When finalizing a video, converting frame rates may be necessary. The difficulty of transitioning between different frame rates varies based on the specific requirements.
S T A N D A R D S C O N V E R S I O N S
Converting between different standards may be required for broadcast or film deliverables. The effort needed to convert varies depending on the format. Most of these conversions can be performed using software.
In the context of video production and post-production, the term "pull down" refers to a process used to change the frame rate of a video. This method is especially common when footage shot at a cinematic frame rate needs to be converted to a frame rate compatible with television systems, or vice versa.
What is Pull Down?
Pull down is a method used to adapt video shot at different frame rates without altering playback speed and audio pitch. This process arises mainly due to differences between the frame rates used in cinema and television. For example, films are typically shot at 24 frames per second (fps), while television standards in the United States use 29.97 fps for NTSC or 25 fps for PAL.
Types of Pull Down
- 3:2 Pull Down: This is the most common form and is used to convert 24 fps film material to 29.97 fps television (NTSC). It works by adding interlaced frames so that two consecutive frames at 24 fps are converted into five frames at 30 fps, repeating some frames according to a specific pattern (usually, the first frame is repeated three times and the second twice).
- 2:2 Pull Down: Used to convert 24 fps material to 25 fps (PAL television), where each frame is repeated once, resulting in a slight acceleration of the video but maintaining simpler synchronization.
Usage of Pull Down
Pull down is crucial in post-production when content needs to be adapted to different broadcast standards without altering the original intent of time and motion in the film. Proper implementation ensures that motion remains smooth and that audio synchronization is not affected. Additionally, it prevents issues of judder (uneven motion of the image) that can occur when frame rates are not properly managed.
To perform a pulldown from 23.976 fps to 29.97 fps, a common process in post-production to adapt cinema content for NTSC television, the steps vary depending on the software you are using. Below, I provide an example of how to apply this pulldown in Avid Media Composer, Adobe Premiere Pro, and DaVinci Resolve.
Avid Media Composer
- Import your footage: Ensure your project is set up with the target frame rate (29.97 fps).
- Create a new sequence: Right-click in the bin, select "New Sequence," and drag your clip into this sequence.
- Apply Motion Effect:
- Right-click the clip in the timeline and select "Source Settings."
- In the "FrameFlex" tab, set the frame rate of the clip to 23.976.
- Return to the timeline, select the clip, right-click and choose "Motion Effect."
- In the dialog that appears, select "Timewarp" and choose "3:2 pulldown" as the type of conversion.
- Ensure the method is set to "Interpolated Field" for better results.
- Review and export: Review the clip in the timeline to ensure that the motion looks smooth and export as needed.
Adobe Premiere Pro
- Import the clip: Bring your footage into Premiere and place it on the timeline.
- Adjust sequence settings: Right-click the clip on the timeline and select "Sequence Settings." Change the frame rate to 29.97 fps.
- Interpret the footage:
- Right-click the clip in the "Project" panel and select "Modify" > "Interpret Footage."
- In "Assume this frame rate," enter 23.976.
- Premiere will automatically handle the pulldown when you place the clip in a 29.97 fps sequence.
- Export: Set up your export with the desired settings, ensuring the final frame rate is 29.97 fps.
DaVinci Resolve
- Set up the project: Ensure the project settings are at 29.97 fps.
- Import and place your clip: Bring your clip into the timeline.
- Change clip settings:
- Right-click the clip in the timeline and select "Clip Attributes."
- In "Video Frame Rate," switch to "Custom" and set to 23.976.
- Apply pulldown:
- In the same window, select the appropriate pulldown option to convert to 29.97 fps. If Resolve does not offer a direct option, ensure the project is correctly set to 29.97, and Resolve should handle the process automatically.
- Review and export: Check that the motion in the video is smooth and export your project.
These steps will allow you to perform a pulldown from 23.976 fps to 29.97 fps using the three most common editing programs in the industry.
The 23.98 format is the simplest to convert to all other standards. Converting Progressive 29.97 to other standards can be challenging and might necessitate hardware conversion using devices like a Teranex or Snell Alchemist. For complex standards conversions, this hardware provides the highest quality with minimal re-editing required.
