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Full-Text Articles in Computer Engineering

No-Reference Image Denoising Quality Assessment, Si Lu Jan 2019

No-Reference Image Denoising Quality Assessment, Si Lu

Computer Science Faculty Publications and Presentations

A wide variety of image denoising methods are available now. However, the performance of a denoising algorithm often depends on individual input noisy images as well as its parameter setting. In this paper, we present a noreference image denoising quality assessment method that can be used to select for an input noisy image the right denoising algorithm with the optimal parameter setting. This is a challenging task as no ground truth is available. This paper presents a data-driven approach to learn to predict image denoising quality. Our method is based on the observation that while individual existing quality metrics and ...


Can Infopipes Facilitate Reuse In A Traffic Application?, Emerson Murphy-Hill, Chuan-Kai Lin, Andrew P. Black, Jonathan Walpole Oct 2005

Can Infopipes Facilitate Reuse In A Traffic Application?, Emerson Murphy-Hill, Chuan-Kai Lin, Andrew P. Black, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Infopipes are presented as reusable building blocks for streaming applications. To evaluate this claim, we have built a significant traffic application in Smalltalk using Infopipes. This poster presents a traffic problem and solution, a short introduction to Infopipes, and the types of reuse Infopipes facilitate in our implementation.


Provisioning On-Line Games: A Traffic Analysis Of A Busy Counter-Strike Server, Wu-Chang Feng, Francis Chang, Wu-Chi Feng, Jonathan Walpole May 2002

Provisioning On-Line Games: A Traffic Analysis Of A Busy Counter-Strike Server, Wu-Chang Feng, Francis Chang, Wu-Chi Feng, Jonathan Walpole

Computer Science Faculty Publications and Presentations

This paper describes the results of a 500 million packet trace of a popular on-line, multi-player, game server. The results show that the traffic behavior of this heavily loaded game server is highly predictable and can be attributed to the fact that current game designs target the saturation of the narrowest, last-mile link. Specifically, in order to maximize the interactivity of the game itself and to provide relatively uniform experiences between players playing over different network speeds, on-line games typically fix their usage requirements in such a way as to saturate the network link of their lowest speed players. While ...


Supporting Low-Latency Tcp-Based Media Streams, Ashvin Goel, Charles Krasic, Kang Li, Jonathan Walpole May 2002

Supporting Low-Latency Tcp-Based Media Streams, Ashvin Goel, Charles Krasic, Kang Li, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The dominance of the TCP protocol on the Internet and its success in maintaining Internet stability has led to several TCP-based stored media-streaming approaches. The success of these approaches raises the question whether TCP can be used for low-latency streaming. Low latency streaming allows responsive control operations for media streaming and can make interactive applications feasible. We examined adapting the TCP send buffer size based on TCP's congestion window to reduce application perceived network latency. Our results show that this simple idea significantly improves the number of packets that can be delivered within 200 ms and 500 ms thresholds.


Infosphere Project: An Overview, Calton Pu, Jonathan Walpole Mar 2001

Infosphere Project: An Overview, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

We describe the Infosphere project, which is building the systems software support for information-driven applications such as digital libraries and electronic commerce. The main technical contribution is the Infopipe abstraction to support information flow with quality of service. Using building blocks such as program specialization, software feedback, domain-specific languages, and personalized information filtering, the Infopipe software generates code and manage resources to provide the specified quality of service with support for composition and restructuring.


Application Of Control Theory To Modeling And Analysis Of Computer Systems, Molly H. Shor, Kang Li, Jonathan Walpole, David Steere, Calton Pu Jun 2000

Application Of Control Theory To Modeling And Analysis Of Computer Systems, Molly H. Shor, Kang Li, Jonathan Walpole, David Steere, Calton Pu

Computer Science Faculty Publications and Presentations

Experimentally, we show that Transmission Control Protocol (TCP)’s congestion control algorithm results in dynamic behavior similar to a stable limit cycle (attractor) when data from TCP flow into a fixed-size buffer and data is removed from the buffer at a fixed service rate. This setup represents how TCP buffers packets for transmission onto the network, with the network represented by a fixed-size buffer with a fixed service rate. The closed trajectory may vary slightly from period to period due to the discrete nature of computer systems. The size of the closed trajectory is a function of the network’s ...


Synthetic Files: Enabling Low-Latency File I/O For Qos-Adaptive Applications, Dylan Mcnamee, Dan Revel, Calton Pu, David Steere, Jonathan Walpole Aug 1998

Synthetic Files: Enabling Low-Latency File I/O For Qos-Adaptive Applications, Dylan Mcnamee, Dan Revel, Calton Pu, David Steere, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Files are a tried and true operating system abstraction. They present a simple byte-stream model of I/O that has proven intuitive for application programmers and efficient for operating system builders. However, current file systems do not provide good support for adaptive continuous media (CM) applications - an increasingly important class of applications that exhibit complex access patterns and are particularly sensitive to variations in I/O performance. To address these problems we propose synthetic files. Synthetic files are specialized views of underlying regular files, and convert complex file access patterns into simple sequential synthetic file access patterns. Synthetic file construction ...


