[24hoursupport] Re: The Myth Of The 100-Year CD-Rom

  • From: Madrachod@xxxxxxx
  • To: 24hoursupport@xxxxxxxxxxxxx
  • Date: Thu, 10 Feb 2005 00:52:07 EST

 
In a message dated 2/9/2005 10:21:50 A.M. Eastern Standard Time, 
chizotz@xxxxxxxxx writes:
I did write, produce, direct, and edit a one-season TV series for the local 
St. Louis market some years ago.
    Cool!  I'd like to get into that.  I like to edit.  I did a T.V. show 
here on PCTV, it was interview with Betty Freidan and a few other feminist's.  
I 
was in T.V. production class at the time, around 1985, and it was supposed to 
be a class side project through that station, but I was the only one that 
showed up when it came time to do the actual editing, so I did it all myself.
    I edited the tape for my comedy single by hand.  That was a lot of work, 
but it was actually kinda fun.

During one editing session, I kept getting bad edits. The picture would jump 
and there was distortion. The engineer explained that the editing machine I 
was using was malfunctioning by not properly synchronizing the timing ticks at 
the edit point. This mis-match of the timing ticks resulted in the "glitch" at 
the edit point.
    Oh, you're talking about professional editing equipment.  I thought you 
were on about home use stuff.

That sounded logical and reasonable, but I wasn't sure if it was the truth or 
just a line the engineer was handing me.
    Yeah, that'd about do it, alright, if I recall correctly.

I found this article at How Stuff Works 
http://electronics.howstuffworks.com/vcr.htm It also explains that there is a 
control track on VCR tapes, which is 
what I am referring to.
    Oh, yes!  The control track.  I've never heard of their being one on home 
vcr tapes.  We had to record the control tracks at the studio before we used 
the tapes.  To do this, we'd just record the colour bars for the duration of 
the tape and that was the control track.

Basically, you can think of the control track as containing timing ticks. The 
VCR reads the control track and synchronizes itself with the time ticks. That 
sets the speed that the tape was recorded at. If at some point on the tape 
the timing of the ticks change, there is a glitch at that point while the VCR 
re-synchs itself to the tape. That's the effect I was getting all those years 
ago when the editing deck I was using was not synching the timing ticks between 
edits.
    Well, from the way the edits I've done on home vcr's WITHOUT using an 
editing board of any kind, I'd say that it's very much like audio take, because 
if you let your first edit run long, even for a second, and then you run the 
tape back to the start point of the next edit, and it's BEFORE the picture on 
the first edit runs out, you'll see a coloured wave wiggle across the screen as 
long as the first edit ran long into the start of the second edit.  Because 
the heads in the vcr are so far apart it takes a while for the erase head to 
"kick in" on the tape.  The record head is already recording before the erase 
head had a chance to erase the tape first.  Once the end of the first edit has 
gone by, the next thing on the tape that's going to be recorded over, is 
static. 
 That's a clean section of tape, and the record head can record a clean 
picture to the tape from that point on because the erase head is what puts the 
static there.  So, that's why I don't think there's such a thing as a control 
track on home video tape.  The reason most t.v.'s show a fluorescent blue 
screen 
when there's a blank tape playing in the vcr is because there's only static on 
the tape and the t.v. is set to eliminate that.
    On an audio tape, the heads on the recorder are MUCH closer together, so 
the time from erase to record head is almost nothing.  But, if you have sound 
on the tape between the two heads, the record head won't completely wipe it 
out as it records and you'll still hear a fraction of a second of what was on 
the tape before, though very muffled.  It's like a bad cross-fade.
    Make sense?  (-:
 
                            Dale


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