Adding and Removing Pull-Down in 24p Clips

Cinema Tools and Final Cut Pro have pull-down removal and addition features that address issues specific to working with 24p video. Pull-down is a process that adds redundant fields to video in order to distribute 24 frames per second into the NTSC standard of 29.97 frames per second. See Frame Rate Basics for more information. Some camcorders, such as the Panasonic AG-DVX100, are designed to shoot in progressive mode at 24 fps (literally 23.98 fps) and then record the video to tape as a 60-field interlaced signal by applying a special kind of pull-down called advanced 2:3:3:2 pull-down. With Final Cut Pro or Cinema Tools, you can remove the redundant fields created by the camera’s pull-down, so that you can edit at 23.98 fps or 24 fps.

When you edit 23.98 fps video, you may need to output it to an NTSC monitor, record it to an NTSC videotape, or send it to another type of NTSC device. Because the NTSC standard specifies a frame rate of 29.97 fps, Final Cut Pro gives you a way to add pull-down back in to the video as you output it. To accommodate various circumstances, Final Cut Pro provides a few different types of pull-down patterns for outputting your 23.98 fps video as 29.97 fps video: 3:2 pull-down, 2:3:3:2 pull-down, and 2:2:2:4 pull-down. (See Pull-Down Patterns You Can Apply to 23.98 fps Video for a description of these pull-down patterns.)

The sections that follow describe a number of ways that you can use Final Cut Pro or Cinema Tools to remove advanced 2:3:3:2 pull-down or 2:3:2:3 pull-down from digital video clips. You can:

What Is 2:3:2:3 Pull-Down?

A 2:3:2:3 pull-down pattern is exactly the same as a 3:2 pull-down pattern, except that it is applied by a digital video camcorder (as opposed to any other type of equipment that could apply the same pattern of pull-down). This manual uses the term 2:3:2:3 when referring to the pull-down that comes from a 24p digital video camcorder; this type of pull-down can be removed using the automated form of reverse telecine. See Removing 2:3:3:2 or 2:3:2:3 Pull-Down with Cinema Tools for more information.

Working with 2:3:3:2 Pull-Down

Some camcorders, such as the Panasonic AG-DVX100, are designed to shoot in progressive mode at 24 fps (actually 23.98 fps) and then record the video to a tape as a 60-field interlaced signal by applying 2:3:3:2 pull-down to it. The 2:3:3:2 pull-down is similar in concept to 3:2 pull-down but has a different pattern of field repetition, as illustrated below.

Figure. Diagram showing the fields added by the 2:3:3:2 pull-down.

There are some advantages to shooting with, and then removing, 2:3:3:2 pull-down instead of working with 3:2 pull-down:

  • Final Cut Pro can easily remove the 2:3:3:2 pull-down while you are capturing, so that you can edit 24 fps (actually 23.98 fps) progressive video.

  • Unlike 3:2 pull-down removal, removing a 2:3:3:2 pull-down does not require the recompression and re-creation of any frames, so it results in a better picture quality. Final Cut Pro eliminates the redundant fields by simply pulling out the frames containing fields with two different images (the frames that were constructed from two different original frames). Only frames containing one still image are left, resulting in a clean picture.

    Figure. Diagram showing the fields removed by the 2:3:3:2 pull-down removal process.

You can remove the 2:3:3:2 pull-down with Final Cut Pro while capturing the source media, or with Final Cut Pro or Cinema Tools after capturing.

Note: See 2:3:3:2 Pull-Down for information about applying 2:3:3:2 pull-down to video (rather than removing it from video).

Removing 2:3:3:2 Pull-Down with Final Cut Pro

You can remove 2:3:3:2 pull-down with Final Cut Pro either while capturing the video or after the clips have been captured.

To remove the pull-down while capturing from a digital video source
  1. In Final Cut Pro, choose Final Cut Pro > Audio/Video Settings.

  2. Click the Capture Presets tab.

  3. Select the preset you want to use, then click Edit.

  4. Select “Remove Advanced Pulldown and/or Duplicate Frames from FireWire sources.”

At some point after removing the 2:3:3:2 pull-down, you may want to output the video with 2:3:3:2 pull-down added back to recapture it with the camera. Or, for NTSC broadcast or distribution, you may want to apply the more conventionally supported 3:2 pull-down. You can output 24p video in either of these pull-down patterns. See Pull-Down Patterns You Can Apply to 23.98 fps Video for more information.

To remove the pull-down in Final Cut Pro after capturing
  1. In Final Cut Pro, select the clips or sequence.

  2. Choose Tools > Remove Advanced Pulldown.

Removing 2:3:3:2 or 2:3:2:3 Pull-Down with Cinema Tools

Clips captured from digital video camcorders that shoot 24p, such as the Panasonic AG-DVX100 camcorder, have the pull-down pattern (also called cadence) information embedded in a way that Cinema Tools can read. If Cinema Tools detects this cadence information when you use the Reverse Telecine feature, the Automated Reverse Telecine dialog appears. It’s a simplified version of the regular Reverse Telecine dialog.

