Operating Systems (OS) Handles basic tasks, like how hardware parts communicate with each other, defines how the user interacts with the computer, how software communicates with the computer, etc. Most OS’s are extendable in function, meaning that functionality can be added to the OS through additional code. Extensions (Mac OS 9) Libraries (Windows [dll], Mac OS X) Drivers (really libraries) usually add functionality for specific hardware devices (printers, audio interfaces)
OS in depth (one slide) Kernel: central core of the OS. It is the first to load during system startup (booting), and remains loaded throughout. Kernel space is separate from user space. Computer crash is a kernel crash. Programs (applications) run in user space. If a program crashes, the kernel (and hence, computer) can continue to run, as long the program wasn’t interacting with the kernel is some crucial way. Geek Link: http://www.bellevuelinux.org/kernel.html http://www.bellevuelinux.org/kernel.html
Multi-user file systems Mac OS X and Windows XP are multi-user OS’s. Each user account has a specific folder or directory for storing data. (home directory) Each user account has specific access permissions to their own folders and other folders on the computer. The musicTech studios make use of a shared student account for easier system administration.
Audio Physical properties (things that can be physically measured). Realm of Acoustics Perceptual properties (how humans perceive physical properties) Psychoacoustics
Physical Properties Frequency Amplitude Spectrum, or spectral content All properties can change over time, as a function of time. That function is usually referred to as the property’s envelope.
Perceptual Properties Pitch (frequency) Loudness (amplitude) Timbre (spectrum) Envelopes can still apply. The relationship of physical scales of measurement to perceptual scales of measurement is logarithmic.
Analog Recording/Playback Analog recording/playback involves the transduction of air pressure fluctuations into corresponding electrical fluctuations. Electrical fluctuations are transduced into corresponding magnetic fluctuations for recording. Signal Chain: Sound wave > microphone > electrical signal > tape deck > magnetic signal > recorded on tape > playback > magnetic signal > electrical signal > amplifier > speaker > sound wave
Digital Recording/Playback Digital recording/playback involves the conversion of electrical impulses into a series of numbers, or samples. The samples can be stored magnetically, optically, or in any way that can represent ones and zeros. (Binary numbers) Signal Chain: Sound wave > mic > electrical signal > Analog-to-Digital Converter (ADC) > storage > Digital-to-Analog Converter (DAC) > electrical signal > amplifier > speaker > sound wave
Recording Quality Analog: quality depends on transduction quality at every step of the chain. Copying requires additional transduction, creating some degradation. (generational loss) Digital: quality depends on quality of ADC/DAC, and especially sample rate and bit resolution. Copying doesn’t create any loss, as the system only has to detect the difference between a one and a zero.
Binary Numbers (base 2) Every counting system has a base, or the rate at which digits or added. Our base 10 system means that there or ten digits possible for any place (0 - 9). Base 2, or binary, uses only two digits per place, 0 and 1. (switches) Each binary place is a bit. (binary digit) Any counting system can be converted to a base 10 number by multiplying each digit by the base to the power of the digit’s place. You count places starting at zero. (ex.) Going from base 10 to binary requires that you know the powers of 2. (ex.)