OpenFlow/Software-Defined Networking (SDN) is a new networking paradigm that virtualizes network infrastructure by decoupling the control and data plane logic of traditional network devices. The controller of SDN has the overall look about network topology and hence provides flexibility to network operators to implement its own routing approaches. However, it could not control the way client works. In this paper, we propose a bitrate adaptation algorithm at the client side in real time combined with a SDN based dynamic path selection for HTTP-based video streaming. Experimental results show that the proposed method can provide users with better Quality of Experience (QoE) with lower number of rerouting, higher average quality and smoother video quality than existing methods under different scenarios of bandwidth fluctuations.