Reversing the Telecine Pull-Down

When you use a telecine to transfer your 24 fps or 23.98 fps film to 29.97 fps NTSC video, the typical way the film’s frames are distributed into the NTSC frames is by the 3:2 pull-down method. The 3:2 pull-down method, described in Working with NTSC Video, inserts extra fields of video. The reverse telecine process removes the extra fields (as shown in the illustration below), changing the frame rate of the video to the original film frame rate. In other words, the reverse telecine process reverses the 3:2 pull-down. Reversing (or removing) the 3:2 pull-down provides a one-to-one relationship between the video and film frames so that your cut lists are accurate.

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

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

Important: If your source clips originated from a special type of DV camcorder that shoots 24p, such as the Panasonic AG-DVX100 camcorder, a simpler form of the Reverse Telecine dialog appears. See Removing 2:3:3:2 or 2:3:2:3 Pull-Down with Cinema Tools for instructions for reversing the pull-down for clips that originated from a 24p-capable DV camera.

Tips for Using Reverse Telecine

Following are some tips for using reverse telecine:

  • Reverse telecine works best if the captured video does not have any dropped frames. If you attempt to use the Reverse Telecine feature on a clip that has dropped frames, a warning appears. See Avoiding Dropped Frames for more information.

  • If you have to reverse the pull-down for several clips, you might want to use the Batch Reverse Telecine feature instead, because it allows several clips to be processed at once. See Using Batch Reverse Telecine for more information.

  • Reversing the 3:2 pull-down with software is a time-consuming process; you’ll need to allow waiting time while your computer does its work. Hardware reverse telecine, performed by a third-party capture card while the video is captured into your computer, is a speedier option.

Determining the Field Capture Information

You need to enter field capture information in the Reverse Telecine dialog. Typically, all of your clips are generated with the same hardware and settings, so you only need to look at a few frames of one clip to determine the field capture mode. A clip can be captured as one field or both fields, with field 1 or field 2 dominance.

Look at the key number and timecode window burn on the video frames to determine the frame sequence and verify whether the video has one or two fields. The key number window burn usually includes the A, B, C, and D frame type indicators. (Also, the timecode often has the number “1” at the end to indicate field 1, and “2” to indicate field 2.) In the Clip window, use the arrow keys on your keyboard to step through a few frames of a clip and observe the sequence of film frame numbers. Refer to the table below to find out your field information.

If the repeating frame sequence is
Then your video contains
In the Reverse Telecine dialog, select as capture mode
AA, BB, BC, CD, DD or A1A2, B1B2, B3C1, C2D1, D2D3
Both fields, with field 1 dominance
Field 1 - Field 2
AB, BB, CC, DD, DA, or A2B1, B2B3, C1C2, D1D2, D3A1
Both fields, with field 2 dominance
Field 2 - Field 1
A, B, B, C, D or A1, B1, B3, C2, D1
One field, with field 1 dominance
Field 1 Only
A, B, C, D, D or A2, B2, C1, D1, D3
One field, with field 2 dominance
Field 2 Only

What Is Field Dominance?

The field dominance of a captured clip is determined by the telecine hardware and is usually not configurable by the user. Video frames are composed of two fields; one field consists of all the even lines of the video, and the other field consists of all the odd lines. At the telecine, the two fields are scanned at different times, which means that the film frame can advance between the time that the first field is scanned and the time that the second field is scanned.

  • When only one field is captured: Field 1 dominance means that only field 1 is captured, and field 2 dominance means that only field 2 is captured.
  • When both fields are captured: Field 1 dominance means that each captured frame is digitized from two video fields, but field 1 occurs earlier.

Note: With field 1 dominance, the two video fields digitized into each captured frame should have the same timecode address, because SMPTE timecode is specified as beginning on field 1. Field 2 dominance, when both fields are captured, means that field 2 occurs earlier and that the captured frame contains video fields with two different timecode values.

