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Author Topic: Camera SMPTE Syncing for post editing using Final Cut Pro  (Read 2268 times)

greg bates

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Camera SMPTE Syncing for post editing using Final Cut Pro
« on: December 15, 2006, 12:15:46 pm »

I am looking for some info and advice for post edit syncing.  We currently have available 2 sony DSR-250's and looking for a third camera of some type. One roving two stationary.   Simply put I want to download all the tapes to Final Cut Pro and have them sync up.  

1. Should I use Drop/Non Drop frame?  
2.Do the all have to be connected to the BNC and have a master clock?  or can I set them into a specific mode that will allow no time delays between tapes.
3. Should I link them to time of day clock.

I am by proxy an audio engineer but have done  a bit of video in the past. I hope I have given enough info. I know I can manually nudge the downloaded tracks to come close but there always seems to be a lag somewhere when I have done this in the past

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Greg Hertfelder

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Re: Camera SMPTE Syncing for post editing
« Reply #1 on: December 29, 2006, 10:59:44 pm »

1. Non-Drop-Frame SMPTE time code records at 30 frames per second (fps); Drop-frame SMPTE time code records 29.97fps to compensate for a slight discrepancy that results in an approximate 90 seconds of error during one rotation of the earth when recording at 30fps (for the full story, read the Drop Frame Time Code paragraph here). It's important to note that video frames are not dropped, just time code numbers; video frames remain sequential. Use drop-frame time code.

2. A SMPTE time code signal fed from the master time code generator to each DSR-250 camcorder by cable would be one solution for later synchronization of videotapes. A wireless or GPS system would be other solutions (more later).

3. A time-of-day clock would be a likely scheme, and a GPS or atomic-based receiver would provide the precise time and convert it to time code.

Horita offers a wireless scenario (model WTS100M, plus master TC generator) for time code distribution up to 100 meters. (Horita also makes a GPS system for greater distances.)

In broadcast ISO-CAM scenarios, a rack of tape decks is assigned to record each camera; a master SMPTE time code generator in the same equipment rack is looped from one tape deck to the next with short cables (delay is too short to be concerned about).

Incidentally, if I were in your shoes, I would pursue the purchase of direct-to-edit recorders at each camcorder instead of videotape. A hard drive recorder would save you hours of downloading time each week, and eventually expensive video head replacement; just drag and drop the video files.
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Mac Kerr

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Re: Camera SMPTE Syncing for post editing
« Reply #2 on: December 31, 2006, 05:03:22 pm »

Greg Hertfelder wrote on Fri, 29 December 2006 22:59

1. Drop-frame SMPTE time code records 29.97 frames a second to compensate for a slight discrepancy in the earth's rotation, and is used by broadcasters (recommended for church programs). Non-drop-frame SMPTE time code records 30 frames a second, and makes sense when one is shooting commercials or other short-form projects.
A quick check here will reveal that drop frame has nothing to do with the earth's rotation. It has to do with the difference between color, and old black and white scan rates. Yes it is to correct a time error, but a time error against a standard wall clock, not the earth.
Greg Hertfelder wrote on Fri, 29 December 2006 22:59

If you use cable to distribute the time code, I suspect that equal length cable runs should be provided to each camcorder from the generator to compensate for potential delays you described. For instance, if the longest cable run between the time code generator and camcorder is 200', you would supply a 200' cable for other cameras, too, and coil up the difference.
There is no need to use equal length cables for timecode. It is important to use equal length cables with component video to keep the signals in phase, but the resolution of TC synchronization is only 1 frame, which is 33ms of time. The time difference between a 200' cable and a 1' cable is going to be in the nanosecond range.

Mac
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Greg Hertfelder

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Re: Camera SMPTE Syncing for post editing
« Reply #3 on: January 01, 2007, 05:44:13 pm »

Thanks for catching an editorial mistake on my part, Mac. I had keyed in the phrase about the earth as a simple marker with intention to revisit and elaborate, and neglected to. I have corrected my original post to reflect your point.
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Re: Camera SMPTE Syncing for post editing
« Reply #3 on: January 01, 2007, 05:44:13 pm »


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