In this paper we propose a new scheme Statistical Expedited Forwarding to support a new class of service that guarantees bounded delay and bounded packet loss performance. The goal of the proposed scheme is to provide the Integrated Services type of performance guarantees, but without maintaining per-flow state in the network core. The target applications are both delay-sensitive and loss-sensitive like IP telephony, video applications and emerging on-line electronic business-related applications. In order to guarantee delay and loss bounds, the effective resource (consisting of bandwidth and buffer) is assigned to each class according to the given QoS requirement. In addition, we further study the fairness among flows in a class. The experiments on several voice and video applications show the strength of the proposed scheme.
In this paper, we present our design and implementation of ASIS multimedia digital library. Besides bibliographic information, our service includes an archive of digital audio and video streams, CD titles, and WWW contents. This system not only aims at end customer supports, e.g., searching, streaming, and browsing operations, but it also facilitates admission control, content production, distribution processes, and license control, etc. We address several design issues in designing a multimedia digital library, e.g., the need for accounting support and system management, for integrating third party system components and varied kind of multimedia, and for a computer aided tool to automatically process the backend production. Our solutions to these problems are presented.
Although H.320 is one of the most popular ITU-T standard for video conference systems, H.323 is receiving wide acceptance in the Internet society. In this paper, we study the problem of transporting video conference traffic to and from the Internet. Some characteristics of the problem are as follows. For example, H.323 video stream is VBR while H.320 video stream is CBR; H.323 is byte-oriented while H.320 is bit- oriented; audio and video packets are transmitted independently in H.323 while they are multiplexed together in H.320; the probability of packet loss in an H.323 network is much higher than in an H.320 ISDN circuit switching network. In this paper, we present our designs and some preliminary experimental results in dealing with these issues.
In this paper, we study the striping of VBR videos on zoned disk array. We apply constant read time approach and round robin block permutation scheme to solve this problem. By using dynamic programming technique, we can obtain an optimal data striping and disk layouts. Moreover, we adopt an admission control policy to dispatch requests on hard disks in order to provide guaranteed services. Simulation results show that our method achieves load balancing on hard disks of a disk array, efficiently utilizes zoned-disk bandwidths and obtains a significant improvement than the traditional data striping scheme.
This paper presents a linear-time method to optimize stored VBR video transmission on CBR channel. Given the transmission bandwidth, we have presented a linear-time method to minimize both the client buffer size and playback work-ahead. In this paper, the service connection time is minimized to maximize the network utilization for the given transmission bandwidth and client buffer. The required work- ahead is also minimized for the minimum response time. The proposed scheme can be extended easily to transmit the VBR video with minimum rate variability. Experiments of many well-known benchmark videos indicate that the proposed method can obtain better (or at least comparable) resource utilization and requires less memory buffer than conventional approaches. By considering the transmission of MPEG-1 video Advertisements with the same work-ahead time, our obtained results shows better network utilization than that of D-BIND. When compares by transmitting the long MPEG- 1 movie Star War, our approach uses smaller memory buffer than that of the combination of MVBA and D-BIND to achieve the same network utilization.
Recently, zoning technique has been applied to disk technology to increase disk capacities. As a side effect, data transfer rates from outer zones of a hard disk are much higher than those from inner zones. Unfortunately, either VBR nature of video streams or the effects of disk zoning are neglected by previous studies on data placement of VBR video streams on a zoned- disk. Our objective is to minimize server buffer size and to maximize disk utilization subject to the capacity constraints of disk zones. To solve the problem, we adopt the concept of constant read time in which a constant period of time is allocated to retrieve a variable-sized disk block. Blocks retrieved from the same disk zone have the same size. This problem is then formulated as a constrained combinatorial optimization problem. In a previous paper, we present an optimum algorithm to solve the data placement problem based on dynamic programming. In this paper, we present suboptimum heuristics to reduce time and space complexities. The algorithms are implemented in C language and run on Linux operating system and Pentium Pro 200. Preliminary experimental results show that our solutions are very effective. For example, our approach guarantees 100 percent of disk storage efficiency and bandwidth utilization and its buffer size requirement is no more than 3 disk blocks for practical examples. We also run our program on MPEG/1 encoded movie 'Star War', the optimized buffer size is slightly more than 2 disk blocks, e.g., 500KBytes for 140-220KBytes variable-sized disk blocks, with 70 utilization. Preliminary performance studies also shows that the proposed CRT scheme is very promising in maximizing system throughput.
In this paper, a novel initial videos allocation scheme and a load shifting algorithm are proposed to reduce the request fail rate for a distributed video server. The initial allocation scheme determines the maximum numbers of requests that can be served and the proposed load shifting algorithm migrates progressing requests among servers to accommodate more users and reduce the request fail rate under skewed request pattern. According to the simulation results, the proposed algorithms can reduce 50 percent request fail rate from that uses SCAN allocation algorithm, and 25 percent request fail rate from that uses the least load first initial allocation scheme with load shifting procedure. In terms of shifting steps, the proposed algorithms achieves 30 percent to 50 percent less than the DASD dancing algorithm.
This paper discusses a novel data placement scheme which optimizes the storage utilization of a NVOD system. The scheme is most distinctive in the following two aspects: (1) It considers the file blocks placement of programs featured different number NVOD channels. (2) The file blocks grouping scheme optimizes the storage utilization of a NVOD system.
In this paper, the design and implementation of a multimedia on demand file server on an inexpensive PC is presented. The server can efficiently record multiple media streams in the UNIX file format and playback multiple media streams simultaneously. The objective of the design is to provide high throughput and high predictable response time. The claims are verified by comparing the throughput, data loss rates and deviations of the response time of the proposed file server and the original file system. When multiple user requests of continuous stream access the file system simultaneously, the low level I/O scheduler alone is not sufficient to keep its I/O throughput at the full raw power. A high level access scheduler aiming at maximizing I/O throughput is presented in this paper. The applications of a read/write multimedia file server include video conference recording/playback, multimedia program store-and-forward hub, and multi-level multimedia storage system.