About A Frames

If your video has window burn, the easiest way to locate an “A” frame is to look at the key number in the video frame, which typically has a letter after it indicating the frame type. This letter is called the frame type indicator. A frames include any frame with a frame type indicator that begins with “A,” including an AA (also known as A1A2), AB (also known as A2B1), A1, or A2 frame. When you view the video a frame at a time, the frame type indicator for an A frame shows an “A” and the frame number is solid (not flickering between two frames).

Figure. Video frame showing the frame type indicator in the window burn.

If you are using non-drop frame timecode and your source clips have not yet been edited, there is a reliable five-frame pattern where an A frame occurs every five frames. Usually, any timecode number ending in “0” or “5” is an A frame (for example, 1:23:14:10 and 1:23:14:15).

During batch reverse telecine, if a clip starts on a timecode number that is not evenly divisible by five (that is, timecode numbers ending in “5” or “0”), Cinema Tools trims frames from the beginning of the clip so that the clip starts on the next frame with a timecode number that ends in “0” or “5.” This is done to make sure that all source clips start on an A frame. Clips that are trimmed are noted in the batch reverse telecine log file, which is named “reverse.log.”

When key numbers are not burned in to the video, finding an A frame is much more difficult. If there is a lot of motion in the video, you might be able to distinguish one of the original film frames from the next in the video. In that case, look for a video frame made up of two fields from the same original film frame, which has different film frames before and after it. Such a frame would be an A frame.

Using Reverse Telecine on a Single Source Clip in Cinema Tools

Use single-clip reverse telecine to perform reverse telecine on one clip. You can also perform reverse telecine on clips using Final Cut Pro. See Using Reverse Telecine on Source Clips in Final Cut Pro for more information.

In most cases, you need window burn to use the Reverse Telecine feature because you need to examine the key numbers or timecode in the clip itself to make reverse telecine settings. However, if your source clips originated from a certain type of camcorder that shoots 24p, such as the Panasonic AG-DVX100 camcorder, you do not need window burn in order to reverse the pull-down. See Removing 2:3:3:2 or 2:3:2:3 Pull-Down with Cinema Tools for specific information.

Note: For reverse telecine to function properly, a media file cannot be in use by any other application. Also, a clip cannot be open in the Finder, nor can it be write-protected. If you perform reverse telecine on clips that are open in another application, an alert message appears warning you that the file is busy.

To use the single-clip Reverse Telecine feature on a clip in Cinema Tools
  1. Choose File > Open Clip, then select the clip in the dialog.

  2. In the Clip window, position the playhead so that a still frame with clearly readable window burn is displayed.

    You need to see the window burn in order to identify the frame type for the Reverse Telecine dialog. Often the first frame will do, but any frame in the clip can be displayed. (Reverse telecine will be applied to the entire clip, regardless of which frame is displayed.)

  3. In the Clip window, click Reverse Telecine.

  4. In the dialog that appears, select the capture mode that indicates the correct field capture for the clip:

    • Field 1 Only: Select this option if the video contains only field 1.
    • Field 2 Only: Select this option if the video contains only field 2.
    • Field 1 - Field 2: Select this option if the video contains both fields, and field 1 is the dominant field (the first field to appear).
    • Field 2 - Field 1: Select this option if the video contains both fields, and field 2 is the dominant field.

    See Determining the Field Capture Information for details.

    Note: If Cinema Tools finds pull-down information embedded in the source clips, a simpler version of this dialog appears. See Removing 2:3:3:2 or 2:3:2:3 Pull-Down with Cinema Tools for more information.

  5. In the Fields area, use the pop-up menu to choose the style of frame types to show (Style 1 shows letters only, and Style 2 shows letters with field numbers), then select the frame type that matches the type of frame currently displayed in the Clip window.

    Your frame type choices vary depending on the field capture mode you selected.

    Figure. Reverse Telecine dialog showing the field options available with the Field 2 Only capture mode selected.
    Figure. Reverse Telecine dialog showing the field options available with the Field 2 - Field 1 capture mode selected.
  6. Select “New (smaller)” or “Same (faster)” to specify the kind of file you want the Reverse Telecine feature to create:

    • New (smaller): This option creates a new clip file that does not contain the extra frames introduced by the 3:2 pull-down. The new file is about 20 percent smaller, 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): This option modifies the current clip 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 originally reference.

