     |
|
|
Color Depth: 1 bit color 4 bit color 8 bit color 24 bit color |
No. of Colors: 2 16 256 16,777,216 |
Compression
(1)
Decreasing the size of stored information by reducing
the representation of the information without significantly diminishing
the information itself, usually by removing redundancies. Requires
decompression upon retrieval. Lossless compression allows the original
data to be recreated exactly. Lossy compression sacrifices some accuracy
to achieve greater compression.
(2)
Reduces
dynamic range by lowering amplitude when an audio signal rises above a
specified threshold. For example, compressors can be used to eliminate
variations in the level of an electric bass, providing an even, solid
bass line. Compressors can also compensate for variations in level
produced by a vocalist who moves frequently or has an erratic volume.
Convolution reverb
In
acoustics, an echo is the convolution of the original sound with a
function representing the various objects that are reflecting it.
Convolution reverbs are sample based reverbs that sound more natural but
are usually less flexible than simulated digital reverbs. They are based
on the idea that one can record the way a room reacts to certain
frequencies. These responses are than triggered by the actual sound that
has to get reverberated. Most convolution reverbs even let you record
your own custom library of room responses.
Cursor
A
special symbol that indicates where the next character you type on your
screen will appear. You use your mouse or the arrow keys on your
keyboard to move the cursor around on your screen.
Creative Sound Blaster
This
format is for Sound Blaster and Sound Blaster Pro voice files. Adobe
Audition supports both the older and newer formats. The older format
supports only 8-bit audio, mono to 44.1 kHz and stereo to 22 kHz. The
newer format supports both 8- and 16-bit audio. Files in this format can
contain information for looping and silence. If a file contains loops
and silence blocks, they expand when you open the file.
Crossfade
A
technique commonly used in editing audio. One sound is faded out while
another fades in, allowing for a smooth transition between the two.
Crossfading is also common in samplers, where it is used to smooth loop
transitions (crossfade looping), and sound design to create hybrid
sounds (one sound morphing or turning into another). While we often
think of this as a digital process, audio engineers have been using two
channel faders on a mixing console to crossfade between two signals or
tracks for many years.
DAT
Digital Audio Tape;
Digital Audio Tape, a magnetic tape
format developed by Sony and Philips in the mid-1980's. DAT uses a
rotary-head format, where the read/write head spins diagonally across
the tape as in a video cassette recorder. Its proper name is "R-DAT",
where "R" for rotary distinguishes it from "S-DAT", an earlier
stationary design. Most computer DAT recorders use DDS (digital data
storage) format, which is the same as audio DAT, but it is not always
possible to read tapes from one system on the other.
DC offset
DC
stands for "Direct Current." A signal whose midpoint is skewed away from
zero is said to have a DC offset; this can result in clicks, clipping or
other problems. You can use the DC Offset process in sound editors to
negate a pre-existing offset and put the mid of your waveform in the
center again.
De-esser
A
dynamics processor or plug-in that reduces the high frequencies that
contain excessive hissing or "S" sounds. They either just lower the
volume of the whole sound when those high frequencies appear or a
usually selectable part of the frequency range. In modern recordings
they also got used for another trick. You might have wondered about
these intimate sounds where the singer seems to crawl into your ear and
you understand every bit of what he or she says. This is done by heavily
turning on the high frequencies followed by a hard working de-esser.
Dial tone
The tone heard in a phone when the receiver is picked up, indicating the
line is available for dialing.
Diamond Ware Digitized
This format is used by
DiamondWare Sound Toolkit, a programmer's library that lets you quickly
and easily add high-quality interactive audio to games and multimedia
applications. It supports both mono and stereo files at a variety of
resolutions and sample rates.
DirectX
DirectX is an API (application programming interface)
for demanding multimedia applications. It provides fairly
direct access to the hardware and handles
tasks like full-color graphics, games, video, and 3-D
animation. Windows had a very
limited multimedia feature set for many years and before
directX many programmers preferred DOS for multimedia purposes.
Now DirectX provides a standard development platform
for Windows-based PCs by enabling software developers to access
specialized hardware features without having to write code that is
hardware-specific.
Disc at once
If you want to create a CD-R to use as a master for a real CD
production, you must write the CD-R in Disc-At-Once mode. In this mode,
the entire disc is written in one pass, without ever turning off the
recording laser. There are other ways of writing a CD, namely
Track-At-Once and Multisession. If you use these writing
formats, the "link blocks" created to link the
various recording passes together will be recognized as "uncorrectable
errors" when you try to master from the CD-R. These links can also
result in clicks when playing back the CD. Disc-At-Once mode provides
more flexibility when specifying pause lengths between tracks. It is
also the only mode that supports sub-indexes.
DMA
Direct
Memory Access/Addressing. DMA is a method of transferring data from one
memory area to another without having to go through the central
processing unit. Computers with DMA channels can transfer data to and
from devices much more quickly than those in which the data path goes
through the computer's main processor.
