Avid Technology Digidesign USD User Manual page 41

To resolve the USD to its internal clock:
From Pro Tools
In the USD Setup area of Pro Tools Ses-
sion Setup window, select Internal from the
Clock Reference selector.
Using the front panel controls
Use the front panel Clock Reference
switch to select Internal.
Using USD Setup
Select Internal/VSO from the USD Setup
Clock Ref pop-up menu.
Variable Speed Override (VSO)
You can varispeed the rate of the USD's
crystal-referenced internal clock, to fine-
tune the speed and subsequent pitch of
Pro Tools and any device receiving its clock
reference from the USD.
Maximum VSO range is ±699 cents (±6
semitones). VSO is available at any posi-
tional reference setting. VSO is not avail-
able from the front panel controls, but can
be controlled directly from Pro Tools and
USD Setup.
To varispeed the rate of the USD's internal
clock:
Using Pro Tools
Choose Windows > Session Setup, and
1
expand the Session Setup window to full
view.
Click to enable VSO (an "X" indicates
2
VSO is enabled).
Adjust the varispeed value using the on-
3
screen slider.
Using USD Setup
In the USD Setup's Variable Speed Over-
1
ride section, check the VSO Enabled box.
An "X" indicates that varispeeding is en-
abled.
The Variable Speed Override section
Use the sliders to adjust the varispeed
2
values in semitone or cent increments. The
actual output word-clock frequency is
shown near the sliders.
– or –
Enter the value in semitones and cents
3
using the editable fields. If the varispeed
value results in an output frequency (sam-
ple rate) that is below 35 kHz or above 50
kHz, the frequency display turns red, and
the actual output frequency is limited to
this value.
When finished, click the Set button to
4
enable the changes.
Using Pitch Memory
Pitch Memory, when enabled, holds the
output sample rate steady even when the
Clock Reference has disappeared or gone
out of lock range. If not enabled, the out-
put sample rate will return to the nominal
rate (for example, exactly 44.1 kHz) when
the Clock Reference disappears or goes out
of lock range.
With Pitch Memory enabled, Pro Tools
continues to play and record at the re-
solved sample rate even if the Clock Refer-
ence source disappears. You might want to
disable Pitch Memory while performing
Chapter 4: Using the USD 37