CAC-live: Centralized assisted cloud P2P live streaming Peer-to-Peer (P2P) live video streaming over the Internet is a developing technology that recently has gained more attention. The use of P2P network with leveraging of local resources of peers, increases scalability and reduces costs. One of the limitations of P2P live video streaming systems is the lack of adequate resources such as available upload bandwidth, both at video source and inside P2P overlay network that lead to reduce the quality of service (QoS) experienced by the users. One solution for this problem is to employ additional on-demand resources such as virtual machines (VM) that are rented from a cloud provider to increase the amount of total available bandwidth. In this paper, we propose an architecture for improving the QoS of the peers by using virtual machines (VMs) dynamically are rented from cloud providers. Estimation of required VMs is performed through a central-based method and the number of VMs is calculated periodically. Our simulation based performance evaluation shows the efficiency of the proposed method.