In this paper, a QoS adjustment scheme is proposed for real-time video transmission applications which deal with heterogeneous receivers. The heterogeneity of the receivers includes the performance difference of user terminals and networks as well as the difference of the user requirements for multimedia services. The proposed scheme considers the user's respective communication environments and calculates a feasible QoS for each user to utilize the system resources like CPU powers or network bandwidths efficiently. The proposed scheme is implemented in a proxy server, which intermediates between a video server and a group of receivers.