Region-of-interest based video coding strategy for rate/energy-constrained smart surveillance systems using WMSNs

Video surveillance systems that involve embedded visual sensor nodes have significant constraints due to their limited energy sources. Reducing the power consumption of the in-node processing and the required bandwidth while maintaining a high QoS is still a challenging task. The difficulty increases when a smart task must be performed on the received video in the destination. In this context, this paper proposes an energy-efficient video coding strategy based on a new and fast region-of-interest (ROI) detection method. The lightweight ROI detection method segments the frame into four regions. And the coding strategy aims to extract two different classes of the ROI for coding and transmission using variable quality levels based on their relevance. Furthermore, the strategy aims to exclude the regions of lower importance and any non-ROI that has insignificant movement. We assess the strategy's ability to perform object recognition tasks at the destination under quality degradation. The performance results using different datasets demonstrate a better trade-off between awareness of ROI quality, energy consumption and bandwidth savings for the proposed strategy compared to other methods. This results in 96% reduction of bandwidth and 93% reduction in energy for some sequences at the expense of a 1-4 dB decrease in PSNR when compared to MJPEG standard. While the recognition accuracy of the YOLOv3 model at the destination outperforms the other techniques by about 4% to 22%.