MACKIE HDR24/96 - Manual (Page 194)

HDR 24/96
sequencer is to make the HDR24/96 the time code master and the sequencer the slave, as
illustrated below.
Time Code
Time Code Master
Sequencer
Time Code Slave
More about Time Code
Just as the Sample Clock runs at a specific rate called the Sample Rate, the time code signal runs at a
specific rate called the Time Code Frame Rate. Unlike a conventional clock, which displays time in
hours, minutes, and seconds, time code further divides a second into frames. A display of a 30fps
(frames per second) time code time might look like this:
0 2 : 1 8 : 5 7 : 2 8
This time code value reads 2 hours, 18 minutes, 57 seconds, and 28 frames. There are four standard
Time Code Frame Rates, each of which has a specific application. These four rates are:
24 fps Used for theatrical film applications worldwide.
25 fps Used for music, broadcast and non-broadcast PAL and SECAM video, and
non-theatrical (broadcast) film applications in countries that use 50 Hz
power.
29.97 fps Used for non-broadcast NTSC video and theatrical film post production
applications in the US, Canada and Japan.
30 fps Used primarily for music applications in countries which use 60 Hz power
(primarily the US, Canada, and Japan).
All of this is very straightforward except for the case of 29.97 fps. Why do we have a 29.97 fps Time
Code Frame Rate when all the other frame rates are nice whole numbers? Well, it's a long story.
Back before color television was around in the U.S., black and white TV ran at 30 frames/sec. In
order to get the extra color information into the picture, the actual video frame rate was slowed down
to 29.97 frames/sec. 29.97 fps time code was invented to run in perfect sync to the NTSC color video
so that each video frame could have a unique time code address. Basically, 29.97 fps time code
counts off 30 frames to represent each second (just like 30 fps time code), but the interval between
frames have been slowed down by about .1% so that it runs at the NTSC color video frame rate. The
bad news is that the count of seconds (and the bigger units of time) is consequently wrong relative to
actual number of seconds that has passed. In other words, at 29.97 fps the counting of each second is
taking longer than a real second. The good news is that you mostly don't care how the time code
seconds compare to actual seconds, you just want all of the gear to be counting at that same rate. And
if you don’t produce anything that is going to synchronize to color NTSC video, you don’t need to
use 29.97 fps time code.
Even though the invention of 29.97 fps time code solved the problem of synchronizing time code to
color NTSC video, it created another problem. While the frame rate of the time code runs at 29.97
HDR 24/96 194