Research On Ultra HD Video Compression Algorithm Based On HEVC

With the rapid development of society and the continuous progress of aerospace technology,the demand for high-definition and ultra-high-definition videos is increasing,and the amount of data generated is also increasing,which brings a huge cost in both video transmission and space storage.At the same time,the complexity of video encoding also affects the application scope and potential of high-definition and ultra-high video.Therefore,while maintaining a certain video quality,improving the compression ratio and reducing the complexity of video encoding are problems that need to be solved urgently.HEVC,as a new generation of high-efficiency video encoding standard,compared with the last generation of video compression encoding H.264,it saves about 50% of the data volume.However,with the development and popularization of high-definition and ultra-high-definition video,the resolution is getting larger and larger,and the number is increasing,and video transmission is also required in the spatial communication system with high bit error rate and limited bandwidth.Undoubtedly,it poses greater challenges to video coding performance and video transmission reliability.Therefore,research on how to improve the performance of video compression coding and reliable video transmission in space communication systems has high application value and research value.This paper has deeply researched and analyzed the issues for HEVC-based video compression encoding and video transmission in space communication systems.The main contributions are the following:(1)Aiming at the problem of reducing the amount of compressed data to meet the limited communication bandwidth while ensuring a certain video quality,this paper proposes a video compression algorithm based on bandelet transform from the perspective of eliminating data statistical redundancy.The algorithm obtains the optimal bandelet basis of the DCT transform coefficients through the Lagrangian method combined with the quadtree division,so as to achieve the best sparse expression of the transform coefficients and improve the compression ratio.The simulation results show that this method can reduce the bit rate by about 8% on average under the condition where the video quality remains unchanged.(2)Aiming at the problem that the computational complexity of the HEVC standard for high-definition and ultra-definition video compression is greatly increased,this paper proposes a compression algorithm based on correlation-based fast intra prediction for the full I-frame compression mode and a A fast compression algorithm for a hybrid coding framework for low-latency compression mode.The correlation-based compression algorithms for fast intra-frame prediction use the correlation between the current coding unit and neighboring units to remove low-probability prediction depths,thereby reducing the number of times to traverse the prediction depths.At the same time,by establishing an intra-frame prediction mode candidate table and utilizing the correlation of prediction modes,a hierarchical mode prediction method is proposed to reduce the number of traversing intra-frame prediction modes.The simulation results show that the generated fast intra-frame prediction algorithm reducs the video encoding time by 34.2% while only losing about 1.2%.The fast compression algorithm of the hybrid coding framework combines the characteristics of the static background video,and uses the moving target detection algorithm to extract the background area and the moving area.The moving area exploits the proposed fast intra-frame prediction algorithm and the standard inter-frame prediction method,whereas the background area adopts the correlation of adjacent frames for intra-frame and inter-frame prediction.The simulation results show that the generated fast compression algorithm of the hybrid encoding framework also reducs the encoding time by about 44.6% with the trade-off that only about 1.6% of the video quality losed.At the same time,this paper utilizes the divided regions extracted by the moving target detection algorithm,and adopts unequal quantization thresholds to compress different regions to improve people's high-quality visual demand for regions of interest.(3)Aiming at the distortion caused by data packet loss or errors in the video transmission process of the space communication system,this paper utilizes the diferrences of reliability among each bit channel in the polar code,and proposes an unequal error protection algorithm based on the polar code.A dimensionality reduction search algorithm is adopted to achieve an approximately optimal polar code structure to improve the performance of the polar code.To reduce the impact of video distortion caused by the space communication system,we protect compressing data with diferrent importance levels by utilizing bit channels with diferrent reliability.The simulation results show that compared with the equal protection algorithm under the same channel conditions,better video quality can be obtained.