Alesis ALESIS M20 Smpte Rate, Time Code Source, 11.3A Internal, SMPTE, Sync, and Offset, Chapter

SMPTE, Sync, and Offset, Chapter 11

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	Incoming video	Frame rate…
to…	is…
Video	NTSC	can select 29.97 or 29.97 drop frame
Video	PAL/SECAM	is set to 25 fps

11.3TIME 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.

11-2 ALESIS M20 REFERENCE MANUAL 1.06