Abstract: The invention relates to a video decoding method for the decompression of an input coded bitstream corresponding to an original video sequence that had been divided into successive groups of frames (GOFs) and coded by means of a subband video coding method. This decoding method comprises, on the one hand, sub-steps for the reconstruction of said first couple of frames of said current GOF, and, on the other hand, for the reconstruction of said (n?1) other couples of frames of the current GOF, sub-steps of decoding the current subbands by combining a previous sub-sampled portion and the new current sub-bitstream of the coded bitstream according to some specific rules, said decoding method being thus applied in order to reconstruct successively each couple of frames of the current GOF, up to the last one.

Abstract: The invention relates to an encoding method for the compression of a video sequence by means of a tridimensional wavelet transform. This method is based on a hierarchical subband encoding process leading to transform coefficients constituting a hierarchical pyramid. A spatio-temporal orientation tree, in which the roots are formed with the pixels of the approximation subband and the offspring of each of these pixels is formed with the pixels of the higher subbands, defines the spatio-temporal relationship inside said pyramid. According to the invention, the initial subband structure of the wavelet transform is preserved, in the encoding process, by scanning the subbands one after the other in an order that respects the parent-offspring dependencies formed in the tree.

Abstract: The invention relates to scalable video encoders, and, more precisely, to an encoder comprising a base layer and at least an enhancement layer circuit, said circuits being capable of generating enhancement layer video data associated with compressed base layer video data and suitable for transmission to a video decoder. In said encoder, the implemented encoding method, based on a hierarchical triangular mesh representation to which a matching pursuit error coding step is specifically adapted, comprises a base layer encoding step and enhancement layer encoding steps. The invention also relates to a corresponding decoding method.

Abstract: The invention relates to a three-dimensional (3D) video coding method applied to a bitstream corresponding to an original video sequence that has been divided into successive groups of frames (GOFs). This coding method, applies to each successive GOF first a spatio-temporal analysis step, itself comprising a motion estimation sub-step, a motion compensated temporal filtering sub-step and a spatial analysis sub-step, and then an encoding step, itself comprising an entropy coding sub-step, performed on the low and high frequency temporal subbands resulting from the spatio-temporal analysis step and on motion vectors obtained by means of said motion estimation step, and an arithmetic coding sub-step, applied to the coded sequence thus obtained.

Abstract: The invention relates to a video decoding method for the decompression of an input coded bitstream corresponding to an original video sequence. The sequence has been divided into successive groups of frames (GOFs) and coded by means of a three-dimensional subband video coding method. According to the invention, the decoding method is iterative and comprises as many iterations as the number of couples of frames in each GOF, each iteration itself including, for the reconstruction of each successive couple of frames of each GOF, the sub-steps of decoding the coded bitstream that corresponds to the current GOF, storing, from the decoded bitstream thus obtained, only the data related to the current couple of frames and appropriate subbands containing some information on at least one frame of said current couple of frames, and, from said related data and said appropriate subbands, synthesizing the two frames of said current couple of frames.

Abstract: The invention, related to an encoding method applied to a video sequence divided into successive groups of frames (GOFs) themselves subdivided into successive couples of frames (COFs), comprises a motion estimation step applied to each couple of frames (COF), a motion-compensated three-dimensional (3D) subband decomposition step applied to each GOF, using a motion-compensated temporal analysis, based on said motion vector fields, and a spatial wavelet transform for defining a decomposition into spatio-temporal subbands, a coding step, for quantizing and coding said spatio-temporal subbands, and a control step.

Abstract: The invention relates to an encoding method for the compression of a video sequence divided into groups of frames (GOFs), each of which is decomposed by means of a three-dimensional (3D) wavelet transform comprising successively, at each decomposition level, a motion compensation step, a temporal filtering step, and a spatial decomposition step. The motion compensation is based on a motion estimation leading to motion vectors which are encoded and put in the coded bitstream together with, and just before, the coded texture information of the concerned spatial decomposition level. The encoding operation of the motion vectors is carried out at the lowest spatial resolution, and only refinement bits of said motion vectors at each of the other spatial resolutions are put in the coded bitstream refinement bitplane by refinement bitplane.

