The process of compressing data in layers such that successive layers provide more information and thus higher quality reconstruction of the original. That is, a single stream of data can supply a range of compression and thus, in the case of video, a scalable range of video resolution and picture quality. This is particularly useful for a muticast where a single stream is sent out and people are connecting over varying bandwidths. The low bandwidth connection can take just the lower layers while the high-bandwidth connection can take all of the layers for the highest quality.