Drop-frame
Every frame :00 & :01 are
dropped for each minute change (60 X 2 = 120) except for minutes with
0’s (00:, 10:, 20:, 30:, 40: & 50:) (6 X 2 = 12, 120 - 12 = 108)
Color video was slowly introduced into broadcast. It was therefore
necessary to make it compatible with black and white receivers and to
design color receivers or televisions to be able to receive black and
white programming as well. In order to accommodate the extra information
needed for color the b&w’s 30 frame/second rate was slowed to 29.97 f/s
for color. Although usually not an issue for non broadcast applications,
in broadcast, the small difference between real time (or the wall clock)
and the time registered on the video can be problematic. Over a period
of 1 hour (SMPTE) the video will be 3.6 seconds or 108 extra frames
longer in relation to the wall clock. To overcome this discrepancy drop
frame is used.
DTMF
Dual Tone Multi-Frequency signals are used by standard push-button
telephones. They are generated using combinations of 679-, 770-, 852-,
941-, 1209-, 1336-, 1477-, and 1633-Hz sine waves.
DVI
DVI is actually both the name of the Digital Video
Interactive hardware system sold by Intel and the file format associated
with that system. DVI technology is essentially a PC-based interactive
audio/video system used for multimedia applications. The DVI system
consists of a board for use in an Intel-based PC, drivers, and
associated software.
DVI is a major competitor of QuickTime,
AVI, and MPEG for market share in
digital audio/video applications.
DVI/IMA ADPCM
Intel's (DVI) and the
International Multimedia Associations (IMA) flavor of
ADPCM compresses 16-bit data to 4 bits/sample (4:1)
by using a different (faster) method than Microsoft ADPCM. It has
different distortion characteristics, which can produce either better or
worse results depending on the sample being compressed. As with
Microsoft ADPCM, use this format with 16-bit rather than 8-bit files.
This compression scheme can be a good alternative to MPEG; it provides
reasonably fast decoding of 4:1 compression, and it degrades sample
quality only slightly.
DVD
Digital Versatile Disc (formerly Digital Video Disc);
new type of
CD-ROM that holds a minimum of 4.7GB (gigabytes), enough for a
full-length movie. The DVD specification supports disks with capacities
of from 4.7GB to 17GB and access rates of 600KBps to 1.3 MBps. One of
the best features of DVD drives is that they are backward compatible
with CD-ROMs. This means that DVD players can play old CD-ROMs, CD-I
disks, and video CDs, as well as new DVD-ROMs. Newer DVD players can
also read CD-R disks. DVD uses MPEG-2 to compress video data.
DVD-A
DVD-Audio; About 15 years after the CD new formats are now available
offering higher quality and additional features, but still on the
familiar 12 cm optical disc. One of those is DVD-Audio. It offers at
least 74 minutes of very high quality, surround sound, plus additional
features (such as video and limited interactivity) that are not
available on CDs.
DVD Players
There are three basic types of DVD players:
-
DVD-Audio player
This could either be an audio-only player (AOP), or a player capable of displaying visual menus, text and still images. -
DVD-Video player
This is referred to as a "V-Player" (Video Player), and is capable only of playing back video contents contained in the VIDEO_TS folder. -
Universal DVD-Audio/Video player
This is capable of playing back DVD-Audio data, displaying menus, text and still images. It can also play "hybrid" DVDs with both DVD-A and video content (contained in a VIDEO_TS folder), as well as standard video DVDs.
Dynamic automation
Dynamic automation lets you change parameters over time. Unlike static
automation, that just remembers a specific setting that you can recall,
it lets you record and play back dynamic changes. It is realized either
by recording real-time movements of faders and knobs or by drawing lines
that represent a parameter on a screen.
EBU
European Broadcasting Union; an organization formed originally by
national radio stations in Europe. Specializes in broadcast audio
distribution technology. Current standardization efforts include
terrestrial digital radio, both for audio and various kinds of data.
Ensoniq Paris
Hard disk recording system from Ensoniq, a vendor originally famous for
producing one of the first workable samplers. Ensoniq originally
developed the Paris hardware somewhere between 1995 and 1997 together
with Emu. later Emu released Paris with a new color scheme and called it
"Paris Pro". Unfortunately, the Paris hardware is no longer being
produced. Some software programmers however seem to continue developing
software on a private basis.
You can visit them at
http://www.myparispro.com/
EQ
Equalizer; An electronic
circuit, that boost or cuts specific frequencies or frequency bands in a
signal to modify and shape its sound.
This basic idea has been realized in some typical designs like Graphic
Equalizer, Parametric Equalizer, Notch Filter, Wah-Wah pedal etc...
FFT
Fast Fourier Transform; An algorithm based on Fourier Theory that music
software uses for filtering, spectral view, and frequency analysis.
Fourier Theory states that any waveform consists of an infinite sum of
sin and cos functions, allowing frequency and amplitude to be quickly
analyzed.
Flanger
An audio effect caused by mixing a varying, short delay in roughly equal
proportion to the original signal. The name comes from
how the effect was produced on big tape reels whereby the flange of the
reel was tapped to slow down a copy of the signal hence produced phasing
effects in the output.
