Timecode as an audio track?

[Rick Sutton]

Well I'm certainly not an expert on SMPTE time code but I do remember having to set the correct frame rate on the TC generator when I used it for striping 2" tape so my board's automation could follow it. So in my experience, yes it does carry frame rate info.

[opentune]

Yes, frame rate info is included. Here´s an article if you´re interested.

SMPTE EBU timecode by Phil Rees

Don´t get shocked - the site plays a short SMPTE clip when loaded (can´t remember the frame rate) - so turn down your speakers...

[synthoid]

SMPTE/LTC does not carry the frame rate explicitly. It is possible to read time code without knowing what frame rate it is using, and so a timecode reader will ordinarily start displaying incoming timecode after it receives just a frame or two.

Each time code frame carries its own frame number, and so if you watch a second or two of the timecode go by, you can figure out the framerate or at least take a pretty good guess. But there is no easy way to distinguish 30fps time code from 29.97fps time code without knowing or assuming something about the clock being used to generate the timecode.

hth,

-synthoid

[synthoid]

Originally Posted by thebighandster

The device allows me to change the fps after i sync to the timecode audio track? doesn this mean that the timecode will be stamped correct and run at the correct speed.

I don't quite understand what you mean to ask... The timecode will run at whatever speed it is being generated at by the timecode master (because you are syncing to a timecode master outside the recorder, right?)

When you change the fps inside the recorder, you are not changing the timecode; you are changing the relationship between the word clock of the recorder and the timecode. Think of it as changing the number of samples per timecode frame. That number is bigger for a lower frame rate than for a higher frame rate (that is, there are fewer samples per frame at 30fps than there are at 25fps).

A decent timecode reader should notice if the frame numbers don't match the frame rate you have selected (for example, frame number 26 is seen when you have selected a frame rate of 25). So, as a practical matter the only important use of a manual fps setting is to distinguish 29.97 from 30, drop from non-drop, etc., i.e., stuff that's not easy for the reader to figure out from a few frames of timecode.

-synthoid

[LX3]

There are some timecode generators that will cross-jam. That is to say (for example) you can set it to generate 25fps, feed in 30fps, and jam to it. It effectively keeps the H:M:S in sync between the incoming and outgoing code, but takes 30frames in and spits out 25frames in the same period.

Seconds move at the same speed regardless of what frame rate you're working in.

So if a unit can cross-jam, it should be possible to set the time using any input code frame rate.