Note: The Reverse Telecine feature cannot be used with temporally compressed video such as MPEG-2-format video.

You can use automated reverse telecine to remove the pull-down either from one clip at a time or from a group (batch) of clips.

To use automated reverse telecine to remove the pull-down in a single clip
  1. Choose File > Open Clip, then select the clip in the dialog.

  2. In the Clip window, click Reverse Telecine.

  3. Choose a frame rate from the “Conform to” pop-up menu:

    • 23.98: This frame rate is useful if you want to later use the Final Cut Pro pull-down feature that lets you output 23.98 fps video as 29.97 fps video. (See Pull-Down Patterns You Can Apply to 23.98 fps Video for more information.)
    • 24.0: You may want to conform and edit the clips at this rate if you plan to include them in a project that contains other clips that are exactly 24 fps.

      Note: If the audio and video are contained in the same clip, and you choose 24.0 from this pop-up menu, the Reverse Telecine feature increases the audio speed by a very small percentage so that it is in sync with 24 fps instead of 23.98 fps.

      Figure. Reverse Telecine dialog showing the "Conform to" pop-up menu.
  4. Select “New (smaller)” or “Same (faster)” to specify the kind of file you want to create:

    • New (smaller): Creates a new media file that does not contain the extra frames introduced by the pull-down. The new file is about 20 percent smaller than before, but this method is slower. Regardless of whether the original file was reference or self-contained, this method creates a self-contained file. (See The Difference Between Self-Contained and Reference Media Files for more information.)
    • Same (faster): Modifies the current media file so that the extra frames are not visible to the editing system, but the data is not removed from the file. This process is faster but does not reduce the size of the file. The resulting file is self-contained if it was originally self-contained, or reference if it was reference.
      Figure. Reverse Telecine dialog showing the file output type selection.

    If you selected “Same (faster),” you can choose whether Cinema Tools checks for cadence discontinuities.

    While removing the pull-down, Cinema Tools looks for breaks in the pull-down cadence. If any breaks are found, it adjusts the processing to accommodate those discontinuities. A cadence discontinuity might occur if a recording was stopped and then started again at another point in the five-frame sequence.

    Checking for cadence discontinuities is more time-consuming for the Same file option than it is for the New file option, so if you select “Same (faster),” you can deselect the “Check for cadence discontinuities” checkbox for the fastest possible processing.

    Note: If this checkbox is deselected and cadence discontinuities exist in the clip, or if the cadence changes from 2:3:3:2 to 2:3:2:3 (or any other pattern) in the middle of a clip because the settings were changed during the recording, reverse telecine cannot be properly performed on the clip.

  5. Click OK to start the pull-down removal process.

If you selected the New file option, you are asked to give the new reversed clip a name and location. If the original clip was connected to a database record, the new reversed clip replaces its connection to the record (regardless of whether or not the new clip overwrites the old clip).

To use automated batch reverse telecine to remove the pull-down from several clips at once
  1. Place all the clips that you want to process in one folder. (Make sure that they are all clips that were captured from a 24p digital video camcorder.)

  2. Choose File > Batch Reverse Telecine.

  3. In the dialog that appears, select any source clip file in the folder that contains the clips you want to process, then click Choose.

  4. Choose a frame rate from the “Conform to” pop-up menu:

    • 23.98: This frame rate is useful if you want to later use the Final Cut Pro pull-down feature that lets you output 23.98 fps video as 29.97 fps video. (See Pull-Down Patterns You Can Apply to 23.98 fps Video for more information.)
    • 24.0: You may want to conform and edit the clips at this rate if you plan to include them in a project that contains other clips that are exactly 24 fps.

      Note: If the audio and video are contained in the same clip, and you choose 24.0 from this pop-up menu, the Reverse Telecine feature increases the audio speed by a very small percentage so that it is in sync with 24 fps instead of 23.98 fps.

      Figure. Batch Reverse Telecine dialog showing the "Conform to" pop-up menu.
  5. Select “New (smaller)” or “Same (faster)” to specify the kind of files you want to create:

    • New (smaller): Creates new clip files that do not contain the extra frames introduced by the pull-down. The new files are about 20 percent smaller than before, but this method is slower. Regardless of whether the original files were reference or self-contained, this method creates self-contained files. (See The Difference Between Self-Contained and Reference Media Files for more information.)

      If you select “New (smaller),” you can also choose to keep or delete the original clip files. To save the original clips in a separate folder, select the Keep Originals checkbox.

