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Audio Puzzle:) Help!

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Mark Tant
Audio Puzzle:) Help!
on Jan 16, 2009 at 1:00:53 pm

Recently 3 companies came together for a last minute fund raiser for a young woman with some special needs. It was not until we got into the editing bay that we found out that the audio that was provided from the audio eng. is gradually falling out of sync with the video over time and we can't figure out why. So that is our puzzle, why is the audio that was mixed down by the audio eng falling out of sync with our cameras video:

Scenario: Cam1 (long shot) took audio feed from sound board. Cam 2 (CU's) on board shot gun mic. Cam 1 audio feed from the sound board syncs to both cameras but not as good quality as the audio that was mixed down by the audio eng. The audio from the audio eng. is best quality but drifts out of sync with both cameras after about 45 sec. We want to be able to use the audio file provided by the audio eng. but can't figure out how to get it to sync up. Any ideas? A fix to this would be greatly appreciated.

Cam 1 shot in SD NTSC
Cam 2 Shot in 24P
Editing with Adobe Pro CS4

We have tried multiple fixes, only with same results. i.e; 1) export audio from timeline and re import as different format 2) export video and re import as different format.

If anyone has some ideas we would greatly appreciate the help. If there is any other info that can be provided that will help please let me know

Mark


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Rob Neidig
Re: Audio Puzzle:) Help!
on Jan 16, 2009 at 6:32:00 pm

Mark,

Is is possible the audio engineer provided an audio file whose sample rate is 44.1 kHz? If it was provided as just an audio CD, then that would definitely be the case. The video on your camera is likely 48 kHz. That would definitely cause them to go out of sync quickly. You can use a program like Sony Sound Forge or Adobe Audition to change the sample rate of the audio only file, or many video editing applications will change it upon import if you tell it to.

Hope this helps. Have fun!

Rob

Rob Neidig
R&R Media Productions
Eugene, Oregon


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Brian Reynolds
Re: Audio Puzzle:) Help!
on Jan 16, 2009 at 9:19:54 pm

All cameras will drift even just a little compared to other other cameras.
This is why timecode locked systems are used.
With your problem use the good sound as your progam sound and cut in the vision only from the other cameras when needed.
If you monitor the audio from the close up cameras and compare that to the good sound you should be able to cut it up ok.
But it going to take a LOT of work.



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Ty Ford
Re: Audio Puzzle:) Help!
on Jan 17, 2009 at 2:14:41 pm

Hello Mark and welcome to the Cow Audio Forum,

The audio provided by the audio engineer. Do you mean that the audio was recorded separately? On what? At what sample rate? And why were the cameras set at differing frame rates?

I have successfully sample rate converted 44.1 audio to 48 and had it match the video. I have also had that not work at all.

If you are trying conversion with CS$, maybe your editing program isn't as good at audio sample rate conversion.

Tough problem because you have such a salad of not matching sources.

Do let us know what happens.

Regards,

Ty Ford




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






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Mark Tant
Re: Audio Puzzle:) Help!
on Jan 17, 2009 at 3:19:40 pm

Thanks for all the input so far. Just some additional clarification. The back camera had an audio feed coming from the sound board. This audio syncs up to both camera with no problems; other than the quality. The problem comes in when the audio guy sent a separate mixed audio file it will not sync to the video. It starts out fine but after about 45-60 seconds it drifts. After reading some of the audio threads on this site I am feeling like the problem is coming from when the audio eng. mixed it and did what ever he did it changed the length of the file and thus throwing off the timing. We are in different parts of the country so it is making the process a little slower in getting things straight. He did send it in 44.1 sample rate but I pulled it into Audition and up sampled it to 48 kHz, but no help. FYI: This was a benefit concert and covering it with video was a last minute decision, with little or no preproduction planning. We did not know the CU camera recorded in 24P until after it was over.

Mark



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Ty Ford
Re: Audio Puzzle:) Help!
on Jan 17, 2009 at 9:16:28 pm

He goofed. He should have used 48 k. Have him send one at 48 rather than convert it at your shop and see if it works.

Ty Ford

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






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John Fishback
Re: Audio Puzzle:) Help!
on Jan 17, 2009 at 11:41:40 pm

If the audio eng used Pro Tools (or any DAW for that matter) to record, ask exactly what frame rate he used. There are many choices that could cause the audio to go out of sync with the video. Let us know his settings. Pro Tools has a number of settings that might on playback bring the well recorded audio back into sync with at least one of the cameras. Then you could cut in the other cam as suggested above, pulling it into sync for short segments.

John

MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.5 QT7.5.5 Kona 3 Dual Cinema 23 ATI Radeon HD 3870
ATTO ExpressSAS R380 RAID Adapter, PDE Enclosure with 8-drive 6TB RAID 5
24" TV-Logic Monitor
Final Cut Studio 2 (up to date)

Pro Tools HD w SYNC IO, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN


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Mark Tant
Re: Audio Puzzle:) Help!
on Jan 24, 2009 at 4:58:33 pm

I am just sending a quick update to say that we are still not sure of the solution to our problem. We are waiting to hear back from the audio guy at this time. Thanks for all of the useful unput.

Mark



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