Research And Implementation Of Prefix-Code-Based Entropy Encoder

With the development of multimedia technology, digital video applications have become very popular, such as digital video broadcasting, remote surveillance, video on demanding, wireless multimedia communication etc. In the past two decades, ITU-T and ISO have established a series of video coding standards, and these standards impulse the video technology very much. However, it is mournful that foreign patents chain the audio and video industries in our country. It is not until the"Information Technology– Advanced Coding of Audio and Video– Part 2: Video"was announced to be a national standard in 2006.3, that gives the correlative fields a golden chance to develop our own standard.This paper first research on main technologies used by AVS standard, which include prediction, transform, quantization, in-loop filter, and entropy encoding, and then focus on the 2D-VLC entropy coder of AVS, which is context-based adaptive coder. This encoder operates on run-level pair, and it uses the type of current block and value of current coefficients to switch VLC code-table. These tables are designed according to the distribution of transformed coefficients, and this way is much better than using only one table to code all residual coefficients in one 8x8 block.For the Exponential-Golomb code is a kind of prefix-codes, and the fact that using prefix-code means there are some strings that cannot be used any more. Moreover, it may have some redundancies in it. Therefore, we introduce a new algorithm that can remove these redundancies in this paper. This algorithm is called prefix-code-based entropy algorithm, for short PCBE. We give a clear mathematical description of it and prove that it can be used in current AVS standard. PCBE build up a mapping using recursion, and this mapping can help to reduce these redundancies. Because multi-tables switch and escape code technologies are employed in AVS, PCBE is improved to support multi-tables switch and escape code, and we get some new recursion expressions and code tables for AVS. Finally, we implement this algorithm in real AVS video coding systems.Experimental results indicate that PCBE has a good performance when test...