A background model based method for transcoding surveillance videos captured by stationary camera

Real-world video surveillance applications require storing videos without neglecting any part of scenarios for weeks or months. To reduce the storage cost, the high bit-rate videos from cameras should be transcoded into a more efficient compressed format with as little quality loss as possible. In this paper, we propose a background model based method to improve the transcoding efficiency for surveillance videos captured by stationary cameras, and objectively measure it. The background model is trained by pre-decoded I frames, and then used to transcode the source stream. Following this method, an H.264/AVC based transcoder employing the background model as long-term reference frame and a difference frame coding based transcoder are implemented and evaluated. Experimental results show that both trancoders save nearly half the used bits while maintaining quality compared with the full-decoding-full-encoding method, and the latter one has slightly better performance.