Interlaced video formats divide frames into two line-based fields. One field consists of the first and subsequent odd lines in the frame, and the other field consists of the second and subsequent even lines in the frame. During the recording process, the two fields are recorded at slightly different moments. For example, when recording NTSC using field 1 dominance, field 1 is recorded 1/60th of a second before field 2.
As a result, video frames can betray the slight time difference between fields with jitter, particularly when they contain fast motion. When broadcast, the fields are displayed on-screen with the corresponding temporal offset. Interlaced video broadcasting is, from the human perceptual perspective, relatively seamless.
Not all interlaced video formats interlace frames in the same way. If you need to mix different interlaced video formats, you may need to change the field dominance of your clips. To work with field-based clips in Backdraft Conform, use video field management tools to make sure results do not introduce interlacing artefacts or field-dominance jitter.
By default, when you edit or composite clips that have conflicting scan formats, Backdraft Conform displays warning messages and requires you to confirm potentially problematic operations. If you are comfortable working with clips that have different scan formats, you can disable these warnings by enabling Ignore Scan Format in the Modules section of the General Preferences menu. See General Preferences.