Flash
Internet & computing Flash is a vector-based moving
graphics format created by Macromedia for the publication of animations
on the world-wide web. Flash (.swf) graphics files can be created in
Macromedia's own Flash program, or else in software applications such as
Adobe's LiveMotion or Corel's RAVE (real animated vector effects)
package. Most web browsers still require a plug-in to be installed
before they can play Flash animations.
Floating point
The term floating point is
derived from the fact that there is no fixed number of digits before or
after the decimal point; that is, the decimal point can float. This
improves the calculating capability of the CPU for arithmetic with real
numbers.
FM synthesis
Frequency Modulation
Synthesis; a music simulation technique that approximates the sounds of
real instruments by modulating and bending raw electronic wave forms.
The first real popular instrument that used this sound generating
technique was the famous Yamaha DX7 keyboard.
Formant
A peak in the frequency response of a vocal tract or
musical instrument. Different vowel sounds are characterized by the
position and shape of their formants. The human vocal tract typically
has five formant regions.
Format
A definition of the manner in
which data is stored; its organization. The pattern in which data are
systematically arranged for use on a computer. It is not only used at
computers. For example, VHS, SVHS, and Beta are three different formats
of video tape. They are not 100% compatible with each other, but
information can be transferred from one to the other with the proper
equipment (but not always without loss; SVHS contains more information
than either of the other two).
FPS
Frames per Second; The rate of how many complete pictures (frames) a
video or film shows per second to create the illusion of a motion
picture. A video frame consists of two interlaced fields
of either 525 lines (NTSC) or 625 lines (PAL/SECAM), running at 30
frames per second (NTSC) or 25 frames per second (PAL/SECAM). Film runs
at 24 frames per second.
Frames
(1) A single screen-sized
image that can be displayed in sequence with other slightly different
images to create motion pictures.
(2) The data on an audio CD
is divided into frames. A frame consists of 588 stereo samples. 75
frames make up one second of audio. Why? Well, 75 x 588 = 44100, and
since the sampling frequency of the CD format is 44100kHz (samples per
second), this equals one second of audio. The data on an audio CD is
divided into frames. A frame consists of 588 stereo samples. 75 frames
make up one second of audio. Why? Well, 75 x 588 = 44100, and since the
sampling frequency of the CD format is 44100kHz (samples per second),
this equals one second of audio.
Frequency sweeps
An oscillator starts generating a waveform at a certain (usually low)
frequency and changes the frequency at a defined speed to another
frequency (usually high), without changing the amplitude of the
waveform. This is useful to determine the frequency response of
circuits, rooms, speakers etc...
Gating
Also called snipping, hacking or slicing. An effect that mutes and
un-mutes a signal more or less rhythmically. This effect has first been
realized with noise gates that had a side-chain function. The side chain
has been fed by a rhythmic signal like drums or a pulsating
Glass Mastering
Part of the CD and DVD disc manufacturing process that uses a laser
(which is modulated by the data to be stored on the disc) to expose
areas of a photo-resist layer on a glass disc, where the final pits are
required. These areas are then developed and the photo resist layer
metallised so that stampers can be grown by electroforming using this
metal layer. The stampers are then used for molding CD and DVD discs.
GSIF
The GigaSampler-Interface support was invented by Nemesys (now Tascam)
to allow multichannel output for the GigaSampler (and later GigaStudio)
software. As ASIO it allows to access the hardware for multichannel
playback over one device. Recording is not possible. You may argue that
the same functionality is also possible with ASIO and GSIF would not be
needed and yes, probably you are right with that. Nemesys certainly had
reasons not to use the already well-supported ASIO interface invented by
a different audio software vendor. GigaSampler / GigaStudio also work
with DirectSound drivers but that does not allow output of multiple
channels at the same time. Because of that, special GSIF support is
needed for multichannel audiocards.
GSIF Multiclient
here are simple technical problems if you want to use different audio
applications at the same time. Now GigaSampler/-Studio originally was
not developed to be used with a Audio-/MIDI-sequencer software at the
same time on the same PC. Still many users demanded that functionality
from the vendors. The solution: a special multiclient driver that allows
the usage of ASIO or MME at the same time as GSIF, usually the physical
output channels need to be assigned to one or the other driver model.
Harmonic (overtone)
Given a signal, we can decompose it with the Fourier transform. Then, a
harmonic (of some particular frequency present in the transform) is any
frequency (also present in the analysis) which is at a whole number
ratio to our base tone. If the signal is periodic, every partial present
in the analysis is harmonic. The term implies an underlying base tone to
which the harmonic in question is related. (Thus, one doesn't say that
components present in a composite signal are necessarily harmonics, even
though they may appear in integer frequency ratios.)
Header
In file management, a header is a region at the beginning of each file
where bookkeeping information is kept. The file header may contain the
date the file was created, the date it was last updated, and the file's
size. The header can be accessed only by the operating system or by
specialized programs.
