30p in 25p timeline at DVinfo.net

Cees van Kempen · April 7th, 2010, 01:47 PM

I somewhere read the advise to shoot wildlife/birds in 30p and then use it in a 25p timeline. So the movements are all just about 20% slowed down. If I intend to do that in FCP, does it mean I have to choose recording I-frame with the nano? Or can 30p long-gop footage also be used in the 25 timeline in order to get a slight slomo effect?

Walter Brokx · April 7th, 2010, 04:45 PM

Hoi Cees, ik ben geen expert, maar ik denk dat het niet uitmaakt, zolang je het materiaal maar laat interpreteren als 25fps.

(In english, for all other people):
I'm not an expert on this subject, but I don't think the format matters as long as you have the footage interpreted as 25fps.

PS.
The difference will only be image quality.

PS2.
You could overcrank 30/25. Then you have your footage at 25fps with the slight slowmo, but without sound.

Dan Keaton · April 7th, 2010, 04:47 PM

Dear Crees,

I do not think that Long-GOP or I-Frame Only would make any difference either.

Unless you are using a very high bit-rate, I would use Long-GOP.

But, as always, we recommend testing your setup and check out your post workflow.

Cees van Kempen · April 8th, 2010, 04:21 AM

Dear Dan,

Thanks for your reply. However, I am getting mixed up. In another thread (name: over/under crank by Ofer Levy) I read a conversation about this subject. This is from the era before over/undercrank as an option in the nano:

In this thread Steve Phillips writes: "so at the moment you can just set the camera to 720 50P or 60P, into an I frame codec then just conform it in Cinema Tools or whatever, a process that takes just seconds."

"Thanks Dan,
I guess there is no point in recording Long GOP as it can not be converted to Slo-Mo by the mentioned technique as far as I understand - you can only do that with I-Frame only."

Are they discussing other things than I do? Does it make a difference to go from 720/60P to a 25P timeline, comparred to 30P to a 25P timeline (I mean in work proces, I realize it are different slo-mo effects).

Hope you can help me out.

Dan Keaton · April 8th, 2010, 08:56 AM

Dear Cees,

Your original question was about recording 30p (without over or under-cranking).

The previous thread was discussing that Cinema Tools worked with I-Frame Only and not Long-GOP.

Based on that thread, if correct, and if you will be using Cinema Tools, then you should consider recording at a higher bit-rate and I-Frame Only.

As always, we recommend testing your workflow prior to any major shoot.

Will you be needing sound? If so, I question the advice of shooting in 30P for a 25p timeline.

Rafael Amador · April 9th, 2010, 10:22 AM

Hi Cees,
The way is "conforming" the p30 stuff to p25.
This is done in CinemaTools.
This is the faster and cleaner way. It doesn't requires rendering.

But, it doesn't works with GOP stuff.
So, you record I frame, or you transcode to an Intraframe codec and then Conform after.

Don't drop the p30 stuff in a p25 sequence. Doesn't work.
rafael

April 7th, 2010, 01:47 PM	#1
Cees van Kempen Major Player Join Date: Jan 2010 Location: Nieuw-Vossemeer, The Netherlands Posts: 455	30p in 25p timeline I somewhere read the advise to shoot wildlife/birds in 30p and then use it in a 25p timeline. So the movements are all just about 20% slowed down. If I intend to do that in FCP, does it mean I have to choose recording I-frame with the nano? Or can 30p long-gop footage also be used in the 25 timeline in order to get a slight slomo effect?

April 7th, 2010, 04:45 PM	#2
Walter Brokx Major Player Join Date: Jan 2010 Location: Maassluis, The Netherlands Posts: 294	Hoi Cees, ik ben geen expert, maar ik denk dat het niet uitmaakt, zolang je het materiaal maar laat interpreteren als 25fps. (In english, for all other people): I'm not an expert on this subject, but I don't think the format matters as long as you have the footage interpreted as 25fps. PS. The difference will only be image quality. PS2. You could overcrank 30/25. Then you have your footage at 25fps with the slight slowmo, but without sound. __________________ Brainstormnavigator searching for the hole in the sky..... Audiovisual Designer (NL) - http://www.brokxmedia.nl

April 7th, 2010, 04:47 PM	#3
Dan Keaton Inner Circle Join Date: Dec 2002 Location: Augusta Georgia Posts: 5,421	Dear Crees, I do not think that Long-GOP or I-Frame Only would make any difference either. Unless you are using a very high bit-rate, I would use Long-GOP. But, as always, we recommend testing your setup and check out your post workflow. __________________ Dan Keaton Augusta Georgia

April 8th, 2010, 08:56 AM	#5
Dan Keaton Inner Circle Join Date: Dec 2002 Location: Augusta Georgia Posts: 5,421	Dear Cees, Your original question was about recording 30p (without over or under-cranking). The previous thread was discussing that Cinema Tools worked with I-Frame Only and not Long-GOP. Based on that thread, if correct, and if you will be using Cinema Tools, then you should consider recording at a higher bit-rate and I-Frame Only. As always, we recommend testing your workflow prior to any major shoot. Will you be needing sound? If so, I question the advice of shooting in 30P for a 25p timeline. __________________ Dan Keaton Augusta Georgia

April 8th, 2010, 04:21 AM	#4
Cees van Kempen Major Player Join Date: Jan 2010 Location: Nieuw-Vossemeer, The Netherlands Posts: 455	Dear Dan, Thanks for your reply. However, I am getting mixed up. In another thread (name: over/under crank by Ofer Levy) I read a conversation about this subject. This is from the era before over/undercrank as an option in the nano: In this thread Steve Phillips writes: "so at the moment you can just set the camera to 720 50P or 60P, into an I frame codec then just conform it in Cinema Tools or whatever, a process that takes just seconds." "Thanks Dan, I guess there is no point in recording Long GOP as it can not be converted to Slo-Mo by the mentioned technique as far as I understand - you can only do that with I-Frame only." Are they discussing other things than I do? Does it make a difference to go from 720/60P to a 25P timeline, comparred to 30P to a 25P timeline (I mean in work proces, I realize it are different slo-mo effects). Hope you can help me out.

April 9th, 2010, 10:22 AM	#6
Rafael Amador Major Player Join Date: Jun 2009 Location: Vientiane (Lao PDR) Posts: 349	Hi Cees, The way is "conforming" the p30 stuff to p25. This is done in CinemaTools. This is the faster and cleaner way. It doesn't requires rendering. But, it doesn't works with GOP stuff. So, you record I frame, or you transcode to an Intraframe codec and then Conform after. Don't drop the p30 stuff in a p25 sequence. Doesn't work. rafael