Avid Technology Digidesign USD User Manual page 51

Generating LTC
In Generator Preset mode, the USD can
generate LTC using either an external or in-
ternal clock reference. This allows the USD
to function as a complete standalone time
code generator.
Make sure LTC is correctly routed and that
all your other gear is properly configured
before you begin. See "Example 1: Using
Set, Down and Up to adjust LTC Gain" on
page 30 for USD LTC instructions. If neces-
sary, adjust the input level for the destina-
tion device.
To generate LTC using Pro Tools:
In the Session Setup window, choose
1
Generate from the Positional Reference
pop-up menu.
Activate "Online Mode" in Pro Tools
2
Start Pro Tools recording or playback.
3
Pro Tools commands the USD to begin gen-
erating LTC with time addresses synchro-
nized to the session timeline.
To generate LTC using the front panel
controls:
Using the USD's Positional Reference
1
switch, select Generate.
Configure the desired time code start in
2
hours:minutes:seconds:frames using the
Set, Up and Down switches. See "Generator
Start Time" on page 46 for instructions.
To begin generating, press and release the
3
Run/Stop+Clear switch.
To generate LTC using USD Setup:
In USD Setup's Positional Ref pop-up
1
menu, select Generate.
In USD Setup's Generator/Bi-Phase Preset
2
window, type in the desired time code start
time, in Hrs:Min:Sec:Frm. To reset, click
Zero.
To begin generating, click Run.
3
When you have finished generating the
4
desired length of LTC, click Stop.
VITC Generation/Regeneration
When you use the USD to regenerate or
generate VITC, you'll be inserting VITC
into an existing video signal. The input is
derived according to the following rule.
VITC Video Source Rule
Since USD has two video inputs (Video In
and Video Ref In), the following rule de-
scribes which of these two signals VITC is
applied to.
• If the Positional Reference is set to Gen-
erate and the Clock Reference is set to ei-
ther of the two video inputs, then VITC
will be applied to the video signal at the
Video Ref In connector and fed to the
Video Out connector.
• Under all other combinations of Posi-
tional Reference and Clock Reference,
VITC will be applied to the video signal
at the Video In connector and fed to the
Video Out connector.
In addition, the USD will not insert new
VITC while reading VITC from an external
source. This is a safety feature to prevent
the loss of existing VITC in the video
Chapter 4: Using the USD 47