Study On Error Resilience For Video Transmission

With the development of network and coding techniques, multimediaapplications are growing rapidly. As a result, the demand of transmittingmultimedia information over radio channel is increasing. Because the data ofmultimedia especially video data is huge, it must be compressed highly toreduce the redundancy for the demand of bandwidth. Using the present videocoding standards, such as MPEG-4 and H.26L which use temporal and spatialhybrid codec and volatile lengthy coding, the compressed stream is extremelyvulnerable against transmission errors. Further more, the fault information willbe propagated in spatial and temporal rapidly so that the quality of thedecompressed images falls or the video communication may even fail entirely.To achieve the best video quality on error prone channel, error resiliencetechnology must be researched.This dissertation deals with the issues of video coding and transmissionover unreliable channels. Based on the video coding standards, especiallyMPEG-4 standard, and many error resilient technologies at present, wepresented some schemes on error resilience emphasis on error concealmenttechniques. Firstly, a brief introduction of traditional video compression technologiesand the development of MPEG&H.26x is given. After analyzing the keytechnologies and characteristics of the video compression standards above, theverified model of MPEG-4 video standards is studied in detail.Then, some typical and mature error resilient technologies are introduced,for example layer coding and multiple description coding, and the principle anddisadvantages of these technologies are analyzed too. After that, manycharacteristic error resilient tools in MPEG-4 standard are deeply researched.What's more, based on the in-depth study on temporal error concealment,spatial error concealment and frequency error concealment, a new boundarymatching concealment algorithm combined with central-search technology isproposed to satisfy the requirements on both speed and accuracy.After the analysis of the advantages and disadvantages of concealmenttechnologies mentioned, we can choose them according to the specific videosequence and error condition. Considering the characteristics of wirelesscommunication, a new adaptive spatial/temporal error concealment method isproposed. Experimental results show that it can obtain much better pictureperformance than the spatial or temporal error concealment algorithms usedsingly.