24p to 25p Audio Issues

[C.Rizos]

I have a bit of a dilemma that's a bit beyond my understanding and have never come across such an issue before perhaps one of you on this forum has a solution

85% of a current documentary I'm working on was shot in 25p PAL and the balance at 24p or 23.976. {sorry not sure which one}

All the 24p material needs to be conformed to PAL Supposedly Finalcut Pro cannot output an omf that conforms 24p to 25 p PAL {which I find highly unlikely} , never the less all picture and audio that was shot in 24p will "supposedly"stay at 24p in the Final Cut Timeline and be exported via OMF as such and obviously be out of sync.

Is there an % percentage amount of pitch shift {ie. pull or pull down etc.??.} that you know of that I can process the 24fps audio clips one at a time to get it in sync and conform to the PAL image..

I should also mention we have already started the dialog edit and sound design on a conformed PAL cut of the picture the 24p stuff are inserts the director wants in the doc.

At any rate any help would be welcome and if I've confused any of you my apologies, i'm just as confused, and not really sure if I'm asking the right question. Ill update as I get more info though. Thanks

[danijel]

Originally Posted by C.Rizos

Is there an % percentage amount of pitch shift {ie. pull or pull down etc.??.} that you know of that I can process the 24fps audio clips one at a time to get it in sync and conform to the PAL image..

I don't quite understand your question, but if the images that were recorded at 24fps are now playing at 25fps, then the number is 24/25= 0.96, or 96% of the original length (or, do the math with 23.976).
I suggest you use one of the high-quality time-stretching algorithms, instead of the pitch-shifting.

[musikwerks]

Speed up your audio by 4.1%. Make sure you adjust your pitch accordingly... or not, if you don't mind it.

[Beaumaloe]

There is a program called Twixtor that may be able to resolve the 2 frame rates to what you need to output.
RE:Vision Effects, Inc. : Products: Twixtor

Good Luck,
Beaumaloe

[Whitecat]

Originally Posted by musikwerks

Speed up your audio by 4.1%. Make sure you adjust your pitch accordingly... or not, if you don't mind it.

+1, on dialogue etc don't even worry about pitch.

Europeans are used to hearing things sped up.

I've tried doing it with pitch-shifting algos (and the good ones at that, PnT, X-Form, etc), but you still get artefacts...

[minister]

Originally Posted by C.Rizos

All the 24p material needs to be conformed to PAL Supposedly Finalcut Pro cannot output an omf that conforms 24p to 25 p PAL {which I find highly unlikely} , never the less all picture and audio that was shot in 24p will "supposedly"stay at 24p in the Final Cut Timeline and be exported via OMF as such and obviously be out of sync.

How do you know that?

There are many ways to do conversions. In Final Cut, you can do conversions that maintain speed.

Do you have the files now? Are you seeing drift and things out of sync?

Before you get your knickers in a twist over the math and sync conversions, let the picture department sort it out and give you something. They may have already dealt with it.

[C.Rizos]

To try and make a long story short the issue has been resolved, through the following method. Import new 23.98 Material into an existing 25p Protools Session via Digitranslator. Use the sample rate conversion option: in my case 48k, and then use the sub menu feature to do a Pull-Up/Pull-Down from NTSC to PAL Film Style.

This will then Copy the 23.98 material and perfectly conform it into the 25p project without the need for pitch shifting afterwards. The reason this works, as far as I can understand, is that 23.98 and 29.97 are so close in timing relationship that nothing more needs to be done so pitch shift is not required.

This Worked 100%

to give you all the background I've included a brief synopsis of what the Post supervisor wrote:

Problem:

The Docmentary was shot with 75% material @ 25fps, and 25% @ 23.98. Because of the amount of material from 25 fps source, we have decided to master on 25fps.
During initial conform, we had chosen to trans-code the 23.98 to 25 fps rather than conforming (re-time) 23.98 to play back at 25fps speed. Doing a trans-code allow us to preserve the exact time of each clip (by adding ~1 frame every second), while a conform would speed up our clips by ~4.01%. This decision was reached due to consideration of amount of external sync from dual system recorder, as well as after watching trans-coded material play back at 25. (There were selective clips that were conformed because a trans-code provided unacceptable result. Mostly of these clips are with camera movements such as pans).
However, since our theatrical release will be play back at 24fps (25 over 24), we had gone in to watch an emulation of playback at Technicolor. Although the 25 conform playback was fine at 25fps, the slowed down playback at 24fps provided unsatisfactory result. The 25 fps material played back slower but smoothly, while the trans-coded 23.98 material played back jerky. We suspect this is because the slower play rate had emphasized the additional frame / second in the trans-code.
Solution:
As a result of the emulation of 25 over 24, we have now decided to re-conform ALL 23.98 material to 25fps.
There are six sections within the film that contains 23.98 materials:

Cory Rizos
Sound Designer / Re-Recording mixer
Supervising Sound Editor
Montreal