprises the steps of obtaining (E40) a routing cue for each client device, of forming (E43) at least one transport packet on the basis of coded data, and of modifying (E45) at least one field of the first portion of each transport packet formed as a function of at least one routing cue obtained. The invention also relates to an associated device for forming packets, a transfer method and devices and a method and device for receiving transport packets formed according to the method briefly described above.

Abstract: For decoding a scalable video stream, in which the images may be decoded by groups of several images, each group being constituted by at least three levels of image temporal hierarchy, the images of the lowest level having the lowest time frequency and the images of each following level having a time frequency at least twice that of the images of the preceding level, a temporal hierarchy level being formed by at least one predetermined time interval, a time interval separating two images in that temporal hierarchy level: during the decoding of at least one temporal hierarchy level, at least one item of information is obtained representing a parameter relative to the content of the video stream over at least one time interval, and an order in the decoding of the images of each group of images is defined as a function of said information obtained.

Abstract: The invention relates to a method and to a device for determining the value of a delay to be applied between sending a first dataset and sending a second dataset, the data being representative of a sequence of coded images, the datasets consisting of data subsets, the coded images being coded according to a first level of resolution and at least a second level of resolution higher than the first level of resolution, the data subsets containing data of a first level of resolution. According to the invention: first and second datasets are obtained (E506); and the value of the delay is determined (E507), the value of the delay being dependent on the number of decoded images that can be formed from the data subsets of the first dataset which contain data of the second or of a second level of resolution.

Abstract: The invention concerns a method of processing a video sequence and an associated device. In relation to the sequence, at least one digital image is compressed by temporal prediction from a plurality of reference images resulting from a plurality of different reconstructions of the same image. The decoding then provides the steps of: obtaining reconstructions of a first image, that were used as reference images for the temporal prediction of at least one other image in the sequence; and combining said reconstructions obtained so as to obtain, for at least part of said first image, at least one display value.

Abstract: The present invention concerns a method and a device (10, 20) for processing a video sequence (101) comprising a series of images composed of blocks, et comprising the steps of: generating (511, 603) a plurality of different reconstructions of at least the same first image (I-1) in the sequence, so as to obtain a respective plurality of reference images (402-413, 517, 518, 610, 611); predicting (505, 606) a plurality of blocks (Bk, 414-416) of the said current image, each from one of said reference images; and processing jointly, for at least two blocks spatially close in the current image and predicted from the same reference image, prediction information (IPk) relating to this reference image.

Abstract: The invention concerns a method and a device (10, 20) for processing a video sequence (101) constituted by images composed of blocks of coefficients, and comprising the steps of: generating (511) first and second reconstructions (402 to 413) of a (same) first image, to obtain first and second reference images (517), the second reconstruction implementing, on a coefficient of a block, a different operation to that of the first reconstruction, predicting (505) a part (414, 415, 416) of said current image (401) on the basis of one of the reference images, wherein the second reconstruction comprises: the obtainment, for a block of the first image, values (Wi) calculated on the basis of the block coefficients and representing spatial frequency information; the selection of a coefficient according to these calculated values, to apply to it said different operation and obtain said second reference image.

Abstract: The invention in particular concerns a method and a device for estimating a level of use of a communication network linking a server and at least one client, said communication network being used to transmit a data stream at a transmission rate corresponding to the temporal frequency of said data stream, said data stream comprising at least one item of information characterizing a theoretical rate dependent on said transmission rate of said data stream. After having obtained (121) said theoretical rate of said data stream, the real reception rate of at least one part of said data stream is evaluated (109). Said theoretical rate and said evaluated rate are then compared (113) to estimate said level of use of said communication network. The level of subscription of a client to multicast sessions may be adapted according to the level of use of the communication network.

Abstract: A method of reconstructing a sequence of video data in a receiving device after the video sequence has been transmitted in encoded form over a network, the encoded video sequence comprising containers of encoded video data, wherein the method includes the following steps: determining (809) containers of encoded video data affected by data losses during their transmission over the network, determining (813) the time that would be necessary for decoding said containers of encoded video data affected by data losses if they had not been affected by data losses, allocating (819, 820, 821) the time thus determined to reconstructing video data of the sequence.

Abstract: A method and device for deblocking filtering of a scalable bitstream during decoding is disclosed. According to the invention, the decoding of at least one part of a picture encoded in a base layer and at least one enhancement layer in a scalable bitstream, the bitstream comprising at least one access unit representing the picture, each access unit comprising a plurality of data elements, each data element belonging to a said layer, comprises the reception (600) of at least one data element of said at least one access unit and, if said at least one data element belongs to an access unit of a predetermined type, the decoding (715, 820) of the data of said data element, and the application (720, 825) of a full deblocking filter to at least one part of the decoded data, the full deblocking filter being applied to all of the.

