Abstract: The invention is made in the technical field of encoding and decoding of bit sequences. The invention proposes a device for compression-encoding an input bit sequence in which Zeroes and Ones occur equally frequent, comprising an XOR gate adapted for receiving pairs of immediately succeeding bits of the input bit sequence as inputs and for outputting further bits of another bit sequence, means for adding a bit to said other bit sequence wherein the added bit is a primary bit which is equal to a primary bit of the input bit sequence or a last bit which is equal to a last bit of the input bit sequence, and means for encoding the other sequence. The XOR gate transforms the input bit sequence into the other bit sequence which comprises more uneven frequencies of occurrence of Zeroes and Ones than the input bit sequence.

Abstract: 3D mesh models are widely used in various applications for representing 3D objects. These models are made of vertices and corresponding triangles, which can be compressed based on prediction and residuals. The present invention improves the accuracy of parallelogram prediction, particularly near sharp features. The proposed 3D mesh model encoding comprises analyzing the spatial or dihedral angles between triangles, clustering triangles with similar or equal dihedral angles, and defining a representative dihedral angle for each cluster. Triangles of each cluster are then encoded relative to individual prediction triangles having the representative dihedral angle according to the cluster. Additionally, the prediction triangle may be mirrored. An indication of the encoding mode is inserted into each vertex of the encoded bitstream.

Abstract: The invention is related to a method and a device for encoding of a bit sequence. Said method comprises generating, for each run of Ones comprised in the bit sequence, a unary representation of length of the respective run of Ones, generating a first sequence by concatenating the generated unary representations of lengths of runs of Ones, generating, for each run of Zeroes comprised in the bit sequence, a unary representation of the length of the respective run of Zeroes, generating a second sequence by concatenating the generated unary representations of lengths of runs of Zeroes, and bit plane encoding the generated first and second sequence of unary representations. In most cases, overall entropy of bit planes of unary representations of run lengths is smaller than entropy of the bit sequence. Thus, more compact encoding can be achieved.

Abstract: The invention concerns a method for embedding video annotation data into a coded video stream. The method comprises the step of—encapsulating said video annotation data into a unit, so-called video annotation unit, of the coded video data stream which format corresponds to at least one format used for sending the associated video data,—inserting an identifiable synchronizing code enabling the identification of said video annotation unit into the video data stream.

Abstract: The invention is related to lossless compression of prefix-suffix-codes wherein a prefix comprises unary code, and to corresponding decompression. The method for lossless compressing prefix-suffix-codes comprises the steps of forming a first contiguous bit sequence from the prefixes, and lossless compressing the first contiguous bit sequence by removing redundancy related to the difference between the first value's frequency in the first contiguous bit sequence and the second value's frequency in the first contiguous bit sequence. Bit values are unevenly distributed in the prefixes while distribution of bit values in the suffixes is more even. Therefore, better compression is achievable if the prefixes are compressed separately.

Abstract: In known image compression, following quantisation, a very sparse distribution of significant (i.e. non-zero) amplitude coefficients of the transformed image signal may be obtained while most quantised coefficients are zeros. A costly task for a transform-based image compression in terms of resulting overall data rate is to record the locations of such significant coefficients within the coding blocks. In quartation processing, a ‘significant square’ (containing at least one non-zero amplitude coefficient in the coefficient block) is recursively divided into four smaller squares until single significant coefficients are reached, and the significance statuses of all generated squares are encoded. However, for some distribution patterns encoding the x-y-coordinates of the significant coefficients as binary numbers will lead to less coding cost.

Abstract: A method for encoding a sequence of integers includes identifying a contiguous sub-sequence in the sequence of integers wherein the sub-sequence includes interrelated integers having a same prefix when being variable length encoded and an independent last integer. A code for the contiguous sub-sequence is formed using a code for an indication of the number of interrelated integers in the contiguous subsequence, a code of a prefix indication, and the suffixes of variable length codes of the integers in the contiguous sub-sequence. In doing so, a single prefix is sufficient instead of n individual prefixes.

Abstract: In known video coding standards there are basically three types of pictures: I, P and B. Video sequences are usually coded in a group of picture structure wherein several P or B pictures are coded following one I picture. However, this GOP structure has some disadvantages with respect to error resilience and storage medium recording. If a P picture is lost e.g. due to transmission channel error, then the subsequent P pictures can not be reconstructed correctly, and the error will propagate temporally and cause unpleasing artifacts. This GOP structure is designed for forward play only and makes complicated a reverse play operation. According to the invention, a reversible GOP structure is used for the video encoding and decoding. The RGOP structure contains both, a forward encoding chain and a backward encoding chain. Each picture in the RGOP structure is assigned to only one of these chains and the video pictures of adjacent RGOP chains are interleaved.

Abstract: The invention is related to a method and a device for encoding of a bit sequence. Said method comprises generating, for each run of Ones comprised in the bit sequence, a unary representation of length of the respective run of Ones, generating a first sequence by concatenating the generated unary representations of lengths of runs of Ones, generating, for each run of Zeroes comprised in the bit sequence, a unary representation of the length of the respective run of Zeroes, generating a second sequence by concatenating the generated unary representations of lengths of runs of Zeroes, and bit plane encoding the generated first and second sequence of unary representations. In most cases, overall entropy of bit planes of unary representations of run lengths is smaller than entropy of the bit sequence. Thus, more compact encoding can be achieved.

