Abstract: In this paper, a cross-layer approach is used to maximize the overall video quality or minimize the end-to-end video distortion under the constraints of resource and delay through cross-layer adaptation of parameters in physical, link, and application (video encoder) layers. The rate-distortion behavior of video encoders under energy constraints is modeled and controlled. The video packet queuing behavior at the link layer is analyzed and the impact of packet loss due to delay bound violation on the end-to-end video distortion is studied. Analysis and experiment demonstrate that the proposed scheme allows us to find optimum energy tradeoff between video encoding and wireless transmission under delay constraints, exploit the link-layer delay as a system resource, and achieve significant performance gain.