Hidden tracks
Normally when creating a CD or a DVD-A, only the sections between CD/DVD
track markers are burned, and the pauses between tracks are replaced by
silence. Some programs however let you burn the exact image of the Audio
Montage to CD or DVD, including any audio between tracks. This makes it
possible to add audio (without track markers) either in between CD/DVD
tracks, before the first track or after the last track, thereby creating
"hidden" tracks or continuous playback between tracks.
High definition audio
Intel® High Definition Audio (HD Audio) is
the specification for the next generation integrated audio solution.
First announced at the Intel Developer Forum, Spring 2003, and gaining
rapid adoption by the PC audio community, it is intended to be a
complete audio specification from the jacks in the PC to the driver
layer of the OS. The HD Audio is featured with Intel’s upcoming
chipset codenamed “Grantsdale” and will be the evolutionary replacement
of AC ‘97.
The following table shows a quick overview of the benefits of the Intel HD Audio Specification over the current AC ’97 Audio Specification.
| AC ’97 | High Definition Audio | Benefit |
| 11.5 MB/s max bandwidth | 24 -48 MB/s bandwith | Bandwidth for more channels and microphone array inputs at higher sample rates |
| Fixed bandwidth assignment, fixed slot base protocol | Dynamic bandwidth assignment | Bandwidth delivered where it's needed |
| Pre-defined DMA usage | General purpose DMAs | Support for multi-streaming / multiple similar device types |
| Single stream support (in and out) | Support for multiple streams (in and out) | Support for new Digital Home / Digital Office usage models |
| Clock provided by primary codec | Clock provided by the Intel® I/O Controller Hub (ICH) | Single, high-quality, stable clock source for synchronization |
| Stability depending on software provider | Unique Microsoft bus driver | Single bus driver for more OS stability and base functionality |
| Limited device sensing / jack retasking | Full device sensing / jack retasking | Support for full audio Plug and Play |
| 2-element (stereo) array microphone support | 16-element array microphone support | More accurate, better quality voice input and recognition |
HRTF
Head related transfer function; the transfer function of the system
resulting from the linear filtering action of placing the human body
(especially the head) in a sound field. The main components arise from
shoulder and ear lobe reflections and from diffraction effects on sound
traveling around the head. Also used to denote the impulse response of
such a system or any processing method simulating such a system (the
usage is quite fuzzy indeed).
IFPI
International Federation Of Producers Of Phonograms
And Videograms;
IFPI represents the recording industry worldwide and
affiliated industry associations.
IFPI's international Secretariat is based in London and is linked to
regional offices in Brussels, Hong Kong, Miami and Moscow. According to
their own statements these are their priorities.
- Fighting music piracy
- Promoting fair market access and adequate copyright laws
- Helping develop the legal conditions and the technologies for the recording industry to prosper in the digital era
- Promoting the value of music in the development of economies, as well as in social and cultural life
IMA
(1) International MIDI association; a consortium formed as a place for
users of MIDI and related software to discuss their problems and
propositions. IMA keeps close contacts with MMA to relay user input and
suggestions to manufacturers.
(2) International Multimedia Association; a professional trade
association of companies, institutions, and individuals involved in
producing and using interactive multimedia technology.
Image
(1) A duplicate, copy, or
representation of all or part of a hard or floppy disk, a section of
memory or hard drive, a file, a program, or data. For example, a RAM
disk can hold an image of all or part of a disk in main memory; a
virtual RAM program can create an image of some portion of the
computer’s main memory on disk.
(2) A exact copy of
a CD as a
file on a computer. CD-images represent the finished CD. If you compare
your CD after burning with the image (verify), you can make sure that it
is perfectly written.
ISRC
International Standard Recording Code; defined by ISO 3901, is an
international standard code for uniquely identifying sound recordings
and music video recordings. IFPI has been appointed by ISO as
registration authority for this standard. In addition to the basic PQ
codes, professional CD burning software allows you to specify an ISRC
code for each audio track.
The ISRC code is structured as follows:
-
Country Code (2 ASCII characters).
-
Owner Code (3 ASCII characters or digits).
-
Recording Year (2 digits or ASCII characters).
-
Serial Number (5 digits or ASCII characters).
The Red Book CD digital audio
standard enables the encoding of ISRCs onto CDs.
ITTS
Interactive text transmission system; It provides the
mechanism for encoding sound associated data on prerecorded media and
for the transport of such data across equipment interfaces. Defines
those system characteristics which are independent of the recording or
interconnection medium.
ITU
International Telecommunication Union; an intergovernmental organization
through which public and private organizations develop
telecommunications. The ITU was founded in 1865 and became a United
Nations agency in 1947. It is responsible for adopting international
treaties, regulations and standards governing telecommunications. The
standardization functions were formerly performed by a group within the
ITU called CCITT, but after a 1992 reorganization
the CCITT no longer exists as a separate entity.
IVC
Intervoice, Inc. a company from Dallas, creates voice automation
solutions. Voice server software, text to speech, advanced speech
recognition and intelligent networks.
Java
A high-level programming language developed by Sun Microsystems. Java
was originally called OAK, and was designed for handheld devices and
set-top boxes. Oak was unsuccessful so in 1995 Sun changed the name to
Java and modified the language to take advantage of the World Wide Web.
