users manual

833 User Guide
42
Frame rate
The rate at which video or motion picture images are recorded or
played back, measured in frames-per second (FPS). All audio and
video devices must be running at the same frame rate to keep audio
and video synchronized. Timecode frame rates are either an integer
or non-integer value. Integer values include 24, 25, and 30 FPS. Non-
integer frame rates include 23.976 and 29.97, and 29.97 drop FPS.
Frequency
The period at which a wave oscillates, measured in hertz (Hz).
Frequencies audible to humans range from 20 Hz for very low
frequency signals to 20 kHz for very high frequency signals.
Gain
An increase (or decrease with negative gain) in the level of an audio
signal. Gain can be applied in several locations, to both analog
and digital signals. In a eld mixer the microphone preamplier
provides a substantial amount of gain at the trim to raise the low
level microphone signal to a usable signal in the mixer. Gain is also
available at the fader. Gain of digital signals or line level analog
signals is often limited. Unity gain is gain stage that neither adds or
subtracts level from a signal.
Headphone monitor
Often a separate bus with a dedicated headphone volume control,
the headphone monitor typically is normalled to the main left/right
output bus of a mixer. Headphone sources can often be selected
among soloed tracks or buses. In some products complex headphone
monitoring of MS Stereo, LR stereo, and ambisonic sources is
available.
High pass lter (audio)
Also referred to as a low-cut lter, this circuit reduces the amount of
low frequency content in an audio signal. A HPF is particularly useful
when recording speech since the human voice does not generate
appreciable energy at low frequencies. The HPF reduces non-speech
signals such as environmental noise, wind noise, and microphone
handling noise, improving the intelligibility of speech and reducing low
frequencies from overloading the input. The high pass lter is placed
in the circuit close to the microphone preamplier.
High pass lters are often frequency selectable, ranging from 20 Hz to
200 Hz. HPF also have a slope, generally from 3 dB/octave to 18 dB/
octave. Greater/steeper slopes offer more attenuation of frequencies
just below the set lter frequency.
Input
The physical connection and associated signal type from external
sources connected to a device. Inputs can include microphone inputs
on XLR connectors or USB audio inputs from a computer. Depending
on the architecture of the mixing console its inputs may be hardwired
to channels or channels can be selected from different inputs.
Input limiter
A limiter circuit reduces the peak signal levels of audio, generally to
prevent signal overload. Analog inputs have a maximum input signal
level that can be reached before overload/distortion is introduced.
Setting the input gain correctly so that input signals do not reach this
maximum level prevents most overload conditions. In the presence of
very high, unexpected signals an input limiter changes the gain of the
incoming signal and prevents it from overloading. Input limiters are
sometimes compressor-type circuits with a ratio of innity:1, meaning
that any increase to the input signal into the limiter at the limiter
threshold does not increase the output signal of the limiter.
Several parameters may be available in a limiter, including knee, ratio,
release, and threshold.
Isolated track
A recorded track of an individual microphone or sound source. “Iso”
recordings allow for post-record mixing of individual sound elements.
iXML
An extensible data schema for audio and related metadata stored
in broadcast WAV les. Manufacturer-specic data generated during
recording is stored in iXML.
Line level
An analog audio signal used to interconnect audio equipment. Line
level may be balanced or unbalanced, referenced to +4 dBu or -10
dBV, professional or consumer respectively.
Low cut lter
See high pass lter.
Microphone level
The audio signal generated by a microphone. Mic level signals are
very low level, requiring a microphone preamplier to bring them to
usable, line levels. Interconnects with microphone level signals can be
subject to noise and interference.
Mid-side linking (inputs)
When mid-side (MS) stereo inputs are used and the inputs are set to
MS linking and MS decoder is activated for those inputs. This yields
a stereo signal with one fader controlling overall input level and the
other fader controlling the “width”, or amount of the side signal
added. With an MS matrix at the input, the signal is sent to an output
bus as left/right stereo. Mixers with MS matrices often allow for
discrete mid and side signal recording. In that case the MS decoder
can be activated at the headphone selection to monitor left/right
stereo.
Mix track
A recorded track that is a sum of multiple tracks. In production sound
the mix track is often a single summed track of all production dialog
elements. Mix tracks can also be sub-mixes of like microphones, such
as a sub mix of just lavalier microphones or just boom microphones.
Monophonic WAV
A WAV le that is comprised of a single track of audio. When recording
multi-track audio with monophonic WAV les each track is recorded
to its own WAV le, with a le name indicating the track number. All
associated monophonic les that are part of a multi-track recording
will be identical lengths.
Mute
A mute control is a convenient on/off switch for a channel and an
easy way to remove a channel from appearing in downstream buses.
Mute an input or channel does not change levels or settings; when
channels are muted and unmuted, their settings remain.
Notes (metadata)
A metadata eld that is saved along with audio data in a recorded
sound le, useful for sound report generation. Some workstation
software recognizes the notes eld and presents it when viewing the
sound le.