      Note: This “Same (faster)” method is available only when the clip has been captured or recompressed to have only one field per frame. This is because reversing the 3:2 pull-down for a clip with two fields per frame requires deinterlacing two different frames, removing one field from each of those two frames, and then making a new frame out of the other two fields. When new frames are being created, a new movie file must be created.

    Tip: If you choose the “New (smaller)” method, the original file is no longer needed, but it is not automatically deleted. A dialog suggests naming the new file the same name as the original, with the extension .rev added. To delete the original file by replacing it with the new one, remove the .rev extension in the dialog so that the new file has the same name as the original. Keep in mind, though, that if you delete the original file, you cannot use reverse telecine a second time if you want to try a different setting.

  7. From the “Conform to” pop-up menu, choose the frame rate that allows you to maintain or restore audio/video sync:

    • 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. Bottom part of the Reverse Telecine dialog showing the "Conform to" pop-up menu and the Standard Upper/Lower checkbox.
  8. Leave the Standard Upper/Lower checkbox selected.

    The Standard Upper/Lower checkbox should be selected unless you find that the reverse telecine process does not produce the correct results. It is only relevant when both video fields are captured; it has no effect if only one field was captured. See Checking Your Reverse Telecine Results for more information.

  9. Click OK to start the reverse telecine process.

If you selected the “New (smaller)” 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).

Note: Occasionally there are clips with individual frame durations that are longer than they should be. This situation can cause the Reverse Telecine feature to report one or more dropped frames, when in fact there aren’t any. If you see this message, try using the Conform feature to conform the clip to 29.97 fps before starting the reverse telecine process again. The Conform feature ensures that all the frames are the same length. See Using the Conform Feature for more information.

As long as you created a new file (by default, with the extension .rev) and did not delete the original file, you can perform reverse telecine a second time if necessary (for example, to try a different field setting).

To prepare to use the single-clip Reverse Telecine feature a second time
  1. Disconnect the current reversed file from its database record.

  2. Connect the original file to the database record.

  3. Rename or move the current reversed file if you want to keep it from being overwritten.

Now you can perform the steps for using the single-clip Reverse Telecine feature on a clip in Cinema Tools as described previously in this section.

Checking Your Reverse Telecine Results

After a telecine 3:2 pull-down transfer, the upper field is typically field 1 and the lower field is field 2, except when using DV. Normally, when the Standard Upper/Lower checkbox is selected, Cinema Tools determines what needs to be done and the clips are processed correctly. However, on rare occasions, video is captured or processed in such a way that field orders are switched, and this can result in flawed reverse telecine results.

To check your results, look at the frames of a clip that has been processed by reverse telecine. As you look at each frame in the clip, you should see the sequence of A, B, C, and D frames repeat and each letter should be clearly legible. You should not see any interfield flicker. The film frame numbers should increase sequentially, and those digits should also be clearly legible. If not, try using the reverse telecine process again, but without selecting the Standard Upper/Lower checkbox.

Using Reverse Telecine on Source Clips in Final Cut Pro

Final Cut Pro includes a menu command that allows you to perform reverse telecine on the clips selected in the Browser.

It is important to understand that, although Final Cut Pro initiates the reverse telecine process, it is Cinema Tools that actually performs the task. Additionally, you are not presented with the same choices as when using reverse telecine directly in Cinema Tools—the settings that are used for the reverse telecine process using Final Cut Pro are the last settings that were used in Cinema Tools. Therefore, you should always perform reverse telecine on a clip directly in Cinema Tools to verify the proper settings before processing clips using Final Cut Pro.

Important: Performing reverse telecine using Final Cut Pro modifies the original media file—you do not have the option of creating a new media file as you do when using Cinema Tools. You must have read-and-write privileges for the media files.

To use Final Cut Pro to perform reverse telecine on source clips
  1. In the Final Cut Pro Browser, select the clips you want to process.

    Note: Only files using a frame rate of 29.97 fps will be processed.

  2. Choose Tools > Cinema Tools Reverse Telecine.

Cinema Tools opens and performs the reverse telecine, displaying a dialog that shows the task’s progress.

