Compressor 4 - About Reverse Telecine

About Reverse Telecine

The most common approach to distributing film’s 24 fps among NTSC video’s 29.97 fps
is to perform a 3:2 pull-down (also known as a 2:3:2:3 pull-down). If you alternate recording
two fields of one film frame and then three fields of the next, the 24 frames in 1 second
of film end up filling the 30 frames in 1 second of video.

A

B

A

B B

C

C

D D D

A B C D A

D A B C D A B C D A B C D A B C D

B C

A A B B B C C D D D A A B B B C C D D D A A B B

C C D D D A A B

B

B

C

C

D D D A

B

A

B B

C

C

D D

B

D

A B C D

A A B B B C C D D D

Field

1

Field

2

Field

1

Field

2

Field

1

Field

2

Field

1

Field

2

Field

1

Field

2

3:2 Pull-Down

One second

Before (23.98 fps)

After (29.97 fps)

As shown above, the 3:2 pattern (actually a 2:3:2:3 pattern since frame A is recorded to
two fields followed by frame B recorded to three fields) repeats after four film frames.
Virtually all high-end commercials, movies, and non-live television shows use this process
prior to being broadcast.

For editing and effects purposes, it is often desirable to remove the extra fields and restore
the video to its original 23.98 fps rate. An additional benefit of restoring the original
23.98 fps rate is that it is easier to convert this to the PAL 25 fps rate.

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Chapter 23

Working with Frame Controls