Consumers increasingly demand high quality of service (QoS) for multimedia applications. Rate control scheme is one of the major methods that provide high video quality for mobile multimedia devices over wireless networks. This paper presents an efficient rate-control scheme which estimates the transmission power level of mobile devices, then adaptively adjusts the encoding bit rate according to the estimated power level to minimize overall distortion over sequences of video frames. Experimental results show that the proposed method can efficiently enhance the video quality and provide better peak signal to noise ratio (PSNR) performance than existing TMN8 rate control method.