M-Audio MIDISPORT 8x8/s [42/52] Smpte and mtc user bits

white (30 non-drop) and color (30 drop) video have different frame rates. While

in Europe and all “PAL” countries, black and white and color video have the

same frame rate of 25 frames per second.

What Frame Rate and Settings Should You Use?

The following table summarizes the frame rates that we recommend you use

when striping SMPTE:

Application Frame Rate

Audio Only 30 non-drop

Video - Color U.S. 30 drop*; 29.97

Video - B/W U.S. 30 non-drop

Video - Color Europe 25

Video - B/W Europe 25

** Note: If you are in the U.S. and using a MIDISPORT 8x8/s to do

audio scoring or MIDI sequencing for your own video, then we

suggest you use 30 non-drop instead of 30 drop. This is because

drop-frame is harder to work with, since time calculations are more

complicated. Non-drop will allow you to sync just as well as drop-

frame; drop-frame is really only a necessity for broadcast

purposes.

SMPTE and MTC User Bits

The SMPTE and MTC standards provide a means for users to “stamp” their

media with reference numbers of their own choosing. This is accomplished by

setting aside some spare data (32 bits) within the time code message to be used

as “User Bits.” SMPTE and MTC allow you to 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 MIDISPORT 8x8/s 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.