THE HORGIE: COLLABORATIVE ONLINE SYNTHESIZER Jorge Herrera Center for Computer Research in Music and Acoustics Stanford, USA jorgeh@ccrma.stanford.edu ABSTRACT The Horgie is a new musical instrument that explores the usage of a web browser as a tool for collaborative music performance online. All the sounds are synthesized by an Actionscript application and the instrument can be simulta- neously controlled on real-time by two performers, each one using a separate browser. Therefore, remote creation and performance of music is now possible without installing any other application beside a web browser with a Flash plug-in (which is already installed in the vast majority of personal computers). Special emphasis was made in the user inter- face in order to enable musicians and non musicians to play the instrument. 1. INTRODUCTION Collaborative music creation and performance is a broad and interesting topic to explore. It has social, aesthetic and technical issues to be considered. There are many ways to include a collaborative aspect in music performance. Fur- thermore, the Internet offers the possibility of remote real- time collaboration. But how music creation and performance can take advantage of this possibility is not clear yet. This does not mean that no work has been done. In fact, there are some remarkable projects to mention. The SoundWIRE group at Stanford’s Center for Com- puter Research in Music and Acoustics (CCRMA) is “con- cerned with the use of Internet networks as an extension to computer music performance, composition and research” 1 . This group has focused on the transmission of uncompressed high quality audio through the Internet, enabling remote lo- cations to perform tele concerts, using any kind of instru- ment or sound source. The results achieved are quite im- pressive, but they require high bandwidth connections and some applications to be installed at the endpoints. Psychosynth [3] is another initiative focused on collab- orative music creation and/or performance. It is a software synthesizer inspired by the ideas of the Reactable [6]. This project provide communication between remote synths over a network, but it requires to install the software in the remote locations. In that sense, it’s not an on-line instrument. 1 http://ccrma.stanford.edu/groups/soundwire/ Other projects, such as PSOs [1], have developed on- line instruments (instruments that run on a web browser). Mainly, this kind of projects have focused on the user inter- face, but have not addressed this collaborative aspect. Another initiative worth mentioning is FMOL (Faust Mu- sic On Line) [5]. A thorough review of the different projects and applications in this field can be found at [2]. The present work proposes a different approach to the use of the Internet for collaborative music making. The idea is to provide a means for music expression using only a browser (no other installation required). All the previously mentioned initiatives require the installation of one or more applications on the machine(s) to be used. This fact impose a barrier that may discourage the potential users. Because of the same reason, the users tend to be only persons that are familiar with computer music. PSO [1] addresses this issue by providing a web browser instrument, but the collabora- tion aspect is handled using a central server to synthesize the sound. The purpose of The Horgie is to provide an easy to use, installation free synthesizer with real-time collabora- tion. The goal is to allow trained and non trained computer musicians to remotely create a sonic experience. Hopefully this will open computer music to a massive new audience. In summary, the main contributions of this work are: • Provide and installation-free synthesizer • Include real-time remote collaboration to the sound creation process • Provide a sound synthesis environment to a wide au- dience, without the need of previous computer music knowledge 2. THE SOUND Unlike other collaborative instruments, The Horgie synthe- size the sounds on the client itself. This is consistent with the idea of no installation required. The only data trans- ferred between clients is control data. Therefore, both can listen the exact same sounds. In this first version, two kinds of synthesis are provided: Frequency Modulation and Granular Synthesis. Furthermore,