Quality Planning for Distributed Collaborative Multimedia Applications

Quality Planning for Distributed Collab orative Multimedia Applications PhD Thesis Mark Claypool Advisor John Riedl University of Minnesota Computer Science Department September Acknowledgements There are many p eople who have help ed me in this work either directly by adding their work to mine or indirectly by giving me vision and supp ort However ab ove all there are two p eople who deserve my deep est gratitude Professor John Riedl and my wife Ka jal As my advisor John has contributed to all levels of this thesis from guidance on writing C co de and English grammar rules to exp erimental design and data analysis to a rich exciting vision of computer science research Most imp ortantly he has provided motivation to p ersevere through the slow dicult parts of research motivation to pursue research problems that make a dierence in the world and motivation to pursue a career as a professor myself I hop e to emulate much of Johns style when I advise my future graduate students Equally imp ortant Ka jal has b een a pillar of strength and supp ort She has b een understanding of the uctuations in the demands on the time of a graduate student She has b een patient through the many years she worked to supp ort us while I was still in school working on this thesis She has b een inspirational when I was down ab out progress or down ab out some exp eriment results And her technical knowledge has provided me with nudges in the right direction when my research lacked fo cus I hop e I can b e as supp ortive of her during her PhD quest as she was during mine I would like to thank the members of my examining committee Professors John Carlis Shashi Shekhar David Lilja and George Wilcox Professors Shekhar and Lilja were also on my Masters committee work which was later molded to this thesis Professors Carlis and Wilcox collab orated with me on the Flying interface work i which b ecame Chapter of this thesis Professor Carlis provided valuable insights during the very last phase of this do cument including writing the abstract and making my nal defense a successful talk I also must thank those who long ago gave me the to ols to achieve a PhD Pro fessors Steven Janke David Ro eder and Michael Siddoway professors at Colorado College taught me the elegance of academic work and gave me insights into com puter science My high school teacher Herr Berndt gave me the appreciation for the richness of life a vision which help ed me see the b eauty in computer science as well Ab ove all my parents taught me how to set my sites high and how to succeed as well as providing me with my rst computer a TRS mo del I I I Little did any of us know it at the time but that computer b ecame the reason I am writing this do cument to day I would like to thank several additional p eople for their direct contributions to my work Dan Frankowski Mike Maley Mike Stein Vahid Mashayekhi and Jo e Hab ermann all worked with me closely during several smaller research pro jects that led to this thesis Without the contributions of the ab ove p eople this work would never have b een completed nor even b egun Vita Mark Claypo ol was b orn in Washington DC on September He attended primary and secondary school in Colorado and nished his secondary education at Nuremburg American High School in Nuremburg Germany In he completed his Bachelor of Arts in Mathematics at Colorado College in Colorado Springs CO He entered the Computer Science program at the University of Minnesota in the fall of He received his MS and PhD in Computer Science in the summer of and the summer of resp ectively iii Abstract The tremendous p ower and low price of to days computer systems have created the opp ortunity for exciting applications rich with graphics audio and video These new applications promise to supp ort and even enhance the work we do in teams by allow ing users to collab orate across b oth time and space Despite their exciting p otential building distributed collab orative multimedia applications is very dicult and pre dicting their p erformance can b e even more dicult Performance predictions must deal with future hardware future software and future users and their requirements The rate of change in new technologies continues to accelerate with each new genera tion of hardware and software introducing new capabilities Furthermore distributed environments have a wider variety of p otential congurations than do centralized systems To determine the computer resources needed to meet distributed application de mands we have developed a exible mo del and a metho d for applying it that allows us to predict multimedia application p erformance from the users p ersp ective Our mo del takes into account the comp onents fundamental to multimedia applications latency jitter and data loss The contributions of this thesis to b oth computer sci entists and computer system developers are a multimedia application quality mo del and metho d for predicting application p erformance and evaluating system de sign tradeos detailed p erformance predictions for three distributed collab orative multimedia applications an audio conference a ying interface to a D scientic database and a collab orative ight simulator the eects of system improvements iv on these multimedia applications a demonstration of measures of jitter that have b een used by jitter researchers showing all reasonable choices of jitter metrics are sta tistically similar and exp erimentbased studies of the eects of highp erformance pro cessors realtime priorities and highsp eed networks on jitter In predicting the b ottlenecks in quality for the ab ove three applications we have identied three general traits pro cessors are the b ottleneck in p erformance for many multimedia applications networks with more bandwidth often do not in crease the quality of multimedia applications and p erformance for many multime dia applications can b e improved greatly by shifting capacity demand from computer system comp onents that are heavily loaded to those that are more lightly loaded Contents Introduction Motivation Problem Our Solution Applications A Taxonomy of Computer Supp ort for Multimedia Quality Overview Related Work Taxonomy Quality of Service Quality Computer Supp ort for Multimedia Capacity Scheduling Reservation Summary Jitter Overview Hyp otheses vi Related Work Teleconferencing Systems Delay Buering Realtime Performance Shared Exp erimental Design Pro cessor Exp eriments Sp ecic Exp erimental Design Jitter versus Pro cessor Load Jitter versus Pro cessor Power Section Summary Realtime Priority Exp eriments Sp ecic Exp erimental Design Results and Analysis Section Summary Network Exp eriments Sp ecic Exp erimental Design Results and Analysis Section Summary Summary Application Metho d Overview Related Work Benchmarks Capacity Planning Study Application Mo del Micro Exp eriments Macro Exp eriments Predictions Summary Audio conferences Overview Related work Audio conference Exp eriments Measuring Pro cessor Load Analyzing UDP Using Silence Deletion Digital Audio Compression Mo del Micro Exp eriments Design Data Collection Results Macro Exp eriments Design Results Predictions Increasing Participants Increasing Silence Potential Audio conference Improvements Quality Summary Flying through the Zo omable Brain Database Overview Related Work Scientic Visualization Neuroscience Compression Network Performance Disk Performance Mo del Micro Exp eriments Predictions Networks Compression Disks .

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