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Audio/Video question: Audio from 2nd source slightly off from built-in mic
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Oneota
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May 16, 2010, 03:21 PM
 
Hello, all,

I've got a concert video where we also had some recording mics making an audio CD. I'd like to use the audio from those mics on the video, but it's ever so slightly out-of-sync. If I line up the starting points exactly on the two audio tracks (the built-in mic and the recording mics), then by the end of the concert, the audio is about 400 milliseconds off, which results in a noticeable delay between hands pressing keys on the keyboard and the actual sound.

Is there a way to ever so slightly stretch the audio so they match up without affecting the pitch, or am I just stuck with the built-in microphone's sound for the video?
"Yields a falsehood when preceded by its quotation" yields a falsehood when preceded by its quotation.
     
Spheric Harlot
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May 16, 2010, 06:33 PM
 
Any pro audio editor can do this. Depending on your setup, it might be easier to accelerate the video ever so slightly.

The eye is more easily outwitted than the ear. Though 400ms over an hour isn't going going to produce too many artifacts.
     
ebuddy
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May 16, 2010, 08:20 PM
 
What am I missing here? How would the two not be in sync? I mean, if there are specific points of equipment anomaly, you could duplicate the entire project for a destructible version and chop at points to try and isolate where the sync issue becomes apparent. If you find an elegant place to chop (like during a break or some other inconsequential point) you might line them back up and have only a few minutes of latency as opposed to the entire latter half of the concert? I mean, you said you lined up the starting points exactly, but my first thought was to take another look at that to be sure. I don't know.

I might be missing something though. Just thought I'd throw that out there.
ebuddy
     
Oneota  (op)
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May 16, 2010, 11:48 PM
 
The two could not be in sync due to very slight differences in the rate at which they record, or something. Since the camera recording the video is not the device that recorded the audio, their conceptions of time just didn't exactly, 100% match up.

There's only one piece on the recording I'm interested in, so unfortunately there's no good breakpoint (it's a recording of me playing Rhapsody in Blue with our local community orchestra, so it's an 18.5 minute long single work). The video starts out perfectly in sync, but by the end, you can see my hands coming down on the piano keyboard almost half a beat before the sound is heard.

Would iMovie be able to accelerate the video with the level of control necessary? I don't have ready access to a version of Final Cut that will run on Snow Leopard.
"Yields a falsehood when preceded by its quotation" yields a falsehood when preceded by its quotation.
     
Oneota  (op)
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May 18, 2010, 05:24 PM
 
*Ping* -- Bueller?
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