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23.97 and 24 fps mixed up


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#1 Evan Warner

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Posted 02 March 2008 - 07:31 PM

Hey All,

I Recently got the re-shoots for my super 16mm short film telecined directly to drive (with an HDCAM backup) in ProRes 422.

However after checking out some things I noticed that our principle photography was telecined at 23.97 FPS where as the new reshoots was done at 24 fps. In Final Cut Pro this causes me to render which is ok but I am most worried about sound. When I'm doing my sound design in pro tools and then go for my mix am I going to have issues? Should I be converting the lab reels to 23.97 before I edit them so they match up? What is the best way of going about this?

Cheers
Evan
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#2 David Mullen ASC

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Posted 02 March 2008 - 07:39 PM

Are you sure the reshoots were transferred at 24 fps instead of 23.976? If you are editing from NTSC downconversions, even 24P HD transfers would now be playing at 23.976 fps, since NTSC is 29.97 fps / 59.94i.

The question is what is the final mix syncing up to? A 24 fps film-out or a 23.98PsF HD master?

Most people cut sound on ProTools using NTSC downconversions running at 23.976 fps (actually 59.94i with a pulldown, unless removed.)
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#3 Thomas Worth

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Posted 02 March 2008 - 08:07 PM

The frame rate they were transferred at is irrelevant. All you have to do is a batch conform in Cinema Tools to whatever frame rate you want. Do that before importing the stuff into FCP and you should be OK.
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#4 Phil Rhodes

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Posted 02 March 2008 - 08:59 PM

Surely he shouldn't even have to render if he does a conform-to on the imported clips?

Of course if you shot at 24 with the sound at 23-point-blah you will have grief, but that is fixable.

P
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#5 Thomas Worth

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Posted 02 March 2008 - 09:21 PM

Surely he shouldn't even have to render if he does a conform-to on the imported clips?

You have to use Cinema Tools to change a clip's frame rate without rendering. FCP doesn't work like Premiere where you can just "interpret" the imported clip as X fps.
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#6 Phil Rhodes

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Posted 02 March 2008 - 09:42 PM

> FCP doesn't work like Premiere where you can just "interpret" the imported clip as
> X fps.

Well that's... bad.
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#7 Thomas Worth

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Posted 02 March 2008 - 09:50 PM

Well that's... bad.

Nah, it's not that big of a deal. You just have to launch another app, but it's included with FCP Studio.
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#8 Evan Warner

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Posted 03 March 2008 - 03:02 AM

Nah, it's not that big of a deal. You just have to launch another app, but it's included with FCP Studio.


Hey Guys, I will check out Cinema tools. let me explain to you exactly what we had done though.

The entire film was shot super 16mm with seperate sound recorded to a fostex in 16bit, 48khz mono.
It was transfered via a spirit and davinci to both HDCam ( as a backup) and Direct to drive. The Direct to drive was encoded in ProRes 422. Opening both Principal and reshoots up in quicktime and going to the inspector gives me 23.97 and 24 fps resepctivly. This is not and never was 29.97 material, I believe it came directly from film at 24fps and was captured that way.

Within FCP if I let FCP match my sequence settings to the 23.97 stuff then the 24 stuff plays back with a green line (real time preview) and visa versa. I'm using a Octo 2.8 Mac Pro so its not a huge issue.


Thomas, I don't understand how the frame rate won't matter?Also I didn't realize that this was a problem until after I had synk up my sound. If I do this method am I going to have to redo all of the syncing?

I appreciate all of you help

Cheers
Evan
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#9 Michael Most

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Posted 03 March 2008 - 09:30 AM

The entire film was shot super 16mm with seperate sound recorded to a fostex in 16bit, 48khz mono.
It was transfered via a spirit and davinci to both HDCam ( as a backup) and Direct to drive. The Direct to drive was encoded in ProRes 422. Opening both Principal and reshoots up in quicktime and going to the inspector gives me 23.97 and 24 fps resepctivly. This is not and never was 29.97 material, I believe it came directly from film at 24fps and was captured that way.


All telecines in North America are set up to run at 23.98, not 24, for "24p" transfers. This is because sync is derived from NTSC based sync equipment, because in order to do simultaneous dual system transfers (i.e., SD and HD - a very common situation, especially for dailies), the two must be correlated and in lock step. So if you ask for a 24 frame transfer, you're going to get 23.98 unless you very specifically order 24p HD only and the transfer house is willing to go along with that (it requires the sync generator to be set up differently, which is not commonly done). In practice, however, it is never necessary to do "hard 24," as 23.98 is still a 1:1 relationship between video and film frames. 23.98 also makes a lot of other post production steps much more straightforward, as many of them are based on standard definition video already (i.e., screening copies, outputs of cuts, post sound work, you name it). The only time you would be likely to get a "hard 24" element would be to have it generated by a scanner, and in that case, you would likely be delivered an image sequence - say, DPX files - which has no inherent frame rate.
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#10 Evan Warner

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Posted 03 March 2008 - 03:14 PM

All telecines in North America are set up to run at 23.98, not 24, for "24p" transfers. This is because sync is derived from NTSC based sync equipment, because in order to do simultaneous dual system transfers (i.e., SD and HD - a very common situation, especially for dailies), the two must be correlated and in lock step. So if you ask for a 24 frame transfer, you're going to get 23.98 unless you very specifically order 24p HD only and the transfer house is willing to go along with that (it requires the sync generator to be set up differently, which is not commonly done). In practice, however, it is never necessary to do "hard 24," as 23.98 is still a 1:1 relationship between video and film frames. 23.98 also makes a lot of other post production steps much more straightforward, as many of them are based on standard definition video already (i.e., screening copies, outputs of cuts, post sound work, you name it). The only time you would be likely to get a "hard 24" element would be to have it generated by a scanner, and in that case, you would likely be delivered an image sequence - say, DPX files - which has no inherent frame rate.

That was very informative Micheal, what does that mean in my case? If it in deed was transferred at 24fps then will the cinema tools method work, will I lose quality? I am going to contact the lab tonight and see what they say too.
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#11 David Mullen ASC

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Posted 03 March 2008 - 04:22 PM

Evan, you need to go to My Controls and edit your Display Name to a real first and last name, as per the forum rules listed when you registered. Thanks.
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#12 Thomas Worth

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Posted 03 March 2008 - 06:54 PM

If it in deed was transferred at 24fps then will the cinema tools method work, will I lose quality? I am going to contact the lab tonight and see what they say too.

No. The image data inside the file and the frame rate are independent of one another. All you need is a tool to "set" the frame rate to what it should be. That's what Cinema Tools does. It doesn't touch the actual image data at all, so the quality is unaffected.
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#13 Evan Warner

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Posted 04 March 2008 - 02:51 PM

No. The image data inside the file and the frame rate are independent of one another. All you need is a tool to "set" the frame rate to what it should be. That's what Cinema Tools does. It doesn't touch the actual image data at all, so the quality is unaffected.

Hey Thomas,

Thanks for you info. I just conformed in within Cinema Tools and it seems to be working great! Also I changed my name David, sorry about that, I didn't realize. Everyone else thank you for your help
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