Graph grammar representation for collaborative sample-based music creation Gerard Roma Music Technology Group Universitat Pompeu Fabra Barcelona, Spain gerard.roma@upf.edu Perfecto Herrera Music Technology Group Universitat Pompeu Fabra Barcelona, Spain perfecto.herrera@upf.edu ABSTRACT This paper proposes a music representation for collabora- tive music creation using shared repositories of audio sam- ples. We explore the use of the graph grammar formalism to organize collective work on musical compositions stored as graphs of samples, and describe an experimental prototype that implements this concept. We then use the compositions created by different users with the prototype to show how this representation allows tracking and analyzing the music creation process. Potential applications of this include find- ing similarities between artists or suggesting sounds for a given compositional context. Categories and Subject Descriptors H.5.3 [Group and Organization Interfaces]: Web-based interaction; H.3.0 [Information Storage and Retrieval]: General; H.5.5 [Sound and Music Computing]: Method- ologies and techniques General Terms Algorithms, Human Factors Keywords network music, collaborative composition, graph grammars 1. INTRODUCTION There have been traditionally great expectations with re- spect to the possibilities of the internet to facilitate collab- orative music creation. The two main problems can be de- fined as remote networked performance, which involves si- multaneous presence of participants from different locations, and collaborative creation, which describes asynchronous creation of contents. While research continues on the for- mer [14], it seems to advance at a slower rate on the lat- ter. As generalized improvements of network bandwidth are stimulating new proposals in the market, most commercial offerings merely try to incorporate networking into the tra- ditional multi-track audio sequencer interface that has be- come dominant for individual music creation. We believe that further research in the higher level aspects of interac- tion is necessary in order to exploit networked computers to create new forms of collective musical creativity. In this sense, two important questions must be asked that belong to different disciplines. The first one is how to organize collaborative work from a practical point of view. Our observation in this respect is that collaboration already happens all the time in electronic music when producers re-use audio samples from other pro- ducers. The question is whether this practice can be gen- eralized to more complex musical structures and, in that case, what strategies related to roles and teams can emerge. This can be investigated using human-computer interaction methodologies. The second question is wether (and how), systems can ex- ploit data generated by users to enhance both compositional and social aspects of music creation, for example by suggest- ing potential collaborators. This can be seen as a traditional information retrieval problem. In this paper we propose using the graph grammar formal- ism as an initial step that allows both issues to be further investigated. Formal languages already facilitate high col- laboration levels in music creation, for example in MUSIC- N style languages such as Max, Supercollider or Pd. User communities of these languages are very active and are con- tinuously sharing and reusing their creations. Our aim is to allow for similarly re-using materials in sample-based com- position. The rest of this paper is organized as follows. First, we review some related work in the field of networked music creation and briefly review the use of grammars in music. Then, we propose a general representation that embeds the graph grammar formalism in the process of music creation. We describe a prototype that implements the proposed rep- resentation to allow sample-based music creation on top of a large repository of audio samples. We use initial data cre- ated using this prototype to show how the proposed repre- sentation can be exploited in the analysis of users creations. 2. RELATED WORK Many projects have researched internet-based collaborative creation. A recurring theme is that general availability of music creation tools allows to participate in music creation to a wider audience than traditional tools do [8][16]. In this sense, simple interfaces and large audio repositories can help exploring creation without the need of specialized musical training. Several projects have explored graph-based inter- faces for web-based composition [5] [17]. However, these Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. AM’10, September 15–17, 2010, Piteå, Sweden. Copyright © 2010 ACM 978-1-4503-0046-9/10/09…$10.00.