Using Batch Reverse Telecine

If you need to reverse the telecine 3:2 pull-down of several clips, you can use the Batch Reverse Telecine command to process several clips at once.

Note: If your source clips originated from a certain type of DV camcorder that shoots 24p, such as the Panasonic AG-DVX100 camcorder, see Removing 2:3:3:2 or 2:3:2:3 Pull-Down with Cinema Tools for more information.

Preparing to Use Batch Reverse Telecine

There are a couple of things you should do before using batch reverse telecine:

  • Before you start a batch reverse telecine process, use the single-clip reverse telecine process on one of your clips and check the results to make sure the settings you plan to use work correctly. See Using Reverse Telecine on a Single Source Clip in Cinema Tools for instructions.

  • If you are working with video that contains two fields, make sure that all your clips have the same field dominance. See Determining the Field Capture Information for more information. Some digitizing hardware may switch unpredictably between field 1 and field 2 dominance. If you find that some of your clips have one and some have the other, you can separate your clips into two field dominance batches and batch process them separately.

Using Batch Reverse Telecine for Multiple Source Clips

Before you use batch reverse telecine to process multiple source clips, make sure to read Preparing to Use Batch Reverse Telecine.

To use batch reverse telecine
  1. Place all the clips that you want to process in one folder.

  2. Choose File > Batch Reverse Telecine.

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

  4. In the Batch Reverse Telecine dialog that appears, select the capture mode that indicates the correct field capture for the clip:

    • Field 1 Only: Select this option if the video contains only field 1.
    • Field 2 Only: Select this option if the video contains only field 2.
    • F1 - F2: Select this option if the video contains both fields, and field 1 is the dominant field (the first field to appear).
    • F2 - F1: Select this option if the video contains both fields, and field 2 is the dominant field.
      Figure. Batch Reverse Telecine dialog showing the capture mode options.

    See Determining the Field Capture Information for details.

    Note: If Cinema Tools finds pull-down information embedded in the source clips, a simpler version of this dialog appears. See Removing 2:3:3:2 or 2:3:2:3 Pull-Down with Cinema Tools for more information.

  5. From the “Conform to” pop-up menu, choose the frame rate that allows you to maintain or restore audio/video sync:

    • 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.

  6. Leave the Standard Upper/Lower checkbox selected.

    The Standard Upper/Lower checkbox should be selected unless you find that the batch reverse telecine process does not produce the correct results. See Checking Your Reverse Telecine Results for more information.

  7. To save the original clips in a separate folder, leave the Keep Originals checkbox selected. If you don’t want to save the original clips, deselect it. (When you deselect the checkbox, the original clips are deleted as each new clip is created.)

    Important: You cannot undo a reverse telecine operation. If you do not save the original clips and later find out that one of the settings was incorrect, you will need to recapture the clips to correct the setting and perform reverse telecine on the clips a second time.

  8. Click OK to start the batch reverse telecine process.

After the process is complete, the following occur:

  • 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 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, or if no codec is 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.

Additionally, you will need to use the Reconnect command to connect the newly created reverse-telecined clips to their records. See Fixing Broken Clip-to-Database Links for more information.

Using Batch Reverse Telecine a Second Time

If, after performing the batch reverse telecine, you decide you need to change a setting and redo the batch reverse telecine, perform the following steps.

To prepare to use batch reverse telecine a second time
  1. Move the clips from the Originals folder to their original folder.

    Note: If you did not select Keep Originals, you must recapture the original clips.

  2. If you would like to keep the current reverse telecine versions of the clips while creating the new versions, you need to move them from the Reversed folder to another folder or rename the Reversed folder (for example, to Reversed 1).

    You can leave the current files where they are if you would like them to be overwritten.

  3. Similarly, you need to move or rename the “reverse.log” file if you would like to save it.

  4. Follow the steps in Using Batch Reverse Telecine for Multiple Source Clips to perform the batch reverse telecine.

Note: If you connected the original reverse-telecined clips to the database records using the Reconnect command, the new reverse-telecined clips should automatically be connected to the database.