DigiDesign SYNC HD Manual page 56

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. The SYNC peripheral will not regenerate
VITC if the positional reference is VITC.
MTC In order for the SYNC peripheral to regen-
erate continuous MTC, the external positional
reference must be moving at normal, 1x forward
speed (±8 %). Outside of this speed range and di-
rection, MTC is generated in bursts every 200
milliseconds. This allows MTC-slaved devices to
read VITC or Bi-Phase properly in either direc-
tion, and at speeds down to zero. The SYNC pe-
ripheral begins regenerating MTC as soon as it
again detects a valid positional reference signal.
To optionally mute idle time MTC output,
see "MTC Output and Idle Muting" on
page 56.
If the positional reference is LTC or VITC, the
SYNC peripheral will regenerate time code ad-
dresses that match the incoming time code ad-
dresses. If the positional reference is a
Bi-Phase/Tach signal, the SYNC peripheral will
generate time code addresses starting at the Bi-
Phase preset start time. (See "Bi-Phase/Tach
Starting Frame" on page 47 for more informa-
tion.)
50 SYNC HD Guide
Generator Preset Mode
In this mode, the SYNC peripheral generates
time code internally from a start time based
upon the Generator Preset Time. Using either
the SYNC peripheral front panel controls or the
SYNC Setup software utility, you can start, stop,
resume, and reset time code generation.
When generating time code in Generator Preset
Mode, the SYNC peripheral time code generator
is resolved (locked) to one of three possible
sources, based upon the following 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 or Video In), then the
time code generator will reference the Video Ref
input.
Frame Rate Restrictions with Video Reference
In any generator mode, if the Clock Reference is
set to a video input (Video Ref or Video In),
Pro Tools is restricted to generating time code at
the incoming video frame rate.
With SYNC peripherals, the Time Code Rate you
choose is dependent on the video format:
• For NTSC, you can choose only 29.97 FPS
or 29.97 FPS DROP.
• For PAL, you can choose only 25 FPS.
In Generator Preset mode, if the Clock Reference
is set to a video input, 24 fps cannot be used as
the SYNC peripheral time code format.