Multiple applications request data from multiple storage units over a computer network. The data is divided into segments and each segment is distributed randomly on one of several storage units, independent of the storage units on which other segments of the media data are stored. At least one additional copy of each segment also is distributed randomly over the storage units, such that each segment is stored on at least two storage units. This random distribution of multiple copies of segments of data improves both scalability and reliability. When an application requests a selected segment of data, the request is processed by the storage unit with the shortest queue of requests. Random fluctuations in the load applied by multiple applications on multiple storage units are balanced nearly equally over all of the storage units. This combination of techniques results in a system which can transfer multiple, independent high-bandwidth streams of data in a scalable manner in both directions between multiple applications and multiple storage units.

Computer system and process for transferring multiple high bandwidth streams of data between multiple storage units and multiple applications in a scalable and reliable manner

State of the art, real-time, rate-adaptive, multimedia applications adjust their transmission rate to match the available network capacity. Unfortunately, this source-based rate-adaptation performs poorly in a heterogeneous multicast environment because there is no single target rate --- the conflicting bandwidth requirements of all receivers cannot be simultaneously satisfied with one transmission rate. If the burden of rate-adaption is moved from the source to the receivers, heterogeneity is accommodated. One approach to receiver-driven adaptation is to combine a layered source coding algorithm with a layered transmission system. By selectively forwarding subsets of layers at constrained network links, each user receives the best quality signal that the network can deliver. We and others have proposed that selective-forwarding be carried out using multiple IP-Multicast groups where each receiver specifies its level of subscription by joining a subset of the groups. In this paper, we extend the multiple group framework with a rate-adaptation protocol called Receiver-driven Layered Multicast, or RLM. Under RLM, multicast receivers adapt to both the static heterogeneity of link bandwidths as well as dynamic variations in network capacity (i.e., congestion). We describe the RLM protocol and evaluate its performance with a preliminary simulation study that characterizes user-perceived quality by assessing loss rates over multiple time scales. For the configurations we simulated, RLM results in good throughput with transient short-term loss rates on the order of a few percent and long-term loss rates on the order of one percent. Finally, we discuss our implementation of a software-based Internet video codec and its integration with RLM.

/pdf/receiver-driven-layered-multicast-2ov624gndk.pdf

Receiver-driven layered multicast

Multiple applications request data from multiple storage units over a computer network. The data is divided into segments and each segment is distributed randomly on one of several storage units, independent of the storage units on which other segments of the media data are stored. Redundancy information corresponding to each segment also is distributed randomly over the storage units. The redundancy information for a segment may be a copy of the segment, such that each segment is stored on at least two storage units. The redundancy information also may be based on two or more segments. This random distribution of segments of data and corresponding redundancy information improves both scalability and reliability. When a storage unit fails, its load is distributed evenly over to remaining storage units and its lost data may be recovered because of the redundancy information. When an application requests a selected segment of data, the request may be processed by the storage unit with the shortest queue of requests. Random fluctuations in the load applied by multiple applications on multiple storage units are balanced nearly equally over all of the storage units. Small data files also may be stored on storage units that combine small files into larger segments of data using a log structured file system. This combination of techniques results in a system which can transfer both multiple, independent high-bandwidth streams of data and small data files in a scalable manner in both directions between multiple applications and multiple storage units.

Computer system and process for transferring streams of data between multiple storage units and multiple applications in a scalable and reliable manner

Nucleotides are required for a wide variety of biological processes and are constantly synthesized de novo in all cells. When cells proliferate, increased nucleotide synthesis is necessary for DNA replication and for RNA production to support protein synthesis at different stages of the cell cycle, during which these events are regulated at multiple levels. Therefore the synthesis of the precursor nucleotides is also strongly regulated at multiple levels. Nucleotide synthesis is an energy intensive process that uses multiple metabolic pathways across different cell compartments and several sources of carbon and nitrogen. The processes are regulated at the transcription level by a set of master transcription factors but also at the enzyme level by allosteric regulation and feedback inhibition. Here we review the cellular demands of nucleotide biosynthesis, their metabolic pathways and mechanisms of regulation during the cell cycle. The use of stable isotope tracers for delineating the biosynthetic routes of the multiple intersecting pathways and how these are quantitatively controlled under different conditions is also highlighted. Moreover, the importance of nucleotide synthesis for cell viability is discussed and how this may lead to potential new approaches to drug development in diseases such as cancer.

/pdf/regulation-of-mammalian-nucleotide-metabolism-and-1fzwegzcxy.pdf

Regulation of mammalian nucleotide metabolism and biosynthesis

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 significant 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 algorithms we propose withstand compression artifacts such as those introduced by JPEG and MPEG, 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.

/pdf/a-feature-based-algorithm-for-detecting-and-classifying-54yncckn7y.pdf

A feature-based algorithm for detecting and classifying scene breaks

The design and implementation of a software decoder for MPEG video bitstreams is described. The software has been ported to numerous platforms including PC''s, workstations, and mainframe computers. Performance comparisons are given for several different bitstreams and platforms including a unique metric devised to compare price/performance across different platforms (percentage of required bit rate per dollar). We also show that memory bandwidth is the primary limitation in performance of the decoder, not the computational complexity of the inverse discrete cosine transform as is commonly thought.

https://www.cs.unc.edu/%7Ekmp/publications/mm93/MM93-paper.pdf

Performance of a software MPEG video decoder

Advances in the stable isotope-mass spectrometric measurement of DNA synthesis and cell proliferation.

A software decoder for MPEG-l video was integrated into a continuous media playback system that supports synchronized playing of audio and video data stored on a file server. The MPEG-1 video playback system supports forward and backward play at variable speeds and random sending and receiving side heuristics are described that adapt to frame drops due to network load and the available decoding capacity of the client workstation. A series of experiments show that the playback system adds a small overhead to the stand alone software decoder and that playback is smooth when all frames or very few frames can be decoded. Between these extremes, the system behaves reasonably but can still be improved.

https://www.cs.unc.edu/~kmp/publications/spie94/mpegvideo.pdf

MPEG Video in Software: Representation, Transmission, and Playback

including the Berkeley MPEG player [6], TclProp, a data Conducting research on continuous media applications is hard, in part because it is necessary to have a complete multimedia system running to be able to evaluate changes to any component such as synchronization, network protocols, or encoding. The Berkeley Continuous Media Toolkit provides customizable support for an entire multimedia pipeline. This demonstration will illustrate several applications and research projects build using CMT while showing how CMT is used to build applications and experiment with innovative multimedia systems research.

/pdf/the-berkeley-continuous-media-toolkit-1w907bw0jv.pdf

Ketan D. Patel

Papers

Performance of a software MPEG video decoder

Advances in the stable isotope-mass spectrometric measurement of DNA synthesis and cell proliferation.

MPEG Video in Software: Representation, Transmission, and Playback

The Berkeley continuous media toolkit