DPS PAR
26 messages in this thread
Would it be possible to get a copy of the PAR specs? Before hearing
of this I was considering getting an Exabyte because of the quality,
and the usability. How does the PAR compare to the Exabyte if the
final output is to VHS? I have also been looking into getting a
bigger Hard Disk. I was considering a 1.75Gbyte SCSI. Will this
work with the PAR? I am tired of running out of HD space.
Dennis:
If your final output is VHS, you won't notice any difference between recording
to the PAR, BetaSP, SVHS or to D-1!
VHS is the great equalizer! <g>
Check your e-mail for the PAR info.
Greg Pyros [Pyros Partnership, Inc] gpyros@pyros.com 11-Jan-94 at 7:43a PST
Greg;
>> Check your e-mail for the PAR info.
Got it.
Thanks, I'll look it over.
Dennis
I believe you need a dedicated drive for the PAR.
The Exabyte is not really a playback device, it's just a tape drive designed
for backing up Unix networks, etc…. and is used in conjunction with tar or
Abekas drivers to transport files onto an Abekas DDR.
With the PAR you can play back real-time jpeg streams and record them onto VHS
(not the best format, however).
As Greg says, once you're going down to VHS there won't be a whole lot of
difference, but I'd bet mastering on an Abekas would be better, and noticeably
so.
John Tissavary (La Luna cie)
John:
>> once you're going down to VHS there won't be a whole lot of difference,
>> but I'd bet mastering on an Abekas would be better, and noticeably so.
I'm not sure what you mean, but if you are saying that mastering on an Abekas
and copying down to VHS will look different than mastering on SVHS (or
anything else, for that matter) and copying down to VHS, I'd have to disagree!
VHS has a resolution of 240 lines, SVHS and everything else is above 400. I
don't think you'd see any difference whatsoever!
To quote myself <g>, "VHS is the great equalizer". Everything looks the same
when copied down to it! (it all looks equally bad!)
Greg Pyros
Greg:
>> … if you are saying that mastering on an Abekas and copying down to VHS
will look different than mastering on SVHS …..I'd have to disagree! <<
Well I'd have to disagree … (but not to be picky) Beta SP with say two
generations wouldn't look substantially different, but one generation of SVHS
is noticeable. If nothing else you would get no generation loss with an Abekas
setup or D1, D2 with 10 even 20 edits. And VHS tapes for distribution are often
copied from a digital source and look better than a SVHS to VHS dub. This is
partly because you are compressing 720 lines of resolution into 240 as opposed
to 400 but also has to do with analog format to format.
This is easy to test. Take a high quality image and output the signal through
your Vista (which is higher than 720) and record the signal directly to SVHS1
and VHS1 and then make a copy of the SVHS1 to VHS2. Compare the VHS1 that was
copied directly from the Vista and the VHS2 that was copied from the SVHS1. I
think its pretty easy to see the difference. If this isn't enough try doing
what you would do to create a SVHS master which is copy the SVHS1 to another
SVHS2 and then copy the second SVHS2 dub to another VHS3 and compare it with
the Vista VHS1 copy. And this is only a one generation master SVHS edit.
-JE
John:
I agree totally with the generation loss! No question there!
But on a master SVHS to VHS, there isn't much of a loss noticable on the VHS.
>> compressing 720 lines of resolution into 240
The 720 is pixels, not lines of resolution! Lines of resolution are defined as
the number of lines that you can see on the system. Each line (to see it!)
consists of a black vertical line and a white vertical line to differentiate it
from the next one, or half the number of pixels. Following this through, VHS
at 200 lines is the equivalent of 400 pixels horizontally. Little old SVHS is
800 pixels, or 10% more than D-1 can hold! (720) <g>
That is why we do our titles at 1008×486, so we get 504 lines of resolution!
Interesting math, no? <g>
Greg Pyros
Greg – The way you stated it was mastering on SVHS and then copying to VHS.
The Abekas meets the CCIR 601 spec for 720 x 486 lines of resolution.
