Memory-Efficient H.264/AVC CAVLC for Fast Decoding

摘要

A fast decoding method is presented for memory-efficient context-based adaptive variable length coding (CAVLC). The CAVLC algorithm in H.264/MPEG-4 AVC significantly increased the compression ratio compared with variable length coding (VLC) of conventional video coding standards such as H.263 and MPEG-4 Visual because of adaptive use of neighboring blocks' context. Implementation of the CA VLC decoding algorithm, however, is much more complicated than existing VLC decoding methods because of frequent access to the unstructured VLC tables, adaptive switching of tables, and five syntax elements. Especially in mobile video terminals such as digital multimedia broadcasting (DMB) and digital video broadcasting — handheld (DVB-H) player, conventional CAVLC decoding algorithms result in increased power consumption due to frequent memory access. This paper presents a new CAVLC decoding method using arithmetic operations instead of the conventional table look-up method that requires a lots of memory access. Experimental results show that the proposed algorithm has 50% higher speed and 95% less memory access comparing with three conventional CAVLC algorithms, such as table look-up by sequential search, table look-up by binary search, and Moon's method.