An ever-increasing installation of surveillance cameras at different places for ensuring public safety, security and asset protection has triggered the need for intelligent video surveillance to monitor the people and their behavior. Violence detection is a prominent application of intelligent surveillance as it plays a vital role in public safety, behavior monitoring, and law enforcement. It deals with identifying whether the violent event or behavior occurred in video sequence or not. Various researchers have developed different techniques and features for the detection of violence in recent years. The purpose of this paper is to provide an expository study of various state-of-the-art approaches for detecting violence in videos. It is evident from the ongoing effort in this field and with the advancement in computer vision technology, previous approaches get surpassed and new methods and features always keep on developing. Therefore, in order to complement ongoing research, it is also imperative to conduct a comprehensive analysis of different works from time to time. In this survey, each work has been critically analyzed, along with its pros and cons. The violence detection techniques have been divided under three categories: handcrafted features based, deep learning and hybrid violence detection approaches that have been extensively reviewed in various sub-categories. The major challenges faced by researchers and the steps involved in the process of violence detection are also discussed. Moreover, unlike typical practices of comparing the performance of models within same datasets, we examined a few models for cross-dataset assessment and revealed their limited generalization. This emphasizes the crucial need for robust model generalization to ensure efficacy across varied real-world scenarios. Finally, the paper carried out a discussion of various research gaps in the current approaches and the possible solutions to be taken to resolve them, laying a solid foundation for future work in this area.
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