Ossia: Towards a Unified Interface for Scoring Time and Interaction
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OSSIA: TOWARDS A UNIFIED INTERFACE FOR SCORING TIME AND INTERACTION Jean-Michaël Celerier Pascal Baltazar Clément Bossut Blue Yeti L’Arboretum LaBRI [email protected] [email protected] [email protected] Nicolas Vuaille Jean-Michel Couturier Myriam Desainte-Catherine LaBRI Blue Yeti LaBRI [email protected] [email protected] [email protected] ABSTRACT events occurring at the same time; the work presented here removes this limitation. Here, we will initially present The theory of interactive scores addresses the writing and the use cases for conditional branching, as well as sev- execution of temporal constraints between musical objects, eral existing works of art which involve conditions. Then, with the ability to describe the use of interactivity in the we will introduce new graphical and formal semantics, re- scores. In this paper, a notation for the use of conditional searched during the course of the OSSIA project. Their branching in interactive scores will be introduced. It is goal is to allow composers to easily make use of condi- based on a high level formalism for the authoring of in- tional branching during the authoring of interactive scores. teractive scores developed during the course of the OS- We will show the compliance with previous research on SIA research project. This formalism is meant to be at the the same field, which allows for strong verification capa- same time easily manipulated by composers, and translat- bilities. We will conclude by presenting the software im- able to multiple formal methods used in interactive scores plementation of these formalisms in the upcoming version like Petri nets and timed automaton. An application pro- 0.3 of I-SCORE, which will be able to edit and play such gramming interface that allows the interactive scores to be scenarios in a collaborative way. embedded in other software and the authoring software, I- SCORE, will be presented. 1. INTRODUCTION 2. A CASE FOR CONDITIONAL INTERACTIVE This article will focus on a novel approach to represent and SCORES execute conditional branching in interactive scores. Inter- active scores, as presented in [1], allow a composer to write Even before the advent of computing, there was already a musical scores in a hierarchical fashion and introduce in- need to write scores containing informations of transport : teractivity by setting interaction points. This enables dif- in western sheet music, manifestations of this are the D. ferent executions of the same score to be performed, while S. Al Coda, D. S. Al Fine, Da Capo, and repetition sign. maintaining a global consistency by the use of constraints There is however no choice left at the interpretation. on either the values of the controlled parameters, or the A case with more freedom for the performer is the fer- time when they must occur. This is notably achieved in mata, which allows for the duration of a musical note to be the current version of the I-SCORE 1 software, presented chosen during the interpretation of the musical piece : the in [2]. score moves from purely static to interactive, since there Previously, interactive scores did not offer the possibil- can be multiple interpretations of the lengths written in the ity to make elaborate choices in case of multiple distinct sheet. 1 http://i-score.org/ There is also the different case of improvisational parts where each musician has the freedom of his own choice Copyright: c 2015 Jean-Michaël Celerier et al. This is an open- during a few bars – or even a whole piece. In our case, the access article distributed under the terms of the Creative Commons choices might involve multiple people at the same time (for Attribution 3.0 Unported License, which permits unre- instance multiple dancers each with his position mapped stricted use, distribution, and reproduction in any medium, provided the and used as a parameter), and lead to completely different original author and source are credited. results. 2.1 Conditional works of art quired, from touchscreen applications to full-fledged in- teractive installations. Several projects have been studied Some of the most interesting cases happen in more recent in the scope of OSSIA, in order to make the creation of times, with the advent of composers trying to push the new complex interactive applications more efficient by us- boundaries of the composition techniques. John Cage’s ing the tools that are developed in this research project. Two (1987), is a suite of phrases augmented with flexible timing : “Each part has ten time brackets, nine which are 2.2 Existing notations for conditional and interactive flexible with respect to beginning and ending, and one, the scores eight, which is fixed. No sound is to be repeated within a bracket.”