Digital Music Composition/Introduction
What is digital music?
In the context of this book, digital music refers to music made using digital hardware or software, typically with a computer workstation.
If you have heard music produced while you were alive, you have almost certainly heard music that has been produced digitally. Music in the digital domain is often associated with electronic music; however this is not always the case. The foundation of electronic music is based on work done in the analog domain, from analog synthesizers to tape loop manipulation. These techniques are still popular today, even though computer-based sequencing and sound modification / generation are industry standard. Computers are, however, regularly used to produce digital equivalents of analog instruments and effects, making the distinction increasingly less important.
Synthesized instruments began to appear relatively soon after music became recorded, in the early 20th century. The exact technology used varied, but the primary lesson to learn is that they used an oscillator to generate a tone at varying frequencies. Amplitude, when mapped out as a function of time, produce a waveform that tells a speaker what point to be at at a given instance. What an oscillator does is produce an indefinitely repeatable pattern that can be directed to the speaker. Through the combination of multiple oscillators, distortions of the waveform, and other techniques, unique sounds may be produced.
Digital techology works with bits, which have only a "on" and "off" state. So, to represent the waveform in computer memory, the waveform is divided into discrete samples, where each sample represents the amplitude of the waveform at a given moment in time. Sound streams use many bits for each of these variables, to achieve a very fine precision in the waveform's representation. Digitalization means that audible artifacts can appear if care is not taken to keep the sound at the highest level of precision possible, and a poor conversion to analog(which often occurs on computers with low-cost integrated sound) will always make what comes through the speakers sound weak and "tinny".
Early synthesizers had no standardized control mechanism; this led to problems and additional hassle in the studio. But after the advent of the MIDI standard in the 1980s, control was greatly simplified. MIDI is a digital protocol that allows one machine(such as a piano keyboard, or a computer) to control another over a cable, triggering the other machine's events. At first, that meant a hardware synthesizer, but much of the hardware used when MIDI was invented has been reduced to software versions today. MIDI files are simply sequences of MIDI events using the "General MIDI" (GM) standard instruments, whose actual sounds are up to interpretation by the playback mechanism; their derision by many is the result of GM's limitations. MIDI is showing its age today, but is still a commonplace and useful tool.
Samplers also appeared in the 1980s. These machines store recordings and play them back; the difference between them and tape recorders are that samplers allow for great variation in the manner of playback. Digital technology makes effects such as reversing, looping, instantaneous restarting, and variable playback speed easy to accomplish. Modern computer sound cards work like a sampler that the computer can control and feed data to on-the-fly. The first sampling computer was the Commodore Amiga, released in 1985. From this computer, tracking was born, introducing digital music composition to the home consumer and started a new generation of musicians and genres.