368432
Personal orchestra: a real-time audio/video system for interactive conducting
Jan Borchers1, Eric Lee1, Wolfgang Samminger2, Max Mühlhäuser3 1 Media Computing Group, Department of Computer Science, RWTH Aachen University, 52056 Aachen, Germany e-mail: borchers@cs.rwth-aachen.de 2 Telecooperation Department, University of Linz, 4040 Linz, Austria e-mail: wolfgang.samminger@liwest.at; eric@cs.rwth-aachen.de 3 Telecooperation Group, Darmstadt University, 64283 Darmstadt, Germany e-mail: max@informatik.tu-darmstadt.de
7453458
Designing time-based interactions with multimedia
The current model of time in multimedia frameworks poses particular problems when designing multimedia systems with time-based interaction. We propose to expand and extend an existing distinction between semantic time and real time from music and film theory to multimedia systems design. The semantic time concept also forms the foundation of a new software framework for multimedia systems that we are building, that, unlike most existing frameworks, includes mechanisms for time-based effects such as time-stretching.
5409418
You're The Conductor: A Realistic Interactive Conducting System for Children
This paper describes the first system designed to allow children to conduct an audio and video recording of an orchestra. No prior music experience is required to control the orchestra, and the system uses an advanced algorithm to time stretch the audio in real-time at high quality and without altering the pitch. We will discuss the requirements and challenges of designing an interface to target our particular user group (children), followed by some system implementation details. An overview of the algorithm used for audio time stretching will also be presented. We are currently using this technology to study and compare professional and non-professional conducting behavior, and its implications when designing new interfaces for multimedia. You're the Conductor is currently a successful exhibit at the Children's Museum in Boston, USA.
14010108
conga: A Framework for Adaptive Conducting Gesture Analysis
Designing a conducting gesture analysis system for public spaces poses unique challenges. We present conga, a software framework that enables automatic recognition and interpretation of conducting gestures. conga is able to recognize multiple types of gestures with varying levels of difficulty for the user to perform, from a standard four-beat pattern, to simplified up-down conducting movements, to no pattern at all. conga provides an extendable library of feature detectors linked together into a directed acyclic graph; these graphs represent the various conducting patterns as gesture profiles. At run-time, conga searches for the best profile to match a user's gestures in real-time, and uses a beat prediction algorithm to provide results at the sub-beat level, in addition to output values such as tempo, gesture size, and the gesture's geometric center. Unlike some previous approaches, conga does not need to be trained with sample data before use. Our preliminary user tests show that conga has a beat recognition rate of over 90%. conga is deployed as the gesture recognition system for Maestro!, an interactive conducting exhibit that opened in the Betty Brinn Children's Museum in Milwaukee, USA in March 2006.
7621577
Towards a quantitative analysis of audio scrolling interfaces
We present the results of a user study inspired by previous work in document navigation comparing rate and position control for navigating an audio timeline. Although interfaces for controlling playback speed (rate) are favored over playback position, we found that position control is, on average, 15-19% faster than rate control when searching for targets 90 to 100 seconds away in the audio timeline. Additional studies are being planned to further characterize audio scrolling performance with position and rate controls.
10851913
Taming heterogeneity - the Ptolemy approach
Modern embedded computing systems tend to be heterogeneous in the sense of being composed of subsystems with very different characteristics, which communicate and interact in a variety of ways-synchronous or asynchronous, buffered or unbuffered, etc. Obviously, when designing such systems, a modeling language needs to reflect this heterogeneity. Today's modeling environments usually offer a variant of what we call amorphous heterogeneity to address this problem. This paper argues that modeling systems in this manner leads to unexpected and hard-to-analyze interactions between the communication mechanisms and proposes a more structured approach to heterogeneity, called hierarchical heterogeneity, to solve this problem. It proposes a model structure and semantic framework that support this form of heterogeneity, and discusses the issues arising from heterogeneous component interaction and the desire for component reuse. It introduces the notion of domain polymorphism as a way to address these issues.
5648139
The problem with threads
For concurrent programming to become mainstream, we must discard threads as a programming model. Nondeterminism should be judiciously and carefully introduced where needed, and it should be explicit in programs. In general-purpose software engineering practice, we have reached a point where one approach to concurrent programming dominates all others namely, threads, sequential processes that share memory. They represent a key concurrency model supported by modern computers, programming languages, and operating systems. In scientific computing, where performance requirements have long demanded concurrent programming, data-parallel language extensions and message-passing libraries such as PVM, MPI, and OpenMP dominate over threads for concurrent programming. Computer architectures intended for scientific computing often differ significantly from so-called general-purpose architectures.
17704367
A Parallel, Linear Programming-based Heuristic for Large-Scale Set Partitioning Problems
We describe a parallel, linear programming and implication-based heuristic for solving set partitioning problems on distributed memory computer architectures. Our implementation is carefully designed to exploit parallelism to greatest advantage in advanced techniques like preprocessing and probing, primal heuristics, and cut generation. A primaldual subproblem simplex method is used for solving the linear programming relaxation, which breaks the linear programming solution process into natural phases from which we can exploit information to find good solutions on the various processors. Implications from the probing operation are shared among the processors. Combining these techniques allows us to obtain solutions to large and difficult problems in a reasonable amount of computing time.
1955659
A framework for comparing models of computation
We give a denotational framework (a "meta model") within which certain properties of models of computation can be compared. It describes concurrent processes in general terms as sets of possible behaviors. A process is determinate if, given the constraints imposed by the inputs, there are exactly one or exactly zero behaviors. Compositions of processes are processes with behaviors in the intersection of the behaviors of the component processes. The interaction between processes is through signals, which are collections of events. Each event is a value-tag pair, where the tags can come from a partially ordered or totally ordered set. Timed models are where the set of tags is totally ordered. Synchronous events share the same tag, and synchronous signals contain events with the same set of tags. Synchronous processes have only synchronous signals as behaviors. Strict causality (in timed tag systems) and continuity (in untimed tag systems) ensure determinacy under certain technical conditions. The framework is used to compare certain essential features of various models of computation, including Kahn process networks, dataflow, sequential processes, concurrent sequential processes with rendezvous, Petri nets, and discrete-event systems.
821388
Subvarieties of the Variety Generated by the Five-element Brandt Semigroup
All subvarieties of the variety B2 generated by the five-element Brandt semigroup are characterized. Based on this characterization, an algorithm is provided that decides if a finite set of identities defines, within B2, a finitely generated subvariety.