Research On The Key Algorithm Of MPEG-4 Video Coding And Bit Rate Control

湖北工业大学硕士学位论文Abstract Web-based multimedia communications are widely used in many fields of sociallife. The massive image and video information has brought great pressure on storagecapacity, bandwidth of transmission channel and computer processing speed.Thisrequires expressing the information using bits as few as possible in the premise ofacceptable reconstruction quantity. MPEG-4 video and audio coding standard has acontent-based interactivity, higher data compression efficiency and scalability features,and widely used in low bit-rate multimedia communication, such as real-timemultimedia monitoring system, digital TV, video phone and so on. As the encoded bit rate is fluctuating and different channels have differentcharacteristics, the channel unable to adapt to changing conditions and implement agood performance in data transferring. So it requires controlling the encoded video bitflow,in order to ensure making full use of network bandwidth to reach the best videoquality and get stable output. In this paper,the key algorithm of video coding and ratecontrol have studied and discussed. This paper begin with analyzing the necessary of video encoding and bit ratecontrol, MPEG-4 coding standard features, sresearch situation and prospect. This paperstudies three aspects. First of all, Using the texture coding, shape coding and motioncoding to achieve the object-based coding and analyse its key algorithms, context-basedcoding, discrete cosine transform, quantization and block matching motion estimation.We use two ways of the ranks of separation and predetermine the zero blocks toimprove discrete cosine transform algorithm.This improvement can reduce thecomputational complexity of discrete cosine transform algorithm and improve encodingspeed. Various search strategies of block matching motion estimation are compared.Forthe diamond search algorithm in the block matching motion estimation,we optimize thesearch steps and computation of sum of absolute error to reduce the duplication ofsearch frequency and the computational of the sum of absolute error. Then, introducetwo aspects of background image coding,named dynamic and static background imagecoding. Analyse the low delay static background image coding, background imagegeneration method and the global motion estimation and global motion compensation ofdynamic background image coding. Finally, introduce bit rate control requirements,principles and bit rate control algorithm of MPEG-4.Key words:discrete cosine transform, motion estimation, background image coding,bit rate control...