The global deployment of IP multicast has been slow due to the difficulties related to heterogeneity, scalability, manageability, and lack of a robust inter-domain multicast routing protocol. Application-level multicast becomes a promising alternative. Many overlay multicast systems have been proposed in recent years. However, they are insufficient in supporting applications that require largescale any-source multicast with highly varied host capacities and highly dynamic membership. In this paper, we propose two capacity-aware multicast systems that focus on host heterogeneity, dynamic membership, scalability, and any source multicast. We extend Chord and Koorde to be capacity-aware. We then embed implicit degreevarying multicast trees on top of the overlay network and develop multicast routines that automatically follow the trees to disseminate multicast messages. The implicit trees are well balanced with workload evenly spread across the network. We also perform extensive simulat...