Disk placement for arbitrary-rate playback in an interactive video server

Multimedia data, especially continuous media including video and audio objects, represent a rich and natural stimulus for humans, but require large amount of storage capacity and real-time processing. In this paper, we describe how to organize video data efficiently on multiple disks in order to support arbitrary-rate playback requested by different users independently. Our approach is to segment and decluster video objects and to place the segments in multiple disks using a restricted round-robin scheme, called prime round-robin (PRR). Its placement scheme provides uniform load balance of disks for arbitrary retrieval rate as well as normal playback, since it eliminates hot spots. Moreover, it does not require any additional disk bandwidth to support VCR-like operations such as fast-forward and rewind. We have studied the various effects of placement and retrieval schemes in a storage server by simulation. The results show that PRR offers even disk accesses, and the failure in reading segment by deadline occurs only at the beginning of new operations. In addition, the number of users admitted is not decreased, regardless of arbitrary-rate playback requests.     

Towards an easy to use authoring tool for interactive non-linear video

With growing bandwidths in the Internet and seemingly unlimited storage capacities on web servers, media became more and more important in the daily use of the World Wide Web. While about ten years ago only text and images with small file sizes (and as a result small resolutions) could be used, it is possible to watch high quality multimedia presentations nowadays. But those rarely exist because of tedious to learn authoring tools. A specialization to one main medium, in our case video, allows creating efficient authoring tools using well known paradigms. This work introduces an authoring tool called SIVA Producer. An iterative process for improving the usability of the authoring tool is described. Furthermore, a distinction of the terms “interactive video”, “annotated video”, “non-linear video” and “hypervideo” is given.     

Personal orchestra: a real-time audio/video system for interactive conducting

We present the first multimedia system to conduct a realistic electronic orchestra. Users can control tempo, dynamics, and instrument emphasis of the orchestra through natural conducting gestures with an infrared baton. Using gesture recognition and tempo adjustment algorithms, the system plays back an audio and video recording of an actual orchestra that follows the users conducting in real time. A major achievement of this system is its ability to vary playback speed in real time while avoiding audio artifacts such as pitch changes. The system has been deployed as an exhibit and has become a major attraction of a large Vienna-based music exhibition center.An erratum to this article can be found at     

Efficient support for interactive operations in multi-resolution video servers

In this paper, we present a placement algorithm that interleaves multi-resolution video streams on a disk array and enables a video server to efficiently support playback of these streams at different resolution levels. We then combine this placement algorithm with a scalable compression technique to efficiently support interactive scan operations (i.e., fast-forward and rewind). We present an analytical model for evaluating the impact of the scan operations on the performance of disk-arr ay-based servers. Our experiments demonstrate that: (1) employing our placement algorithm substantially reduces seek and rotational latency overhead during playback, and (2) exploiting the characteristics of video streams and human perceptual tolerances enables a server to support interactive scan operations without any additional overhead.     

VideoMap: An interactive and scalable visualization for exploring video content

Computational Visual Media - Large-scale dynamic relational data visualization has attracted considerable research attention recently. We introduce dynamic data visualization into the multimedia...     

Instructional video in e-learning: Assessing the impact of interactive video on learning effectiveness

Interactive video in an e-learning system allows proactive and random access to video content. Our empirical study examined the influence of interactive video on learning outcome and learner satisfaction in e-learning environments. Four different settings were studied: three were e-learning environments—with interactive video, with non-interactive video, and without video. The fourth was the traditional classroom environment. Results of the experiment showed that the value of video for learning effectiveness was contingent upon the provision of interactivity. Students in the e-learning environment that provided interactive video achieved significantly better learning performance and a higher level of learner satisfaction than those in other settings. However, students who used the e-learning environment that provided non-interactive video did not improve either. The findings suggest that it may be important to integrate interactive instructional video into e-learning systems.     

An analytical model for interval caching in interactive video servers

Design of servers to meet the quality of service (QoS) requirements of interactive video-on-demand (VOD) systems is challenging. Recognizing the increasing use of these systems in a wide range of applications, as well as the stringent service demands expected from them, several design alternatives have been proposed to improve server throughput. A buffer management technique, called interval caching, is one such solution which exploits the temporal locality of requests to the same movie and tries to serve requests from the cache, thereby enhancing system throughput.In this paper, we present a comprehensive mathematical model for analyzing the performance of interactive video servers that use interval caching. The model takes into account the representative workload parameters of interactive servers employing interval caching and calculates the expected number of cached streams as an indication of the improvement in server capacity due to interval caching. Especially, user interactions, which sensitively affect the performance of interval caching, are realistically reflected in our model for an accurate analysis. A statistical admission control technique has also been developed based on this model. Using this model as a design tool, we apply the model to measure the impact of different VCR operations on client requests and rejection probability, as well as the effect of cache size.     

