DisplayCast is a many to many Intranet screen sharing system. Its screen capture mechanism creates a sequence of pixmap images of the screen updates. Prior systems that used a similar approach were designed to operate over constrained wide-area networks and did not exploit the Intranet network conditions to achieve high capture rates. First we empirically analyzed the screen contents for a variety of scenarios. We showed that screen updates were sporadic with long periods of inactivity. When active, screens were updated at far higher rates than was supported by earlier systems. The mismatch was pronounced for interactive scenarios. Even during active screen updates, the number of updated pixels were frequently small. We showed that crucial information can be lost if individual updates were merged. When the available system resources could not support high capture rates, we showed ways in which updates can be effectively collapsed. Next, we investigate compression mechanisms for streaming these updates. Even while using a hardware encoder, lossy compressors such as H.264 were unable to sustain high frame rates. Though Zlib lossless compression operated within the latency and compression rate requirements, the compression efficiency was poor. By analyzing the screen pixels, we developed a practical transformation that significantly improved compression rates. DisplayCast incorporates these observations. It shares the processor and network resources required for screen capture, compression and transmission with host applications whose output needs to be shared. DisplayCast is agile and uses faster processing capability to achieve even higher performance. Our system components operate natively in Windows 7, Mac OS X and iOS and is deployed in a production setting. DisplayCast is released under a New BSD License.

A panel at ACM Multimedia 2012 addressed research successes in the past 20 years. While the panel focused on the past, this article discusses successes since the ACM SIGMM 2003 Retreat and suggests research directions in the next ten years. While significant progress has been made, more research is required to allow multimedia to impact our everyday computing environment. The importance of hardware changes on future research directions is discussed. We believe ubiquitous computing—meaning abundant computation and network bandwidth—should be applied in novel ways to solve multimedia grand challenges and continue the IT revolution of the past century.

Faithful sharing of screen contents is an important collaboration feature. Prior systems were designed to operate over constrained networks. They performed poorly even without such bottlenecks. To build a high performance screen sharing system, we empirically analyzed screen contents for a variety of scenarios. We showed that screen updates were sporadic with long periods of inactivity. When active, screens were updated at far higher rates than was supported by earlier systems. The mismatch was pronounced for interactive scenarios. Even during active screen updates, the number of updated pixels were frequently small. We showed that crucial information can be lost if individual updates were merged. When the available system resources could not support high capture rates, we showed ways in which updates can be effectively collapsed. We showed that Zlib lossless compression performed poorly for screen updates. By analyzing the screen pixels, we developed a practical transformation that significantly improved compression rates. Our system captured 240 updates per second while only using 4.6 Mbps for interactive scenarios. Still, while playing movies in fullscreen mode, our approach could not achieve higher capture rates than prior systems; the CPU remains the bottleneck. A system that incorporates our findings is deployed within the lab.

DisplayCast is a many to many screen sharing system that is targeted towards Intranet scenarios. The capture software runs on all computers whose screens need to be shared. It uses an application agnostic screen capture mechanism that creates a sequence of pixmap images of the screen updates. It transforms these pixmaps to vastly improve the lossless Zlib compression performance. These algorithms were developed after an extensive analysis of typical screen contents. DisplayCast shares the processor and network resources required for screen capture, compression and transmission with host applications whose output needs to be shared. It balances the need for high performance screen capture with reducing its resource interference with user applications. DisplayCast uses Zeroconf for naming and asynchronous location. It provides support for Cisco WiFi and Bluetooth based localization. It also includes a HTTP/REST based controller for remote session initiation and control. DisplayCast supports screen capture and playback in computers running Windows 7 and Mac OS X operating systems. Remote screens can be archived into a H.264 encoded movie on a Mac. They can also be played back in real time on Apple iPhones and iPads. The software is released under a New BSD license.

The design and implementation of a search engine for lecture webcasts is described. A searchable text index is created allowing users to locate material within lecture videos found on a variety of websites such as YouTube and Berkeley webcasts. The index is created from words on the presentation slides appearing in the video along with any associated metadata such as the title and abstract when available.

TalkMiner is a search engine for lecture webcasts. Lecture videos are processed to recover a set of distinct slide images and OCR is used to generate a list of indexable terms from the slides. On our prototype system, users can search and browse lists of lectures, slides in a specific lecture, and play the lecture video. Over 10,000 lecture videos have been indexed from a variety of sources. A public website will be published in mid 2010 that allows users to experiment with the search engine.

