The increasing demand for multimedia content imposes a heavy workload on the content sources and routers, leading to high energy bills. Among many works towards greening the Internet, very little attention has been paid to make the entire multimedia streaming system energy-efficient, from source to end-users. In this thesis, we perform an energy measurement of the entire multimedia streaming system, and conclude that the energy usage is affected by the session size, the underlay network setting, and network infrastructure. Based on the measurement, we propose E2Stream, an application-layer approach to make the multimedia streaming energy-efficient. Our evaluation results show that E2Stream is effective in reducing system-wide work-induced power, and is flexible in adapting to various network infrastructures and existing systems.