Gees, I hope you're sitting down

Timecode first appeared in 1967 as a solution to synchronise sound and picture on the 2" quad video recorders. It came about as a need to positively identify the absolute time reference of a piece of tape being edited. It is an 80 bit digital signal recorded on to either a dedicated TC track or auxiliary analogue track on a video recorder, or onto a standard track on an audio multitrack. This 80 bit signal is called a 'word' and one of these words is written either: 30 times a second (SMPTE 30ND used in NTSC black and white), 30 times a second but modified for colour (SMPTE 30DF used in NTSC colour video. DF stands for drop-frame and rsults in an overall frame rate of 29.97 fps. This needed to happen due to a slight variance related to phase difference in the colour encoding of the NTSC signal. It is achieved by dropping 2 frames at the beginning of each minute, except for every 10th minute where it counts 30.) 25 times a second (EBU 25. Used in countries such as New Zealand, Australia, the UK... Same digital structure as SMPTE 30ND.) Film 24 (International cine film standard is exposed and prejected at 24 fps. Does not include 180degree or Imax film)
It is roughly a square wave, with the sonic frequency alternating between 1.2 KHz and 2.4 KHz at 30 fps. I say roughly a square wave because it is slightly rounded to allow an analogue tape machine's amplifiers to process and record it with a minimum of distortion. Digital machines don't have a problem since they are recording square waves anyway. (Doesn't that make you sick??)
To record it you need a timecode generator, to read it you need a timecode reader, to use it you need a synchroniser of some sort. There are of course units which any or all of these devices in one box. I think you can find more info at the SMPTE site. something like
www.smpte.org or
www.smpte.com. Have a hunt. If you want to hear a 1 second sample of timecode, go to
www.philrees.co.uk and look at his 'What is SMPTE page'. Feel free to email me. I have loads more info on it but I'm not sure what equipment you're using so I won't give recommended levels etc.... I think my fingers would fall off.
[This message has been edited by nomadnz (edited 07-02-2000).]