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Research On Rate-Distortion Optimization And Rate Control Algorithm Based On H.264/AVC

Posted on:2006-06-12Degree:MasterType:Thesis
Country:ChinaCandidate:Y CengFull Text:PDF
GTID:2168360155954970Subject:Computer application technology
Abstract/Summary:PDF Full Text Request
The main object of video coding is to minimize the distortion subject to a constraint bit rate. Rate-distortion analysis and rate control play a key role in video coding and communication systems by providing the rate-distortion optimized compression performance, assuring the successful network transmission of the coded video data, and achieving the best visual quality at the receiver. Among various macroblock types, H.264/AVC obtains the best compression performance by the rate-distortion optimization(RDO) algorithm. However, due to the characteristic of RDO algorithm and the use of some refined motion estimation methods, the computation complexity increases linearly with the number of macroblock(MB) type, and the video processing time increases greatly. In addition, MB activity characteristic is distinctly different among the MBs in the same frame. The same quantization parameter is used for all the MBs, apparently it is not perfect.In this thesis, from the extensive experiment results of various QCIF video test sequence, it is clear that the strong correlation of MB type exists in spatial domain, no matter intra I frame or inter P/B frame. In order to analyze the MB type relationship between the neighbor MBs, mean of squared difference and sum of absolute difference (SAD) are introduced to measure the complexity of MB in I frame or the activity of MB in P/B frame, respectively. Then the strict prediction rule is set down. Finally, an adaptive MB encoding algorithm is proposed based on MB type spatial domain prediction. And the algorithm is implemented on H.264/AVC test model JM7.6. Extensive experimental results show not only video coding time decreases greatly, but also video quality and compression performance retain no worse. Accordingly, the disadvantage of RDO algorithm is lessened so that the encoder work efficiency is improved effectively.In addition, due to the distinct difference among the MBs in the same frame, in order to improve bit allocation, one MB layer adaptive-quantization strategy is proposed based on JM7.6 rate control algorithm. The experimental results show the modified algorithm improves the video quality and ensures the output bit stream more close to target bit rate.
Keywords/Search Tags:Rate Distortion Optimization, Macroblock Type, Rate Control, Predict Coding, H.264/AVC, Video Coding
PDF Full Text Request
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