Free run time code at DVinfo.net

Khoi Pham · May 4th, 2007, 08:19 AM

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.

May 4th, 2007, 08:19 AM	#1
Khoi Pham Major Player Join Date: Nov 2004 Location: Dallas Posts: 747	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. __________________ Khoi Pham www.proeditproductions.com

May 4th, 2007, 10:14 AM	#2
Pete Bauer Wrangler Join Date: May 2003 Location: Eagle River, AK Posts: 4,100	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 __________________ Pete Bauer The most beautiful thing we can experience is the mysterious. It is the source of all true art and science. Albert Einstein Trying to solve a DV mystery? You may find the answer behind the SEARCH function ... or be able to join a discussion already in progress!

May 4th, 2007, 10:22 AM	#3
Khoi Pham Major Player Join Date: Nov 2004 Location: Dallas Posts: 747	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. __________________ Khoi Pham www.proeditproductions.com

May 5th, 2007, 08:44 AM	#4
Jerome Marot Regular Crew Join Date: Jul 2006 Location: Munich (Germany) Posts: 107 Images: 4	I did the same with 2 cameras and indeed they are off a few seconds after 3-4 hours.

May 5th, 2007, 09:25 AM	#5
Daniel Epstein Trustee Join Date: Jan 2006 Location: New York, NY Posts: 1,267	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.

May 5th, 2007, 10:18 PM	#6
John L. Miller Major Player Join Date: Feb 2007 Location: Huntington, WV Posts: 260	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.

May 6th, 2007, 08:46 AM	#7
Daniel Epstein Trustee Join Date: Jan 2006 Location: New York, NY Posts: 1,267	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.