Newbie Post: How To Timecode?

[ChrisLyon]

This really is my first post in a while. I'm not going to lie when I say I know little about production timecode keeping- who holds the keys and how it all works.

Would someone mind taking the time to explain timecode to me? Here are the questions I have:

1. Where is timecode generated on set? In camera? Audio department?
2. What equipment is used to generate TC?
3. What equipment is used to read TC?
4. Depending on where the TC is generated, how do the other devices on set read TC?
5. What is jam sync and how is it used?

I think anyone answering these questions should assume a frame rate of 24 non-dropframe and please note if anything is special for the Red that post production or crew should be aware of including the purchasing of equipment to achieve proper timecode between audio dept, camera, and slate.

Also, anyone answering should assume I don't know anything.

Thanks in advance,
Chris

 

[Cail Young]

1. Where is timecode generated on set? In camera? Audio department?

This depends on your production style. For most work, the audio department is responsible for TC - because it's used to sync audio to picture (as well as identify footage in post, but primarily it's an audio sync thing)

Occasionally where the camera audio is the primary recording camera dept will be responsible for TC.

2. What equipment is used to generate TC?

When audio is in charge, either the recording device, or an external unit like the Ambient or Denecke boxes.

When camera is in charge, either the camera or an external unit as above.

3. What equipment is used to read TC?

The slate, if it is a TC slate, will need to read the signal, as will whatever the 'slave' gear - so if audio's in charge, the camera has to read TC. Vice versa when camera is in charge.

4. Depending on where the TC is generated, how do the other devices on set read TC?

Most TC is what's called LTC - Linear Time Code or 'litsee' - it is carried as an audio-frequency pulsing signal on cables or through wireless systems. Videotape also has VITC - Vertical Interval Time Code - but it's not really important for our purposes.

The TC reader in any device is able to decode the LTC signal and convert it into either a display, or metadata, or some other TC signal for internal use.

5. What is jam sync and how is it used?

Jam sync is used to align independent TC clocks. Best simple example is a TC slate. If you have a slate with no internal clock, as soon as you remove the LTC input the display will either freeze or go blank - it has no idea what the signal is. If, however, it has an internal clock and TC generator, you can "jam" the internal generator to an external source, and then if the external source is lost it can still display (depending on the quality of the clock, of course) accurate TC even though there's no connection.

The RED ONE uses an interesting method. When you enable JAM SYNC, it stores the offset between the external signal and its internal Time-Of-Day timecode clock and then uses the offset TC as the timecode track. It will look for TC every time you roll, but if there's no input it will keep using that offset until you lose power or restart.

I think anyone answering these questions should assume a frame rate of 24 non-dropframe

If you're using FCP and you're in the US I would strongly recommend shooting 23.98 - FCP has some issues with 24.00 TC and audio.

please note if anything is special for the Red that post production or crew should be aware of including the purchasing of equipment to achieve proper timecode between audio dept, camera, and slate.

The best-case scenario is you have a master clock - ambient and denecke amongst other sell one - that you then jam smaller TC generators to, which are attached to both camera and sound. You also jam your slate from it. These run Time Of Day timecode, and you re-jam everything at lunch. Because the standalone TC generators are all the same model and (sometimes) better than the ones in the other hardware, you're less likely to see drifting through the day between the clocks.

Without a master clock, you can still jam the smaller units and a slate to an audio recorder's clock and attach it to the camera.

If you'd rather not have a TC box on the camera, you can jam with a radio link from the audio device, or just jam hardlined - bearing in mind that while the hardline is not there you're relying on the accuracy of the two clocks.

Hope this helps!

 

[ChrisLyon]

That helps a lot. I suppose we will just rely on audio dept to provide that signal for our shoot.

And the Red can pick up the wireless signal or is that a piece of equipment that we need to have externally?

@FCPvs24: Seriously!? How does film out work properly? I mean, you loose like 6 seconds over a 2 hour film, right? Are film out houses used to seeing 23.98fps output to film often? It seems so strange! :blink:

Thanks!

 

[Cail Young]

And the Red can pick up the wireless signal or is that a piece of equipment that we need to have externally?

No, you use a radio mic kit or a dedicated TC transmitter/receiver system.

@FCPvs24: Seriously!? How does film out work properly? I mean, you loose like 6 seconds over a 2 hour film, right? Are film out houses used to seeing 23.98fps output to film often?

The difference between 23.98 and 24.00 is small enough that it shouldn't affect your final product.

24 and 25, though, that's another matter.

 

[Tom Visser]

That helps a lot. I suppose we will just rely on audio dept to provide that signal for our shoot.

And the Red can pick up the wireless signal or is that a piece of equipment that we need to have externally?

@FCPvs24: Seriously!? How does film out work properly? I mean, you loose like 6 seconds over a 2 hour film, right? Are film out houses used to seeing 23.98fps output to film often? It seems so strange! :blink:

Thanks!

In theory, you could do it wirelessly, but the standard is usually the audio recorder is the time code master (in some instances it could be an Ambient or Denecke lockit box, but more often than not, the lockit boxes are jammed to the recorder).

On good hardware, the drift is very minimal. In some cases you could jam only a couple of times per day. Most people are more anal, though and will jam every hour, if not more. So lets say your sound department has a Sound Devices 788t or Nagra VI. This recorder would be the master. Either sound or someone else would provide a couple of Denecke lockit boxes which would be occasionally jammed to the recorder. The digital slate, is also basically a lockit box with a display, if it is a modern unit. So every once in awhile, perhaps in conjunction with media swap or battery replacement, these boxes would all be rejammed back to the master clock, or the recorder. If you are purchasing new gear, the Ambient ACD301RF would be an interesting piece of kit.
http://ambient.de/produkte/timecode/tc_klappe/tc_klappe_e.html
rather than having to hardwire a cable to jam sync, it handles it automatically wirelessly. You also don't have to retask an audio Rx/Tx set and worry about gain levels, etc... it operates on a totally separate RF band, 418MHz in the US I believe. They also sell the RF section separately, so you could also purchase one to connect directly to the camera and also jam the camera's TC wirelessly too... completely unnecessary, but on the other hand, not too expensive all things considered and does offer a certain convenience level. Denecke has a new lockit box that is quite inexpensive, though, so such gucci wireless gear would really be an extra luxury.

 

[ChrisLyon]

Thanks, guys.