依據樂曲分析之演算作曲系統建構

Abstract

演算作曲並非電腦科技的專利。從莫札特的骰子音樂到約翰．凱吉的機遇音樂，都可以說是運用演算規則進行作曲的實例。但是在二十世紀電腦科技出現之後，成為電腦音樂的一門重要研究方向。它使作曲家能夠專注在巨觀層次上去進行作曲，而不需要一個個設想、手動抄寫每個音符。同時，二十世紀許多現代樂曲樂風所講究的方法論，也與演算作曲相互呼應，本論文便透過演算作曲系統的實作來檢驗這點。

本論文透過將兩種現代音樂風格－－序列主義（serialism）及簡約主義（minimalism）的樂曲分析轉化為演算程式，對樂曲進行再創作來探討音樂風格與演算作曲的緊密關係。第一章首先探討過去既有的演算作曲，並且特別觀察互動作曲與純演算作曲的異同之處。第二章則檢視了過去幾種代表性的電腦演算作品及程式，了解各自的原理、操作方式、生成的樂風以及限制所在。第三章則是兩種音樂風格代表性樂曲《Structure Ia》及《Phrygian Gates》的基本結構分析，第四章則說明依據分析所建構而成的樂曲演算程式，整體的演算運作原理及操作方式。

依據樂曲分析所建構的演算作曲系統，除了可以使用原本樂曲的樂風進行再創作之外，還可以透過調變這些音樂特徵的相關參數產生新的樂風可能性。而本文所使用的 Max/MSP 物件導向程式語言，能夠快速地依據需要改變系統中各層級的結構。

From Mozart's dice music to John Cage's indeterminate music, many music works in history were composed using algorithmic techniques. However, with computer technology appeared in 20th century, the algorithmic composition becomes an important topic in computer music research. It lets composers focus on the macro-level of composition and do not need to think and compose note-by-note. At the same time, the many methodologies of contemporary music styles in 20th century are corresponding with algorithmic composition. This thesis wants to examine this fact by practically building an algorithmic composition system.

In this thesis, we transfer the music analyses of two contemporary music style, serialism and minimalism, into algorithmic programs, than examine the relationship between music style and algorithmic composition by re-composing. Chapter 1 discuss existing algorithmic compositions, especially on the similarities and differences between interactive composition and pure algorithmic composition. Chapter 2 is a survey of several classic works and programs of computational algorithmic composition, including their principles, operations, music styles and limites. Chapter 3 is the basic stractural analyses of two characteristic works of each styles, "Structure Ia" and "Phrygian Gates". Chapter 4 represent the algorithmic composition program we build according the analyses, showing its mechanism and methods.

Using this algorithmic compositional system based on analyses of musical works, we can not only re-compose music in existing styles, but also modulate these parameters of musical characteristics to create possibility of new music style. In this thesis, we using object-oriented program language Max/MSP, which can change the system structures in different level efficiently, based on what we need.