Reverse telecine, Conform – Apple Cinema Tools 3 User Manual
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Chapter 2
The Cinema Tools Workflow
Step 4:
Prepare the clips for editing (processing the clips)
Cinema Tools has two powerful features that can be used on your clips prior to editing
them: the Reverse Telecine feature and the Conform feature.
Reverse Telecine
The Reverse Telecine feature (for NTSC transfers only) provides a means of removing
the extra fields added during the 3:2 pull-down process of the telecine transfer. You
need to do this when you intend to edit the video at 24 fps. See “
page 22 for information on what a 3:2 pull-down is and why you might want to reverse
it. See “
Reversing the Telecine Pull-Down
” on page 113 for details on its use.
Conform
The Conform feature is useful both to correct errors in video clips and to change the
frame rate (timebase) of a clip. Cinema Tools lets you select the frame rate you want to
conform a clip to.
In order to understand the Conform feature, you need to know a bit about the nature
of QuickTime video files. Each video frame within a QuickTime file has a duration
setting that defines the length of time that a particular frame is displayed (normal NTSC
or PAL-based QuickTime video has the same duration assigned to all frames). For
example, the NTSC video rate has a value of 1/30 of a second (actually 1/29.97 of a
second) assigned to each frame. The PAL video rate is 1/25 of a second.
Occasionally when capturing video clips, the duration of some frames is set to slightly
different values. While the differences are not visible when playing the clip, they can
cause problems when Cinema Tools creates the cut list or if you use the Reverse Telecine
feature on it. In these cases, you would conform the clip to its current frame rate.
There are also times when you may want to change the frame rate of a clip. If you
transferred 24 fps film to video by speeding it up (either to 30 fps for NTSC or to 25 fps
for PAL—in each case ensuring a one-to-one relationship between the film and video
frames), the action during playback will be faster than the original film, and the audio
will need to have its playback speed adjusted to compensate. You can use the Conform
feature to change the clip’s frame rate to 24 fps, making it play back at the original film
rate and stay in sync with the audio. See “
” on page 111 for
details on using the Conform feature.
Note: Be sure to use the Conform feature on a clip before editing it in Final Cut Pro.
Also be sure the editing timebase in Final Cut Pro’s Sequence Preset Editor is set at the
same rate you are conforming to.
See “
Determining How to Prepare Source Clips for Editing
more information.
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