AVS Decoder Optimization Based On DM642

With the development of electric and information technology,video becomes one of the most important components in modern human life.Both of early analog video and now digital video have been widely used.These applications of video are very useful,such as analog TV,digital TV,video telephone,video security,video meeting, tele-education and so on.Because of the bigger distortion in transmission than digital video,analog video has lost its primary position gradually.In the same time,digital video has been used more and more,with the development of integrate circuit technology.However,if we transfer digital video by base band,the data is tremendous.In according to compress digital video,it comes forth various standards,such as H.261, H.263,H.264 proposed by ITU-T and MPEG1,MPEG2,MPEG4 proposed by ISO MPEG.AVS expert group was founded in 2002.It proposed Advanced coding of audio and Video Standard,which we have the freedom information property right.AVS is also an international standard now.More than ever,the highest degree of industrialization is MPEG2,then MPEG4 and H.264,and AVS is the lowest.Although the industrialization of AVS is just beginning,AVS has many advantages compared to other standards.It can achieve the similar code efficiency to H.264,while the complexity of implement is much less,about 70%at encoder and 30%at decoder. Another advantage of AVS is the low price of patent licensing.The development of IC technology has provided a new hardware platform for video processing.TI's multimedia processor TMS320DM642 is specially developed for multimedia applications.It is one kind of 32 bit fixed-point DSP chip.It can convenience process video signals with its excellent processing performance and abundant on-chip peripherals.So,it has been widely used in the area.We use SEED-VPM642 from SEED as our hardware platform.According to the characteristic of DSPs,we transplant our program and optimize it.It simulates the working state of IPTV set top box and uses UDP protocol to transmit encoded AVS Standard Definition(720x576)video bitstream from PC to DSPs,then the DSPs decodes the bitsream and display it on moderator.We adopt a lot of useful methods to optimize the program:structure adjust of the program;using intrinsics and data patch in luma and chroma interpolations;using assembly language which makes efficiency of the decoder higher in IDCT;using DMA to transmit data without CPU resource;we configure L2 Cache appropriately according to DM642's two levels Cache structure: 128k Cache and 128k RAM.Finally,our decoder can decode 42 frames per second standard definition video.It can be use in IPTV,video security and other areas.