    • Same (faster): Modifies the current clip files so that the extra frames are not visible to the editing system, but the data is not removed from the files. This process is faster but does not reduce the size of the files. The resulting files are self-contained if they were originally self-contained, or reference if they were reference.
      Figure. Batch Reverse Telecine dialog showing the output file type selections.

    If you selected “Same (faster),” you can choose whether Cinema Tools checks for cadence discontinuities.

    While removing the pull-down, Cinema Tools looks for breaks in the pull-down cadence. If any breaks are found, it adjusts the processing to accommodate those discontinuities. A cadence discontinuity might occur if a recording was stopped and then started again at another point in the five-frame sequence.

    Checking for cadence discontinuities is more time-consuming for the Same file option than it is for the New file option, so if you select “Same (faster),” you can deselect the “Check for cadence discontinuities” checkbox for the fastest possible processing.

    Note: If this checkbox is deselected and cadence discontinuities exist in the clip, or if the cadence changes from 2:3:3:2 to 2:3:2:3 (or any other pattern) in the middle of a clip because the settings were changed during the recording, reverse telecine cannot be properly performed on the clip.

  6. Click OK to start the pull-down removal.

After the process is complete, the following occur:

  • If you selected “New (smaller),” for each clip in the folder, a new clip with the same name is created and placed in a Cinema Tools–created subfolder named Reversed. If you selected Keep Originals, the original files are placed in a Cinema Tools–created subfolder named Originals. If you selected “Same (faster),” the new versions of the clips replace the old versions, in their original folder.

  • If Cinema Tools is unable to complete the reverse telecine process for a clip, that clip is moved into a Cinema Tools–created subfolder named Skipped. A clip is not processed if it doesn’t contain a video track, if the frame rate is not supported, if the clip does not contain cadence information, or if there is no codec found for the video track.

  • A text file appears at the top level of the folder you started with, named “reverse.log.” This log gives the date and time that the process started and ended, as well as a start time for each clip. If any problems were encountered, such as running out of disk space or memory, an error message describing the problem also appears in the log.

Pull-Down Patterns You Can Apply to 23.98 fps Video

When editing 23.98 fps video, you may want to output it to an NTSC monitor, record it to an NTSC videotape, or send it to another type of NTSC device. When you need to do this, you can use the pull-down addition feature in Final Cut Pro. Pull-down addition is a software method of converting 23.98 fps video to the NTSC standard of 29.97 fps.

There are three pull-down patterns that Final Cut Pro can apply to 23.98 fps video.

3:2 Pull-Down

3:2 pull-down is the same type employed by a telecine. See Working with NTSC Video for more information. Because 3:2 pull-down is the conventionally supported pull-down pattern for NTSC devices, you need to use this pull-down pattern to record to an NTSC device, such as an SD television, an MPEG-2 encoding device, or a high-end finishing system.

Figure. Diagram showing the fields added by the 3:2 pull-down.

2:3:3:2 Pull-Down

Another type of pull-down you can use is 2:3:3:2 pull-down. As with 3:2 pull-down, the “3” in the pattern represents three fields, where one redundant field is added to the original two fields of a frame. See Working with 2:3:3:2 Pull-Down for details about this pattern and the advantages it provides.

Although 3:2 pull-down is the conventionally supported pattern for NTSC devices, you may want to use 2:3:3:2 pull-down to output video that you can record to tape and yet later convert back to 23.98 fps with the advantages of 2:3:3:2 removal (the ability to remove the pull-down without the recompression and re-creation of any frames).

2:2:2:4 Pull-Down

The 2:2:2:4 pull-down pattern is not typically supported for recording devices or cameras, but because it requires the least amount of processing power, it’s a good choice if you are editing 23.98 fps video and want to preview it with as many real-time effects as possible on an NTSC monitor. This pattern is also useful if you need to output video for display from an older, slower computer (or a computer with a heavy processing load) that drops frames when you try to output 3:2 or 2:3:3:2 pull-down video.

Figure. Diagram showing the fields added by the 2:2:2:4 pull-down.

Adding Pull-Down to 23.98 fps Video

Final Cut Pro lets you add pull-down to 23.98 fps video as you output it via FireWire. As discussed in the previous section, this is useful when you are editing 23.98 fps video and want to output it to an NTSC device.

Important: You must have a FireWire device connected and the sequence must have a 23.98 fps timebase for the pull-down options to appear. They do not appear if the sequence has a 24 fps timebase.

To add pull-down back in while sending 23.98 fps video to an NTSC device via FireWire
  1. In Final Cut Pro, select the sequence in the Timeline.

  2. Choose the type of pull-down to use from the RT pop-up menu in the Timeline.

    See Pull-Down Patterns You Can Apply to 23.98 fps Video for details about the available patterns.

  3. Output the video using your FireWire connection.

    Refer to the Final Cut Pro documentation for details about outputting video.

The pull-down is performed on the video that is sent out of your computer via FireWire.