This paper tries to prolong the lifetime of wireless video sensor networks in which each sensor node operates in event-driven manner. The proposed method first selects the route to the sink node in lifetime-aware fashion. Then it finds the optimal encoding bit-rate that maximizes the lifetime function of the se-lected route by utilizing the event statistics, remaining battery energy of each node and the analytic power consumption model of video encoder, wireless transceiver and memory. Furthermore, the proposed method additionally controls encoding frame-rate of the capturing node to balance the lifetime of each node within the selected route when the event occurrence rate distribution over the network is significantly unbalanced. Experimental results show that the proposed method extends the lifetime of the target network by 183.53% on average compared with a conventional bit-rate allocation method.