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-   -   Free run time code (https://www.dvinfo.net/forum/canon-xh-series-hdv-camcorders/93198-free-run-time-code.html)

Khoi Pham May 4th, 2007 08:19 AM

Free run time code
 
Anybody here use free run timecode to sync the cameras with the remote?
I have 3 and they all started at the same time but by the end of the day all 3 of them are off by 3 or 4 seconds? I have try drop, non drop, but no luck.

Pete Bauer May 4th, 2007 10:14 AM

Three or four seconds within a day is a bit more than I'd have expected. I did a TC synch check with 2 XL-H1's last year and the drift rate between the two cameras was about 1 second per day:

http://www.dvinfo.net/conf/showpost....8&postcount=43

Khoi Pham May 4th, 2007 10:22 AM

Ok thanks, I will bring my remote with me to the shoot and set them just before and reset them often to minimized it, a few frames off is easier to resync that a few seconds off.

Jerome Marot May 5th, 2007 08:44 AM

I did the same with 2 cameras and indeed they are off a few seconds after 3-4 hours.

Daniel Epstein May 5th, 2007 09:25 AM

This kind of drift is pretty typical because the cameras clocks (frame rates) are just a tiny bit off when they aren't genlocked. Also when you power down the cameras the internal clocks keep time and this often causes a different amount of drift.

John L. Miller May 5th, 2007 10:18 PM

I have had the same problem, so I restart the clocks just before the shooting begins and once that scene is over, I will reset them again. It is the only way to avoid a lot of unnecessary editing. Sometimes I wonder if the problem is not necessarily the clock, but the transport mech being slower at actually starting on one cam or the other. If this is the case, one should restart the free run every time you have to stop recording on a camera.

Daniel Epstein May 6th, 2007 08:46 AM

The problem is not the transport mechanism of the cameras it is the quality of the cameras clocks/crystals which have been an issue for as long as video has been around. This is one reason why professional cameras have genlock inputs. Remember Genlock synchonizes the frame rate of multiple sources so they can be switched seamlessly maintaining proper sync. If you disconnect the sync they will drift apart and no longer switch seamlessly. This is essentially what is happening with mutliple unconnected cameras
When you think of 30 frames a second x 60 seconds per minute, 60 minutes per hour or 108000 frames per hour you begin to realize it doesn't take a very large difference in the cameras clocks to end up with a drift of a few seconds over several hours. Add in power on and off and the cameras have plenty of reasons to drift from an electrical standpoint.
This is one reason why I like to send sound to all my cameras so I have another reference to judge sync by if the timecode isn't perfect.


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