Location Independent Names For Nomadic Computers, David Steere, Mark Morrissey, Peter Geib, Calton Pu, Jonathan Walpole Jun 1998

Location Independent Names For Nomadic Computers, David Steere, Mark Morrissey, Peter Geib, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Recent advances in the Domain Name System (DNS) and the Dynamic Host Configuration Protocol (DHCP) have enabled a new approach to supporting mobile users: location independent naming. In this approach, machines use the same hostname from any internet location, but use an IP address that corresponds to their current location. We describe a protocol that implements location independent naming for nomadic computers, i.e., machines that do not need transparent mobility. Our protocol allows hosts to move across security domains, uses existing protocols, and preserves existing trust relationships. Therefore, it preserves the performance and security of normal IP for nomadic ...


Flow And Congestion Control For Internet Streaming Applications, Shanwei Cen, Calton Pu, Jonathan Walpole Dec 1997

Flow And Congestion Control For Internet Streaming Applications, Shanwei Cen, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The emergence of streaming multimedia players provides users with low latency audio and video content over the Internet. Providing high-quality, best-effort, real-time multimedia content requires adaptive delivery schemes that fairly share the available network bandwidth with reliable data protocols such as TCP. This paper proposes a new flow and congestion control scheme, SCP (Streaming Control Protocol) , for real-time streaming of continuous multimedia data across the Internet. The design of SCP arose from several years of experience in building and using adaptive real-time streaming video players. SCP addresses two issues associated with real-time streaming. First, it uses a congestion control policy ...


A Player For Adaptive Mpeg Video Streaming Over The Internet, Jonathan Walpole, Rainer Koster, Shanwei Cen, Crispin Cowan, David Maier, Dylan Mcnamee, Calton Pu, David Steere, Liujin Yu Oct 1997

A Player For Adaptive Mpeg Video Streaming Over The Internet, Jonathan Walpole, Rainer Koster, Shanwei Cen, Crispin Cowan, David Maier, Dylan Mcnamee, Calton Pu, David Steere, Liujin Yu

Computer Science Faculty Publications and Presentations

This paper describes the design and implementation of a real-time, streaming, Internet video and audio player. The player has a number of advanced features including dynamic adaptation to changes in available bandwidth, latency and latency variation; a multi-dimensional media scaling capability driven by user-specified quality of service (QoS) requirements; and support for complex content comprising multiple synchronized video and audio streams. The player was developed as part of the QUASAR t project at Oregon Graduate Institute, is freely available, and serves as a testbed for research in adaptive resource management and QoS control.


Dynamic Load Distribution In Mist, K. Al-Saqabi, R. M. Prouty, Dylan Mcnamee, Steve Otto, Jonathan Walpole Jul 1997

Dynamic Load Distribution In Mist, K. Al-Saqabi, R. M. Prouty, Dylan Mcnamee, Steve Otto, Jonathan Walpole

Computer Science Faculty Publications and Presentations

This paper presents an algorithm for scheduling parallel applications in large-scale, multiuser, heterogeneous distributed systems. The approach is primarily targeted at systems that harvest idle cycles in general-purpose workstation networks, but is also applicable to clustered computer systems and massively parallel processors. The algorithm handles unequal processor capacities, multiple architecture types and dynamic variations in the number of processes and available processors. Scheduling decisions are driven by the desire to minimize turnaround time while maintaining fairness among competing applications. For efficiency, the virtual processors (VPs) of each application are gang scheduled on some subset of the available physical processors.


Physical Media Independence: System Support For Dynamically Available Network Interfaces, Jon Inouye, Jim Binkley, Jonathan Walpole Jan 1997

Physical Media Independence: System Support For Dynamically Available Network Interfaces, Jon Inouye, Jim Binkley, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Advances in hardware technology has fueled the proliferation of dynamically configurable network interface cards. This empowers mobile laptop users to select the most appropriate interface for their current environment. Unfortunately, the majority of system software remains "customized" for a particular network configuration, and assumes many network characteristics remain invariant over the runtime of the software. Physical Media Independence (PMI) is the concept of making assumptions about a particular device explicit, detecting events which invalidate these assumptions, and recovering once events are detected. This paper presents a model supporting PMI. Based on device availablilty, the model identifies implicit device-related assumptions made ...


Adaptive Methods For Distributed Video Presentation, Crispin Cowan, Shanwei Cen, Jonathan Walpole, Carlton Pu Dec 1995

Adaptive Methods For Distributed Video Presentation, Crispin Cowan, Shanwei Cen, Jonathan Walpole, Carlton Pu

Computer Science Faculty Publications and Presentations

This paper describes problems and solutions for delivering real-time, multi-media presentations across the Internet. A key characteristic of presentations of continuous media datatypes, such as digital video and audio, is their need for predictable real-time data delivery. For example, an NTSC quality video presentation requires video frames to be displayed every 1/30th of a second. Variations in this display rate can be observable as stalls or glitches in the video stream and reduce the quality of the presentation [6]. Delivering such presentations across the Internet is difficult because highly variable band- width and latency make it difficult to predict ...


Device And Physical Data Independence For Multimedia Presentations, Richard Staehli, Jonathan Walpole, David Maier Nov 1995

Device And Physical Data Independence For Multimedia Presentations, Richard Staehli, Jonathan Walpole, David Maier

Computer Science Faculty Publications and Presentations

Multimedia computing promises access to any type of visual or aural medium on the desktop. But in this networked future, will every type of media be accessible from every terminal device? Current multimedia standards do not allow content that is authored for high-bandwidth workstations to scale down for low-bandwidth applications. The problem is that application requests are commonly interpreted as requests for the highest possible quality and resource overloads are handled by ad hoc methods. We can begin to solve this problem by specifying Quality of Service (QOS) requirements based on functionality rather than on content encoding and device capabilities.