Disclosed are computer-implemented methods, non-transitory computer-readable media, and systems for document identification. One computer-implemented method includes extracting a sequence of image frames from a video clip capturing an impact of an object against a surface. A stream of audio signals is extracted from the video clip. Using a trained document identification model, a first score and a second score is generated based on the sequence of image frames and the stream of audio signals, respectively. The trained document identification model is trained with a plurality of historical video clips, where each video clip captures an impact of a document against a surface. An identification score is generated based on the first score and the second score. Whether the object in the video clip is a document is determined based on a comparison between the identification score and an identification threshold.