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Re: surround recording

Subject: Re: surround recording
From: Dan Dugan <>
Date: Tue, 29 Jun 2004 22:16:43 -0700
>  >  >Lucky I guess. Yes, I try to tail slate.  For a class project, we ra=
n
>>>4 (MT-90) MD's for 70+ mins and found the drift between them was on
>>>the order of one second.
>>
>>In sound travel time, that's 1,150 feet at normal temperature, or 16
>>feet per minute, not good synch at all.
>
>What an interesting way to think of it: time-space drift.

If the mics are 15 ft apart, and the drift between machines is 6
inches per minute, after ten minutes the mics are now either ten feet
or twenty feet apart (depending on which way the drift is) in terms
of delay time.

>To get the
>74 min takes in sync by changing the sample rate, 1 second per 4400
>is too small to create a noticeable pitch shift.  MD's are on par
>with traditional 16mm film "sync" which was +/- 4 frames (1/6 second)
>in 11 mins wasn't it?

The requirement for lip synch, within about 20 ms, is way, way looser
than what you need for stereo or multichannel synch--around .02 ms. A
factor of 1000! Do put clicks at the tail, too.

-Dan Dugan


________________________________________________________________________
________________________________________________________________________


"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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