In a wireless video sensor system, encoder and transmitter parameters should be jointly adjusted for the optimal tradeoff between video quality and energy consumption under variable channel conditions. The optimization of the system can be further enhanced by exploiting relative importance of moving objects in remote surveillance applications. This paper presents an energy efficient wireless video sensor node for remote surveillance using content-aware pre-processing and an energy- and content-aware feedback control scheme. A low-overhead pre-processing engine detects the region of interest (ROI) in a frame defined as the macroblocks with moving objects, and an encoder selectively processes ROI macroblocks, resulting in reduction of both computation and transmission energy with minimum quality degradation of the ROI. We also propose an energy- and content-aware control scheme that jointly tunes the system parameters to maintain target transmission energy with minimum degradation of the ROI quality under varying wireless channel conditions. Compared to conventional encoding approaches, the proposed design consumes up to 56 percent less energy at the same quality.