This article reprises the description of the Berkeley software-only MPEG-1 video decoder originally published in the proceedings of the 1st International ACM Conference on Multimedia in 1993. The software subsequently became widely used in a variety of research systems and commercial products. Its main impact was to provide a platform for experimenting with streaming compressed video and to expose the strengths and weaknesses of software-only video decoding using general purpose computing architectures. This article compares the original performance results with experiments run on a modern processor to demonstrate the gains of processing power in the past ten years relative to this specific application and discusses the history of MPEG-1 video software decoding and the Berkeley MPEG research group.

The ACM Multimedia Special Interest Group was created ten years ago. Since that time, researchers have solved a number of important problems related to media processing, multimedia databases, and distributed multimedia applications. A strategic retreat was organized as part of ACM Multimedia 2003 to assess the current state of multimedia research and suggest directions for future research. This report presents the recommendations developed during the retreat. The major observation is that research in the past decade has significantly advanced hardware and software support for distributed multimedia applications and that future research should focus on identifying and delivering applications that impact users in the real-world.The retreat suggested that the community focus on solving three grand challenges: (1) make authoring complex multimedia titles as easy as using a word processor or drawing program, (2) make interactions with remote people and environments nearly the same as interactions with local people and environments, and (3) make capturing, storing, finding, and using digital media an everyday occurrence in our computing environment. The focus of multimedia researchers should be on applications that incorporate correlated media, fuse data from different sources, and use context to improve application performance.

Pen-based user interfaces are becoming ever more popular. Gestures (i . e . , marks made w ith a pen to invoke a command) are a valuable aspect of pen-based UIs, but they also have drawbacks. The challenge in designing good gestures is to make them easy for people to learn and remember. With the goal of better gesture design, we performed a pair of experiments to determine why users find gestures similar. From these experiments, we have derived a computational model for predicting perceived gesture similarity that correlates 0.56 with observation. We will incorporate the results of these experiments into a gesture design tool, which will aid the pen-based UI designer in creating gesture sets that are easier to learn and more memorable. Keywords Pen-based user interfaces, pen gestures, multi-dimensional scaling, similarity, perception INTRODUCTION Pen and paper is a versatile, powerful, and ubiquitous technology [17]. Pen-based user interfaces are becoming more widespread [9] and ha...

Interest in pen-based user interfaces is growing rapidly. One potentially useful feature of pen-based user interfaces is gestures, that is, a mark or stroke that causes a command to execute. Unfortunately, it is difficult to design gestures that are easy 1) for computers to recognize and 2) for humans to learn and remember. To investigate these problems, we built a prototype tool for designing gesture sets. An experiment was then performed to gain insight into the gesture design process and to evaluate the tool. The experiment confirmed that gesture design is very difficult and suggested several ways in which current tools can be improved. The most important of these improvements is to make the tools more active and provide more guidance for designers. This paper describes the gesture design tool, the experiment, and its results. Keywords pen-based user interface, PDA, user study, gesture, UI design INTRODUCTION This work explores the process of gesture design with the goal of impr...

We have developed a parallel software-only processing system for creating real-time video effects such as titling and compositing (e.g., picture-in-picture) using compressed Internet video sources. The system organizes processors into a hierarchy of levels. Processes at each level of the hierarchy can exploit different types of parallelism and coordinate the actions of lower levels. To control the effect, control messages must be distributed to processors in the hierarchy while preserving the independence of each level. This requires a control mechanism that supports efficient delivery of messages to groups of processors, tunable reliability semantics, and recoverable state information. We describe a mechanism that meets these requirements that uses IP-Multicast, the Scalable Reliable Multicast protocol, and the Scalable Naming and Announcement Protocol. We also describe an optimization that provides a flexible framework for linking the control of different aspects of one or more related video effects.

hternet video is emerging as an important mtitimedia ap pHcation area.Video effects are important dernents in conventional video, but they are tiequently used in hternet ~ideo.Current hard~~based video effects proc~sing SG lutions ~e not w~matched for the ~+abti@ of kternet video (ie., bit rates, packet loss, jitter, etc.).A SO*+ ody solution, in contrast, provides the fl~ubtity to match this &[email protected] key to a sohe solution is to ~\Tloit pardeh~m.This paper presents the design of a pardel soti+ordy video Meets processing system and pretinary e~~erirnentd r~ts that mTlore the use of temporal pardl&~m.hternet packet video is emerging ~an important mtitim~ dia appEcation area The hltdticast Backbone (h~one) conferencing tool vic and NetJfeeting from hficrosoft are CSamplfis of bternet packet video conferencing took.Real Video tiom Re&Ne&orks.NetShow from hficrosoft, and IP/TV tiom Precept are axaples of vide~on-demand streaming hternet packet video applications.Th~e appEcations ~e used for a variety of purposw and audienc~s.using a vide~on-demand system, a single r~ cipient views stored material.Video conferencing is used by smti groups for meetings and by larger groups to attend re mote evmts (~g., classes, conference, concerts, etc.).Large broadcasts involve thousands of people %uned" into an ongokg program originating born eithw Eve sourc~or stored archives.For tfis paper, we group ~of these applications under the general term Internet Video (N).bternet video is &aractded by ~%abtity.Frame rates, bit ratw, and jitter are d variable in W applications.h contra~t, a tdevision system, whether adog or digitd, is &aracterized by constwt frame rates, bounded bit rates, and s.mchronous transmission.~appfimtions must *O ded n 036-S~9E!OOOS S5.

