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Problems with audio drift in FCP from ProTools mix

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1stbaseman
Problems with audio drift in FCP from ProTools mix
on May 1, 2007 at 2:46:45 pm

Hi all,

I was refered by Jerry Hofmann from the FCP forum, he is an instructor of mine. I'm working on sweetening some short films and I'm having trouble with sync to video when I bounce out the mix from ProTools and import the bwav into FCP. The original timeline from FCP was DVCPro 720p/24. It's media shot on a HVX100 on P2 cards. I kicked out an OMF from the FCP project and opened with Protools. I checked the session setup and the frame rate was 24 fps. This caused the audio to drift out of sync when it was re-linked to the video in FCP. I changed the frame rate in ProTools session setup to 29.97 drop, repeated the same the process of importing a broadcast wav into the FCP session only to find out that the audio is now running really fast and not even close to syncing up.

Please help, any suggestions would be much appreciated, I have deadlines looming!

Thanks,

Jay Shields
Owner
1stbase Productions
Centennial, CO




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Ty Ford
Re: Problems with audio drift in FCP from ProTools mix
on May 1, 2007 at 9:15:26 pm

Hey,

Were you using 48 kHz sample rate consistantly?


Ty Ford

Ty Ford's "Audio Bootcamp Field Guide" was written for video people who want better audio. Find out more at http://home.comcast.net/~tyreeford/AudioBootcamp.html
or http://www.tyford.com
Download Ty Ford's "Existential Boogie" from iTunes now.


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1stbaseman
Re: Problems with audio drift in FCP from ProTools mix
on May 2, 2007 at 5:41:56 am

Hi Ty, yes it's a 16/48k session at 24 fps. Problem is that it's HD video with a frame rate of 23.976. I do not have that setting in my session setup and I'm cannot do a pull up/down because I do not have a sync i/o. I'm going to try another Mix/24 rig tomorrow to see if I can change the session setting and bounce out the mix again. However, I'm getting conflicting reports on whether or not the Mix/24 rig will be able to change the session settings. I'm interested to see if my rig with 5.1.3 version of ProTools software can accomplish this or not. If I can do a pull up/down w/out the sync i/o on my rig, how much of the pull up or down should I apply?

Any tips would be great.

Jay



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Ty Ford
Re: Problems with audio drift in FCP from ProTools mix
on May 2, 2007 at 1:17:35 pm

This is slightly over my head.

I have been told that audio timecode should be set to what ever the video editor's session frame rate is, regardless of the shooting frame rate. That's if the project will end up as video and not film. Then different rules apply. I don't have any direct experience with trying it though.

You might try posting this question on the r.a.m.p.s newsgroup rec.art.movie.production.sound.

Regards,

Ty


Ty Ford's "Audio Bootcamp Field Guide" was written for video people who want better audio. Find out more at http://home.comcast.net/~tyreeford/AudioBootcamp.html
or http://www.tyford.com
Download Ty Ford's "Existential Boogie" from iTunes now.


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Kevin Lacy
Re: Problems with audio drift in FCP from ProTools mix
on Apr 27, 2009 at 8:44:41 am

I know the original question here is years old but I have spent the last three days researching and finally discovering a solution. I had a video editor give me an OMF of a FCP project in which the session framerate was 25fps (PAL -- I know! Don't ask!). The OMF contained 48K/16 Bit audio files. No Problem teher. Imported into Nuendo 3.x, dix my mixing/sweetening and exported a 48K/16Bit wav file. When this file was imported back into FCP, it slowly drifet out of sync, further and further out of sync as more and more time elapsed.

It turns out that in FCP, capture settings are independant of session settings and since the las this she had captured in FCP (for another project) was at 24fps, the wav file was incorrectly stretched by FCP because it wanted the "cptured" data to lock against a video with a higher framerate. It's a dumb piece of software. By that, I don't mean it's bad, it's just dumb in the sense that it does things without telling you and witout asking questions. It makes assumptions; usually the right ones but sometime the wrong ones. So, teh solution here was to make sure the capture settings were the same as the session settings and re-import.

Another solution was for me to take my nice original 48K/16Bit wav file mix and marry it to the QuickTime MOV file using QTPro. As long as you specifcy the same frame rate as the session is in FCP, you can import this MOV into FCP and it won't convert anything since the MOV file matches the session settings of your FCP project. Discard the imported MOV image and only keep the audio from teh MOV file. Voila! It doesn't do any conversion and you are back in business.

It took 3 d ays of searching for the answer to this one. Hopefully someone in my situation will find this post after only an hour of shaking their head when faced with this issue and this post will save them days of rendering and rerendering mixes and QT MOV files, trying to figure it out.

I promise, it works! :)


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Ty Ford
Re: Problems with audio drift in FCP from ProTools mix
on Apr 27, 2009 at 2:45:01 pm

Kevin,

Thanks for the extra effort. Yes, I too have run into similar problems with FCP. There are intake, session and output settings. There is ONE thing that I remember. I'm not sure if you have to prompt FCP in preferences with this, but upon placing your first clip on the timeline, my current FCP system asks if I want the session to have the same settings as the clip.

Thanks again for sharing your experiences with this forum. You make us all stronger in doing so.

Regards,

Ty Ford

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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Hoping Chen
Re: Problems with audio drift in FCP from ProTools mix
on Jan 13, 2011 at 6:11:05 pm

Thanks a lot for this post. I ran into a similar problem and you did save me a lot of time. Thanks a lot!


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