Abstract: Optimised bit allocation is important in video compression to increase the coding efficiency, i.e. to make optimum use of the available data rate. In view of the human visual system, a human usually pays more attention to some part of a picture rather than to other parts of that picture. Therefore the bit allocation should be optimised for different-attention picture areas (GOBi). The inventive distortion-driven bit allocation scheme allocates the coding/decoding error distortion to picture areas consistently with the human visual system, and satisfies the constraint of bit rate as well. The invention uses a distortion/bitrate/rhoquantisation parameter histogram analysis. Based on corresponding tables (DGOBi[QPn], RGOBi[QPn] and ?GOBi[QPn]), the relationships between quantisation parameter, rate, distortion and percentage of non-zero coefficients for the different-attention areas are determined (PREALUTI, DISALL, RALL).

Abstract: International image or video coding standards uses hybrid coding, wherein a picture is separated into pixel blocks on which predictive coding, transform coding and entropy coding is employed. The transform coding is effective because the prediction error samples are correlated in the frequency domain. However, when the prediction quality is getting better and better, spatial domain coding becomes more effective than transform coding. According to the invention, it is first determined in which corner of a current block the first non-zero amplitude value is located. Based on the related zeros run length value in that block, a pre-defined scan path is selected, i.e. a context-based adaptive scan mode is used.

Abstract: When for video coding Intra refresh is used, which inserts Intra coded blocks into previously Inter coded pictures, an efficiently adapted rate control method is required for error resilient video coding. A method for adaptively determining a bit budget for encoding video pictures comprises pre-analyzing each of the pictures of a group of pictures, wherein a relative complexity index is calculated for each picture, allocating bits to the pictures based on their relative complexity index and encoding each of the pictures with the allocated number of bits. The pre-analysis comprises selecting pictures for Intra refresh coding, extracting attention area information from the selected pictures, encoding at least the macroblocks of the attention area using Intra mode, calculating for each picture a complexity index, and calculating from the complexity indices of the pictures of the group a relative complexity index for each picture. Thus, a subjectively better video quality is achieved.

Abstract: The invention is related to a method for encoding a sequence of integers, to a storage device and to a signal carrying such encoded sequence and to a method for decoding such encoded sequence. Said method comprises the steps of identifying a contiguous sub-sequence in the sequence of integers wherein said sub-sequence comprises interrelated integers having a same prefix when being variable length encoded and an independent last integer, and forming a code for the contiguous sub-sequence by help of code for an indication of the number of interrelated integers in said contiguous subsequence, a code of a prefix indication and the suffixes of variable length codes of the integers in the contiguous is sub-sequence. Thus, if there are n integers of which each is encoded with the same prefix then, instead of n individual prefixes for the integers, a single prefix for the contiguous subsequence is sufficient.

Abstract: When video sequences are obtained from e.g. news, interviews, conferences and sports matches, flashlight often appears in the video due to photographing. When encoding the video sequence, the intensity changes a lot so that the motion estimation can not find a well-matching block in a previous picture. Accordingly, the video encoder will encode in intra mode and thereby generate much more bits than for the neighbouring non-flash pictures. According to the invention, not the real flash picture is encoded in the video sequence but an artificial non-flash or de-flashed picture, and some indications and parameters are inserted into the bit stream to model the flash effect. The decoder can regenerate the flash picture by reconstructing the non-flash picture and then adding the flash effect. The number of bits required for coding flash pictures is thereby significantly reduced.

Abstract: An adaptive video presentation method for automatically presenting a video with stream-embed information based on content analysis of the video on a smaller display with a limited screen size is provided. The method comprises steps of determining a salient object group containing at least one salient object based on perceptual interest value of macroblocks for each frame of said video, extracting a window having a minimum size containing the salient object group for a scene of the video, characterized in that it further comprises steps of comparing size of the extracted window with the smaller display size; and presenting at least a selected area of the extracted window containing at least a part of the salient object group for the scene on the smaller display in different operation modes based on the result of the comparison steps for different motion mode for the scene of the video.

Abstract: The frame following a scene cut is usually coded as an I picture. In CBR encoding, the encoder will try to keep the bit rate constant, which will often cause serious picture quality degradation at scene changes. In VBR encoding, more bits will be allocated to the first frame of the new scene and the bit rate will increase significantly for a short time. Therefore subsequent frames must be coded in ‘skipped’ mode, which will often cause jerk artifacts. According to the invention, in each frame belonging to a scene change period, areas are determined that have different human attention levels. In the frames (n?1, n?2, n?3) located prior to the first new scene frame, to the areas having a lower attention level less bits are assigned than in the default encoding, and in the frames (n, n+1, n+2) located at and after the scene cut the thus saved bits are additionally assigned to the areas having a higher attention level.

Abstract: The present invention provides a salience estimation method for object-based visual attention model. The method comprises steps of segmenting the image into a plurality of objects to be estimated, extracting feature maps for each segmented object, calculating the saliences of each segmented object in a set of circles defined around a centre pixel of the object based on the extracted feature maps, and integrating the saliences of each segmented object in all circles in order to achieve an overall salience estimation for each segmented object. The present invention is much more human vision inosculated and of low computing complexity.