Quantels definition of Resolution:
>>A measure of the greatest amount of detail that can be seen, or resolved, in
a reproduced image.
Whilst it is influenced by the number of PIXELS in an image (e.g. High
Definition approx 2000×1000, Broadcast 525/60, 720×486) it also depends on the
quality of lenses, display tubes, film process, film scanners etc.<<
By your reasoning that 400 lines of resolution = 800 pixels, then an Abekas
would have 972 pixels (486 x 2) which is greater than little old SVHS. Which is
erroneous. And this is active lines with 525 standard. Whereas we both agree
SVHS has a maximum of 400 lines. This CCIR 656 which is the technical specs for
CCIR 601 goes on to state "identical to the analog standards except that the
_WHOLE_ of the analog *half-lines* are included." which equals 720. (actually
729 but that's math for you <g>)
Which does make for some interesting math! <G>
-JE
What's in a line? Lines of resolution are vertical, which means that
they measure the horizontal number of pixels! The other direction
(486 or 525, depending on what you are counting) is fixed! Not much
to measure there! <g>
By this calculation, the Abekas (720×486 pixels) has 720/2, or is
capable of 360 lines of horizontal resolution.
Don't get me wrong, there are many other factors influencing the
quality of an image, such as color clarity, etc., where D-1 shines.
But in pure resolution numbers, that's the math!
>> What's in a line? << Is that anything like "what's in a name?, by
any other name…" <g>
Well Greg, I couldn't get an answer about horizontal resolution on D1
from Quantel or Textronix because they said Digital was different
than Analog. There are no specs for Horizontal resolution for
Digital. "Why not" I asked, "because resolution was calculated as an
analog value long before digital and was not based on the number of
pixels which could be counted, as monitors where different; they were
just a phosphorous tube upon which an electron gun was scanned." So
resolution was determined by electron scan lines and was calculated
only for a monochrome value, which is how resolution is still
calculated today.
Then as time goes on, monitors get color and are no longer scan lines
on a phospor tube but divided into pixels with three elements red
green and blue created with a mask. But resolution is still being
calculated the same way ie:as a monochrome analog signal. There
really is no direct relationship any more because the scans are no
longer continuous and you have guns or a gun firing at individual
pixels. The term when applied to the analog output of a VTR is
produced through the use of an oscilloscope. Which is doable because
an oscilloscope is a monochrome device and has a continuous analog
sweep. But this says nothing about output to a Monitor, where
resolution becomes dependent on the quality of the monitor. A
Broadcast monitor can go upward of 440 with home TV's somewhere
around 240. So whats the resolution difference between D1 to Beta SP?
Same problem. Apples and Oranges. And in a dub from D1 to Beta SP,
the Beta SP copy becomes the determining factor.
Your math looks good to me! <g> and your reasoning sound. Only problem
is I can't find any information to substantiate your conclusion. Got
any ideas? This is still somewhat irrelevant for the reasons I stated
previously, as the most important factor is S/N ratio and crosstalk,
but interesting! <G>
Who knows? It all seems logical, but… <g> All I know is what looks
good visually and on the waveform monitor and vectorscope. All the
rest is pure theory, anyway! But I still call VHS 'the great
equalizer'! <g>
If there is any format that could be called the "Great Equalizer" I
would say that _VHS_ deserves the title.
And I have no doubt that you know what looks good visually and what's
correct on WFM and VS.
If by saying that "the rest is pure theory, anyway" you are saying
that there is a subjective element to what looks good, I agree. But
there are technical specifications to support this subjectivity. The
real point is that its important to bring the video quality of
animations up to the highest standards possible, and to guide peoples
decisions in the purchase of animation output equipment to this end.
So that what the animator's clients and others see when one says
"this was created with 3D Studio" is the High Quality of 3DS and not
what the Great Equalizer does to it.
Jumping in here… For my own work I would like "to bring the video
quality of animations up to the highest standards possible " – but,
unless you are taking applications for hardware grants (sign me up
for a Videodisk recorder, betacam SP deck, and animation controller.
