sbarrkum@csserv2.ic.sunysb.edu (Sereno A. Barr Kumarakulasinghe) (05/30/91)
I want to record whats on a computer screen directly onto a VCR. If the output is in RGB or mono output how would I get about doing this. Would one of those thingys that take the computer output and enable it to be viewed on a TV screen do the trick (what are they called). Thanks Barr Kum
CDO@ibm-b.rutherford.ac.UK (Chris Osland) (05/30/91)
On 30 May 91 07:21:53 GMT you said: > >I want to record whats on a computer screen directly onto a VCR. >If the output is in RGB or mono output how would I get about >doing this. > >Would one of those thingys that take the computer output and enable it >to be viewed on a TV screen do the trick (what are they called). > >Thanks > >Barr Kum > There's been a lot on this in the last couple of months. Briefly, the options: 1. Use a camera; loads of quality problems. 2. Use a standards convertor; loads of money. 3. Use a system that produces an NTSC (US,Japan) or PAL (rest of the world) compatible RGB signal and put it through an NTSC/PAL convertor. 4. Use a system that produces an NTSC or PAL composite signal direct. A plea for sanity on this: the majority of output viewed on a high-res screen IS NOT SUITABLE for recording onto videotape. Realize that to get a watchable sequence (as opposed to a session transcript) you will almost certainly need (a) to junk most of the text (b) to alter the colours to less saturated ones (c) to thicken or junk loads of thin lines (d) to reduce the usual multi-focus arrangement of windowed screens down to one where there is a single area of interest. Cheers Chris Osland Head of Computer Graphics Rutherford Appleton Laboratory, UK
kskelm@happy.colorado.edu (05/30/91)
In article <1991May30.072153.17869@sbcs.sunysb.edu>, sbarrkum@csserv2.ic.sunysb.edu (Sereno A. Barr Kumarakulasinghe) writes: > > I want to record whats on a computer screen directly onto a VCR. > If the output is in RGB or mono output how would I get about > doing this. > > Would one of those thingys that take the computer output and enable it > to be viewed on a TV screen do the trick (what are they called). A GenLock, and YES.
siri@otc.otca.oz (Siri Hewa) (05/31/91)
In article <1991May30.072153.17869@sbcs.sunysb.edu> sbarrkum@csserv2.ic.sunysb.edu (Sereno A. Barr Kumarakulasinghe) writes: > >I want to record whats on a computer screen directly onto a VCR. >If the output is in RGB or mono output how would I get about >doing this. > >Would one of those thingys that take the computer output and enable it >to be viewed on a TV screen do the trick (what are they called). > >Thanks > >Barr Kum First you have to find out about your computer o/p got TTL RGB, or Linear RGB(1 volt pp). If you got linear, then to transfer that into composite video,which you can record on a vcr, you need a Encoder. Encoder can be NTSC, or PAL. Depend on what format you want to record. If you want good quality, then buy a industrial Video Encoder. Otherwise you can design one by your self. There are lots of video encoder IC,s on the market. TTL RGB, only need to cut down to 1 volt level,before you feed into a video encoder. Siri Hewawitharana. |||| OTC || Network R&D Australia. siri@otc.otca.oz.au
drw900@viz.anu.edu.au ("Drew R Whitehouse") (05/31/91)
In article <1991May30.084541.1@happy.colorado.edu>, kskelm@happy.colorado.edu writes: |> In article <1991May30.072153.17869@sbcs.sunysb.edu>, sbarrkum@csserv2.ic.sunysb.edu (Sereno A. Barr Kumarakulasinghe) writes: |> > |> > I want to record whats on a computer screen directly onto a VCR. |> > If the output is in RGB or mono output how would I get about |> > doing this. |> > |> > Would one of those thingys that take the computer output and enable it |> > to be viewed on a TV screen do the trick (what are they called). |> |> A GenLock, and YES. You wouldn't happen to an amiga person, or maybe SGI ? In general a genlock is NOT all you need, unless you happen to be lucky enough to have a machine that already can generate NTSC/PAL signal. If you are, you need an RGB->composite covertor (and possibly a genlock ). If you don't have a machine that produces video signal you need a "scan covertor" that filters a hires signal down to video resolution and put's it in a NTSC/PAL format. (quite a bit more expensive than a genlock). Sometimes another alternative (depending on your application) is to buy another framebuffer for your machine that produces video (eg Vista boards for PC's). Drew PS anyone, correct me if I'm wrong, I just going through all this myself. Anyone care to explain the difference between a sync signal and a BB (blackburst) signal. // Drew Whitehouse, E-mail: drw900@anusf.anu.edu.au // Visualization Group, Fax : +61 (0)6 247 3425 // Australian National University, Phone : +61 (0)6 249 5985 // Supercomputer Facility. // GPO Box 4, Canberra ACT Australia 2601.
