-- In this paper, we propose a novel rate control system by applying the discrete linear quadratic rate control method (DLQ) to transmissions of MPEG2 streams in IP networks. We give out the detail deduction for disturbed-DLQ-regulator problem and the corresponding methods to implement the results into media streaming rate control. Study shows that DLQ is superior to conventional rate control schemes especially in client buffer utilization. Besides the basic DLQ method, we also investigate DLQ under heavy-traffic scenarios and provide improvements for this special case. The influences of delay, with respect to different mean values and variances, are discussed carefully.