Scalable Video Streaming over ALC (SVSoA): a Solution for the Large Scale Multicast Distribution of Videos
Résumé
This paper introduces a novel approach, SVSoA, for the streaming of hierarchically encoded videos using multicast IP, which fully benefits from the Asynchronous Layered Coding (ALC) reliable multicast protocol. The main assets of this approach are: (1) it is massively scalable, (2) it is naturally TCP friendly, (3) it is immediately deployable and does not rely on any QoS service in the network, (4) it supports clients heterogeneity and ensures a minimum video quality to each of them since the enhancement layers are only received in a second step, after the base video layer, (5) it is up to a certain point immune to long bursts of packet losses, and finally (6) it is compatible with any video hierarchical encoding scheme (temporal, spatial or qualitative, with a fine or rough granularity). Many of these features result from the intelligent use of ALC as the underlying transport protocol. This solution is well suited to the large scale distribution of videos or television programs over the Internet. Yet it is not suitable for interactive applications like video-conferencing because of the playing delay it induces. This paper details the key parameters of the approach and the associated trade-offs. Experiments carried out with a fullf eatured implementation of both ALC and our streaming solution, using a spatially encoded MPEG-4 video, confirm its benefits, especially in congested environments.