Time code?

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2lim

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Hey i have been hearing a lot about time code recently, and since i have never seen a need for it i have never investigated it's use, and how it is done. My question is : What is time code, how does it work, and how would i go about putting timecode on a track on an analog recorder?
 
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).]
 
okay so lets say i have a yamaha mt120(four track analog) and my friend has a minidisk multitrack, how would i go about syncing these with time code. Also is there a computer program that i can get that will generate time code
 
Well one important question, are the two machines designed to respond to synchroniser inputs? ie. External capstan control, serial transport etc... One of the machines you are intending to use must have this in order for it to respond to the synchroniser's capstan and/or transport commands.
 
2lim, It should be in the manuals.
My guess is you cn totally forget about the Yamaha. I've yet to see a low end casette multitrack with the possibility to sync to other machines.
Concentrate on the minidisk. Those are digitals beasts where the synching could be done in software (I think) and would therefore be cheaper, so there some possibility there. The manuals should have an explanation of how you sync it to other equipment if possible.

If not, theres an easy way out: Bouncing:
Record 4 tracks on the Yamaha, mix it down to stereo on the minidisk, and record two more tracks there. You'd still get a total of six tracks out, without any noticable increse in noise. The problem is that you can't re-record one of the four initial tracks without having to also redo the mix and the later two tracks, so you have too "keep your tongue straight" as we say in Sweden. :)
I used this technique with a Yamaha MT2X and a Fostex something or another once upon a time. I had a drum-machine synced to the Yamaha, and bass, guitar and an electric piano recorded on the three tracks, mixed that down to two stereo tracks on the Fostex, recorded song and backing vocals on the two other channels. This made a couple of perfectly good sounding rock'n'roll demos.
 
Alright.......... i checked the manuals, and it looks like i will have to go with the bouncig method because, as you guessed, the yamaha cannot sync to other machines.
 
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