Papers › Hidden Two-Stream Convolutional Networks for Action Recognition

Hidden Two-Stream Convolutional Networks for Action Recognition

2 Apr 2017arXiv:1704.00389archive 2025-07-28

Yi Zhu, Zhenzhong Lan, Shawn Newsam, Alexander G. Hauptmann

Analyzing videos of human actions involves understanding the temporal relationships among video frames. State-of-the-art action recognition approaches rely on traditional optical flow estimation methods to pre-compute motion information for CNNs. Such a two-stage approach is computationally expensive, storage demanding, and not end-to-end trainable. In this paper, we present a novel CNN architecture that implicitly captures motion information between adjacent frames. We name our approach hidden two-stream CNNs because it only takes raw video frames as input and directly predicts action classes without explicitly computing optical flow. Our end-to-end approach is 10x faster than its two-stage baseline. Experimental results on four challenging action recognition datasets: UCF101, HMDB51, THUMOS14 and ActivityNet v1.2 show that our approach significantly outperforms the previous best real-time approaches.

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