On the coding of the enhancement layer of an MPEG-2 SNR scalable coder

Two-layer video using SNR sealability can be used to offer error resilience to video applications where channel resources are unreliable. in the event of information loss or corruption, increased priority and/or protection ca n be given to the base layer bitstream in order to ensure minimum base laye r picture quality. However, SNR scalability is disadvantaged by a significa nt increase in total bit-rate compared to an equivalent single-layer coder operating at the same quality. In this paper we identify the DCT bit alloca tion of the enhancement layer as the primary cause of inefficiency citing t wo specific areas where coding efficiency is compromised From this, the uni que probability characteristics exhibited by the enhancement layer are used to develop an alternative approach to enhancement layer DCT coding. Exploi ting the conditional and adaptive coding features facilitated by arithmetic coding, four enhancement layer coding schemes are proposed and compared to the standard coder. The results show that a hybridized arithmetic coder co mbining run-length and base layer conditioning coding techniques emerges as the best approach, delivering up to 20-25% better compression in the enhan cement layer and outperforming even the single-layer equivalent through muc h of its operating range. (C) 1998 SPIE and IS&T. [S1017-9909(98)00303-1].