Specifications

160 LightJockey Help file - (C) Martin Professional 2010
LightJockey Help
The source of the MIDI time code must be configured via the hardware setup dialog.
Reference Interface
The LightJockey implementation has been written and tested with a MIDISPORT 8X8S from MidiMan.
This interface is an external 19" rack-mount and connects to the PC either with USB or standard
RS232. The interface converts SMPTE time code to MIDI time code and has provisions for striping
SMPTE code to an audio media as well. The interface automatically recognizes the SMPTE frame
type received. The interface also has 8 MIDI channels out and 8 MIDI channels in. See more details
at www.midiman.net (link valid at the time of writing).
Notes on SMPTE frame types
SMPTE time code (and thus MIDI time code) exists in a number of variations that varies in the number
of frames that are transmitted pr second).
SMPTE to MTC interfaces should by itself be capable of auto detecting the received SMPTE frame
type and embed this information in the MTC. However, if this not the case, make sure that to match
the maximum frame number in the cue list entries does not differ from the number of frames in the
actual time code or the cue list will not synchronize properly.
SMPTE formats includes
24 fps (frames 0-23)
25 fps (frames 024)
30 fps - drop frame (0-29 frames, two 'dropped' every 1 minute)
30 fps (frames 0-29)
Notes on SMPTE to MIDI time code
The conversion from a SMPTE source to MIDI time code has two effects. The full SMPTE time code is
broken down into 8 separate MIDI messages, and 4 MIDI messages are sent pr SMPTE frame
received. This effectively halves the resolution of the converted time code since a total of 8 messages
(two SMPTE frames) are needed. For this reason, if possible, select the highest possible frame rate
when striping the media with time code.
Subsequently, the conversion also means that upon completion of the 8 messages LightJockey is
notified 2 frames later than the actual SMPTE time code is received by the interface. This is not a
problem if the time-codes are logged directly from the interface since the 'delay' is constant. However,
if programming entries from a SMPTE time code reference, remember to subtract 2 frames from each
time code entry.
Preferences menu
MIDI Timecode
MTC Timeout -> Stop List on Timecode time-out - with this option enabled the cue list will stop
executing if the MIDI time code times out. Note that a timing threshold for timeout can be set in the
hardware configuration.
MTC Timeout -> Restart List on Timecode time-out - to have the cue list automatically restart when
the time code transmission is stopped, check this option. Use this option to avoid having to manually
restart the cue list when the time code is terminated and then restarted.
This option should also be used if the time-code is paused and resumed during the execution of the
cue list - in this case, make sure to add an 'AutoSeek MTC' command at the top of the cue list. This
will ensure that the cue list continues at the appropriate line when the time-code is resumed.
MTC Timeout -> Ignore Timecode time-out - With this option enabled, the cue list ignores any
timeouts on the MTC stream.
Sync Frames - enable sync frames to skip a number of time code frames from the time code source
before 'locking' on to the time code. Some time code sources may require a one or more complete
time codes before they start to transmit 'correct' time code. Incorrect time code may cause a waiting
cue list to execute one or more incorrect commands.
See also using time code in cue lists, cue list commands