JKL
JKL keyboard commands. The keys J, K and L are used for transport
functions in Audio/Video workstations. It developed as a quasi standard.
Jog/Shuttle Dial
A round dial found mainly on some VCRs
and DVD players which allows the easy movement forward or backward
within a software program (usually a movie). The jog/shuttle dial is an
intuitive and simple means of moving forward or backward at multiple
fast or slow motion speeds. In order to go forward, one simply turns the
dial right. In order to go backward, the dial is turned left. The
jog/shuttle dial is easy to use and easy to find on a remote control or
component and is also easy to use simply by touch in a dark room. Such
dials may also be found on other components to tune a radio station for
instance, but they are used primarily for video with VCRs, laserdisc
players and DVD players.
Latch Automation Mode
Latch Records adjustments you make to automation settings and creates
corresponding edit points on track envelopes. It begins recording, when
you first adjust a setting, and continues to record new settings until
playback stops.
Latency
In general the time lag
between a request and the action being performed. Latency can reflect
network time delays or MIDI and audio playback timing errors. Regarding
audio interfaces like soundcards it's the
delays occurring when you're recording or playing back. This delay is
known as soundcard latency. It depends on the processing power of the
soundcard, the drivers and the speed of the host computer.
Leveler
A leveler reduces signal level differences in audio material. It can be
used to process recordings where the level unintentionally varies. It
will boost low levels and attenuate high level audio signals but on a
much more general basis than a compressor or even a limiter.
Limiter
A limiter is designed to ensure that the output level never exceeds a
certain set output level, to avoid clipping in following devices.
Conventional limiters usually require very accurate setting up of the
attack and release parameters, to totally avoid the possibility of the
output level going beyond the set threshold level. Software limiters
often adjust and optimize these parameters automatically, according to
the audio material.
Loudness maximizer
A specialized effect designed to
boost signals as well as increase the perceived level of the audio
signal. It uses the headroom on a CD to achieve the maximum perceived
loudness of a song or advertising clips.
Marker
A Symbol like a colored vertical line that identifies a specific
position in a sound or video file. You can save it with the sound file.
They can be used to mark looping points, for designating regions in a
file or just to remember points of interest like glitches, song start
and end or rough descriptions of the content. You normally can label a
marker and search for it later.
MADI or AES10
Multichannel Audio Digital Interface; a unidirectional multichannel
digital audio transmission standard originated by the AES. MADI is based
on the FDDI (Fibre Distributed Data Interface) transmission format, but
usually uses coaxial cable instead of optical fibre. Accommodates up to
56 channels and 24 bits per sample. Used for point-to-point multichannel
digital audio connections in studio and broadcasting environments.
Measure
Term for a bar of music, commonly used only in the U.S.
A musical notation for a repeating pattern of musical beats.
Metadata Commands
Metadata command markers indicate when an instruction (function) will
occur in a streaming media file. You can use command markers to display
headlines, captions, link to Web sites, or any other function you
define.
MF
Multi frequency or CCITT R1 signals are used internally by the telephone
networks. They are generated by a combination of 700-, 900-, 1100-,
1300-, 1500-, and 1700-Hz sine waves. It is usually used on trunk
circuits or pay telephones.
Microsoft ADPCM
The Microsoft ADPCM format provides 4:1
compression. Files saved in this format expand automatically to 16-bits
when opened, regardless of their original resolution. For this reason,
use this format with 16-bit rather than 8-bit files.
Microsoft .NET Framework
The .NET Framework is
an integral Windows component for developing, building and running
software applications and Web services. It
should make the development of platform independent applications easier
and more effective.
Microsoft Windows Media®
The digital formats of audio and video files featured by Microsoft's
Windows.
MIDI
Musical Instrument Digital
Interface. A standard protocol for communication between electronic
musical instruments and computers. It transmits
information of which notes should be played how loud and other control
information like volume, pan etc. Normally it doesn't transmit any audio
data except sending short sound samples via Midi SDS.
MIDI clock
A timing reference signal that can be sent within the
MIDI data stream used to synchronize pieces of equipment together. MIDI
clock runs at a rate of 24 pulses per quarter note. This means that the
actual speed of the MIDI clock varies with the tempo of the clock
generator (not like
MIDI time code, which runs at a constant
rate). MIDI clock itself does not carry any location information - the
receiving device does not know what measure or beat it should be playing
at any given time, just how fast it should be going. To transmit that
kind of information you need the MIDI song position pointer.
Midi SDS
Sample Dump Standard; standardized by the Midi Manufacturers
Association, this protocol allows unified downloading of sample data to
synthesizers and samplers through the MIDI bus. Utilizes SysEx messages
and offers two separate modes: open loop and closed loop. Open loop
corresponds to the usual MIDI connection topology, in closed loop
configuration a separate return cable is used to provide feedback. SDS
is extraordinarily slow, even in the context of the MIDI physical layer.
