Lee Bell wrote:

> As I understand it (still learning before selecting equipment, software,
> etc.), digital video can be loaded and edited with a computer and
> transferred back to a video media.  I presume that the transfer back could
> be in any format the user choses.  This suggests that anyone with the right
> computer hard and software, could load and convert pretty much any format to
> pretty much any other, DVD perhaps being the exception.

Lee --
A good concept to begin with is the idea of a "native" format.  The native
format is the electronic standard used by whatever piece of equipment we happen
to be discussing.  In North America and Japan the most familiar format for color
TV pictures has been NTSC.  This is what analog color TV cameras put out, and
what videotape recorders (VTRs) record and playback.  Life was easy then --
"video" meant "NTSC."  Nobody worried about native format, because everything
was the same.  In other parts of the world the standard was PAL or SECAM, but
still, no worries, everything was the same unless you had to send a video
program into a part of the globe that used a different format.

Then along came computers, and we learned a new word: "Digital."  The old,
familiar analog video and audio signals were now converted to zeros and ones.
This uncovered lots of advantages, but also created a major dis-advantage:  you
now have to be aware of what format is native to your equipment.

The newer digital video cameras and recorders come in a bewildering variety of
native formats.  Most of the consumer gear out there seems to be settling on the
DV standard.  It's small, cheap, and you can record hours and hours of material
on a single tape.  Other current digital formats include DVCam, DVC, DVC-Pro,
DVC-Pro50, and Digital BetaCam.  Each of these are actually recording formats
which take in a video signal and, using their own unique compression scheme,
squeeze lots of pictures onto a very small amount of tape.  Most of the VTRs
that handle these formats will not play most of the other formats.  Some VTRs
will play one or two other formats, but none will play them all.  Adding to the
problem is the fact that video cameras can have any number of picture elements
(pixels) from a couple hundred thousand to several million, and the picture can
be almost square (4x3) or wide-screen (16x9).

We are fortunate that almost all of these cameras and VTRs -- whatever their
native formats -- will provide good ol' NTSC video output as an option.  This
makes hooking together multiple components a bit easier, but by using NTSC you
lose one of the properties that makes digital video great:  the ability to make
multiple copies of a program without "generational loss" -- degradation of the
video signal which occurs each time you copy the tape.  So it is always best to
purchase equipment whose native format is compatible to the other equipment you
have.

When you transfer video from a camcorder or VTR to your computer for editing, an
optional video capture card is required to convert the video from its native
format to a digital signal that the computer program understands. (Some of the
newer Macs are being sold with Firewire already installed, but if your camera
doesn't output Firewire you still need an add-on capture card.)  This usually
involves further compression of the video signal beyond whatever was done in the
camera and VTR.  Once the editing is complete the video passes back through a
video output card and is converted back to NTSC (or whatever it was before) so
that it can be recorded onto tape for viewing or sharing.

I'm not familiar enough with computer video systems to speak on this next point
with absolute certainty, but I believe that the computer program and video card
you will use for editing must "see" the native format of the original video.
i.e.: if the original video was some variant of NTSC (including DV, DVCam, DVC,
etc.) your computer software and video card must understand the particular
digital video format that is native to your VTR, or else you must use the analog
NTSC option.  If the original was PAL, your computer software and video card
must understand PAL.  No hardware and software that I am aware of will
understand both.  (Somebody correct me -- gently! -- if I am wrong on this
point.)    8^)

SO --
No, you can't transfer NTSC video (or DV, or DVCam, or DVC, or Firewire) to a
computer editing system, edit it, and then output the finished program to a PAL
video recorder.  Unless you put the signal through a Standards Converter first.
The computer is, in effect, converting the incoming video from the VTR's native
format to the computer's native format, and then converting it back to the VTR's
native format upon output, but that only works within the universe of the TV
standard in which the original video was recorded -- NTSC, SECAM, or PAL (and
its variants.)  Converting to a different standard for output would require the
computer to add or drop 100 lines of video and add or subtract 10 picture frames
every second, as I mentioned in my earlier post.  That's more decision-making
than the average Mac or PC -- and the average video card -- are capable of.

It would be nice to have, but it will not work.  Maybe someday, when we return
from a beautiful vacation diving on the GBR, all of our PAL underwater videos
will be able to be played on our home NTSC VTRs.  (I had to get in a diving
reference somewhere!)

Dive safe [\],
-Dave

--
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Dave DeBarger
[log in to unmask]

"ASSETS make things possible.  PEOPLE make things happen!"
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