In this report, we present our solution for the task of temporal action localization (detection) (task 1) in ActivityNet Challenge 2020. The purpose of this task is to temporally localize intervals where actions of interest occur and predict the action categories in a long untrimmed video. Our solution mainly includes three components: 1) feature encoding: we apply three kinds of backbones, including TSN [7], Slowfast[3] and I3d[1], which are both pretrained on Kinetics dataset[2]. Applying these models, we can extract snippet-level video representations; 2) proposal generation: we choose BMN [5] as our baseline, base on which we design a Cascade Boundary Refinement Network (CBR-Net) to conduct proposal detection. The CBR-Net mainly contains two modules: temporal feature encoding, which applies BiLSTM to encode long-term temporal information; CBR module, which targets to refine the proposal precision under different parameter settings; 3) action localization: In this stage, we combine the video-level classification results obtained by the fine tuning networks to predict the category of each proposal. Moreover, we also apply to different ensemble strategies to improve the performance of the designed solution, by which we achieve 42.788% on the testing set of ActivityNet v1.3 dataset in terms of mean Average Precision metrics.
在本文中,我们介绍了我们为Activitynet Challenge 2018提交的修剪活动识别(Kinetics)和修剪事件识别(Moments in Time)任务。在这两个任务中,非局部神经网络和时间段网络被实现为我们的基础模型。多模态线索,如RGB图像,光流和声信号也被用于我们的方法。我们还提出了新的非本地为基础的模型,进一步提高识别精度。集成模型后的最终提交在动力学验证集上达到83.5%的前1准确度和96.8%的前5准确度,在MIT验证集上达到35.81%的前1准确度和62.59%的前5准确度。
Dense-Captioning Events in Videos: SYSU Submission to ActivityNet Challenge 2020
School of Data and Computer Science, Sun Yat-sen University(中山大学数据与计算机学院);Key Laboratory of Machine Intelligence and Advanced Computing, Ministry of Education(教育部机器智能与先进计算重点实验室);Guangdong Province Key Laboratory of Information Security Technology(广东省信息安全技术重点实验室)
Multi-Agent Reinforcement Learning Based Frame Sampling for Effective Untrimmed Video Recognition
Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences(中国科学院深圳先进技术研究院);University of Chinese Academy of Sciences(中国科学院大学);Baidu Inc.(百度公司)