The recent advent of the Internet hfulticast service has enabled a number of .mccessfulreal-time multimedia applications, yet the scalabii@ of these applications remains challenged by the inherent heterogeneity of the underlying Internet.One promisiig approach for taming this heterogene ity is to encode each media flow as a layered signal that is striped across multiple.multicast groups, thereby allowing a receiver to tune its individual reception rate by modulating its subscription to multicast groups.Though significant progress had been made on media transport protocols and congestion control strategies for adjusting multicast groups in this fashio~comparatively little work has been devoted to extending the session directory service and address allocation architecture to meet the needs and requirements of layered media.Moreover, the large-scale deployment of layered media formats is hindered by the lack of support for layered formats in existing session directory tools.To overcome these limitations, we propose a new architecture for session advertisement and caching that exploits multicast "admbistrative scope" through protocol proxies to admit layered media formats and reduce the start-up latency of a directory-stice client by an order of magnitude or more.Our architecture is fully compatible with the existing directory service allowing our implementation, -which is split acro.w a new session directory tool and network proxy, to be incrementally deployed within the current Internet multimedia conferencing architecture.

The development of MBone videoconferencing tools has led to a large number of seminars being broadcast over the Internet.Most MBone seminars have little remote participation.One reason might be the absence of goodfloor control mechanisms.This paper describes a tool we developed, called the Questionboard, that implements floor control to facilitate question asking in large-scale MBone seminars.The qb protocol is described including the mechanisms used for reliable transmission of data and the floor control and crash recovery protocols.2. This author's current address is radhika

This paper introduces the notion of “universal interaction,” allowing a device to adapt its functionality to exploit services it discovers as it moves into a new environment. Users wish to invoke services — such as controlling the lights, printing locally, or reconfiguring the location of DNS servers — from their mobile devices. But aprioristandardization of interfaces and methods for service invocation is infeasible. Thus,the challenge is to develop a new service architecture that supports heterogeneity in client devices and controlled objects, and which makes minimal assumptions about standard interfaces and control protocols. There are five components to a comprehensive solution to this problem: 1) allowing device mobility, 2) augmenting controllable objects to make them network-accessible, 3) building an underlying discovery architecture, 4) mapping between exported object interfaces and client device controls, and 5) building complex behaviors from underlying composable objects. We motivate the need for these components by using an example scenario to derive the design requirements for our mobile services architecture. We then present a prototype implementation of elements of the architecture and some example services using it, including controls to audio/visual equipment, extensible mapping, server autoconfiguration, location tracking, and local printer access.

This paper describes research issues in the design and implementation of a video-on-demand system. Issues related to database design and population, user interface design, media formats, tertiary storage and video file server management, video delivery, and copyrights are discussed.

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

The authors describe an exploratory study performed to compare three different interface styles for ad hoc query to a database. Subjects with wide-ranging computer experience performed queries of varying difficulty using either an artificial, a graphical, or a natural language interface. All three interfaces were commercial products. The study revealed strengths and weaknesses of each interface and showed that interaction with the natural language interface was qualitatively different than interaction with either the graphical or artificial language systems.>

PICASSO is a graphical user interface development en-vironment built using the Common Lisp Object System (CLOS). This paper describes how CLOS features in-cluding multiple inheritance, instance methods, multi-methods, and method combinations were used to imple-ment the system. In addition, the benefits and draw-backs of CLOS development are discussed including code quality, maintainability and performance. 1.