In addition, operating SDS reliably is quite difficult (to use SDS in
closed loop mode, the physical cabling has to be changed, for instance)
and so the standard is not currently widely deployed in studio
environments.
MIDI song
position pointer
A MIDI message that tells the slave device where to start playback from.
It is sent when both devices are stopped, not while they play. It just
synchronizes the starting point of the playback.
MTC
MIDI Time Code; is used to synchronize two or more devices. MTC messages
are an alternative to using MIDI Clock and
Song Position Pointer
messages. MTC is essentially digital SMPTE mutated
for transmission over MIDI. SMPTE timing is referenced from an absolute
"time of day". On the other hand, MIDI Clocks and Song Position Pointer
are based upon musical beats from the start of a song, played at a
specific Tempo. For many (non-musical) cues, it's easier for humans to
reference time in some absolute way rather than based upon musical beats
at a certain tempo.
Mixed mode CD
A special type of CD which contains different types
of information in separate tracks on the CD. The most common form of
mixed mode CD places computer data in track 1 and audio information in
the subsequent tracks.
MOD files
Files with the extension .mod belong to tracker software which, in their
purest form, allow the user to arrange sound samples stepwise on a
timeline across several monophonic channels. A tracker song, when saved
to disk, typically incorporates all the sequencing data plus samples,
and thus during the format's heyday it became almost a sport to create
long, complex .mod (or .sng) files which were nonetheless
smaller than 880 kB.
MMA
Midi Manufacturers' Association; a consortium formed to promote and
refine the MIDI specification and to guide in the implementation of the
standard. MMA extensions to the original MIDI specification include MIDI
time signaling and SDS.
MME
(Multi Media Extension) The MME devices (or drivers) have been invented
by Microsoft with the not very well known operating system called
"Windows with Multimedia Extensions 1.0" that was based on Windows 3.0
and was the base for later released Windows 3.1 and 3.11. The name of
the OS ("Multimedia Extensions") was also used for the API to access
soundcards. Windows MME 1.0 was really the first Microsoft operating
system that provided a universal API that worked with any soundcard
hardware exactly the same way (if there was a driver). The same API with
small modifications is used until today to playback and record wave
audio.
Modulation
The variation of some characteristic of a signal or a parameter of an
algorithm producing the signal to achieve some specific goal. Examples
include amplitude modulation (time-variant scaling of a signal (AM,
tremolo)) and frequency modulation (variation of the repetition rate of
a (quasi-) periodic signal (FM, vibrato)).
MP3
MPEG1 or 2, layer 3 audio coding; a lossy, perceptual audio coding
format widely used for the transmission of stereophonic sound, both in
commercial and non-commercial environments. Layer 3 is the most
sophisticated of the 3 layers specified for MPEG1 and MPEG2 (They share
the same audio bitstream formats, only the allowed bitrates differ.
Funny enough, MPEG2 allows only three of the lower bitrates.). The
standard does not specify the codec, per se, only the bitstream.
However, implementation issues have stabilized fairly well by now. MP3
offers excellent audio quality for music and similar sound encountered
on soundtracks at relatively low bit-rates (in the range from 48kbps to
196kbps). Isn't suitable for very low bitrate speech coding, for which
different methods exist. The acronym comes from the common filename
extension used for files of this content. (FYI: MPEG1 layer 1 audio
coding is used in DCC under a different name.)
MPEG
Motion Picture Experts Group; a joint consortium of motion picture
engineers. Standardizes movie related material. Commonly known for its
MPEG1, MPEG2 and MPEG4 standards, which pertain to the digital coding
and transmission of moving picture and associated sound (MPEG1-2), and
multimedia (MPEG4, in draft stage).
Multitasking
The capability of a computer with a single CPU to
simulate the processing of more than one task at a time. Multitasking is
effective when one (or more) of the applications spends most of its time
in an idle state, waiting for a user-initiated event such as a keystroke
or mouse click. There are two basic types of multitasking, preemptive
and cooperative. In preemptive multitasking, the operating system
parcels out CPU time slices to each program. In cooperative
multitasking, each program can control the CPU for as long as it needs
it. If a program is not using the CPU, however, it can allow another
program to use it temporarily. OS/2, Windows 95, Windows NT, the Amiga
operating system and UNIX use preemptive multitasking, whereas Microsoft
Windows 3.x and the MultiFinder (for Macintosh computers) use
cooperative multitasking.
Multiband compressor
Multiband compressors have been developed to overcome a problem that
came up when compressing mixes or complex sounds. A full band compressor
always compresses the whole signal and doesn't differentiate between
frequencies. If you tried to compress the bass drum of a complete drum
mix, also the hi-hat and the cymbals were compressed which contain
mainly high frequencies. So you had "pumping" cymbals. The multiband
compressor avoids this problem by dividing the frequency spectrum in
different bands, that get compressed separately. This leads to a very
present and tight sound when applied correctly and to maximum perceived
loudness.
