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About 3:2 pulldown


    When you transfer 24-fps film to 29.97-fps (NTSC) video, you use a process called 3:2 pulldown, in which the film frames are distributed across video fields in a repeating 3:2 pattern. The first frame of film is copied to fields 1 and 2 of the first frame of video, and also to field 1 of the second video frame. The second frame of film is then spread across the next two fields of video--field 2 of the second video frame and field 1 of the third frame of video. This 3:2 pattern is repeated until four frames of film are spread over five frames of video, and is then repeated.

    The 3:2 pulldown process results in whole frames (represented by a W) and split-field frames (represented by an S). The three whole video frames contain two fields from the same film frame. The remaining two split-field frames contain a video frame from two different film frames. The two split-field frames are always adjacent to each other. The phase of 3:2 pulldown refers to the point at which the two split-field frames fall within the first five frames of the footage.

    Phase occurs as a result of two conversions that happen during 3:2 pulldown: 24-fps film is redistributed through 30-fps video, so each of four frames of 24-fps film is spread out over five frames of 30(29.97)-fps video. First, the film is slowed down 0.1% to match the speed difference between 29.97 fps and 30 fps. Next, each film frame is repeated in a special pattern and mated to fields of video.

    When you apply 3:2 pulldown to footage, one frame of the film (A) is separated into two or three interlaced video fields (B), which are grouped into video frames containing two fields each.
    When you apply 3:2 pulldown to footage, one frame of the film (A) is separated into two or three interlaced video fields (B), which are grouped into video frames containing two fields each.