| As video technology progresses,people's demands for video quality and compression efficiency rise,and more effective coding requirements are required to meet the public's daily needs.The High Efficiency Video Coding(HEVC)specification was announced in 2013.It achieves the same file resolution and compression efficiency as H.264/AVC while reducing the video stream by half.The HEVC standard can efficiently process video streams due to advanced coding technologies;however,the complexity of the coding algorithm has greatly increased,as shown mainly by the inter-frame prediction module.As a result,the primary research emphasis is on improving coding accuracy without losing HEVC video quality.The HEVC standard has gradually grown to popularity as the primary video technology standard.The codec libraries FFmpeg and X265 are more compliant with the HEVC standard codec collection.Both are scalable and can run on a wide range of processor architectures.The Sunway processor is a homegrown processor built on my country's own architecture.It has independent controllability and can be used on servers as well as desktop computers.In comparison to x86,Intel,and other architectures,the codec library for processing HEVC standard video on the Sunway platform is not ideal.Both the FFmpeg encoding and decoding library and the X265 encoding library are not entirely available to the Sunway processor,since they cannot accept the Sunway architecture when compiled on the Sunway 421 processor and must be transplanted to the Sunway 421 based on the Sunway architecture.The codec feature library will have floating-point exceptions during the video conversion phase after transplantation,and even after the two will perform video conversion normally,the conversion performance of the HEVC standard video is limited.This thesis performed similar code transplantation and optimization work in order to promote the successful operation of multimedia applications on the domestic Sunway 421 cpu.The below are the core job material and contribution points:1.Summarized the core technologies used in the HEVC standard video processing phase,reviewed the codec libraries currently available on the market,and picked the FFmpeg codec library and X265 coding library as appropriate for porting to the Sunway 421 processor.It also outlines the two's key feature editing method while viewing film.2.The issues with the FFMPEG codec library and the X265 codec library that were installed on the Sunway 421 processor are extensively investigated.During the program compilation process,it is discovered that the two libraries are unable to understand the Sunway architecture;A floating-point exception error has occurred during the conversion to HEVC standard video;the X265 encoding library lacks the ability to invoke the Open MP thread library.The above issues were resolved by including instructions in the compilation stage to understand the Sunway architecture,use Sunway floating-point control register instructions,and writing the compilation file of the X265 encoding library to connect to the Open MP threading library.3.The encoding performance of X265 video encoding function library transplanted to Sunway architecture is low.The output of each encoding module of the video encoding of the X265 encoding library is evaluated in order to improve the domestic platform's audio and video processing capability.In order to address the issue that the encoding module in the HEVC encoding format consumes a significant amount of time during the video transfer phase of the Sunway processor,the encoding module is optimized by using Open MP multithreading technology,code optimization and vectorization technology.Experiments are used to determine if the optimization process described in this thesis has an optimization effect on the X265 video encoding library on the Sunway platform.The results of six test sequences show that the optimized X265 encoding library has video encoding time efficiency and video PSNR value.Both of them have made some progress. |
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