<g>), I, like most people, am going to have to compromise quality for
affordability. Hardware like the DPS PAR certainly looks like a way
to make a good compromise, at least until I can afford something
better.
Chris
>> there are many other factors influencing the quality of an image<<
You said it, not me<g>. I would argue that these factors will make a
noticeable difference when dubbing to VHS. Although VHS greatly narrows color
bandwidth and resolution, it is logical that having a greater bandwidth to
start with will provide better results in the "narrowing down" process (comb
filter, reduction in resolution, chroma crawl, etc…).
This is probably why video producer/distributors spend so much money on dubbing
equipment, and usually start with a pretty solid master tape.
I don't think S-VHS should be compared to BetaSP, because the color under
process causes chroma delay which will worsen when dubbed to VHS.
John "writing an article with a bunch of video technobabble so I think I know
what I'm talking about<g>" Tissavary
>>"writing an article with a bunch of video technobabble so I think I know what
I'm talking about<g>"
I would love to read your finished article and also see your demo
reel. The preliminary work I saw looked great, and I can't wait to
see how it turned out!
My demo will be finished by tuesday unless the edit suite I've booked blows up,
or the engineer dies before I'm done<g>. And the article will be completed as
soon as the demo is finished.
I'll be happy to get copies of both to you.
John Tissavary (La Luna cie)
Hey John, I'd love to see a copy of your reel when it's done. Can you
send one over to me?
>>To quote myself <g>, "VHS is the great equalizer". Everything looks the same
when copied down to it! (it all looks equally bad!)
I would like to add to your quote, Greg. " And to make VHS look worse dub from
a noisy master such as VHS, SVHS, 8mm. "
In other words, if one shoots on beta SP and makes a vhs copy it looks
bad compared to beta SP copy but it will look a whole lot worse if
one shoots on VHS and makes a vhs copy. This is one case where it
pays to have the strongest links of the chain in the front end,
starting with the lens in a camera or the frame buffer in the
computer. The reason for this is due primarily to Y/C delay and
video noise. The resolution issue can get complicated because one
can't compare pixels directly with resolution of video systems. Too
many people overrate this resolution issue, especially for graphics.
Since resolution has to do with picture detail and graphics has to do
with cleanliness and sharpness I'd put my money into a system with a
lower resolution in trade for higher sig. to noise, Y/C delay and
k-factor specs.
>>higher sig. to noise, Y/C delay and k-factor specs.
How to the Targa, ATVista and Illuminator Pro compare in this regard?
>>How to (do?) the Targa, ATVista and Illuminator Pro compare in this regard?
I couldn't tell you since I've never seen any specs on my targa+ in
this regard. I don't own the other two boards to do a visual but
maybe Kevin Krell will pop in with the answer. He is a dealer with
good knowledge of the products. My opinion of the targa+, however is
that its sig to noise is low compared with the Magni VGA producer
Pro. by my visuals.
The main difference, I think, would come from the initially greater
color depth and bandwidth of D1/Abekas. I realize that VHS reduces
all that to a lower resolution and narrower bandwidth, but you're
giving the VHS tape more color information to start from. I'm no
expert, though. I would invite a video proffessional in on this
thread to set me straight (not that I don't trust you, or anything…
<g>). One thing we definitely agree on is that it all looks equally
bad. VHS really sucks. And while we're on the subject… what's
with NTSC anyway <g>?! <dg>.
John:
>> And while we're on the subject… what's with NTSC anyway?
We all know what NTSC stands for, don't we?
"Never Twice the Same Color"!
Greg Pyros
ROL! :^)
John Tissavary (La Luna cie)
Your message came in blank, John.
John Tissavary (La Luna cie)
John;
Thanks for your reply. I'm attempting to sell some stuff. When I do, I will
need to decide which way to go. Since I am just getting started in this, I
probably will go with a PAR, but by then, I could change my mind and go with a
Exabyte.
Dennis