Two-Three Pull-Down

The 2-3 pull-down allows for a smooth transfer to NTSC video without any unwanted or noticeable pitch changes in the audio. It consists of a combination of speed change and frame-to-field counting.

The following steps are involved during the process:

• The film speed is slowed or pulled down to 23.976 fps (-0.1 %).

• The first frame of film is transferred to the first 2 fields of video.

• The second frame of film is transferred to 3 fields of video, the 2 fields of the second video frame, and just the first field of the third video frame.

  Note

  This is where the 2-3 part of the name comes from. Each alternating frame of film is transferred to 2 fields of video, then 3 fields of video, and so on.

• The third film frame is transferred to the second field of video frame 3 and the first field of video frame 4.

• The remaining film frames are transferred in this manner, alternating between 2 and 3 fields of video, until the end of the transfer. After 4 frames of film have been transferred this way, an even 5 video frames will be created. Over the course of one second, 24 frames of film and 30 frames of video will have gone by. Because they are running at -0.1 %, the actual frame rate is 29.97 video frames per second, the NTSC standard.

In order to make accurate decisions regarding audio pull-down and video pull-up when working with NTSC film transfers in Nuendo, it is important to have a clear understanding of 2-3 pull-down.

Even though 29.97 fps (video speed) is a faster frame rate than 24 fps (film speed), the video is running -0.1 % slower than the original film due to the 2-3 transfer process. Therefore, you need to slow the audio down a bit so that production audio, such as DAT tapes or files from a field recorder from a film shoot are played back in sync with NTSC video.