6 results about "Embedding distortion" patented technology

The disclosure relates to methods of generating or modifying a bitstream. These methods comprise obtaining (e.g., generating or receiving) the bitstream, wherein the bitstream contains coded time series data, determining a measure of distortion in relation to a portion of the coded time series data, and embedding distortion metadata into the bitstream, wherein the distortion metadata includes information indicative of the determined measure of distortion. The disclosure further relates to methods of transcoding or decoding such bitstream, as well as corresponding apparatus, programs, and computer-readable storage media.

The invention discloses a non-additive HEVC (High Efficiency Video Coding) video steganography method based on an inter-frame distortion transmission chain. The embedding process comprises three parts of carrier extraction, distortion transmission chain construction and distortion cost updating. The method comprises the following steps: firstly, dynamically screening HEVC compressed video steganography carriers, and dividing the carriers into three classes according to position features; constructing an inter-frame distortion transfer chain based on the motion vectors of the three carriers; and finally, calculating three types of carrier embedding distortion cost values, and realizing minimum distortion path embedding based on STC coding, specifically, completing information embedding of the first type of carrier according to the initial distortion cost value, dynamically correcting the cost value of the second type of carrier through a distortion transfer chain, and completing embedding so as to realize cascade steganography. Embedding of the third type of carriers is completed in the same manner; the method has the advantages that the sampling point distortion change caused by inter-frame distortion transfer is reflected by constructing the space-time coupled inter-frame distortion transfer chain, the inter-frame distortion drift is inhibited, the steganography rate distortion fluctuation is reduced, the visual quality is improved, the bit rate increase is reduced, and the security is enhanced.

The present invention discloses a non-additive HEVC video steganography method based on an inter-frame distortion transfer chain. The embedding process of the method includes three parts: extracting carriers, constructing a distortion transfer chain, and updating a distortion cost. First, HEVC compressed video steganography carriers are dynamically screened and divided into three categories according to position characteristics. Then, an inter-frame distortion transfer chain is constructed based on motion vectors of the three types of carriers. Finally, the embedding distortion cost values ​​of the three types of carriers are calculated, and minimum distortion path embedding is achieved based on STC coding. Specifically, the information embedding of the first type of carrier is completed according to the initial distortion cost value, the cost value of the second type of carrier is dynamically corrected and embedded through the distortion transfer chain to achieve cascaded steganography, and the embedding of the third type of carrier is completed in the same way. The method has the advantage of reflecting the sample distortion change caused by the inter-frame distortion transfer by constructing a spatiotemporally coupled inter-frame distortion transfer chain, suppressing the inter-frame distortion drift, reducing the distortion fluctuation of the stegoscopy rate, and improving the visual quality, reducing the bit rate growth, and enhancing the security.

The present invention discloses a video steganography method based on the principle of motion vector distortion allocation, including: pre-coding: performing inter-frame predictive coding on the coded frame to obtain the partitioning method of the macroblock and its sub-blocks and the original motion vector set; distortion calculation: obtaining candidate motion vectors, calculating the embedding distortion caused by local optimality perturbation; adjusting the embedding distortion to obtain the adjusted distortion that maintains the non-uniformity within the block group; calculating the complexity distortion of the motion vectors, and combining the adjusted distortion to calculate the final joint distortion; information embedding: according to the carrier vector and the final joint distortion, combining with STC coding to perform information embedding on the secret information to obtain the stego carrier vector, replacing the candidate motion vectors corresponding to the elements of the stego carrier vector that are different from the values of the elements of the carrier vector into the original motion vector set to obtain a new motion vector set; re-coding: maintaining the partitioning method of the macroblock and its sub-blocks in the pre-coding, and performing inter-frame predictive coding on the new motion vector set again.

The present application belongs to the technical field of big data mining, and particularly relates to a knowledge perception recommendation method of multiple hyperbolic spaces. The present application proposes a network model based on multiple hyperbolic spaces, and designs feature interaction between different hyperbolic spaces, thereby effectively learning data of different distributions. Moreover, because the knowledge perception recommendation method is based on hyperbolic space, it inherits the related advantages of hyperbolic embedding, such as avoiding embedding distortion problems, obtaining more hierarchical embedding results, and the like, which are not possessed by existing knowledge perception recommendation methods based on Euclidean space. The present application breaks through the shackles of the existing knowledge perception recommendation method, which cannot judge the sensitivity of the knowledge attribute of the user to the commodity, integrates hyperbolic distance information into embedding learning, mines the potential hierarchy of the user commodity bipartite graph, and scores the sensitivity of the knowledge attribute of each user to the commodity.

The present invention relates to a robust video steganography method and device based on adaptive quantization. The secret message embedding process of the method includes: extracting PCA features from the steganographic video; constructing a mapping relationship between PCA features and QIM quantization step lengths; and using an adaptive QIM algorithm to perform adaptive video steganography embedding based on the mapping relationship between PCA features and QIM quantization step lengths. The secret message blind extraction process of the method includes: extracting PCA features from the steganographic video; querying the corresponding quantization step length based on the PCA feature value; and using an adaptive QIM algorithm to extract the secret message based on the queried quantization step length. The present invention applies the adaptive QIM algorithm to video for the first time, adaptively determines the quantization step length based on the heavily compressed channel and video content, and minimizes embedding distortion and improves security under the premise of the same robustness. At the same time, the scheme combines error correction code technology to achieve reliable covert communication on social network channels.