My Audio Track Slows Down in FCP at DVinfo.net

Go Back   DV Info Net > The Tools of DV and HD Production > All Things Audio

All Things Audio
Everything Audio, from acquisition to postproduction.


Reply
 
Thread Tools Search this Thread
Old November 6th, 2008, 11:44 PM   #1
New Boot
 
Join Date: Dec 2007
Location: Eugene, Oregon
Posts: 6
My Audio Track Slows Down in FCP

I hooked up a flash recorder to the sound board, at an event i was shooting, so i could get the best audio. I recorded it as an mp3. In FCP I cued it up to the video and audio from my cameras but after a few minutes it's off. What's up?
Dustin Whitaker is offline   Reply With Quote
Old November 7th, 2008, 05:20 AM   #2
Inner Circle
 
Join Date: Mar 2005
Location: Hamilton, Ontario, Canada
Posts: 5,742
Quote:
Originally Posted by Dustin Whitaker View Post
I hooked up a flash recorder to the sound board, at an event i was shooting, so i could get the best audio. I recorded it as an mp3. In FCP I cued it up to the video and audio from my cameras but after a few minutes it's off. What's up?

It could stem from a variety of causes but the bottom line is the sample rate clocks of the video and of the file from your flash recorder aren't absolutely rock-solid identical. FCP should let you adjust the length of your audio file to bring it into sync. I'm a Windows guy and not familiar with FCP but perhaps someone else can guide you on the details of how to go about it. One of the problems with consumer MP3 recorders is that their clocks just aren't up to the accuracy required for double-system recording and the MP3 compression introduces additional variables. For best results record to an uncompressed file format such as wav and insure that the audio recorder is set to 48kHz sample rate if you can to avoid the need for conversion when it comes into your editor. (48kHz is the standard for video and is the rate the camera is running at. Music recorders default to the CD standard of 44.1 kHz but some consumer MP3 recorders run at even lower sample rates.)

If the problem is too severe to fix with minor adjustments in the length of the audio file or if the sound gets distorted when you tweak the file length, try playing back the audio in the recorder you used to make it, connecting the analog audio out of the recorder to the audio in on your soundcard and re-record it directly into FCP.
__________________
Good news, Cousins! This week's chocolate ration is 15 grams!
Steve House is offline   Reply With Quote
Old November 7th, 2008, 12:34 PM   #3
Inner Circle
 
Join Date: Sep 2003
Location: Portland, Oregon
Posts: 3,259
Quote:
Originally Posted by Steve House View Post
...insure that the audio recorder is set to 48kHz sample rate if you can to avoid the need for conversion when it comes into your editor...
Steve's advice is solid, I'll just emphasize that converting your mp3 to a 16 bit 48KHz aiff should be your first step before you bring it into your project.
Seth Bloombaum is offline   Reply With Quote
Old November 8th, 2008, 08:06 PM   #4
New Boot
 
Join Date: Dec 2007
Location: Eugene, Oregon
Posts: 6
Thanks, I converted the mp3 file to an aiff and it doesn't slow down.
Dustin Whitaker is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > The Tools of DV and HD Production > All Things Audio

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 05:33 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network