. The brackets are of the form : 200000 $ 204500 We chose to compare the existing notations in a scale that and are indicated at the top of each sequence. goes from purely textual like most programming environ- Branching scores can be found in Boulez’s Third sonata ments, to purely graphic like traditional sheet music. Sim- for Piano (1955–57) or in Boucourechliev’s Archipels (1967- ilarily, there are multiple ways to define interactivity and, 70) where the interpreter is left to decide which paths to consequently, multiple definitions of what is an interactive follow at several points of bifurcation along the score. This score. principle is pushed even further in the polyvalent forms The programmatic environments generally take a preex- found in Stockhausen’s Klavierstücke XI (1957) where dif- isting programming language, like LISP, and extend it with ferent parts can be linked to each other to create a unique constructs useful for the description of music. This is the combination at each interpretation. Some of these compo- case with for instance Abjad [5], based on Python and sitions have already been implemented in computers, how- Lilypond, a famous music typesetting software based on ever it was generally done in a case-by-case basis, for in- a TEX-like syntax. There are also programming languages stance using specific Max/MSP patches that are only suit- more axed towards interpretation and execution of a given able for a single composition. The use of patches to record score, which can take the form of the program itself. This and preserve complex interactive musical pieces is described is the case with Csound and CommonMusic [6]. In gen- in [3]. eral, programming languages of this kind offer a tremen- The scripting of interactive pieces can also be extended dous amount of flexibility in term of flow-control. How- towards full audio-visual experiences, in the case of artistic ever, they require additional knowledge for the composer installations, exhibitions and experimental video games. to write scores with it. Multiple case studies of interactive installations involving The purely graphic environments allow compositions of conditional constraints (Concert Prolongé, Mariona, The scores without the need to type commands, and are much Priest, Le promeneur écoutant) were conducted in the OS- closer to traditional scores. For instance, multiple Max/MSP 3 4 SIA project. Concert Prolongé (i.e. extended concert) of- externals, Bach for Max/MSP [7], note~ , rs.delos and fers an individual listening experience, controllable on a MaxScore [8] allow to write notes in a piano roll, timeline, touchscreen where the user can choose between different or sheet music from within Max. But they are geared to- "virtual rooms" and listen to a different musical piece in wards traditional, linear music-making, even if one could each room, while continuously moving his virtual listen- build a non-linear interactive song by combining multiple ing point – thus making him aware of the (generally unno- instances, or sending messages to the externals from the ticed) importance of the room acoustics in the listening ex- outside. perience. Mariona [4, section 7.5.3] is an interactive ped- Finally, there is a whole class of paradigms that sit be- agogic installation relying on automatic choices made by tween the two, with the well-known "patcher"-like lan- the computer, in response to the users behaviours. This in- guages: PureData, Max/MSP, OpenMusic [9], PWGL [10]. stallation relies on a hierarchical scenarization, in order to These software work in term of data-flow : the patch rep- coordinate its several competing subroutines. The Priest resents an invariant computation which processes control is an interactive system where a mapping occurs between and/or audio data. In each case, it is possible to work the position of a person in a room, and the gaze of a vir- purely graphically, and flow control is generally imple- tual priest. Le promeneur écoutant 2 (i.e. the wandering mented as a block that acts on this data ([expr] in Pd/- listener) is a stand-alone interactive sound installation de- Max or [conditional] and [omif] in OpenMusic, signed as a video game with different levels of exploration, for instance). These software all allow to use a textual mainly by auditory means. programming language to extend the capabilites or express In closing, interactive applications for exhibitions offer some ideas more easily. various situations in which conditional constraints are re- 3 http://www.noteformax.net 4 http://arts.lu/roby/index.php/site/maxmsp/rs_ 2 http://goo.gl/et4yPd delos ecution of the score that would lead to this case. This has practical implications especially when working with hard- ware, which can have hard requirements on the input data. This means that the notation will have to be grounded with solid formal semantics. 2.4 Formal semantics The current work is based on previous work at the LaBRI by Jaime Arias, Mauricio Toro and Antoine Allombert, that attempt both to formalize the composition semantics and to provide ways for real-time performance of interac- Figure 1.