Efficient support for interactive browsing operations in clusteredCBR video servers

Providing efficient support for interactive browsing operations such as fast-forward (ff) and fast-backward (fb) is essential in video-on-demand and other multimedia server systems. In this paper, we propose two basic approaches to scheduling interactive browsing operations: 1) the prefetching approach and 2) the grouping approach. Block-skipping and frame-skipping algorithms are presented for constant bit rate (CBR) data blocks. These algorithms can precisely schedule video streams for both normal play and interactive browsing operations     

Towards hierarchical context: unfolding visual community potential for interactive video retrieval

Community structure as an interesting property of network has attracted wide attention from many research fields. In this paper, we exploit the visual community structure in visual-temporal correlation network and utilize it to improve interactive video retrieval. Firstly, we propose a hierarchical community-based feedback algorithm. By re-ranking the video shots through diffusion processes respectively on the inter-community and intra-community level, the feedback algorithm can make full use of the limited user feedback. Furthermore, since it avoids entire graph computation, the feedback algorithm can make quick responses to user feedback, which is particularly important for the large video collections. Secondly, we propose a community-based visualization interface called VideoMap. By organizing the video shots following the community structure, the VideoMap presents a comprehensive and informative view of the whole dataset to facilitate users’ access. Moreover, the VideoMap can help users to quickly locate the potential relevant regions and make active annotation according to the distribution of labeled samples on the VideoMap. Experiments on TRECVID 2009 search dataset demonstrate the efficiency of the feedback algorithm and the effectiveness of the visualization interface.     

Search for a moving object in a problem with many searchers

Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 109–114, September–October, 1995.     

Design considerations for the development of interactive video in nurse education

Nurse education is one area which combines both a high level of technical skill and knowledge within a working environment in which inter-personal skills are vital. Thus it was considered appropriate to carry out a feasibility study on the use of interactive video in nurse education. The subject chosen was that of intravenous care because of the increasing evidence demonstrating both the hazards to the patient of poor practice and the poor knowledge base of practitioners, medical and nursing, in a climate of increasing technology and pharmacology associated with the intravenous route. The complexity of such a subject required a richness in the educational strategies employed in interacting with the video and the knowledge base within the computer. Furthermore, the need for independant validation of the content was essential in a development area that aimed to provide a high, if not national standard of care for a nursing procedure. Developments in this area highlighted the need for a team approach to the design and development process involving subject experts and designers led by an educational systems analyst. This paper will outline the design methodology employed in a feasibility study for an interactive video program for the training and assessment of nurses in the care required by a patient receiving intravenous therapy and medication.     

The system design for GALATEA,an interactive real-time computer graphics system for movie and video analysis

The extraction of information from movie film and videotape has always been a very tedious process. Yet the usefulness of these media in biomedical research, behavioral science, industrial testing, etc., is apparent. We are developing a system, GALATEA, for the rapid extraction of data from film or video using interactive graphics. The key aspects of GALATEA are: the user indicates what features are of interest using an x, y digitizing pen. These pen positions are the only data the system sees, so that full digital image encoding is avoided. The user can trace the features while the film runs (frame-by-frame analysis is not necessary). The user has constant feedback in the form of an animated, computer-generated movie (Kinegram), overlaid on the original film image and running synchronously with it. It is this kinetic feedback of the data entered that makes the system efficient. Structured programming, real-time programming techniques, data structures for time-dependent pictures and dynamical graphics ‘tools’ are covered. A detailed discussion is given of Slippage or soft degradation in real-time systems under fluctuating load conditions.     

The interactive use of a video database in teacher education: Creating a knowledge base for teaching through a learning community

This study explores how pre-service student teachers acquired knowledge of good teaching practices through the interactive use of a video database and an online discussion forum, where the student teachers shared their teaching videos and received comments or suggestions from members of a learning community. A small group of student teachers was involved in this collaborative learning community during their teaching practicum in their third and fourth years of study. Content analysis of the sharing in the discussion forum and individual student teacher reflections provides insight into the use of a collaborative learning community to create a knowledge base for teaching. Suggestions regarding how this new technology can support teacher education are discussed.     

Interactive video technology: Enhancing professional learning in initial teacher education

The University of Sussex In-School Teacher Education Project (InSTEP) uses interactive video technologies to enhance initial teacher education programmes for science trainee teachers. With four Internet Protocol cameras and mounted microphones in both school laboratories and the university teaching room, trainees and their tutors have access to live interaction with schools. This paper presents some of the findings of a 2 year evaluation of InSTEP aimed at identifying the benefits for trainee teachers. There has been an increase in the use of video material for teacher training purposes, however, trainee teachers are often intimidated by carefully selected extracts featuring experienced teachers. InSTEP activities are live and capitalise on all the opportunities associated with normal classroom practice. Literature points to InSTEP-type activities having the potential to enhance the development of trainees’ observation skills, develop reflective thinking, to provide authentic illustrations of classroom practice, enable remote observation and facilitate the coaching of trainees by mentors. A fourth generation model of evaluation was undertaken with data generated by semi-structured interviews with university tutors and mentors supported by a questionnaire and group interviews with the trainees. Our main findings point to InSTEP enhancing and accelerating the growth of trainee teachers’ professional knowledge through enabling reflective practice, facilitating collaborative learning and supporting the development of the language of pedagogy.     

