SMPTE, Sync, and Offset, Chapter 11

11-2 ALESIS M20 REFERENCE MANUAL 1.06

11.2 SMPTE RATE
SMPTE Rate cycles through six different SMPTE frame rates and types; this affects both
SMPTE time code input and M20 SMPTE time code output. It is not possible to receive and
transmit different frame rates simultaneously.
• 24 film
• 25 European (PAL) video
• 29.97 NTSC color video
• 29.97 Drop NTSC color video drop frame
• 30 American monochrome video, most audio applications
• 30 Drop American monochrome video drop frame
When receiving SMPTE time code, input and output frame rates are set to the incoming
frame rate (displayed by the SMPTE frame rate indicator). 29.97 and 30 frames/sec are not
identified automatically due to possible source speed variations, and must be set manually.
Frame rates when receiving video are adjusted automatically, as follows:
Clock Source is set
to… Incoming video
is… Frame rate…
Video NTSC can select 29.97 or 29.97 drop frame
Video PAL/SECAM is set to 25 fps
11.3 TIME CODE SOURCE
This switch selects either:
• The time code generated by the M20, with the start time set in the Internal Gen pages
(Internal mode)
• An outside SMPTE source (External mode)

11.3A INTERNAL

Time code generated by the M20 appears at the Time Code Output jack. The internal
generator generates SMPTE/EBU time code according to several parameters that are set in
Int Gen Edit mode. Code may be generated only when the transport is moving, or when it is
stopped. The numbers of the time code being generated may be referenced to tape in several
ways, or set independently by the user.
TC Input button: In any case, the internal generator of the M20 will only start issuing
code when the white TC Input button, below the TC Track meter and Record Arming
button, is turned on. As long as the TC Source is set to Internal, the internal
generator (NOT the rear panel Time Code In jack) is considered the “input” source
for this button.
When the TC track is not in Input mode and is playing back, the time code output comes
from the TC track on the tape, if there is time code printed.