Specifications

Pro Tools Reference Guide544
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 Broad-
cast Union) format because it’s used by broad-
casters throughout most of Europe.
24 fps Frame Format
This format is used for high-definition video
and film applications. Film is typically photo-
graphed and projected at a 24 fps frame rate, so
this SMPTE format is useful when one time code
frame should equal one film frame
23.976 fps Frame Format
This format is used for high-definition digital
video production using NTSC video equipment,
and film applications.
Working with Film-Originated
Material
When you do post production work in
Pro Tools, you will usually work with video ma-
terial. 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 before 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 trans-
fer, or you might end up working with audio
that has not been adjusted (production sound).
Typically, during the Telecine process, a master
digital video tape is created, along with a work
copy on Betacam or 3/4-inch analog video tape
for the picture editor to use. At the same time, a
new audio master may be created by slowing
down, or pulling down by 0.1%, the production
sound to compensate for the change in speed
from film to NTSC video. (See Figure 47 on
page 546.)
Guide Tracks and Conforming
In the Video editing process, the audio track
produced by the video editor (the “guide track”)
is rough and needs to be enhanced and im-
proved by the audio engineer. For this reason,
the audio engineer will need to re-assemble the
original sound elements in a process known as
conforming.
3:2 Pulldown
A film clip that lasts 1000 seconds consists of
24,000 film frames (pictures). If you want to
transfer that film to 1000 seconds worth of
NTSC color video, you have to fit 24,000 film
frames into 29,970.02997 video frames.
The Telecine stage of video post production
Telecine machine
converts film frames
to video fields using
Digital video
3:2 Transfer
Analog video
“work tape”
master
Production audio
30
fps Non-Drop
48 kHz
Telecine
29.97
fps
48 kHz
Sample rate conversion
or A-D-A (analog stage)
29.97
fps
29.97
fps
“simo” or “simul” DAT
Analog
audio