Article Free Access Share on Cache consistency and concurrency control in a client/server DBMS architecture Authors: Yongdong Wang Computer Science Division-EECS, University of California, Berkeley, CA Computer Science Division-EECS, University of California, Berkeley, CAView Profile , Lawrence A. Rowe Computer Science Division-EECS, University of California, Berkeley, CA Computer Science Division-EECS, University of California, Berkeley, CAView Profile Authors Info & Claims SIGMOD '91: Proceedings of the 1991 ACM SIGMOD international conference on Management of dataApril 1991 Pages 367–376https://doi.org/10.1145/115790.115855Online:01 April 1991Publication History 92citation621DownloadsMetricsTotal Citations92Total Downloads621Last 12 Months40Last 6 weeks4 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my Alerts New Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Methods for automatic presentation of relational information in the form of directed graphs are discussed. An overview of the graph-layout problem is presented along with a summary of several different layout algorithms. A divide-and-conquer layout algorithm called Compoze is described in detail. This algorithm produces especially good results on large graphs of several hundred vertices.>

The design and implementation decisions made for the three-dimensional data manager POSTGRES are discussed. Attention is restricted to the DBMS backend functions. The POSTGRES data model and query language, the rules system, the storage system, the POSTGRES implementation and the current status and performance are discussed.>

Abstract This paper describes a visual command language for a workstation with a bit‐mapped display and a mouse that can be used to create different user interfaces. Primitive interface components can be combined into more complex user interfaces. The user specifies interconnections between these components over which data and commands can be sent by pointing with a mouse. Primitive interface components are described for creating several different database user interfaces. The design and implementation of the software architecture is described, including the primitives for database interfaces and the communication protocols used by the system.

Abstract A general‐purpose browser for directed graphs is described. The browser provides operations to examine and edit graphs and to generate a layout for a graph automatically that minimizes edge crossings. Two layout algorithms were implemented. A hierarchical graph layout algorithm was found to be best for directed graphs. The graph browser also has facilities that allow it to be integrated with other applications (e.g. a program browser). These facilities and our experiences building a program call‐graph browser are described.

This paper presents the preliminary design of a new database management system, called POSTGRES, that is the successor to the INGRES relational database system. The main design goals of the new system are to

This paper describes a screen-oriented I/O facility, designed as a part of Rigel, a high-level database programming language. The novel features of the I/O facility, called Screen Rigel, include the use of formatting techniques to lay out text and data on the screen. Applications written in Screen Rigel can directly access the database using the database constructs already in Rigel. In addition, Screen Rigel has access to the data dictionary so the programmer can use the data descriptions in the database instead of respecifying them. These features make Screen Rigel programs simple to write and highly data and terminal independent.

This paper describes FADS --- a Form Application Development System which is an interactive system for the development of form-based database applications. FADS reduces the amount of work required to implement a forms application by suppressing much of the detail which would be required by conventional tools (e.g., a screen definition system, a database system, and a programming language). FADS provides direct access to a relational database, a standard model of the user interface, built-in form constructs, and an integrated development and debugging environment. Using FADS, form applications can be developed quickly and the resulting systems are easy to modify.A prototype implementation of the FADS kernel has been completed.

The design and implementation of a local network operating ystem based on the UNIX1operating system is described. UNIX has been extended to allow existing programs to access remote resources with no source program changes. Programs may access remote files, have a remote working directory, execute remote programs, and communicate with remote processes using the standard UNIX interprocess communication mechanism (pipe's). An efficient message-oriented interprocess communication mechanism and asynchronous I/O were added to the system to support the development of distributed applications and to make it easier to connect the local network to packet-switched networks.

Language constructs to support the development of data base applications provided in the programming language rigel are described. First, the language type system includes relations, views, and tuples as built-in types. Tuple-values are introduced to provide more flexibility in writing procedures that update relations and views.Second, an expression that produces sequences of values, called a generator, is defined which integrates relational query expressions with other iteration constructs found in general-purpose programming languages. As a result, relational expressions can be used in new contexts (e.g., as parameters to procedures) to provide new capabilities (e.g., programmer-defined aggregate functions).Lastly, a data abstraction facility, unlike those proposed for other data base programming languages, is described. It provides a better notation to specify the interface between a program and a data base and to support the disciplined use of views.All of these constructs are integrated into a sophisticated programming environment to enhance the development of well-structured programs.

An approach to automating the selection of implementations for the data representations used in a program is presented. Formalisms are developed for specifying data representations and implementation structures. Using these formalisms, algorithms are presented which will recognize the use in a program of known data representations (e. g., stacks, queues, lists, arrays, etc.) so that alternative implementations can be retrieved from a library and which will, for those representations not recognized, generate alternative implementations with a wide range of space-time tradeoffs. Experience with using these algorithms indicates they are reasonably successful, although there are several problems that must be solved before automatic implementation selection systems will be practical.