Experimental Study of Issues in End-to End QoS

Quality of Service (QoS) guarantees for \u27delay sensitive\u27 networked applications must be end-to-end. This paper presents an experimental study of this class of applications where the endpoints are computer workstations. The experiments show that operating system effects dominate any jitter in the network. Our conclusion is that QoS provision by the workstation operating system is as important for maintaining end-to-end guarantees as is network QoS. In local-area settings, operating system influences may be more challenging for end-to-end QoS than network influences. The important influence variables are the degree of multiprocessing, the employed transport protocol (e.g. UDP or TCP), and the priorities assigned to processes

Active Scores: Representation and Synchronization in Human-Computer Performance of Popular Music

Computers have the potential to significantly extend the practice of popular music based on steady tempo and mostly determined form. There are significant challenges to overcome, however, due to constraints including accurate timing based on beats and adherence to a form or structure despite possible changes that may occur, possibly even during performance. We describe an approach to synchronization across media that takes into account latency due to communication delays and audio buffering. We also address the problem of mapping from a conventional score with repeats and other structures to an actual performance, which can involve both “flattening” the score and rearranging it, as is common in popular music. Finally, we illustrate the possibilities of the score as a bidirectional user interface in a real-time system for music performance, allowing the user to direct the computer through a digitally displayed score, and allowing the computer to indicate score position back to human performers

Active Scores: Representation and Synchronization in Human-Computer Performance of Popular Music

Computers have the potential to significantly extend the practice of popular music based on steady tempo and mostly determined form. There are significant challenges to overcome, however, due to constraints including accurate timing based on beats and adherence to a form or structure despite possible changes that may occur, possibly even during performance. We describe an approach to synchronization across media that takes into account latency due to communication delays and audio buffering. We also address the problem of mapping from a conventional score with repeats and other structures to an actual performance, which can involve both “flattening” the score and rearranging it, as is common in popular music. Finally, we illustrate the possibilities of the score as a bidirectional user interface in a real-time system for music performance, allowing the user to direct the computer through a digitally displayed score, and allowing the computer to indicate score position back to human performers

A Dynamic Timed-Language for Computer-Human Musical Interaction

In this paper, we present the programing of time and interaction in Antescofo, a real-time system for performance coordination between musicians and computer processes during live music performance. To this end, Antescofo relies on artificial machine listening and a domain specific real-time programing language. It extends each paradigm through strong coupling of the two and strong emphasis on temporal semantics and behavior of the system. The challenge in bringing human actions in the loop of computing is strongly related to temporal semantics of the language, and timeliness of live execution despite heterogeneous nature of time in the two mediums. Interaction scenarii are expressed at a symbolic level through the management of musical time (i.e. events like notes or beats in relative tempi) and of the 'physical' time (with relationships like succession, delay, duration, speed). Antescofo unique features are presented through a series of paradigmatic program samples which illustrate how to manage execution of different audio processes through time and their interactions with an external environment. The Antescofo approach has been validated through numerous uses of the system in live electronic performances in contemporary music repertoire by various international music ensembles.Ce papier présente le système temps-réel Antescofo et son langage dédié. Celui-ci permet de décrire des scénarios temporels où des processus de musique électronique sont calculés et ordonnancés en fonction du jeu d'un musicien. Pour ce faire, Antescofo couple un système de suivi de partition avec un module réactif. L'originalité du système réside dans la sémantique temporelle du langage adaptée aux caractéristiques critiques de l'interaction musicale. Le temps et les événements peuvent s'exprimés de façon symbolique dans une échelle absolue (en seconde) ou des échelles relatives à des tempos. Nous aborderons les caractéristiques du langage et de la partie réactive d'Antescofo illustrées à travers une série d'exemples paradigmatiques

Languages for Computer Music

Specialized languages for computer music have long been an important area of research in this community. Computer music languages have enabled composers who are not software engineers to nevertheless use computers effectively. While powerful general-purpose programming languages can be used for music tasks, experience has shown that time plays a special role in music computation, and languages that embrace musical time are especially expressive for many musical tasks. Time is expressed in procedural languages through schedulers and abstractions of beats, duration and tempo. Functional languages have been extended with temporal semantics, and object-oriented languages are often used to model stream-based computation of audio. This article considers models of computation that are especially important for music programming, how these models are supported in programming languages, and how this leads to expressive and efficient programs. Concrete examples are drawn from some of the most widely used music programming languages

LC: A Mostly-strongly-timed Prototype-based Computer Music Programming Language that Integrates Objects and Manipulations for Microsound Synthesis

Ph.DDOCTOR OF PHILOSOPH