Question: Jam Sync TC on DV, is it possible?

T

thisiswells

Retired
If one were to record a TC audio signal from a standalone TC generator into one of the audio channels on a DVX100 would it be possible to interpret/decode that audio channel as an authentic timecode track within an Avid editor?

The utility of this application would be for syncronising multiple non-jam sync miniDV camcorders in a live multicamera venue where each camera would be recorded ISO and sync'd within the editing program. Having a common timecode reference among all cameras would be valuable.

Is this a feature currently implemented in any of the Avid products at any price range? And, if not, what would be a reasonable technical explanation of the impractibilities of such a system? Would a lack of black burst into each camera create compromise in sync ability? What hardware and software would you need to accomplish this task (if at all possible) ?

Thank you.
Brian Wells
 
Hi Brian -

This is possible with Avid products (Xpress Pro and MC Adrenaline, etc.). LTC is recorded on one of the audio channels. This LTC is common to all the cameras as a TC generator has been jammed from a known master (an audio recording device for example). I use a Horita LTC timecode generator for this. You do need such a device for each of the cameras. There are GPS devices that get their time source from satellites, but those only work reasonable well outside. Having a master clock from which to originate the timecode is always best. Aaton perfected this method years ago with the Origin C.

Things to watch out for on the set is if recording audio on one of the channels and LTC on he other, the automatic gain control affects both channels so the LTC will drop in loud situations. One way is to deal with LTC only and not have a mic on the other channel to affect overall recording quality.

As far as capturing it and using it, it id rather straightforward. Capture like you would any other DV source, picture and sound (track with LTC). Keep in mind the picture delay in the older DVX100 cameras, the audio can be delayed on the fly during capture by setting the "Delay Audio" by "n" number of frames 1 -10. Set this accordingly.

Once captured, select all the clips and select "read audio timecode" from the "special" menu. The system will then decode the timecode from the audio channel and automatically add it to the AUXTC1 column. From there you can use it for grouping in multicamera, EDL's, etc.

Let me know how this works out for you -


Michael
 
Thank you.

Thank you.

MichaelP said:
Keep in mind the picture delay in the older DVX100 cameras, the audio can be delayed on the fly during capture by setting the "Delay Audio" by "n" number of frames 1 -10. Set this accordingly.
Click to expand...

Michael--

Thank you for helping me with this. I have found the following info for the "Delay Audio" provided by Adam Wilt (as credited below) and thought this would be helpful as well for anyone considering this option. Appreciate confirmation of this "fabled feature."

Will keep all of your info in mind when preparing for future productions. Thanks.

Brian

------------------------------------------
DVX100, 60i, 2 fields
DVX100, 30p (played as 60i) 3 fields
DVX100, 24p (played as 60i)3 - 4 fields
DVX100, 24p (played as 24p)4 fields / 2 frames

DVX100A, 60i or 30p 0 fields, perfect!
DVX100A, 24p lags about 1/60 sec

http://www.adamwilt.com/24p/#AudioAdvanceTable
 
How to use LTC on double-system sound

How to use LTC on double-system sound

MichaelP said:
This is possible with Avid products (Xpress Pro and MC Adrenaline, etc.). LTC is recorded on one of the audio channels. This LTC is common to all the cameras as a TC generator has been jammed from a known master (an audio recording device for example). I use a Horita LTC timecode generator for this. You do need such a device for each of the cameras. There are GPS devices that get their time source from satellites, but those only work reasonable well outside. Having a master clock from which to originate the timecode is always best. Aaton perfected this method years ago with the Origin C.

Things to watch out for on the set is if recording audio on one of the channels and LTC on he other, the automatic gain control affects both channels so the LTC will drop in loud situations. One way is to deal with LTC only and not have a mic on the other channel to affect overall recording quality.

As far as capturing it and using it, it id rather straightforward. Capture like you would any other DV source, picture and sound (track with LTC). Keep in mind the picture delay in the older DVX100 cameras, the audio can be delayed on the fly during capture by setting the "Delay Audio" by "n" number of frames 1 -10. Set this accordingly.
Click to expand...

Next question to ask, and I wonder why nobody did, is how to use that same setup for doing double system sound.

Or at least how to capture it later, because that would be the real problem. How do I get Avid to identify a sound track, recorded on an MD for instance, where one channel is the audio and the other is the same time-code as on one or several DV cameras?

Another suggestion to jamming sync on several TC generators, like the Horita or Denecke, would be to wire the TC signal from external audio recorder to several wireless receivers on the DV cameras. Signal interruption might be a problem there though.

Whatever the system used, manual audio level is a must on the cameras and their channels shouldn't be linked.


Carlos
 
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