Apple Final Cut Pro 6 - Manual (Page 1471)

686 Part IV Real Time and Rendering
Mixing Frame Rates
Clips with any Final Cut Pro–supported frame rate can be added to a sequence and
played back in real time. Depending on whether the clip frame rate is faster or slower
than that of the sequence, Final Cut Pro skips or repeats frames of the sequence clip.
Nonmatching frame rates are handled three ways.
If a clip and sequence have matching frame rates:
Each frame of the clip’s media file is played back in the sequence. No frame rate
conversion occurs, even when the clip and sequence codecs don’t match. Ideally, your
clip and sequence frame rates should always match.
If a clip’s frame rate is slower than the sequence frame rate:
Final Cut Pro repeats frames of the clip’s media file as necessary to create the
appearance of playback at the sequence frame rate. The repeating pattern is not
necessarily compatible with standard pull-down or frame duplication patterns of other
formats. In cases with interlaced footage (such as a PAL clip within an NTSC sequence),
fields are sometimes doubled (instead of frames) to avoid field stuttering.
If a clip’s media file frame rate is faster than the sequence frame rate:
Final Cut Pro drops frames of the clip’s media file as necessary to create the appearance
of playback at the sequence frame rate. Because frames are skipped, you won’t always
be able to trim these clips with frame accuracy. In those cases, you may want to open
the original clip in the Viewer to set a specific In or Out point before editing the clip
into the sequence.
Issues When Working with Mixed Frame Rates
When you add a clip to a sequence and the frame rates don’t match, Final Cut Pro
places the clip as accurately as possible in the Timeline. However, because of the
differences between some frame rates, there may be a one-frame shift on either the
In or Out point of the clip. This is normal behavior caused by the limitations of
mixed-frame-rate editing. After you add a nonmatching clip to a sequence, always
check to make sure your clip In and Out points appear the way you want, and adjust
them if necessary.
Copying and pasting clips from one sequence to another can also create
mixed-frame-rate scenarios. Frame rate errors can accrue if you repeatedly copy
sequence clips to new sequences with nonmatching frame rates. When possible, it’s
always better to edit with master clips from the Browser instead of dragging clips
between sequences.
Motion has a different frame repeating and frame skipping pattern than Final Cut Pro,
so you may see different frames repeated than expected when including Motion
projects in a Final Cut Pro sequence.