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Study On Reference Picture Selection Algorithm Based On AVS-M

Posted on:2009-11-13Degree:MasterType:Thesis
Country:ChinaCandidate:Z G DaiFull Text:PDF
GTID:2178360245488738Subject:Traffic Information Engineering & Control
Abstract/Summary:PDF Full Text Request
Block-based hybrid coding technique is used to compress video data in AVS video coding standard and all other video coding standards. The low bit-rate video stream compressed by motion compensated hybrid codecs is extremely vulnerable against transmission errors. Real-time video stream transmission in Internet or wireless environments is a challenging task requiring high-compression efficiency as well as robust error control. Once an error occurred in transmission, not only the effects of fault information would be propagated in spatial and temporal rapidly which may result in very poor objectionable visual quality severely, but also the video communication system could be in failure. Just bandwidth limitation and quantitative distortion are considered in traditional rate-distortion optimal algorithm which is not suitable for packet lossy environment. Hence how to improve the video quality with the limited available bit rate has become a serious task.This thesis first reviews the principle of rate-distortion optimal for video coding. In particular, the end-to-end error propagation distortion on pixel level precision is studied based on the analysis of the propagation distortion and concealment distortion in AVS-M video encoding and transmission. Subsequently, this thesis adopts a general transmission distortion estimation model. The accuracy of this estimation is demonstrated via simulation results for video transmission over packet loss channel, which illustrates that actual distortion can be estimated by used expectation model approximately. This model provides an efficient method for coding parameters optimal selection over error prone environment.The reference picture selection methods with non-feedback for error resilient coding are researched in this thesis. A non-feedback key reference picture selection algorithm is realized. Combined with general transmission distortion estimation model and rate-distortion optimal strategy, the key reference picture selection algorithm can determine which reference picture should be selected through comparing the distortion expectation of previous key picture and previous picture. This method can limit error propagation between two key reference pictures and minimizes error diffused distortion. Simulation results show that key reference picture selection algorithm improves video quality efficiently and enhances the robustness of video coding observably.Reference picture selection methods with feedback are also studied in this thesis. A reference picture selection algorithm based on the feedback of key pictures is proposed, which choose the correctly received key picture as the reference picture of the current coding key picture. Simulation results show that this method can restrict the error propagation between two correctly received key reference pictures accurately and achieve better error-resilient performance.
Keywords/Search Tags:Video Coding, Error Resilience, Rate-Distortion Optimization, End-to-End Distortion, Reference Picture Selection
PDF Full Text Request
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