This study introduces an automated system for fine-grained stroke recognition in broadcast table tennis videos, designed to address challenges in manual annotation and tactical analysis during international competitions. The proposed framework integrates an Adaptive Temporal Difference Model with a Transformer Encoder (ATDT), leveraging a combination of Temporal Difference Networks (TDN) and Temporal Adaptive Modules (TAM) to enhance spatial and temporal feature extraction. To enhance feature discriminability, we employ supervised contrastive learning, which promotes better representation learning for fine-grained action recognition. The system is divided into two primary modules: the Action Segmentation Module (ASM) and the Action Recognition Module (ARM). ASM precisely identifies the start and end times of each stroke action by incorporating ball trajectory analysis to identify precise hit timings and placements. The precise segmentation facilitates the subsequent ARM to implement a three-stage recognition process: forehand and backhand classification, group-based classification, and intra-group action classification. This hierarchical approach improves the system’s ability to differentiate between subtle stroke variations, even under the constraints of low-resolution broadcast footage. To validate the framework, the MISTT dataset was collected, comprising 3,618 stroke action clips from 18 international matches, with professional player annotations. The proposed ATDT model outperformed existing methods, achieving a top-1 accuracy improvement of 18% for forehand strokes and 25.58% for backhand strokes compared to baseline models. Moreover, our automatic annotation system takes only 1/30 of the time compared to the manual annotation process, demonstrating its efficiency.

We propose a real-time shot spot analysis system specifically designed for basketball videos captured from a court view perspective, even in the presence of camera movements such as panning, zooming-in, and zooming-out. Our method consists of two stages: the first stage focuses on identifying the precise frame of the shot, while the second stage predicts the shot event category (i.e., 3-point shot, 2-point shot, or free-throw) and localizes the shot spot from a top-view perspective. Compared to existing end-to-end methods for shot event prediction, our method offers significant advantages. It effectively mitigates the overfitting problem and demonstrates superior performance in predicting 3-point shot and free-throw events. To the best of our knowledge, this work is the first real-time system capable of accurately localizing shot spots in basketball games captured by a moving camera with a court view.

We propose a fine-grained basketball shot analysis system called ScoreActuary to analyze the players' shot events, which can be applied to game analysis, player training, and highlight generation. Given a basketball video as input, our system first detects/segments shot candidates and then analyzes "Shot Type", "Shot Result", and "Ball Status" of each shot candidate in real-time. Our approach is composed of a customized object detector and a trajectory-aware network to learn the information of ball trajectory. Compared to the existing methods that analyze basketball shots, our algorithm can better handle videos with arbitrary camera movements while improving the accuracy. To the best of our knowledge, this work is the first system that can analyze fine-grained shot events accurately in real basketball games with arbitrary camera movements.

This paper proposed the adaptive knee voltage detection (KVD) technique to improve the output voltage accuracy of the primary side regulator. Owing to the insertion of the snubber circuit for reducing overshoot voltage, conventional KVD technique fails to get the output voltage information and thus to deteriorate the output voltage accuracy. Analysis of the snubber circuit and the resonance of the primary side can determine the band-pass filter in the proposed AKVD technique to get high accuracy output information without being affected by any kinds of resonances. Test chip designed in VIS 0.5μm BCD process demonstrates the accuracy of the output voltage higher than 99%. Besides, any abnormal detection won't happen and thus the output ripple can be kept low.

Processing large volumes of streaming data in near-real-time is becoming increasingly important as the Internet, sensor networks and network traffic grow. Online machine learning is a typical means of dealing with streaming data, since it allows the classification model to learn one instance of data at a time. Although many online learning methods have been developed since the development of the Perceptron algorithm, existing online methods assume that the number of classes is available in advance of classification process. However, this assumption is unrealistic for large scale or streaming data sets. This work proposes an online Chinese restaurant process (CRP) algorithm, which is an online and nonparametric algorithm, to tackle this problem. This work proposes a relaxing function as part of the prior and updates the parameters with the likelihood function in terms of the consistency between the true label information and predicted result. This work presents two Gibbs sampling algorithms to perform posterior inference. In the experiments, the online CRP is applied to three massive data sets, and compared with several online learning and batch learning algorithms. One of the data sets is obtained from Wikipedia, which comprises approximately two million documents. The experimental results reveal that the proposed online CRP performs well and efficiently on massive data sets. Finally, this work proposes two methods to update the hyperparameter $\alpha$ of the online CRP. The first method is based on the posterior distribution of $\alpha$, and the second exploits the property of online learning, namely adapting to change, to adjust $\alpha$ dynamically.