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Old September 26th, 2005, 02:24 PM   #1
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Genlock Vs. Timecode Synch

Hello,

A discussion has been circulating through the office regarding upcoming
cameras and their feature of genlock. My question which has gone unanswered
is if there is really any practical benefit to having genlock instead of just
timecode synch.

After questioning a few individuals, I have not heard one applicable situation
for the utilization of genlock where timecode sync would not work just as well.

Thanks,

Jeremy.
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Old September 26th, 2005, 02:50 PM   #2
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In a true production environment you would want all the VTR's, cameras, etc. in a suite to have the same sync (genlock) but not the same timecode.
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Old September 26th, 2005, 03:31 PM   #3
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If you are using an analog switcher, genlock is necessary to prevent hue shifts when dissolving or cutting between inputs.

Some switchers nowadays have frame stores, which deals with the synchronization problem. The discontinued Videonics MX1 way back when had this, and was only $1000.

I've never dealt with timecode sync, so wouldn't know if that would do the same thing as genlock.
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Old September 26th, 2005, 03:38 PM   #4
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I have no experience with studio equipment. Keep that in mind when reading this reply. The genlock signal gives you the sync pedestal including color burst. A device receiving this sync has only to lock it's horizontal master oscillator directly to the horizontal line rate and its color subcarrier oscillator directly to the color burst i.e. the phase detectors operate at the frequency being synthesized). With time code lock neither of these signals is directly available so the local oscillators must be scaled to some lower frequency and the phase comparisons done with the time code carrier (to be honest, I've never looked at LTC on a 'scope but it has the definite aroma of IRIG B about it i.e. amplitude modulated audio frequency carrier). This scheme requires higher effective loop bandwidths and thus would not give as tight a lock as with the black burst signal. In support of this way of thinking I note that some audio equipment locked to blackburst promises sample accurate timing. Resolved to time code it does not. While time code based sync is doubtless good enough for cutting between scenes from cameras locked with it in post it may not be good enough for switching or fading between cameras in real time.
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Old September 26th, 2005, 06:27 PM   #5
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Thanks for the replies!
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