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Posted by David McCall on 10/08/07 14:38
"Rick Merrill" <rick0.merrill@NOSPAM.gmail.com> wrote in message
news:yrudnTlZAaVZpJfanZ2dnUVZ_qHinZ2d@comcast.com...
> Richard Crowley wrote:
>> "Rick Merrill" wrote ...
>>> My concern is that the generator is not keeping very
>>> good timing so the audio begins to lag over the course
>>> of a couple of hours recording. AFIK there is no time
>>> sync on the audio, just on the video.
>>
>> No equipment, even professional will hold sync over "a
>> couple of hours". Or even over one hour. They is why
>> we use gen-lock and timecode, etc.
>
> Call me suspicious, but if "gen-lock" signal is off by
> 0.1% then after 10 hours of recording there will be a 1%
> cumulative error.
>
> It is the accuracy of the gen-lock that comes from the black-burst
> generator and that's what I wanted to know.
>
> In other words, does anyone ever check the accuracy of a genlock
> signal (e.g. one that was purchased on the cheap from ebay)?
>
I doubt that anyone would notice a 0.1% error as long as everything
remains in sync. The whole purpose of gen-locking is to insure that
every device in your system starts every frame at the same time.
This includes cameras, audio and video decks, switchers, etc..
As long as everything is in sync there should be no problem.
If any device is allowed to free run, it will likely drift over time.
David
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