… for Codecs & Media
Tip #503: Why Timecode Starts at 01:00:00:00
It all comes down to finding what you seek.
Back in the old days of video tape, all programs originating in North America (and, perhaps, elsewhere) started at timecode hour 01. A tradition that often continues today for broadcast, mostly out of habit. Why?
NOTE: Programs originating in Europe, I discovered many years ago, tended to start at hour 10. This made it easy to quickly see which part of the world a program originated from.
Back in the days of large quad videotape machines, each of which could easily cost a quarter-of-a-million dollars, the tape reels were 15-inches in diameter and weighed up to 30 pounds. The tape flew through the system at 15 inches per second – all to create a standard-definition image!
Setting up a quad tape system for playback required tweaking each of the four playback heads on the machine and adjusting them for alignment, color phase, saturation and brightness. (It was these machines that first taught me how to read video scopes.)
The problem was that getting this much iron moving fast enough to reliably play a picture took time. Eight seconds of time.
So, the standard setup for each tape required recording:
- 60 seconds of bars and tone (to set video and audio levels)
- 10 seconds of black
- 10 seconds of slate
- 10 seconds of countdown
If timecode started at 0:00:00:00 for the program, that would mean the setup material would start at 23:58:30:00. Since 23 hours is after 0 hours, sending the tape machine to seek the starting timecode – an automated feature that was used all the time in the high-speed, high-pressure turnaround of live news – means the tape deck would scan forward to the end of the tape.
To prevent this, all programs started at 1 hour (or 10 hours) with setup starting at 00:58:30:00.
And now you know.