Convert 24p to 60i with FFmpeg 3:2 Pulldown

This article demonstrates how to convert a 24p (23.976 fps) progressive video into a broadcast-standard 60i (59.94 fps interlaced) stream using FFmpeg. You will learn the exact FFmpeg commands and video filters required to apply a 3:2 pulldown, set the correct interlacing flags, and ensure the output is compatible with television broadcast standards.

To apply a 3:2 pulldown and output a 60i stream, FFmpeg utilizes the telecine filter. This filter takes the progressive frames and distributes them across interlaced fields in a repeating 3:2 pattern, raising the frame rate from 23.976 fps to 29.97 fps (which represents 59.94 interlaced fields per second, or 60i).

The FFmpeg Command

Use the following command to perform the conversion using the H.264 codec:

ffmpeg -i input_24p.mp4 -vf "telecine=pattern=23,fieldorder=tff" -c:v libx264 -flags +ilme+ildct -pix_fmt yuv420p output_60i.mp4

Breakdown of the Parameters

• -vf "telecine=pattern=23,fieldorder=tff":
  • telecine=pattern=23: Applies the standard NTSC 3:2 pulldown. The “23” pattern specifies how the progressive frames are mapped to interlaced fields (alternating between 2 fields and 3 fields).
  • fieldorder=tff: Sets the field order to Top Field First (TFF), which is the standard for high-definition (HD) interlaced video. If you require standard-definition (SD) compatibility, you can change this to bff (Bottom Field First).
• -c:v libx264: Selects the H.264 video encoder.
• -flags +ilme+ildct: These flags are critical for interlaced output.
  • ilme: Forces the encoder to use interlaced motion estimation.
  • ildct: Forces the encoder to use interlaced discrete cosine transform. Without these flags, the encoder will treat the video as progressive, destroying the interlaced structure.
• -pix_fmt yuv420p: Ensures standard pixel format compatibility for playback devices.

Alternative for ProRes (Broadcast Mastering)

If you are mastering for broadcast delivery and require Apple ProRes instead of H.264, use this command:

ffmpeg -i input_24p.mp4 -vf "telecine=pattern=23,fieldorder=tff" -c:v prores_ks -profile:v 3 -vendor ap10 -pix_fmt yuv422p10le output_60i.mov

In this ProRes variation, the telecine filter functions the same way, but the prores_ks encoder natively handles the interlacing flags based on the filter chain, resulting in a high-quality 10-bit ProRes 422 HQ file ready for broadcast.