This paper presents a combinatiorial characterization of broadcast authentication in which a transmitter broadcasts v messages e1(s), , ev(s) to authenticate a source state s to all n receivers so that any k receivers cannot cheat any other receivers, where ei is a key. Suppose that each receiver has l keys. First, we prove that k < l if v < n. Then we show an upper bound of n such that n v(v - 1)/l(l - 1) for k = l - 1 and n /+ for k < l - 1. Further, a scheme for k = 1 - 1 which meets the upper bound is presented by using a BIBD and a scheme for k < l - 1 such than n = / is presented by using a Steiner system. Some other efficient schemes are also presented.

Scalable video coding offers efficient video transmission to a variety of display devices over heterogeneous and error-prone networks. Scalable video coding has been strenuously researched in recent years and state-of-the-art international coding with scalability has been standardized as SVC, which is an extension of H.264/AVC. This paper summarizes the recent advanced research that has been done for improving the quality and reducing the complexity of scalable video coding (including SVC), as well as for improving the quality assessment techniques. It is intended to give researchers a critical, technical overview of what is required to develop more efficient scalable video coding in the future.