A new unequal error protection scheme based on FMO

This paper presents a novel scheme for video transmission over error-prone networks. The proposed scheme exploits the error resilient features of H.264/AVC and employs an unequal error protection (UEP) approach to protect effectively the streams. A novel algorithm is proposed to classify macroblocks into slice groups using the explicit mode of Flexible Macroblock Ordering (FMO). A rate distortion optimized algorithm is used to assign unequal amounts of FEC protection to the resulting slice groups according to their importance. In addition, a Converged Motion Estimation (CME) is proposed to further improve the proposed UEP scheme. The idea behind the CME is to make the macroblocks be referenced in a skewed manner, such that highly important macroblocks are converged on only a few and the use of redundancy for error protection is efficient. Simulation results show the superiority of the proposed method over other approaches for transmission of H.264/AVC streams.     

Contour-based strike zone shaping and visualization in broadcast baseball video: providing reference for pitch location positioning and strike/ball judgment

The strike zone plays a crucial role in baseball. Pitches which pass through the strike zone count as strikes, three of which strike out the batter. Besides strike/ball judgment, the strike zone also provides the reference for positioning pitch locations, about which sports fans and professionals have an intense interest in compiling statistics. This paper presents contour-based strike zone shaping and visualization in broadcast baseball video. We first detect the home plate, which determines the vertical limits of the strike zone. Then, an efficient algorithm is designed for batter contouring and the points of curvature extremes on the batter’s contour are computed to locate the dominant points which determine the horizontal limits of the strike zone. The experiments show that the proposed framework is able to shape the strike zone fairly well in various baseball sequences, needless of manual operation and additional camera setting. The proposed strike zone shaping and visualization will be able to assist in pitch analysis and statistics compiling.     

Ball tracking and 3D trajectory approximation with applications to tactics analysis from single-camera volleyball sequences

Providing computer-assisted tactics analysis in sports is a growing trend. This paper presents an automatic system for ball tracking and 3D trajectory approximation from single-camera volleyball sequences as well as demonstrates several applications to tactics analysis. Ball tracking in volleyball video has great complexity due to the high density of players on the court and the complicated overlapping of ball-player. The 2D-to-3D inference is intrinsically challenging due to the loss of 3D information in projection to 2D frames. To overcome these challenges, we propose a two-phase ball tracking algorithm in which we first detect ball candidates for each frame, and then use them to compute the ball trajectories. With the aid of camera calibration, we involve physical characteristics of ball motion to approximate the 3D ball trajectory from the 2D trajectory. The visualization of 3D trajectory and the applications to trajectory-based tactics analysis not only assist the coaches and players in game study but also make game watching a whole new experience. The experiments on international volleyball games show encouraging results. We believe that the proposed framework can be extended and applied to various kinds of sports games.     

Buffer-Sharing Techniques in Service-Guaranteed Video Servers

Advances in networking and storage technology have made it possible to deliver on-demand services over networks such as the emerging video-on- demand (VOD) applications. Although a variety of studies have been focused on designing video servers suitable for VOD applications, the number of concurrent on-demand services supported by such servers is often limited by the I/O bandwidth of the storage systems. Recently, several researchers have focused on providing guaranteed services instead of on-demand services in a VOD system. A service is said to be guaranteed if every viewer can be served within a specified waiting time after the video has been subscribed. This paper describes a model called a buffer-sharing autonomy, which combines batching and bridging techniques to provide guaranteed services to VOD systems. We also describe how buffer-sharing techniques can be used in this model to provide the same services with fewer buffer resource through the use of playback-rate alteration. Additionally, in order to make buffer sharing efficient, it is important to group appropriate video streams together to share buffer resource. Four grouping policies are proposed for this purpose and the benefits yielded are also analyzed and compared. Finally, the results of our experiments show that the proposed buffer-sharing techniques promise the provision of guaranteed video services at low cost.     

Dynamic Buffer Management for Near Video-On-Demand Systems

Advances in networking and storage technology have made it possible to deliver on-demand services over networks such as the emerging video-on-demand (VOD) applications. A variety of studies have been focused on designing a video server suitable for VOD applications. However, the number of concurrent on-demand services supported by the server is often limited by the I/O bandwidth of the storage systems. This paper describes a discrete buffer sharing model which uses batching and buffer sharing techniques in video servers to support a large number of VOD services. Two operations, splitting and merging, enable the model to fully utilize system resources such as buffers and disk bandwidths. Moreover, this paper also introduces the concept of imprecise video viewing which assumes that a limited amount of quality loss is acceptable during video playback. Based upon this assumption, three shrinking strategies are explored to reduce buffer requirements. Finally, the results of experiments show that our methods perform better than traditional buffer management techniques for VOD systems.     

Physics-based ball tracking and 3D trajectory reconstruction with applications to shooting location estimation in basketball video

The demand for computer-assisted game study in sports is growing dramatically. This paper presents a practical video analysis system to facilitate semantic content understanding. A physics-based algorithm is designed for ball tracking and 3D trajectory reconstruction in basketball videos and shooting location statistics can be obtained. The 2D-to-3D inference is intrinsically a challenging problem due to the loss of 3D information in projection to 2D frames. One significant contribution of the proposed system lies in the integrated scheme incorporating domain knowledge and physical characteristics of ball motion into object tracking to overcome the problem of 2D-to-3D inference. With the 2D trajectory extracted and the camera parameters calibrated, physical characteristics of ball motion are involved to reconstruct the 3D trajectories and estimate the shooting locations. Our experiments on broadcast basketball videos show promising results. We believe the proposed system will greatly assist intelligence collection and statistics analysis in basketball games.