Abstract: The method for transmitting video data encoded in a scalable video stream representing said video data in a plurality of layers, comprises, for at least one layer: a step of obtaining (317) pre-encoded macroblocks of said scalable video stream representing said video data in a plurality of layers, a step of grouping (319) macroblocks, used for inter layer prediction, of the pre-encoded macroblocks obtained by the obtaining step, into first groups of macroblocks, a step of grouping (319) macroblocks, not used for inter layer prediction, of the pre-encoded macroblocks obtained by the obtaining step, into second groups of macroblocks, a step of estimating a loss variability over a network, a step of selecting (331) groups of macroblocks from the first and second groups of macroblocks based on the loss variability estimated by the estimating step and a step of transmitting (333) the groups of macroblocks selected by the selecting step over the network.

Abstract: To identify data losses in a video sequence transmitted between a server and at least one client over a communication network, the sequence comprising a plurality of video data containers coded using scalable video coding employing a predetermined number of hierarchical levels, the video data containers being transmitted over the network via a series of data transport packets: a process (311) is carried out of detecting losses and of locating the video data affected by those losses, without decoding the video data, by combining information coming from transport packets and information coming from video data container headers. Application for improving decoding on receiving a video sequence.

Abstract: The video coding method comprises: a step (605, 610) of obtaining at least two bandwidth values, a step (620) of coding a base layer so that the rate of the coded base layer data is less than or equal to the lowest bandwidth, and for at least one bandwidth greater than the lowest bandwidth, at least one step (630, 635) of coding an enhancement layer so that the sum of the rate of the data of said coded enhancement layer and the rate of the data serving as a reference of a reference layer of said enhancement layer is less than said bandwidth. In embodiments, during the step of obtaining at least two bandwidth values, bandwidth values received by at least two coded video data destinations are obtained.

Abstract: The method of transmitting a video stream over a network between a transmission device and at least one reception device comprises: —a step (502) of encoding so-called “primary” data of the video stream according to a first type of encoding, —a step (516, 518) of obtaining so-called “secondary” video data, dependent on the primary data, by the simulation of transmission errors potentially suffered by the video stream and at least one method of masking losses due to said transmission errors able to be implemented by a reception device able to decode the primary video stream encoded according to the first type of encoding, —a step (520, 522) of encoding secondary data according to a second type of encoding different from the first type of encoding, and —a step of transmitting, by means of the network, primary data encoded according to the first type of encoding and at least some of the secondary data encoded with the second type of encoding.

Abstract: The method of coding a sequence of images comprising at least one group of a plurality of original images, in several scalability layers, comprises, to code said group of original images, a step of coding at least one base layer on the basis of the group of original images to code to constitute an intermediate data stream. The method also includes a step of storing the intermediate stream in a storage space of a mass memory. Iteratively, the method performs, for each other scalability layer to be coded: a step of obtaining prediction data for the layer to code in said intermediate data stream, a step of coding the layer to code using said prediction data and the group of original images and a step of adding, in the storage space, the coded layer to the intermediate stream.

Abstract: For transmitting a sequence of video images on a network between a server and a client, that sequence being coded according to a hybrid predictive coding mode and comprising a plurality of images, each image being broken down into a plurality of macroblocks of pixels: the plurality of macroblocks is classified (E212) into at least two groups of macroblocks according to a predetermined criterion; these groups of macroblocks are completed (E216, E226) by additional macroblocks; at least two scalable coding levels are created (E214, E224) from these groups of macroblocks; unequal protection against transmission errors is applied (E218) to the groups of macroblocks based on the predetermined criterion; and the scalable coding levels are transmitted (E220) on the network.

Abstract: The method of transmitting image data of a sequence of images comprises, for at least one image of said sequence of images: a step of coding an initial image at a first resolution, a step (602, 607) of determining a corrective signal representing the difference between the image temporally following the initial image at a second resolution and an image at the second resolution calculated from the initial image at the first resolution, a step (603, 604, 608, 609) of coding said corrective signal and a step of transmitting the coded image at the first resolution and the coded corrective signal.

Abstract: A method of determining priority attributes respectively associated with a plurality of containers defining at least one image at a plurality of spatial resolution levels comprises the following steps: for at least two distinct spatial resolution levels considered, selecting at least one container (L1, L2; L1, I1) relative to a level lower than the level considered so as to optimize a rate-distortion criterion obtained by the use, for the decoding of the image at the level considered, of only the containers (L1, L2; L1, I1) selected as data relative to said lower level; associating with each of the selected containers (L1, I1, L2) an attribute representing a priority increasing with the maximum level for which the container is selected. A coding method, devices and computer program that are associated therewith are also provided.