Additional Audio Delay - MOTU V4HD User Manual

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Choose one of these sample rate conversion
options when the rate for the chosen digital I/O
bank needs to be four times the V4HD system
clock rate or one quarter of the system clock rate.
Either way, the digital I/O bank remains resolved to
the V4HD system clock.
ADAT In 44.1/48 versus ADAT In 88.2/96
The V4HD provides two sets of ADAT optical
digital I/O connectors, which together provide 8
channels at 44.1 or 48 kHz or 8 channels at 88.2 or
96 kHz. These options let you specify the sample
rate being received by the V4HD on its optical
input(s), from the other optical device. The
received signal will then be sample rate converted
to the V4HD's system clock rate, which can be any
supported rate, even 176.4 or 192 kHz.

Additional Audio Delay

The Additional Audio Delay option (Figure 8-1)
lets you add a certain amount of delay, specified in
fractions of a video frame, to the V4HD's audio
output.
The main purpose for this feature is to allow you to
compensate for any inherent delay in a video
monitor connected to the V4HD. For example,
LCD displays often have a small delay in them —
from the time they receive a video frame to the
time at which they actually display it on their
screen. Depending on how you are monitoring the
accompanying audio signal, the audio will likely
not have this same delay. As a result, the audio will
be heard slightly ahead of the delayed video signal.
This option lets you delay the audio signal by the
same amount as the video display, so that audio
and video are properly aligned with one another.
This option affects audio passing through the
V4HD in two scenarios:
Playback from Final Cut Pro
■
V4HD CueMix monitoring
■
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Playback from Final Cut Pro
The Additional Audio Delay option can be applied
to audio being played back from Final Cut Pro to
align it to Final Cut Pro's video output.
For example, let's say you are viewing Final Cut Pro
output on a plasma monitor connected to one of
the video outputs on the V4HD. This plasma
monitor has an inherent one-frame delay (from the
time it receives a frame to the time it displays it). In
addition, you are listening to Final Cut Pro's audio
output — in 5.1 surround — via studio monitors
connected to the V4HD's analog audio outputs.
Even though audio and video depart the V4HD
outputs completely in sync with one another, the
image on the plasma will be running one frame
behind the audio you hear from the surround
monitors. Use the Additional Audio Delay option
(Figure 8-1) to delay the V4HD's audio output by
one frame to match the image on the plasma.
V4HD CueMix monitoring
The Sync CueMix audio with video output option
(shown in Figure 8-1 and described below) ensures
that audio and video remain perfectly in sync with
each other when they pass through the V4HD from
its inputs to its outputs. However, you may still
need to compensate for the inherent video signal
delay in external devices connected to the V4HD.
Therefore, when the Sync CueMix audio with video
output option is checked, the Additional Audio
Delay option can be applied for exactly that
purpose.
For example, let's say you are capturing some SD
footage from a camcorder connected to a V4HD
SD video input, and you are monitoring it on an
HD plasma monitor connected to an HD video
output on the V4HD. This plasma monitor has an
inherent one-frame delay (from the time it receives
a frame to the time it displays it). In addition, the
camcorder stereo audio output is connected to a
pair of V4HD audio inputs, and you are listening to
the camcorder's audio output via studio monitors
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