world. The MIDISPORT’s SMPTE write functions are available via the front
panel controls in both MIDI Interface and stand-alone modes, whereas the
SMPTE read/regenerate function is only available when in a MIDI interface
mode. This section describes the operation of each of these functions.
The MIDISPORT saves all SMPTE configuration parameters internally and
remembers them upon power up. The factory defaults for these parameters are
30 fps format, 01:00:00:00 write offset, 00 00 00 00 user bits, and 10 frame
flywheel.
SMPTE Writer
The SMPTE Writer generates continuous SMPTE data at the SMPTE OUT port of
the MIDISPORT. This allows the MIDISPORT to be used as a SMPTE master
clock, or to "stripe" an analog or digital audio track with SMPTE time code. To
start the SMPTE writer, press and release the WRITE pushbutton on the
MIDISPORT front panel. The WRITE LED will remain illuminated as long as the
MIDISPORT is writing SMPTE. Writing may be stopped by pressing the WRITE
pushbutton while writing is active. This will stop the SMPTE writing and turn off
the WRITE LED.
The SMPTE writer always starts writing at a preset time. This time is known as
the "Start Time" or "Write Offset." This start time may be set manually from the
MIDISPORT front panel, or via Remote Control software. To set the start time
manually, see the SMPTE "Write" button section of this manual.
The SMPTE writer outputs SMPTE with the format indicated on the MIDISPORT
front panel. This format may be set manually via the FORMAT pushbutton, or via
Remote Control software. The SMPTE writer is capable of generating SMPTE in
five common formats: 24fps, 25fps, 29.97fps, 30 drop-frame and 30 non-drop.
The SMPTE writer also outputs User Bits according to SMPTE conventions. The
user bits are encoded in the SMPTE data stream in addition to the actual time
code. The user bits may be set by the Remote Control software. Another way to
set them is to write SMPTE time code into the MIDISPORT SMPTE In port with
the desired user bits in that data stream. Either way, the MIDISPORT will
memorize the latest set of user bits and store them internally for later use.
When the SMPTE Writer is running, the SMPTE reader is disabled. In fact, the
SMPTE writer may override the SMPTE Reader at any time. While the writer is
running, the front panel "Format" button is also disabled. The writer must be
stopped before the output format may be changed.
SMPTE Reader
The SMPTE Reader locks to SMPTE time code coming into the MIDISPORT
SMPTE In port, regenerates it to SMPTE Out, and converts it to MIDI Time Code
(MTC). MTC is sent to the host computer whenever the MIDISPORT is in MIDI
interface mode and detects valid incoming SMPTE.
23
