Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Communicate > Image communication, multimedia communication > Image coding

Research on an Adaptive Macroblock Encoding and Rate Control Algorithm Based on H.264/AVC

Author ZhangLang
Tutor GongJianRong
School Nanjing University of Posts and Telecommunications
Course Signal and Information Processing
Keywords Video compression coding Video Quality Rate Distortion Optimization Rate Control Macro-block type Predictive Coding H.264/AVC
CLC TN919.81
Type Master's thesis
Year 2011
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The main goal of video compression encoding bit rate is limited , as far as possible so that the minimum coding distortion . Rate-distortion optimization and rate control technology has an important place in order to achieve optimal compression efficiency to ensure that the encoded data transmission channel success , and get the best video quality at the receiving end . H.264/AVC macroblock encoded using rate distortion optimization strategy , pick a variety of coding mode congregation , making the coding efficiency achieved optimal . However macroblock type , the H.264/AVC defined more various fine predict technology coupled with the characteristics of the rate-distortion technology led to doubling computational complexity greatly increase in encoding time . In addition , experiments show that having a significant difference between the macro block of the same frame , such a difference macroblock by the same quantization parameter coding is obviously not ideal . The experimental statistical herein a variety of the result of the coding of the QCIF test sequence analysis showed that regardless of the picture type is I , P or B frames , the image encoding macro-block type having a strong correlation in the spatial domain . In order to better analyze this paper were introduced variance of the correlation of the macro-block type to measure the the airspace complexity of the I frame macroblock , the absolute difference (SAD) of metric P / B frame macro block of time-domain activity . Then according to the macroblock type activity or complexity macroblock work out the criteria for pre - side . Based on the type of macroblock airspace in accordance with the criteria of these predictions , forecasts, improving the rate-distortion algorithm , verify The model JM8.6 improved adaptive algorithm in H.264/AVC . The large number of experiments show that the improved adaptive algorithm not only greatly improve the speed of image coding , image coding quality and compression efficiency substantially independent . The defect has been improved so that the rate-distortion optimization algorithm greatly improves the efficiency of the encoder . In addition , in order to further improve the reasonable rate allocation , significant differences based on P frame macroblock level of activity , this paper presents the macroblock level adaptive quantization scheme , on JM8.6 bit rate control algorithm to make improvements . The final experimental results show that the the macroblock adaptive quantization improved encoding of the image quality , and makes the output bit rate closer to the target bit rate .

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