Computing While Composing Miller Puckette ∗ size and process musical sound. It can be argued that The field of computer music can be thought of the computer has been the one addition to the clas- as having two fundamental branches, one concerned sical orchestra since the advent of percussion early with the manipulation of musical sounds, and the in the twentieth century. This is a great achieve- other concerned with symbolic representations of mu- ment. CGM is now generally accepted, and the sta- sic. The two are iconized by Max Mathews’s MU- tus of a musician in the Mathews tradition essen- SIC program and Lejaren Hiller’s ILIAC Suite, both tially depends on how good his or her output sounds, of 1957, although both have important antecedents. in the same way as that of an orchestral string or The two branches might provisionally be given the wind player. CGM has become a normal, respectable, names “Computer Generated Music” (Denis Baggi’s middle-class occupation. term for it) and “Computer Aided Composition”— The development of CAC, on the other hand, has or CGM and CAC for short. (In France the latter seen a deepening realization that the problems of the is called “Composition Aid´eepar Ordinateur”. The field are much more difficult than they may have ap- corresponding English acronym, “CAC”, is less than peared at first. In hindsight, this should have been mellifluous and someday we should settle on a better obvious to everyone all along: CGM is in effect build- one.) ing instruments (which were previously made of wood As a field, CAC has flown a very different tra- and the like), but CAC is in effect making the com- jectory from CGM. While in the United States the puter carry out thought processes previously carried great strides between 1957 and 1980 were on the out in human brains. Clearly, a piece of wood is CGM side, in Europe during the same period we saw easier to understand than even a small portion of a work by Xenakis (starting as early as 1962), Koenig human brain. Ultimately, CAC researchers will have (Project 1, 1964), and many others that, taken to- to settle for much less than a full understanding of gether, can be seen as the first proof that CAC could even a single musical phenomenon. The best that be widely useful in creating new music. Meanwhile can be hoped for is partial solutions to oversimplified in the United States, many people, myself included, versions of the real problems. thought of CAC as a topic of computer science re- search, not likely ever to give rise to tools useful to Computational Complexity musicians. Interest in CAC has grown in the USA in From my point of view, having come to computer the intervening years, but excepting the brilliant ex- music in the year 1979, the comparative situations of ample of David Cope, work in the USA on this topic the two branches in the year 2006 come as a surprise. has lagged behind that in Europe. To the user of a 16-bit DEC PDP-11 computer, the Today CGM is ubiquitous and CAC appears futur- manipulation of musical symbols looked trivial com- istic. An entire generation of composers and other pared to the hard practical problems posed by the musicians has learned to use the computer to synthe- sheer size of the problem of sound synthesis. A five- ∗ 2 second, one-channel soundfile was a large object in CRCA, Cal(it) , UCSD. This article appears as the preface to Carlos Agon et al., Eds., the OM Composer’s book, Editions 1979, and the realization of a piece of computer mu- Delatour France / IRCAM, 2006.) sic lasting ten minutes could easily require a solid 1 week of computer time. Back then I was exceedingly one used a program that someone else had written. lucky even to have that possibility. Now, in 2006, For the most part, each program was written for its three IRCAM pieces from the 1980s can be run si- own particular, special purpose. Over the following multaneously in real time on a computer small and decade, however, this began to change for two rea- light enough that it could easily be thrown several sons. First, people learned to write large, flexible rows into the audience. programs (troff being my favorite example) powerful The symbol manipulators, on the other hand, enough that different users could turn a given pro- whose programs once only took a few thousand arith- gram to very different purposes. metic operations and a one- or two-inch stack of Second, and more subtly, the possibilities for com- punched cards to run, now take their place as the bining different bits of software together began to heaviest computer users in all of music. The growth multiply. An important step was the invention of the in complexity of CAC algorithms appears to have Unix operating system, which unified all I/O through outrun the ability of computers to run them. The one very simple and clean abstraction. This permit- Markov chains of the early days (a few hundred arith- ted users to direct one program’s output to another metic operations per note, say) have given way to program’s input, frequently without the need even to combinatorial search and optimization problems re- choose a name for the data passing between the pro- quiring as many trillions of calculations as the user grams. This made it possible for a relatively simple can afford to wait for. The imagination of composers program such as “tr” to be put to all sorts of different and researchers in CAC far outstrips the supply of uses. Try it on a headerless soundfile, for instance, to available computation power. put a classical music lover’s teeth on edge, in a way I In general, the cost of CGM per audio sample has doubt the program’s original designer had imagined. not remained constant, but has not grown quickly. A parallel development was underway in the com- The best CGM of the seventies, thirty years ago say, puter music community. Here the roots of the idea probably cost less than ten thousand arithmetic op- reach all the way back to about 1958 when Max erations per sample of output. The speedup in com- Mathews’s MUSIC N programs began to offer recon- puting in the intervening years has allowed us the figurable unit generators, which the user configured luxury of running the classic CGM algorithms in real in a network to generate musical sounds, predating time, thus changing the nature of the pursuit fun- and anticipating the modular synthesizers built by damentally. The algorithms themselves have grown Moog and others in the 1960s. By the mid 1980s somewhat more complex as well, but the universal many researchers were thinking about trying to turn preference for real-time synthesis and processing has this notion of reconfigurability to use in passing data put a lid on that growth. of other formats than audio signals. CAC has not become real-time at all. Since it ap- Programs themselves (such as MUSIC, Max/MSP, peals to the composer in us (whereas CGM appeals or OpenMusic) have become complicated and diffi- to the performer in us), it seems reasonable to expect cult to develop, but once the paradigm for making that CAC software will continue to absorb all the interconnections has been worked out, they are com- computing resources that can possibly be brought to paratively easy to extend. Users can contribute ex- bear on it. Anything allowed to grow will naturally tensions and benefit from each other’s work, without do so. having to worry about the tricky stuff such as GUIs or file formats. Programmers and users In another sense, however, a patch is itself a pro- gram, and the job of connecting simple functions to- About 1970, when I started using the computer— gether to make larger ones can be thought of as pro- there was only one in my town—there was no dis- gramming. In this sense, the trend toward patch- tinction between computer users and computer pro- based software can be seen as shifting the level on grammers. It only occasionally happened that some- which the user programs the computer away from 2 the C or Lisp code itself and into the “language” of a general movement in CAC away from formal and patches. It may be that this is fundamentally a bet- mathematical tools, in favor of more intimate modes ter level at which to operate a computer, than either of interaction with the computer, even up to direct that of code or that of the user of a large, monolithic manipulation of data structures by composers. So for program such as a database application. instance when early CAC researchers wrote computer programs whose output might be an entire piece of Art music and the computer music, today we see developments such as Open Mu- sic which, in their graphical orientation and patch- In Europe and its former colonies such as the U.S., ing metaphor, encourage the composer to proceed by composers, since early in the twentieth century, have experimentation and intuition instead of by formal paid much attention to problems of symbol manipu- planning and specification. lation and combinatorics. This idea found an early The field of CAC in general is moving away from expression in Shoenberg’s 12-tone harmony, contin- mathematical and computer science constructs, and ued through the serialism typified by Webern and toward a more useful and powerful working relation- later Boulez, and may have culminated in the various ship with the rest of the composition process.