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Posted by David McCall on 10/25/98 11:48
"Richard Crowley" <rcrowley@xpr7t.net> wrote in message
news:127b8mnq07t7sc4@corp.supernews.com...
>
> <mmaker@my-deja.com> wrote in message
> news:1148558425.917828.229330@i40g2000cwc.googlegroups.com...
>> Richard Crowley wrote:
>>> 10 pounds in a 5 pound sack.
>>> As they say on the right side of the Pond,
>>> "You do the maths."
>>
>> As I said, I take it you've never actually shot HDV.
>>
>> Next, I presume, you'll be telling us that VHS is better than DVD
>> because DVD is compressed and VHS isn't.
>
> Sorry, perhaps you don't understand what we mean
> by the "bandwidth" of the recording medium.
If compression is such an evil thing, I'm surprised that you don't
shoot everything at 320 x 240 so as to be able to avoid using
compression at all. DV is so heavily compressed that most
professionals insisted that it wasn't anywhere near suitable for
broadcast use. Well guess what, money talks. DV is being
broadcast every day.
So now DV is OK, but watch out for that HDV stuff. It isn't
good enough for anything but home movies either.
When people think MPEG-2 they immediately think we are
talking the bandwidth available on DVDs. That has almost
no bearing on HDV. HDV is recorded at the bandwidth of
DV tape which is much higher than DVDs.
MPEG-2 is a very flexible format. You can make every
frame be an I frame and have quality as good as or better
than DV depending on the available Bandwidth of the
recording medium. If you tried to cram HD onto DV tape
compressing each frame separately, as you do with DV,
then the quality wouldn't be much to write home about,
but HDV uses delta compression.
By using delta compression the information can be spread
across time. All other things being the same, this scheme
gives you a lot more effective bandwidth.
If you wave the camera around and zoom like so many people
tend to do when shooting interlaced video, then it isn't going to
look very good. The motion artifacts will be abundant. However,
if you shoot taking the compression into account, I'll bet that
HDV will look far superior on an HD display than DV would
look scaled to the same resolution.
David
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