An application layer multicast mechanism, CD-Media, is proposed based on the combination of central-control and distributed self-organization. This mechanism with different hierarchies is stable and suitable for the quasi-real-time application. Special servers with high performance is deployed in the higher levels to organize the star topology, and they are responsible for the construction and maintenance of Mesh network and multicast tree in the lower levels. In the lower levels a distributed protocol for self-organization is used and Mesh-first strategy is adopted in the Cluster. Multicast technologies both in application layer and network layer are combined to make use of their own advantages to achieve higher performance. An experiment is delicately designed to show the advantage of CD-Media, and it is convinced that it will be a promising mechanism in overly multicast.