Proceedings of the International Computer Music Conference 2011, University of Huddersfield, UK, 31 July - 5 August 2011 RECONSIDERING LAPTOP ORCHESTRAS AS A COMPUTATIONAL GRID FOR MUSIC PERFORMANCE Stephen David Beck, Chris Branton Center for Computation & Technology Louisiana State University Baton Rouge, Louisiana, USA [email protected], [email protected] ABSTRACT time, distribute control messages, and manage other per- formance information. [11] Laptop orchestras have become a popular ensemble form Each LO composition consists of a unique combina- for the exploration of interactive computer music as a group tion of software, user interfaces, and physical devices. endeavor. Although its roots date back to the mid-1980s, it Configuration can range from the very simple (a single has only been in the past five years or so that these groups piece of code on each machine), to the very complex (Wii- have been established at universities, schools of music motes, iPads, custom UI and laptops, all driven by a net- and as stand-alone entities. As the number of ensembles worked time-sync). Laptops may all behave the same, or and the number of pieces written for these groups grows, have specialized individual roles. [3] we need better tools to manage the orchestra’s technical side. In reconsidering the laptop orchestra as a compu- tational grid for music, we are able to adopt a range of well-established tools and techniques used for managing scientific computational grids and apply them to this new environment. We will discuss the basis for our position, describe in general some important developments in our research, and highlight some additional steps we are tak- ing to further support the cyberinfrastructure of laptop or- chestras. 1. INTRODUCTION Figure 1. Our ensemble rehearses a work for laptops, Laptop Orchestras [10] (LOs) have recently become a very Wii-motes and an iPad. popular activity among academic institutions interested in identifying innovative teaching methods for electroa- Distribution, management and control of the neces- coustic and computer music education. This interest has sary software across a heterogeneous collection of net- spawned a new generation of ensemble acronyms remi- worked devices is a tremendous challenge for LOs. Each niscent to this author of efforts to name electronic music composition has a unique collection of core software, mid- studios with a sense of humor and irony. Ensemble names dleware and user-interface software that must be initial- such as PLOrk, SLOrk, BLOrk, L2Ork, LOLs, FLEA, and ized, launched and performed. The complexity of each HELO1, just to name a few, illustrate the passion many piece and skill of each performer can affect the amount of their respective ensembles have for this 21st century of time needed to prepare a piece for performance. And version of earlier experiments in technology-based group this “performance complexity” scales exponentially to the performance such as the Leauge of Automatic Music Com- number of laptops involved and the technical skill level posers and the Hub. [7] of the performers involved. Princeton’s laptop orchestra Typically, Laptop Orchestra composer-performers de- identified software configuration as perhaps one of their velop software to interpret human gestures through com- most significant problems. [11] puter interfaces that in turn control virtual instruments and processes that ultimately render music. Compositions can be improvised or scored, of determined or indeterminate 2. CHALLENGES FOR LOS length, with or without acoustic musicians. Laptops of- ten communicate across WiFi networks to synchronize While the interest in establishing Laptop Orchestras as a viable musical ensemble is seen in the rapid growth of 1In order, these groups are the Princeton LO, Stanford LO, Boulder LO, Linux LO, the LO of Louisiana, Florida Laptop Ensemble, and the such ensembles around the US and the world, the chal- Huddersfield Experimental LO. lenges of managing these groups are substantial. First and 460 Proceedings of the International Computer Music Conference 2011, University of Huddersfield, UK, 31 July - 5 August 2011 foremost is the distribution and maintenance of software compositions, preventing them from operating correctly. infrastructure. So a specific “de-configuration” script had to be created so that the computer would return to a neutral audio con- 2.1. Software and Version Control figuration after his piece was completed. Finally, the biggest challenge is the general demands There are a wide array of software environments available of concert performance. Imagine trying to prepare a lap- to composers and ensembles for the creation of music for top piece for performance. You need to be sure you have Laptop Orchestra. Max [15] [9] is a widely used graphical the right software, the right middleware, that all the pe- programming environment for MIDI, audio and video. Its ripherals were properly connected, and that you have the history is rich with applications for