Scalable codec architectures for Internet video-on-demand

The heterogeneous structure of the Internet is a great obstacle for establishing real-time video services. Scalable video codecs, generating bit-streams decodable at different rates, have been proposed to address the heterogeneity problem. In this paper, we review standard-compliant and non-compliant codec architectures for Internet video-on-demand. For compression based on the H.263 standard, we have developed a compatible architecture that allows to switch between pre-encoded bit-streamers of different bitrates. This architecture provides excellent streaming performance for point-to-point communication scenarios that offer a low delay feedback channel. Then we present a non-compliant fully scalable video codec based on a spatiotemporal resolution pyramid. This approach can encode embedded lower bit-rate layers at the same overall hit-rate as needed by H.263 single-layer coding and can also support multicasting. The complexity of both schemes is sufficiently low to allow software-only implementations of Internet video services. This is demonstrated by means of an implemented World Wide Web video server application.