Specifications
Pro Tools Reference Guide620
MIX Core PCI core card, which connects to au-
dio interfaces and contains the DSP for a
Pro Tools|24 Mix TDM system.
MIX Farm PCI card with additional DSP for
Pro Tools|24 MIX systems.
MP3 (MPEG Layer 3) An adjustable-quality au-
dio compression format developed by the
Fraunhofer Institute.
MTC (MIDI Time Code) Non-SMPTE form of
time code that is used by some devices (includ-
ing Pro Tools) to send and receive timing infor-
mation.
nondestructive editing Leaves audio files intact.
As you edit audio within Pro Tools, you are only
editing the regions, or “pointers,” to audio files
that are stored on the hard drive, unless you ex-
plicitly choose destructive modes (during re-
cording, or when using AudioSuite processing).
non-drop frame Time code that is not in drop-
frame format. In North America, the standard
format outside of color video production or post
production is typically 29.97 fps non-drop
frame.
NTSC Video standards developed by the Na-
tional Television Standards Committee. NTSC
color video runs at 29.97 frames per second;
NTSC black and white video runs at 30 fps. Used
primarily in North and South America and Ja-
pan.
Nyquist frequency The highest audio frequency
that can be accurately sampled, equivalent to
one-half of the sampling frequency. The
Nyquist sampling theorem showed that the
sampling rate must be at least twice the highest
frequency present in the sample in order to ac-
curately reconstruct the original signal.
offline (media) Not connected to or directly ac-
cessible by a computer.
offline (synchronization) Not under the control
of (or controlling) another device for synchro-
nized playback or recording.
OMS (Open Music System) A “MIDI operating
system” for Mac OS 9, developed by Opcode. It
handles the exchange of MIDI data between ap-
plications, including timing signals such as
MTC. OMS is replaced by AMS (Apple’s Audio
MIDI Setup utility) in Mac OS X.
online (media) Connected to and directly acces-
sible by a computer.
online (synchronization) Controlled by (or con-
trolling) another device for synchronized play-
back or recording.
peak indicator Indicator light designed to warn
of the possibility of clipping, which illuminates
as a device’s input reaches a preset degree of
headroom.
performance volume A storage volume that has
been designated to record and/or play back me-
dia files in a Pro Tools session.
PFL (pre fade listen) Sometimes called a “cue,”
this is a channel’s level before it is attenuated or
boosted by the fader setting. Master faders are
PFL in Pro Tools. See also pre-fader.
playlist A group of regions arranged on an audio
or MIDI track.
positional reference Common reference that
provides location information that various de-
vices can use to establish synchronization dur-
ing playback and recording. Most commonly,
the information is delivered in the form of
SMPTE/EBU Time Code.
post-fader Output from a track (typically a send)
that is governed by the channel’s fader setting.