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LTC Time Code Support with Avid MC?

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Richard Spangenberg
LTC Time Code Support with Avid MC?
on Apr 23, 2011 at 7:45:22 pm

I've been considering getting Horita equipment for LTC. Plan to use it on five cameras and 2 or 3 multichannel audio recorders (32 channels)

The idea is to have one timecode wireless transmitter for all receivers that is constantly on so all video and audio equipment and to keep them in snyc whether they start or stop or run continuously.

Does anyone know if this will work in the latest Avid Media Composer and what the complications are. There are evidently issues with group definitions, matching code in audio recorders to frames in the camera, etc. Or know the transmitter can be set to different fps, but there is no reason to think that will match the cameras depending upon when they start, etc.

It gets a bit complicated and I am doing the right thing? Is there anything to read or where do I go before spending $$$.

The think the standard SMTPE approach is not only more expensive, but the need to jam synch, drift and no wireless support sounds even more complicated.

One big general HELP is in order.

Thanks,

Rick


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Bouke Vahl
Re: LTC Time Code Support with Avid MC?
on Apr 24, 2011 at 9:17:04 am

I'm not sure if i get it, but nevertheless, some random thoughts...

LTC is just an audio signal. With the correct attenuation you can use any transmitter / receiver you may have laying around. (TC is a fairly simple and robust signal that cannot be overmodulated)
Ambient makes transmitters / recievers just for timecode, they are less than 300 bucks a piece.

You can feed it to the TC in of your cams / sound recorders if they have it. This works and has nothing to do with Avid.

If you don't have TC in, you can record it onto an audio channel and use Avids 'read audio timecode'. This works great from version 5.
(Older versions needed a reelname to be present, and a new reelname for each TC break. This is fixed since version 5.)

If that fails for whatever reason, there is always my set of tools:
http://www.videotoolshed.com/product/26/fcp-auxtc-reader

It says it's for FCP, but it will work for Avid as well.
It can read LTC from QT movies, and from wave / BWF files.
But with Avid, you don't really need it.
(Could be handy for testing on set though.)

The stability of the clock is perhaps not really important as well.
Even if there is a drift, it will be a small one. Since the purpose is probably to sync material, the starting points will not be too far apart (10 minutes max) so the drift will be minimal.
Unless you spend a lot of money on genlocking as well, you cannot expect frame accuracy.
Reason, since there is no genlock, a TC frame can be half over a video frame, and thus it is guessing where it belongs.
But normally this is not a problem, and if it is, it is a very easy correction.

The drift on jam synced cameras is horrible. Depending on the stuff, it can be up to a second or more over a shooting day. Don't do it...

I've created a software LTC generator myself (as well as readers of course), and my generator drifts just a few frames over 24 hour without any lock. Probably as good as a hardware one.
But, since your cams also will drift, it is really unimportant.
You can even run Jumpstart on your Ipod / iPhone and use the TC from there. It will just work fine for the reasons mentioned.

If you want the next step, get Ambient LockIt boxes, cams that are genlockable, and be prepared to spend a lot of money.
(It is very good stuff, and it's worth it!)


Now, i don't know what you mean by Group defenitions, and what problems that can give....
Different frame rates will always be a problem, do avoid that at all cost.
BUT, you can mix the tape / disk timecode with audio timecode on an audio track.
Avid assings the audio timecode as AUX timecode, and that is different metadata. If all metadata for AUX matches, there is no problem also. (But i would advise not to mix, as it will create huge confusion....)

IOW, if you need timecode hardware, check the ambient products.
If you need timecode software (readers, loggers, generators, custom stuff), contact me.

hth,

Bouke

http://www.videotoolshed.com/
smart tools for video pros


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Richard Spangenberg
Re: LTC Time Code Support with Avid MC?
on Apr 26, 2011 at 1:26:32 pm

Thanks for the input. Very informative. Seems like Avid will work fine with LTC. There does appear to be an issue with multiple clips from one camera. Obviously, the LTC is continuous run through the transmitter so the time code captured should be correct. But, I believe you would want to group the cam as one entity under some group definition so all it's clips can be seen on one video/audio track. Not sure how to do that? Maybe can't be done.

Appears to be now that a remaining issue is how to get the TLC to work in ProTools latest version. Odd thing to think that Avid doesn't have these two products working together somehow this very essential TC subject. Havn't seen any info on how to do it in Protools. Any advice? And, will your conversion save the day on this one. I guess you would need to use the converted TC file on both Avid and ProTools. With 32 tracks, that might prove interesting.


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Bouke Vahl
Re: LTC Time Code Support with Avid MC?
on Apr 27, 2011 at 11:36:52 am

[Richard Spangenberg] "There does appear to be an issue with multiple clips from one camera."

Did you test this or is this an assumption?
It used to be in previous versions, but afaik, it is fixed since version 5

However, you need to subclip if there is a TC break in the recording.
This can happen if the cam shoots tape and is set to Rec Run. It then has continuous TC, while there are breaks in the LTC.
Avid cannot find those, but my software can!
Another option is to shoot TOD on the cam as well, but that will burden the ingest procedure of course, as Avid will need to preroll each clip. Pick your poison.

Not sure what you mean by the ' group definiton '.
Are you referring to multicam?
That can be done based on AUX TC as well, no problems there.

I don't know anything about ProTools, but if you export your rough mix from Avid to Protools, it does not matter anymore, does it?
ProTools probably works with BWF files, and my software can convert Wave / BWF with LTC where the files get stamped the LTC tc in the files.
However, i've not done this for 32 channels. I could make it work this way, but i need some info on what you are recording.
(I take it you record mono, as with a 32 channel 24 bit Poly file your recording time would be very short...

Bouke

http://www.videotoolshed.com/
smart tools for video pros


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