Shoot 29.97i or convert for deliverable?

Forum|Forum|2 years ago
October 2, 2023
4 replies
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I have a proposed upcoming project under early discussions. It's for a non-profit, where the more likely destination is client web use. But, if possible, it would be pitched to public TV.

Local public uses NPB standards, everything in 29.97i drop-frame. Of course that's 59.94.

That would not be my primary choice to shoot in. But I know a workable practice has been shoot 24p, edit, then take to Ae and do 3:2 pull-down.

Is that still the best thing, other than shooting in interlaced?

This topic has been closed for replies.

R Neil HaugenAuthor

Legend

Thanks for those responding ... but perhaps I'd also like @Jarle Leirpoll , @Warren Heaton10841144 , and @Michael Grenadier to opine? I do like a range of experienced thoughts. The more the merrier ...

Everyone's mileage always varies ...

M

Michael Grenadier

Legend

Just finished a pbs cutdown. I was told to deliver 29.97, but the piece was mastered as 24p Gonna see if 24p will be accepted... I've mentioned this to the client, but as usual, radio silence. Not sure what the best way to add pulldown to make it 29.97... If I remember correctly not a simple process to get the best quality, bwdik...

Warren Heaton

Community Expert

Thanks for the breakdown, Warren. Lots of good info.

However, there’s some confusion in your language regarding pull up and pull down. It is not accurate to say “pull down is, by definition, 23.976 or 24 to 29.97 or 30” as it’s has a wider adopted usage (particularly with regard to audio) by which it more meaningfully defines “pull up” (through inversion).

It’s possible the term ‘pull down’ comes originally from electrical engineering, but it more likely comes from the claw action of film cameras and projectors. It was first used in television when confronted with 24fps film and was used in the formulation ‘3:2 pull down’, encompassing two processes (the creation of fields and the speed change from 24fps to 23.976fps).

Since that early history, the term ‘pull down’ is now used to refer to introducing the above field cadence whether or not a speed change is necessary (as you have detailed), and also specifically to these speed changes (in audio post) - meaning the speed changes that have been made on picture and therefor the speed changes necessary for audio to remain in sync. ‘Pull down’ as a speed change is particularly important in audio post discussions, and is the only context in which ‘pull up’ can be made sense of.

(I have never encountered the term ‘pull up’ used to refer to a format conversion by which interlaced material is made into progressive - would be very interested if you have a specific reference / link to anything, anywhere that does).

I’ve never found a good reference for the history, but there’s a good reference for audio implications (with a handy chart!) here, which includes this summary: "An audio pull up or pull down is needed when there is a frame rate change on the picture that affects its length."

In considering this in an audio post context, one can start to make sense of pull up (from 47.952kHz to 48KHz, or from 48kHz to 48.048kHz, for example) and pull down (from 48.048kHz to 48kHz, for example)

Again, there’s common usage which loosely refers to any field-deriving process - but being aware of the (also widely used) speed change meaning is important.

R.

Pull-down comes from moving film down through the transport mechanism during the telecine process. The Standard Handbook of Video and Television Engineering by Jerry Whitaker and Blair Benson has very detailed diagrams of the process. It is also discussed in the After Effect User Guide > Importing Footage > Importing and interpreting video and audio.

Thank you for pointing out that referring to reverse 3:2 pull-down as "pull up" can cause confusion. I'll try to use the proper name rather than slang in the future. It also gets called reverse telecine or inverse telecine.

Removing 3:2 pull-down is specific to i29.97 footage that has 3:2 pull-down present in the first place and restores the original p23.976. The process does not apply to footage that is i29.97 to begin with.

Remote Index

Hello R Neil Haugen,

I think your proposed workflow is best and will give you most long term flexibility.

I suggest shooting 23.98p or 29.97p and doing a conversion at the end or their specific delivery requirements. (I haven't used AE to do conversions before.)

R.