It is a standard practice to have one minute (60 seconds) of properly recorded video and timecode on the beginning of each source tape, prior to the start of the actual program material. This us usually arranged in the following way:
One of the main reasons for such a long "header" and "tail" of black is because the videotape machines need pre-roll and post-roll time, and they insist that the timecode and video signals be pristine during the pre- and post-roll intervals, so that proper synchronization of all the tape transports involved can be ensured. This means that a problem with the source tape outside the interval actually sourced for an edit can prevent you from successfully performing the edit.
Such problems can be caused by "crash edits", i.e. pressing STOP and then starting to record additional material by pressing RECORD and PLAY -- neither the timecode track nor the CTL track is properly continuous across a "crash edit". Similar problems can occur from not having sufficient header before the start of the program material or after the end of the program material.
A particularly baffling situation for the edit controller occurs when a previously-recorded tape is put back into the recorder, and a small additional segment is recorded "on top" of the old material, but not starting (quite) at the beginning of the tape. In this case the edit controller will see "time warps" across the crash edit boundaries. When the edit controller is trying to seek to a given timecode on such a tape, the discontinuities in timecode can drive the edit controller into crazy behavior as it vainly goes to-and-fro looking for the missing times.
For source material tapes (e.g. tapes recorded off the Abekas,
off a camera, or off the screen of a workstation)
there is no real advantage to making the duration of the black and
tone sections exactly 20 seconds each -- manually pressing
the BLACK and COLOR BARS and DISK 1 buttons on the video switcher
at approximately the right times is fine.
Recommended Practice: Never Append to an Existing Tape
Never try to append additional source material to a source tape. Record a source tape in one pass with proper header and trailer, then write protect it and never write on it again (at least not until the tape is recycled for the next project). Videotape is cheap, the lost time due to "surprise" problems with the tape is expensive -- especially because it usually only shows up in the final editing session, shortly before The Big Deadline.
While frugality is a virtue, it is astonishingly easy to get confused
and to record over the end of your previous source material.
Resist the temptation, always use a fresh tape.
Recommended Practice: Always Write-Protect Tapes After Recording
The instant you take a tape out of a video recorder, your first instinct should be to activate the write-protect feature on the tape. That way if you should accidentally mistake your freshly-recorded source tape for that fresh blank tape for the next segment, you won't erase what you just recorded.
The convention for write protecting a tape is different for each tape format:
Any tape which does not have a label on it is defined to be blank. This is an absolute rule. This rule applies to video tape, audio tape, and computer tape. If you don't want your tape to be erased, put a label on it. At a minimum, grace it with a post-it (tm) note with your name scrawled on it.
The recommended minimum label for a videotape has the following information on it:
In addition to labeling the tape, it's usually a good idea to label
the spine of the tape box as well, so that the tape can be easily
found once it's put on a bookshelf or on top of an equipment rack.
Just the short title will suffice. Master tapes usually benefit
from putting one of the red MASTER stickers immediately above the label.
Both the Betacam and U-matic tapes have a label intended for applying
to the spine of the box.
Only with the VHS tapes is it necessary to take out the label card and
turn it over to write on it.
Recommended Practice: Always Record Color Bars and Tone
Not all videotape machines reproduce colors quite the same way. The color bar pattern in our studio is generated by an FCC-approved broadcast quality Master Sync generator; it's time and color accuracy is directly traceable to frequency standards at the National Bureau of Standards (now NIST). Every other professional studio also uses similar pattern generators. Thus, if you record this standard pattern onto your tape, when you play back the tape in a different machine the reproduced signal can be compared to the local master sync reference, and the time-base corrector's processing amplifiers ("Proc Amps") can be tweaked so that the signal output by the tape player is exactly what it should be. (This is a standard feature in all waveform analyzer instruments). If the test pattern reproduces properly, so will your program.
For exactly the same reasons, tapes with audio on them should have a standard tone recorded along with the standard color bar pattern. The SMPTE standard tone is a 1 kHz sine wave recorded at +0dB in all channels. When the tape is being played on a new player (or after the passage of time), this makes it easy to adjust the gain and balance so that the program audio will be reproduced exactly as it was recorded.
In our studio, pressing the RED button marked "color bars" button on
the video switcher will cause the standard color bars pattern to be sent
to all the recorders.
Similarly, pressing the "tone" button on the audio mixer
(located halfway up on the far right edge of the mixing board)
will send the standard tone to all the recorders.
Note that +0dB is LOUD, so be sure to turn down the volume on the
Recommended Practice: Audio Channel Assignments
For master tapes, it is conventional to assign narration to audio channel one (LEFT), and to assign music and special effects to audio channel two (RIGHT). If the tape is stereo audio, so note it on the label.