We describe a new approach to the detection and classification of scene breaks in video sequences. Our method can detect and classify a variety of scene breaks, including cuts, fades, dissolves and wipes, even in sequences involving signi cant motion. We detect the appearance of intensity edges that are distant from edges in the previous frame. A global motion computation is used to handle camera or object motion. The algorithm we propose withstands JPEG and MPEG artifacts, even at very high compression rates. Experimental evidence demonstrates that our method can detect and classify scene breaks that are difficult to detect with previous approaches. An initial implementation runs at approximately 2 frames per second on a Sun workstation.

Systems need to run a larger and more diverse set of applications, from real-time to interactive to batch, on uniprocessor and multiprocessor platforms. However, most schedulers either do not address latency requirements or are specialized to complex real-time paradigms, limiting their applicability to general-purpose systems. In this paper, we present Borrowed-Virtual-Time (BVT) Scheduling, showing that it provides low-latency for realtime and interactive applications yet weighted sharing of the CPU across applications according to system policy, even with thread failure at the real-time level, all with a low-overhead implementation on multiprocessors as well as uniprocessors. It makes minimal demands on application developers, and can be used with a reservation or admission control module for hard real-time applications. 1 Introduction With modern processor speeds and memory capacities, systems can now run a wide diversity of application tasks, and they need to in order to meet us...

Despite recent advances, battery life continues to be a limiting factor in mobile multimedia systems. Significant energy savings can be achieved by adapting systems at runtime to match the execution requirements of different tasks. This paper introduces an on-line dynamic voltage/frequency scaling (DVS) feedback technique that reduces voltage and frequency to match the playback rate. A PI controller adjusts the decoder’s speed to keep constant the occupancy of the buffer between the decoder and the display, effectively matching the average decode rate to the display rate without the need for any off-line profiling. MPEG simulation results show that this technique reduces decoder power consumption while providing strong real-time guarantees. 1.

Device independent I/O has been a holy grail to operating system designers since the early days of UNIX. Unfortunately, existing operating systems fall short of this goal for multimedia applications. Techniques such as caching and sequential read-ahead can help mask I/O latency in some cases, but in others they increase latency and add substantial jitter. Multimedia applications, such as video players, are sensitive to vagaries in performance since I/O latency and jitter affect the quality of presentation. Our solution uses adaptive prefetching to reduce both latency and jitter. Applications submit file access plans to the prefetcher, which then generates I/O requests to the operating system and manages the buffer cache to isolate the application from variations in device performance. Our experiments show device independence can be achieved: an MPEG video player sees the same latency when reading from a local disk or an NFS server. Moreover, our approach reduces jitter substantially. ...

One of the new applications evolving in the Internet is streaming audio/video. A major reason for the growing popularity of Web broadcasting is the compelling new services that can be offered by streaming digital content. Internet-based services are being developed which offer the same look, feel, and functionality as traditional broadcast television. In addition, new, "value-added" services, like VCR-style interactivity and video hyperlinks are being developed. Interest in these Internet-based services has contributed to a push to develop similar services for the broadcast television market. We are poised both on the verge of seeing the development of new paradigms for interacting with audio/video, and on seeing the merging of broadcast television and Internet-based broadcasts. Before this process can be considered successful, a number of technical challenges, derived from the various ways in which content is physically delivered, must be solved. In this paper, we focus on t...

The current streaming technology is based on a model that a server sends encoded streams and that a client does decoding and rendering in real time. In this model, a client must have a powerful hardware and must have specific decoders to handle various compression algorithms (e.g. MPEG, H-263, etc.). This paper starts with a different assumption: network bandwidth is available so that it is no longer a bottleneck. Based on this assumption, we present a new streaming model where both the server and the client participate in the decoding process. The new model reduces the processing requirement at client to the level that a thin device with 486-class CPU (called Sun Ray 1*) is able to play the full-size (640X480) NTSC video at 30 frame/sec. Furthermore, the decoding at client becomes independent of any compression algorithm so that Sun Ray 1 can play streams of various compression algorithms without specific decoders.

supporting latency-sensitive threads in a general-purpose scheduler Systems need to run a larger and more diverse set of applications, from real-time to interactive to batch, on uniprocessor and multiprocessor platforms. However, most schedulers either do not address latency requirements or are specialized to complex real-time paradigms, limiting their applicability to general-purpose systems. In this paper, we present Borrowed-Virtual-Time (BVT) Scheduling, showing that it provides low-latency for realtime and interactive applications yet weighted sharing of the CPU across applications according to system policy, even with thread failure at the real-time level, all with a low-overhead implementation on multiprocessors as well as uniprocessors. It makes minimal demands on application developers, and can be used with a reservation or admission control module for hard real-time applications. 1

We address the problem of fairness in a feedback-controlled multicast video distribution scheme. In a fair scheme each receiver should receive a video stream with a quality that is commensurate with its capabilities or the capabilities of the path leading to it, regardless of other receivers or network paths. This fairness problem results from the fact that multicast communication trades economy of bandwidth with granularity of control. Distributing video using individual feedback-controlled point-to-point streams results in high bandwidth utilization but the granularity of control is high as communication parameters can be negotiated individually with each receiver. In contrast, using a single multicast stream has good bandwidth economy, but very low granularity of control. In this paper we propose, implement and experiment with a system that spans the spectrum represented by the two extremes above. In the scheme, called destination set grouping (DSG), a source maintains a small numbe...

This paper discusses the current state of compression for digital video on the desktop. Today there are many choices for video compression that yield different performance in terms of compression factor, quality, bitrate, and cost. Users want a single low cost solution which, unfortunately, today is non-existent. Consequently, users will have to develop applications in an environment with multiple representations for digital video unless PC's can be assigned to dedicated applications. Alternatively, programmable compression/decompression boards can be used to solve the problem. Eventually, special-purpose hardware solutions will be replaced by general-purpose software running on desktop parallel processors which will be implemented by multiple CPU's per chip.

This project investigates the JPEG standard for still image compression in connection with software processing of digital video, referred to as Motion JPEG. Network transmission protocols for transmission of continuous media are presented and discussed as well, in addition to issues concerning image processing required during playback of digital video. A software based Motion JPEG video player, called jpegvid is constructed and implemented, and essential subjects of the implementation are described. The video player provides several options in order to trade of image quality versus frame rate, for instance scaling of video frames and forcing grayscale output from originally color video sequences. The jpegvid video player is tested, and the experiments and results are presented. Contents 1 Introduction 1 1.1 Project Description : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1 1.2 Organization of the Report : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 2 Dig...