Vari Lite Virtuoso DX User Manual download pdf (Page 335)

SHOW CONTROL BY EXTERNAL DEVICES : MIDI/SMPTE TIMECODE

02.9651.0001 C 23-Sep-02 309

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 is 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)

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 258). 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.

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Vari Lite Virtuoso DX User Manual Page 335