NEXT
When Steve Jobs left Apple, he decided to create the best computer
possible ! The result is the NeXT. This prodigious computer impressed a
lot of people when it was presented! Its technical features, its object
oriented operating system and its graphical interface, even its black
case were very far from the standards (remember how many black-cased
computers there were in 1988: not many)! And NeXTStep is always
considered as a reference. It was sold with a lot of great programs and
a very powerful 400 dpi laser printer. Some technical features were a
bit strange (grayscale display, no floppy drive, no hard disk), but were
modified in the next generation with the NeXT Station and the NeXT Cube
040.
Noise Gate
Gating, or noise gating, is a method of dynamic processing that mutes
audio signals below a certain set threshold level. As soon as the signal
level exceeds the set threshold, the gate opens to let the signal
through. Some gates offer additional features, such as auto calibration
of the threshold setting, a side chain input,
a look-ahead predict function, and frequency selective triggering.
Noise reduction
There are basically two types of noise reductions in
use. Single and double ended systems. Single-ended noise reduction
systems use dynamic filters to reduce the level of audible noise in a
signal. Double-ended noise reductions process (compress) the signal
during recording and then 'unprocess' (expand) it on playback.
Normalize
To boost the level of a waveform to its maximum
amount without clipping, limiting, compressing or changing it in any
other way. This maximizes resolution and minimizes certain types of
noise like aliasing.
Notch filter
A
filter that eliminates a narrow
frequency range from a
signal without affecting the rest of the sound.
Ogg Vorbis
Ogg Vorbis is an open source audio codec designed to
compete with MP3. Since it is not licensed like MP3, software using this
codec does not have to pay royalties.
OS
Operating System;
The software on your computer that controls the basic
operation of the machine. The operating system performs such tasks as
recognizing keyboard input, sending output to the monitor, keeping track
of files and directories on the disk, and controlling other connected
devices such as disk drives and printers.
OSQ
Original Sound Quality. This is Wavelabs proprietary lossless compressed
audio format. It can significantly reduce the audio file size without
affecting the audio quality at all.
PCM
Pulse-code modulation (PCM) is a modulation technique. It is a digital
representation of an analog signal where the magnitude of the signal is
sampled regularly at uniform intervals. Every sample is quantized to a
series of symbols in a digital code, which is usually a binary code. PCM
is used in digital telephone systems. It is also the standard form for
digital audio in computers and various compact disc formats.
PDA
Personal
Digital Assistant; a small hand-held computer that in the most basic
form, allows you to store names and addresses, prepare to-do lists,
schedule appointments, keep track of projects, track expenditures, take
notes, and do calculations. Depending on the model, you also may be able
to send or receive e-mail; do word processing; play MP3 music files; get
news, entertainment and stock quotes from the Internet; play video
games; and have an integrated digital camera or GPS receiver.
Phase-meter
A meter that shows the relation of the left and right channel. If you
have a mono signal you get a straight line in the middle. A signal on
the right channel gets a 45° line to the right, a signal on the left
channel gets a 45° line to the left side. A real stereo signal gets a
waveform like the one below.
Phaser
Similar
to flanging, phasing introduces a variable phase-shift to a split signal
and recombines it, creating psychedelic effects first popularized by
guitarists of the 1960s. The Sweeping Phaser effect sweeps a notch- or
boost-type filter back and forth about a center frequency. A phase is
similar to a flange except that instead of using a simple delay,
frequencies are phase-shifted over time. If a phase is used on stereo
files, the stereo image can be dramatically altered to create some
remarkably interesting sounds.
Phase reverse
This
turns the signal "upside down", which is the same as inverting the phase
by 180°. No settings are needed for the operation. There is no audible
change when you invert the phase of a mono signal. However, if one
channel in a stereo pair is out of phase with the other, this will lead
to artifacts such as a drop in the bass register and a "blurred" stereo
image. The most common use for this function is therefore to fix a
stereo recording where one of the channels has accidentally been
recorded out of phase with the other. Another Application is to mix two
signals with inverted phase to listen to the difference of the signals.
This is useful to find out the effect that has been applied to a sound
file or to determine if sounds are identical.
Physical modeling
Physical modeling tries to emulate parts of a real instrument by
algorithms. It's an extremely good choice for synthesis of many
classical instruments, especially those of the wind and brass families.
Its parameters directly reflect the ones of the real instrument and
excellent emulations can be produced. Original synthesis is fairly easy
on PM platforms. Serious processing power is needed, something that
limits the polyphony of current PM implementations. In addition,
instrument design can be very time consuming. Some types of instruments
are more difficult to model, as well, especially instruments with
significant two plus dimensional effects. These include e.g. drums and
plates, and, to some extent, string instruments. Sometimes these
problems can be solved by using modeling alongside other synthesis
methods or expanding our models to include samples as excitation or by
allowing traditional sound processing methods (effects, filtering etc.)
to be applied within our instrument. Sometimes not. Progress is fast,
techniques are developing constantly and the field will certainly get
even more attention as time goes by and serious commercial applications
continue to appear.
