Transcript PowerPoint Presentation - Basic Computer 101 and Basic Digital

Basic Computer 101 and
Basic Digital Audio
basic is a relative term
Listening
Paul Lansky, Smalltalk (1988, available on
CD of same title, New Albion NA 030 CD)
Otto Luening, Low Speed (1952, available
on OHM: Early Gurus of Electronic Music,
in Bracken Library)
Reading Discussion
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
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.
Digital Audio
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.)
Reading Assignment
Roads, Chapter 1. Due 1/24