Final Cut Pro 5 features a new filter called Shift Fields. You may have noticed that this filter sometimes gets applied to your clips automatically. This happens when you mix video from different sources into a sequence (known as a mixed-format sequence); the Shift Fields filter will automatically adjust the field dominance so that all clips are uniform.
When you add a clip to a sequence, Final Cut Pro checks to make sure that the field dominance of the incoming clip's media file matches the field dominance of the sequence. If it doesn't match, Final Cut Pro automatically applies the Shift Fields filter to the clip to make it match the sequence's field dominance. Without the filter, the clip would stutter during playback because the fields would play in the wrong order. This is especially noticeable when you view your video on an external NTSC or PAL video monitor.
The Shift Fields filter has a single parameter called Direction Control, which allows you to manually adjust the filter. If you need to do this, use the following guidelines:
For example, if you add an HDV 1080i60 clip with upper-field dominance to a DV NTSC sequence with lower-field dominance, the HDV clip field dominance must be adjusted to match the sequence (this is where the Shift Fields filter comes into play—set its Direction Control parameter to +1).
The Shift Fields filter isn't necessary when editing media into sequences in which the clip and sequence field dominances match.