M-Audio Biport 2x4s [39/48] Smpte offset

encode these User Bits into the time code message without affecting the

time code itself.

Because there are 32 User Bits available, they can be further subdivided

into 8 nibbles (one nibble = 4 bits), each of which can represent a binary-

coded decimal (BCD) digit. A typical set of User Bits might look like

this:

0 4 1 9 0 3 1 2

This could be interpreted as April 19, shot 03, take 12. Although this is

one method of encoding user bit information, you may designate the

digits in any way that you desire.

Many inexpensive sync boxes ignore User Bits because they have no

way to set them or read them. The BiPort 2x4s User Bits can be set via

the Remote Control software and may be displayed with some outboard

device such as the MIDIMAN SMPTE Time Window. The User Bits are

also transmitted via MIDI message to the MIDI application that you are

using. If your sequencer is capable of displaying User Bits information,

then you may read the User Bits there as well.

The BiPort 2x4s is capable of reading and writing SMPTE User Bit

groups U1 through U8. The values of the User Bits output during writ-

ing may be set with the Remote Control software. When reading User

Bits from an incoming source, a MIDI User Bits message is sent to the

application each time sync is acquired and whenever a change in User

Bits is detected.

SMPTE Offset

An “offset” is the starting time of the first frame of time code and may

be set to any time value in the range 00:00:00:00 through 23:59:59:29.

Usually, you can set your offset to any value in this range, but some-

times the production environment will dictate the offset requirements.

The BiPort 2x4s has a default write offset of 01:00:00:00. If you need to

change the offset time, you may do so via the supplied Windows

Remote Control software.

IMPORTANT: Try to avoid high offsets that may wrap

around (from 23:59:59:29 back to 00:00:00:00). Some pro-

grams become confused by this wrap-around. Choose an

offset that will allow your entire session to be striped with-

out rolling over the 24:00:00:00 time code value.