interactive computer correct computer configuration. And you have to do that music, and it is a language commonly used in the devel- for each laptop in the ensemble. And you have to do that opment of laptop orchestra music. Max can operate as an 8-10 times, depending on how many pieces you would interpretive application (i.e. running an application from perform on a concert. This quickly becomes a time prob- a user-defined document) or it can compile a standalone lem that is magnified exponentially by the techical savvy runtime application from a user-defined document. Max (or lack thereof) of the individual performers in the en- is a commercial program distributed by Cycling74 2. semble. ChucK [13] is an easy-to-use open-source audio pro- gramming language that runs scripts within a compiled virtual machine. It is a fairly lightweight environment to 3. A CONTEXT FOR GRID COMPUTING work with, especially because the programming is done through simple text files, and it has built-in hooks for man- In discussing these challenges with some of my colleagues, aging network communication using OpenSoundControl we realized that the laptop orchestra was in fact a grid (OSC) [14]. Both the Princeton and Stanford laptop or- computer for music. Grid computing is a form of dis- chestras have created a lot of LO music using ChucK, and tributed computing where a virtual supercomputer is cre- they have made these works available on the ChucK web- ated out of a loosely coordinated network of computers, site 3. Our group has used it, in large part, because it is all acting in concert towards a large common task. Grids very easy to get students started with the language. are largely comprised of heterogenous collections of com- There are plenty of other possible environments such puters, each connected to a common network, but not tied as SuperCollider [8], and composers are also creating works directly to one another in any synchronous way. [4] for laptop ensembles directly in programming languages Grids are used in all kinds of scientific applications, like Java. Jason Freeman’s LOLC is written in Java, and with the SETI@home [2] project being perhaps the best uses JSyn [5] as its sound engine. As well, some com- known. Here, participants in the project donate “down” positions rely on external peripheral devices such as Wii- cycles from their home computers for the purpose of pro- motes that require other middleware (i.e. OSCulator) to cessing radio astronomy data in the search for extraterres- translate data into OSC. trial intelligence. A central computer communicates with The point here is that Laptop Orchestras need to man- each computer, sending the networked machines bits of age a variety of core and middleware environments across data to process when they are not doing anything for the any number of laptop computers. This means checking to owner of the computer. The grid leverages available cy- make sure these environments are up-to-date AND mak- cles without tightly connecting processes across comput- ing sure that the compositions are compatible with those ers. particular software versions. That is, it is possible that a Laptop orchestras are also computer grids, although ChucK script might not be compatible with the most re- perhaps not at the same scale as SETI@home. Still, they cent version of ChucK, and so it is important to have ac- are a loosely coordinated group of computers tasked to- cess to both current and previous software versions. This wards the common goal of a musical composition. By is no easy task when dealing with one computer, let alone recognizing this, we are able to identify new kinds of so- five or twenty-five computers. lutions that can address the critical challenges posed by software version control, configuration and performance. 2.2. Configurations and Performance We have embarked on a project we call GRENDL, for GRid-ENabled Deployment for Laptop orchestras. This A second challenge is the variety of configurations that project uses the SAGA framework to build a command- are used for laptop ensemble music and the likelihood line application that manages laptop orchestra configura- that such configurations could conflict with one another. tions and provides controls for the performance of music A specific instance of this happened with our group. A composed for these ensembles. composer wanted to use the audio driver Soundflower to reroute an audio stream generated by a command-line ap- plication into Max. The problem was that when he was 3.1. GRENDL done, his specific audio configuration interfered with other The GRENDL project builds off the premise that laptop 2http://www.cycling74.com orchestras are, in fact, computational grids for music. It is 3http://chuck.cs.princeton.edu an integrated system that deploys, manages, and controls 461 Proceedings of the International Computer Music Conference 2011, University of Huddersfield, UK, 31 July - 5 August 2011 software and hardware technologies needed for the perfor- tor runs the quit mode.