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Old June 12th, 2010, 09:46 PM   #1
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Join Date: May 2010
Location: USA
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Syncing concerns with 24p footage

I'm shooting some dialogue scenes (mainly narration, but some dialogue exchanges) and I want to make sure the audio stays synced with the video. I'm shooting on the Canon 7d, 24p footage, and one of my friends is recording with a relatively cheap condenser microphone (we're on a pretty low budget). He will be recording the audio through his computer as we don't have a mixer, (I'm assuming through logic). Now what I'm worried about is the syncronization. I'm editing through FCP (24p sequence settings) and I don't really have a clue what settings he needs to have applied to make this sync correctly. Is it all done in post? Should he be in 12-16bit? What are your experiences?
Gary Lew is offline   Reply With Quote
Old June 13th, 2010, 12:17 AM   #2
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Join Date: May 2006
Location: Camas, WA, USA
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You might have some drift because the clock in the camera and the clock in the computer aren't locked. That said, if he has a decent sound card, it should have a solid clock circuit.

BTW, it doesn't matter if you shoot in 24p or 30p and he records in 48kHz or whatever. A ten minute interview takes ten minutes for both the video and the audio. Real time is real time.

To be safe, have the talent clap their hands in front of the camera both before and after the take. Line up the audio and video with the first clap and check that the final clap is good too. If not, stretch or squish the audio duration as needed. (In Vegas, you can hold the Ctrl key while dragging the end of the audio clip to change the duration.)

Record in 24-bit, 48 kHz if possible. If not, go for 16-bits, 48 kHz. Don't use 12-bits if more are available. 48 kHz is the standard sampling rate for video, including DVDs and Blu-ray Discs. There's no need to record at 96 kHz or some other rate.

Using a computer as a recorder is a fine way to go if you are in a fixed location and have power. If possible, run a long microphone cord, so you can put the PC and its noisy fan in the next room. On a budget, a Behringer mixer into an M-Audio Audiophile soundcard can get decent results for not too much money. The mixer will give you XLR inputs and phantom power, so you can attach a pro mic to it. That will give much better results than going straight into a stock PC soundcard.

Best of luck with your project!
Jon Fairhurst
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