PRG V676 User Manual 3.5 - Manual (Page 395)

V676 ® / V476 ® CONTROL CONSOLE USER MANUAL 377
MIDI/SMPTE TIMECODE
Overview
The console will also accept MIDI/SMPTE timecode messages, which can be generated internally or from an external
source. The messages generated by the internal timecode generator can be run independently or in sync with an
external timecode. If the external timecode source drops out, the internally synchronized timecode allows the MIDI
operation to continue. When the internal clock is selected, any external timecode will be ignored.
Note: Only one form of timecode - either MIDI or SMPTE - can be input at one time. MIDI Out will not output MIDI
timecode.
Timecode can be programmed and played back using the Timecode window. During a record operation, the console
will map all appropriate front panel actions to the registered timecode as those events take place. Unless specified
otherwise, the internal clock will begin counting at 00:00:00:00.
Timecode has four fields, 00:00:00:00 (or AA:BB:CC:DD):
+ AA - hours (00-24)
+ BB = minutes (00 through 59)
+ CC = seconds (00 through 59)
+ DD - frames (00 through 29)
Timecode will also be displayed in the central touchscreen on the front panel:
Synchronizing Protocol
To prevent unexpected interruptions in the MIDI execution of events, a synchronizing protocol is built into the system.
This feature can be turned off and on using the Timecode Autoswitch checkbox at the Settings window (refer to
"Settings Window" on page 328). During normal operations, the system will wait for each timecode frame before
performing the required calculations for each time period. If the incoming timecode arrives approximately on time, and
the frame number agrees with the expected time from the system internal clock, the system remains synchronized
with the external timecode. If the system begins receiving frames which are outside of the above timing tolerance, the
following occurs:
+ If the Timecode Autoswitch is enabled and the system is synchronized awaiting the next frame, and the expected
frame is not received within 2 frames, the board will begin running on its internal time clock.
+ If the Timecode Autoswitch is enabled, the system will continue executing events in the normal sequence using
its internal time clock, until the system can resync. At that point, the external time clock will take over again and
the internal clock will sync to those values.
+ If the Timecode Autoswitch is disabled, the system will stop executing events until timecode is resynced. After
resyncing, execution of events will resume.