Clownfish: Edge and Cloud Symbiosis for Video Stream Analytics

Deep learning (DL) has shown promising results on complex computer vision tasks for video stream analytics recently. However, DL-based analytics typically requires intensive computation, which imposes challenges to the current computing infrastructure. In particular, cloud-only solutions struggle to maintain stable real-time performance due to the streaming over the best-effort Internet, while edge-only solutions require the DL model to be optimized (e.g., pruned or quantized) carefully to fit on resource-constrained devices, affecting the analytics quality. In this paper, we propose Clownfish, a framework for efficient video stream analytics that achieves symbiosis of the edge and the cloud. Clownfish deploys a lightweight optimized DL model at the edge for fast response and a complete DL model at the cloud for high accuracy. By exploiting the temporal correlation in video content, Clownfish sends only a subset of video frames intermittently to the cloud and enhances the analytics quality by fusing the results from the cloud model with these from the edge model. Our evaluation based on a system prototype shows that Clownfish always runs in real time and is able to achieve analytics quality comparable to that of cloud-only solutions, even under highly variable network conditions. Clownfish is generally applicable to all video stream analytics tasks that can leverage temporal correlations.