Based On Embedded Linux Operating System, Mpeg-4 Decoder Design,

With the development of multimedia application constantly,it is required that new video compression technology has to guarantee high video quality and lower bit-rate at the same time. In recent years MPEG-4 has attracted most attention in multimedia application with its advantages such as low bit-rate and object-based interoperability. MPEG-4 Simple Profile(SP) can efficiently satisfy the trade off between bit-rate and video quality . with the capability of preserving good quality under low bit-rate and high compression rate,and computation complexity lower than other profiles,it has become the mainstream of MPEG-4 video application.The application of MPEG-4 is nowadays a hotspot of research in video domain.In recent years in embededded,especially the research and application in portable consumptive product is very seething.With a purpose of researching and designing a MPEG-4 decoder system under the operating system of embedded Linux,After a detailed analysis of the common algorithms of video compression and the process and algorithms of MPEG-4 SP video coding and decoding,this thesis implements the prototype of MPEG-4 software decoder building,with the synchronization control mode of the audio controlling the video and time stab at the same time,for the multimedia file format of AVI video and MP3 audio.According to the advantages and disadvantages of embedded system,this thesis give part optimization design on the general C language level and video decoding algorithms.At the end of article,the part module of MPEG-4 decoding system——EZWcoding and decoding system is verified,based on the environment of PC platform,VC++6.0,and it is compared with the DCT(Discrete Cosine Tranform) algorithm.The comparison results show that, although EZW algorithm has many advantages such as high compression rate, good video quality, high PSNR(Peak Signal to Noise Ratio), it has many disadvantages such as occupying too much system resources, very great computation quantuty, high complexity etc.The research results show that ,although MPEG-4 has many advantages such as high compression rate,good video quality,temporal and spatial scalability, it has many disadvantages such as very great computation quantity,requried high system performance and resources, high complexity. So,MPEG-4 decoding algorithms and application platform have to be optimized further for realtime MPEG-4 video decoding algorithms implemented based on embedded system with a little resources.