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Old October 13th 17, 10:48 AM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Default Timecode on programme-as-broadcast archive material

On Thu, 12 Oct 2017 23:29:24 +0100, Graham.
wrote:

On Thu, 12 Oct 2017 21:13:18 +0100, "NY" coalesced
the vapors of human experience into a viable and meaningful
comprehension...

Brian, what I was meaning is that the timecode - or at least, the burnt-in
timecode that is displayed on-screen in examples such as the in-house
version of an episode of Blue Peter that I mentioned - starts at 10:00:00.00
(ie 10 hours, zero minutes etc), I was expecting it to start at zero hours,
but now people have talked about needing a time code for the run-up
stabilisation time before the start of the programme, I can see why a
pre-zero time of 23:59:30 would be a bad thing.

And I can see why they chose 10 rather 01 as the starting hour, because it
allows you to mentally or literally mask off the leading digit and get a
time which at any instant is the true elapsed time since the start.


By the way, were there ever times when a programme spanned more than one
tape? Did they have a means of the first VTR (when it reached a designated
TC) triggering the run-up of a second VTR and then seamlessly switching
transmission from one to the other at the correct frame?



I don't know how often they *did* do it, but they certainly had the
technology *to* do it as that is how editing was done.

I'll tell you about something that was routinely done at Granada in
the mid '80s, because I saw it for myself. When Coronation St was to
be played out from VTR they cued up a pair of C format machines, the
second one carrying a copy that was called "the guard", so should
anything go wrong, like a head clog, the operator could very quickly
switch to the other machine.


The use of timecode also had to be given some thought when recording
raw material on a shoot, the two main methods being "run/record" and
"time of day", each with its pros and cons depending on what type of
shoot it was.

Run/record meant that the timecode would be zeroed at the start of
each tape and the generator, built into the recorder, would only
advance the time while the machine was recording. This would mean that
the timecode would also be an indication of the amount of tape used,
which would help to keep track of it and avoid running out in the
middle of a take. This would be most useful when shooting with a
single camera. It would also be possible to continue using the same
tape on a second day by setting the timecode generator to whatever
value had been reached previously.

Time of day meant just what it says; The timecode generator would run
continuously so the timecode would be the same as the time of day.
This would be useful on a multicamera shoot where the material would
have to be synchronised later. All recorders would either be fed from
a master generator, or each would have its own built-in generator and
they'd all be set carefully at the start of the day. This inevitably
meant a more extravagant use of tape, because if partially used tapes
were used on a second day, there was a possibility of a "timewarp",
where earlier timecode values could occur at later parts of the tape,
which could confuse the editing equipment when searching for material.
Typically, time of day recording would be used with multiple
camcorders where the tapes (or cassettes) would be the smaller sizes
anyway, so there would be some waste but not so much.

Rod.