Pink noise
Pink noise has a spectral frequency of 1/f and is found mostly in
nature. It is the most natural sounding of the noises. By equalizing the
sounds, you can generate rainfall, waterfalls, wind, rushing river, and
other natural sounds. Pink noise is exactly between brown and white
noise (hence, some people used to call it tan noise). It is neither
random nor predictable; it is fractal-like when viewed. When zoomed in,
the pattern looks identical to when zoomed out, except at a lower
amplitude.
Pitch bender
This effect varies the pitch of the source audio over time. You can
sometimes use a graph to "draw" a tempo to create smooth tempo changes
or other effects, such as that of a record or a tape speeding up or
slowing down.
Pitch correction
Most Pitch Correction effects provide two ways to make pitch adjustments
for monophonic instruments or voices. Automatic mode analyzes the audio
content and automatically corrects the pitch based on the key you
define, without your having to analyze each note. Manual mode creates a
pitch profile that you can adjust note-by-note. You can even
over-correct vocals to create robotic-sounding effects. The Pitch
Correction effect detects the pitch of the source audio and measures the
periodic cycle of the waveform to determine its pitch. The effect can be
used on audio that contains a periodic signal (that is, audio with one
note at a time, such as for a saxophone, violin, or vocals). Nonperiodic
audio, or periodic audio with a high noise floor, can disrupt the
effect's ability to detect the incoming pitch, resulting in incomplete
pitch correction.
Pitch shifter
A pitch shifter lets you transpose a sound with or without changing it's
length. The earlier versions like the famous Harmonizer from Eventide
didn't let you preserve the formants of the sound
and if you changed the pitch more than 2 or 3 halftones upwards it
sounded like Mickey Mouse. Modern pitch shifters let you preserve the
formants in a sound to avoid that effect.
PPM-meter
Peak program meters; Unlike VU-meters, PPM meters can show you even the
fastest peaks in an audio signal. At least in the digital domain. Analog
PPM-meters still have some (very short) reaction time. The integration
time is the time how fast the PPM bar moves. If it is too short the bar
is flickering at some signals and if it is too high the PPM-bar reacts
too slowly. Here are some widely used integration times for PPM-meters.
|
Scale |
Integration Time |
| UK PPM | 10 ms |
| EBU PPM | 10 ms |
| DIN PPM | 5 ms |
| Nordic PPM | 5 ms |
PQ code(d)
PQ refers to the first two (of the eight, named from P to W) subchannel
bits on CDs. These are used to carry auxiliary data, such as track
information, the table of contents (TOC), catalog numbers, ISRC
(International Standard Recording Code) information, de-emphasis status,
SCMS copy propagation control and so on. The majority of this
information is carried over the Q channel, accumulated in 98 bit frames,
whereas the P channel carries a simplistic code denoting the starts and
ends of CD tracks, lead-in and lead-out areas. Most current CD players
are sophisticated enough not to use the P channel code at all, since all
relevant information is also available through the more sophisticated Q
coding scheme. The addition of PQ code is a major portion of the CD
mastering process - often manufacturing plant bound masters are simply
referred to as being PQ coded or PQed.
Pre-emphasis
Pre-emphasis is a basic noise reduction process that is implemented by a
CD player. For pre-emphasis to occur, the CD player must support the
pre-emphasis flag.
Prerecord buffer
Even if you don't push record button, the input signal gets recorded
into a memory if your software supports that. This memory is called the
prerecord buffer. When you start recording the sound recorded in the
prerecord buffer just gets appended to the beginning of your recording.
Therefore the program has recorded even before you decided to push the
record button. This is especially useful when you want to make very
sure, that you don't cut off the beginning by pressing the record button
too late.
Punch-In/Out
The term comes originally from analog tape machines. It means
the
action of switching a tape machine to record while it plays back and is
usually followed by a punch out. With most multitrack machines, both
punching in and out can be accomplished without stopping tape. Most new
machines have auto punch in/out where you set points in advance, and let
the machine do the work. Software basically just imitates that function
and lets you set the punch-in/out points by markers or on the fly.
Q-sound
Since the introduction of stereo equipment in the 1950's, scientists and
listeners alike have set their sights on finding an even better audio
experience - true 3D audio. Throughout the sixties and seventies numbers
were crunched, algorithms designed and sound tests developed. But few
could create an effective 3D audio experience. Then in the early 1980's,
QSound's inventors were setting up a complex microphone arrangement when
they discovered that sound was coming from a location it wasn't supposed
to be coming from. They had inadvertently created 3D audio! Intrigued,
they tried to replicate the event in a reliable manner.
Eight years
later, after thousands of hours of consultation with neurological and
medical specialists and half a million human listening tests, they
produced what some skeptics said was impossible: 3D positional audio.
They called the technology "QSound®" and it has become synonymous with a
rich and realistic sound experience.
Quick Time
A video and animation system developed by Apple Computer. QuickTime is
built into the Macintosh operating system and is used by most Mac
applications that include video or animation. PCs can also run files in
QuickTime format, but they require a special QuickTime driver. QuickTime
supports most encoding formats, including Cinepak, JPEG, and MPEG.
QuickTime is competing with a number of other standards, including AVI
and ActiveMovie.