Specifications

SYNC I/O Guide48
Requirements for Read/Regeneration of LTC,
VITC and MTC
LTC The external positional reference must be
moving at normal, 1x forward speed (±8%).
VITC The positional reference must be LTC or Bi-
Phase/Tach, at any readable speed, forward or
reverse, or when the positional reference is set to
Generate. SYNC I/O will not regenerate VITC if
the positional reference is VITC.
MTC In order for SYNC I/O to regenerate contin-
uous MTC, the external positional reference
must be moving at normal, 1x forward speed
(±8%). Outside of this speed range and direc-
tion, MTC is generated in bursts every 200 mil-
liseconds. This allows MTC-slaved devices to
read VITC or Bi-Phase properly in either direc-
tion, and at speeds down to zero. SYNC I/O be-
gins regenerating MTC as soon as it again de-
tects a valid positional reference signal.
If the positional reference is LTC or VITC,
SYNC I/O will regenerate time code addresses
that match the incoming time code addresses. If
the positional reference is a Bi-Phase/Tach sig-
nal, SYNC I/O will generate time code addresses
starting at the Bi-Phase preset start time. (See
“Bi-Phase/Tach Starting Frame” on page 45 for
more information.)
Generator Preset Mode
In this mode, SYNC I/O generates time code in-
ternally from a start time based upon the Gener-
ator Preset Time. Using either SYNC I/O Setup
(Windows only) or the SYNC I/O front panel
controls, you can start, stop, resume, and reset
time code generation.
When generating time code in Generator Preset
Mode, the SYNC I/O time code generator is re-
solved (locked) to one of three possible sources,
based upon the following Generator Reference
rule.
Generator Reference Rule
◆ If the Clock Reference is set to Internal, LTC,
Pilot Tone, Bi-Phase/Tach, Digital (AES/EBU), or
Digital (Word Clock), then the time code gener-
ator will lock to the selected clock reference.
– or –
◆ If the Clock Reference is set to one of the two
video inputs (Video Ref In or Video In), then the
time code generator will reference the Video Ref
In connector.
Frame Rate Restrictions with Video Reference
In Generator Preset mode, if the Clock Reference
is set to one of the two video inputs (Video Ref
In or Video In), Pro Tools is restricted to gener-
ating time code at the incoming video frame
rate.
With the SYNC I/O, if the video format is set to
NTSC, only 29.97 fps and 29.97 DF fps may be
chosen as the time code format, and, if the video
format is set to PAL, only 25 fps may be chosen
as the time code format.
In Generator Preset mode, if the Clock Reference
is set to one of the two video inputs, 24 fps can-
not be used as the SYNC I/O time code format.
These restrictions are removed when not in
Generator Preset mode.
To optionally mute idle time MTC output,
see “MTC Output and Idle Muting” on
page 53.