User`s guide

Chapter 23: Synchronization Concepts 333
30 FPS Drop Frame Format
This format is used for sound recordings
done for film-originated programs that are
destined for NTSC broadcast.
29.97 Non-Drop Frame Format
This format is used with NTSC color video.
It runs at a rate of 29.97 FPS.
29.97 Drop Frame Format
NTSC color video has an actual frame rate
of 29.97 FPS, so an hour’s worth of frames
(108,000) running at 29.97 FPS Non-Drop
will take slightly longer than one hour of
real-time to play. This makes calculating
the actual length of a program difficult
when using 29.97 Non-Drop time code. A
program which spans one hour of 29.97
Non-Drop time code addresses (e.g. from
1:00:00:00 to 2:00:00:00) is actually 60
minutes, 3 seconds and 18 frames long.
To make working with 29.97 time code eas-
ier for broadcasters, the SMPTE committee
created 29.97 Drop Frame time code,
which runs at exactly the same speed as
29.97 Non-Drop (non-drop frame) time
code, but compensates for the slower speed
by “dropping” (omitting) two frames at the
top of each minute, with the exception of
every 10th minute. For this reason, the
time code address of 1:01:00:00 does not
exist in drop frame code because it has
been skipped.
At the end of a program which spans pre-
cisely one hour of drop frame time code
(1:00:00;00 to 2:00:00;00 for example), ex-
actly one hour of real time has elapsed.
Although it sounds complicated, drop
frame time code allows broadcasters to rely
on time code values when calculating the
true length of programs, facilitating accu-
rate program scheduling.
25 FPS Frame Format
This format is used with the European PAL
video standard, which runs at a 25 FPS
frame rate. This format is also called the
EBU (European Broadcast Union) format
because it’s used by broadcasters through-
out most of Europe.
24 FPS Frame Format
This format is used exclusively for film ap-
plications. Film is typically photographed
and projected at a 24 FPS frame rate, so this
SMPTE format is useful when one time
code frame should equal one film frame.
Working with Film-
Originated Material
When you do post-production work in
Pro Tools, you will usually work with video
material. However, it is possible that the
video you are working on was shot on film.
Film footage and production sound go
through separate conversion processes be-
fore they reach video, and the audio post-
production stage. The film is transferred to
video using a process called Telecine, using
a method called 3:2 Pulldown. Audio can
also be pulled down during the transfer, or
you might end up working with audio that
has not been adjusted (production sound).