V-HairStudio: an interactive tool for hair design

Graphical models of natural objects have become increasingly complex and sophisticated. Although researchers have made significant progress in modeling complex objects in the last decade, representing human hair realistically continues to challenge us. It presents problems in all aspects of computer graphics technologies, such as shape modeling, manipulation, rendering, and dynamic simulation. The article introduces a hair-designing system. Based on the cluster hair model, this designing tool provides a rich set of functionality for interactive hairstyle design in two levels of abstraction. The system is more powerful, and at the same time, more convenient and efficient for hair styling and manipulation than previous modeling systems. We can divide existing hair models into two categories: explicit geometric models and volume-density models     

Optimal strategies for maintaining a chain of relays between an explorer and a base camp

We envision a scenario with robots moving on a terrain represented by a plane. A mobile robot, called explorer is connected by a communication chain to a stationary base camp. The chain is expected to pass communication messages between the explorer and the base camp. It is composed of simple, mobile robots, called relays.     

The virtual interactive presenter: a conversational character for interactive television

This paper describes the development of a conversational interface for interactive TV. With the advent of multi-channel digital TV, accessing Electronic Programme Guides (EPGs) will become increasingly complex. We claim that a conversational interface can support incremental refinement of user selections, thus assisting user choice without requiring extensive knowledge of the editorial categories used in the EPG. We present the system architecture and describe the building blocks of this system in terms of underlying technologies, namely speech recognition, Natural Language Processing, dialogue modelling, character animation and multi-modal presentation. The use of an animated character appears to influence the implementation of each of these basic techniques. After giving an overview of the system behaviour and architecture, we describe the various building blocks of a conversational agent as implemented in our system and to what extent each of the underlying technologies are influenced by the use of a conversational character. We report current results by describing example dialogues from the system. Finally, we compare our approach with other interface agents' paradigms.     

Storage and retrieval methods to support fully interactive playout in a disk-array-based video server

One of the most important challenges in a videoon-demand (VOD) system is to support interactive browsing functions such as fast forward and fast backward. Typically, these functions impose additional resource requirements on the VOD system in terms of storage space, retrieval throughput, network bandwidth, etc. Moreover, prevalent video compression techniques such as MPEG impose additional constraints on the process since they introduce interframe dependencies. In this paper, we devise methods to support variable rate browsing for MPEG-like video streams and minimize the additional resources required. Specifically, we consider the storage and retrieval for video data in a diskarray-based video server and address the issue of distributing the retrieval requests across the disks evenly. The overall approach proposed in this paper for interactive browsing is composed of (1) a storage method, (2) sampling and placement methods, and (3) a playout method, in which the sampling and placement methods are two alternatives for video-segment selection. The segment-sampling scheme supports browsing at any desired speed while balancing the load on the disk array, as well as minimizing the variation on the number of video segments skipped between samplings. In contrast, the segment-placement scheme supports completely uniform segment sampling across the disk array for some specific speed-up rates. Several theoretical properties for the problem studied are derived. Finally, we describe experimental results on the visual effect of the proposed frame-skipping approach.     

Eventor: an authoring system for interactive multimedia applications

Programming, testing, and maintaining interactive multimedia applications (IMAs) are still difficult and expensive, while substantial progress has been made to reduce the burden on authors. As IMAs get larger and more complex the difficulties will increase. To overcome the complexity of such IMAs, we argue that authoring systems should provide such facilities as (1) a traditional and intuitivedivide-and-conquer paradigm for solving large and complex problems in various fields, (2)formal specification of the behaviors of IMAs for checking the syntactic correctness of visual expressions or semantic anomalies, and (3)automatic aids like validation of temporal constraints and verification of visual expressions. In this paper, we investigate the properties of IMAs for recognizing the inherent interactivity and concurrency. We propose a specification method based on Milner'sCalculus of Communicating Systems (CCS), which is a well-known formal mechanism for specifying the concurrency in various distributed applications. We also design and implement an authoring system calledEventor (Event Editor), which is based on CCS and composed of three tools: a Temporal Synchronizer, a Spatial Synchronizer, and a User Interaction Builder. They focus on describing the temporal and spatial synchronizations and user interactions while they rely on existing tools in Intel's Digital Video Interactive (DVI) for supporting other functionalities. By editing a simple computer aided instruction (CAI) application, we illustrate that our specification mechanism is well-suited for handling the interactivity of multimedia applications, and Eventor is a simple, efficient, and powerful enough tool to handle practical applications. Especially the incremental refinement and the formal specification based on the CCS allow Eventor to be extended with formal verifications to cope with large and complex applications.