Abstract: The invention relates to an encoding method for the compression of a video sequence by means of a three-dimensional wavelet transform. This method is based on a hierarchical subband encoding process leading to transform coefficients that constitute a hierarchical pyramid. A spatio-temporal orientation tree, in which the roots are formed with the pixels of the approximation subband and the offspring of each of these pixels is formed with the pixels of the higher subbands, defines the spatio-temporal relationship inside said pyramid. The initial subband structure of the wavelet transform is, in the encoding process, preserved by scanning the subbands one after the other in an order that respects the parent-off-spring dependencies formed in the tree, and flags “off/on ” are added to each coefficient of the tree in view of a progressive transmission of the most significant bits of the coefficients.

Abstract: The invention relates to a color video coding method using the so-called 3D-SPIHT algorithm applied to the color space constituted by the luminance plane Y and the chrominance planes U and V in the 4:2:0 format. A wavelet decomposition of the U and V planes is performed over a number of resolution levels which is the number of resolution levels of the wavelet decomposition of the luminance plane minus one. The full resolution color U or V plane may be seen as an approximation of the full resolution luminance plane, and, the size of said full resolution color U or V plane being the same as the size of the first level approximation in the multiresolution decomposition of the Y plane, the n-th resolution level of the luminance has the same size as the (n?1)-th level of the chrominance. Each pixel (i,j) of the approximation sub-band at the lowest resolution of the Y plane is associated with the pixel at the same location in the corresponding sub-band of the U and V planes.

Abstract: The invention relates to the field of video encoders and, more particularly, to an encoding method based on an adaptation of the matching pursuit method to an error texture coding process inside triangular meshes. Said process is restricted, at each iteration of the method, to a specific triangle selected according to a predefined criterion. An optimal strategy for atom positioning inside this triangle then consists either in arbitrarily selecting the geometrical barycenter of the selected triangle as the center of the atoms, or re-using the error energy information for atom center positioning, the Displaced Frame Difference (DFD) energy barycenter inside the selected triangle having the highest energy being in the second case arbitrarily chosen as the center of the atoms.

Abstract: The invention relates to an encoding method for the compression of a video sequence divided into groups of frames decomposed by means of a tridimensional wavelet transform. According to this method, based on the hierarchical subband encoding process SPIHT and applied to the band-pass subbands of a spatio-temporal orientation tree defining the spatio-temporal relationship within the hierarchical pyramid of the obtained transform coefficients, a vectorial DPCM, using either constant prediction coefficients or adaptive ones for taking into account scene changes, is used to separately encode the lowest frequency spatio-temporal subband, and the quantification of the prediction error observed when constructing a spatio-temporal predictor for each vector of transform coefficients having components in each frame of said subband is carried out by means of a scalar or vectorial quantization.

Abstract: The invention relates to scalable video encoders, and, more precisely, to an encoder comprising a base layer and at least an enhancement layer circuit, said circuits being capable of generating enhancement layer video data associated with compressed base layer video data and suitable for transmission to a video decoder. In said encoder, the implemented encoding method, based on a hierarchical triangular mesh representation to which a matching pursuit error coding step is specifically adapted, comprises a base layer encoding step and enhancement layer encoding steps.

Abstract: The invention relates to an encoding method for the compression of a video sequence by means of a tridimensional wavelet transform. This method is based on a hierarchical subband encoding process leading to transform coefficients constituting a hierarchical pyramid. A spatio-temporal orientation tree, in which the roots are formed with the pixels of the approximation subband and the offspring of each of these pixels is formed with the pixels of the higher subbands, defines the spatio-temporal relationship inside said pyramid. According to the invention, the initial subband structure of the wavelet transform is preserved, in the encoding process, by scanning the subbands one after the other in an order that respects the parent-offspring dependencies formed in the tree.

Abstract: The invention relates to the field of video encoders and, more particularly, to an encoding method based on an adaptation of the matching pursuit method to an error texture coding process inside triangular meshes. Said process is restricted, at each iteration of the method, to a specific triangle selected according to a predefined criterion. An optimal strategy for atom positioning inside this triangle then consists either in arbitrarily selecting the geometrical barycenter of the selected triangle as the center of the atoms, or re-using the error energy information for atom center positioning, the Displaced Frame Difference (DFD) energy barycenter inside the selected triangle having the highest energy being in the second case arbitrarily chosen as the center of the atoms.