chughes@unix1.tcd.ie (Conrad Hughes) (05/31/91)
In <1991May30.072153.17869@sbcs.sunysb.edu> sbarrkum@csserv2.ic.sunysb.edu (Sereno A. Barr Kumarakulasinghe) writes: >I want to record whats on a computer screen directly onto a VCR. >If the output is in RGB or mono output how would I get about >doing this. >Would one of those thingys that take the computer output and enable it >to be viewed on a TV screen do the trick (what are they called). Modulator? Yep. The one problem you may find is that the modulator outputs at the same frequency as your VCR, in which case you may see a perfect image on the TV, thru the VCR, but the VCR itself is not tuned to the modulator correctly, and so it records an untuned image. There's generally a twiddly bit somewhere which changes the frequence your VCR / the modulator works on. If the mono is composite video (or are you in the states - dunno what output you use if you are), you may be able to plug that straight into your VCR - have a look in the VCR manual if you have a SCART (or any other) socket on the VCR; it might tell you. What I'd love is the circuit for an RGB -> UHF / CVBS modulator, I hear they're trivialish, but they're quite expensive to buy... I'd also want to hook sound into the UHF o/p... posted on behalf of Merlin Hughes (hughesmp@vax1.tcd.ie) --SICK-- You suffer... But why?
tmkk@uiuc.edu (K. Khan) (05/31/91)
In article <chughes.675656609@unix1.tcd.ie> chughes@unix1.tcd.ie (Conrad Hughes) writes: >In <1991May30.072153.17869@sbcs.sunysb.edu> sbarrkum@csserv2.ic.sunysb.edu (Sereno A. Barr Kumarakulasinghe) writes: > >>I want to record whats on a computer screen directly onto a VCR. >>If the output is in RGB or mono output how would I get about >>doing this. ^^^ > >>Would one of those thingys that take the computer output and enable it >>to be viewed on a TV screen do the trick (what are they called). > >Modulator? Yep. Nope. A modulator takes a COMPOSITE NTSC video signal and modulates it with a carrier for a particular TV channel, e.g. channel 3 or 4. The original poster wants to convert an RGB video signal, which requires somethig considerably different than a modulator. What Sereno really wants is a scan converter which turns the RGB signal into a composite NTSC signal which can then be piped driectly into the input on the VCR (no RF modulator is necessary; in fact, the use of a modulator will lessen the picture quality). Sereno, if you give us more specifics as to what type of computer and video display you want to record, I or others might be able to give you more specific pointers to devices which will help you.
henry@cs.arizona.edu (Tyson R. Henry) (05/31/91)
There are several ways to convert computer screens into video. Many vendors sell boards that output NTSC video. For example, I think you can get one for the mac for hundreds of dollars and one for the Iris for about a thousand. There are also some new VCRs and laserdisk recorders that have RGB input. One possible problem with these is that they have to match the scan rate of your computer (while RGB is a standard, the rate at which screens are drawn is NOT a standard, everything is different). I have not tried contacting the manufacturers of these machines. It would be best to get a demo and make sure it works with YOUR computer before you buy one. I think these machines start about $1-2k. There are different grades of NTSC video. For example the board that plugs into the mac does not produce very good video. Once again, try to get a demo so you know what you are getting into. There are several companies that make general scan converters that claim to be able to take any RGB input and produce NTSC. Some names: RGB Spectrum -- $14,995 2550 9th St. Berkeley, CA 94710 TEL: (415) 848-0180 FAX: (415) 848-0971 Lyon Lamb Video Animation Systems, Inc. -- $24,950 4531 Empire Ave. Burbank, CA 91505 Tel: (818) 843-4831 Fax: (818) 843-6544 Folsom Research Inc. 526 East Bidwell St. Folsom, CA 95630 Tel: (916) 983-1500 FAX: (910) 997-0955 I have seen a demo of the Lyon Lamb converter. It produces broadcast quality NTSC and can pan and zoom across the screen. Since NTSC is such a poor standard it is important to be able to pan and zoom so you can zoom in to show details. The pan and zoom can be change under program control through an RS232 port. I have not seen demos of the other machines, but I have heard that they are not as good as the Lyon Lamb--they do not produce "broadcast quality." We got an on site demo of the Lyon Lamb, all we had to pay was the federal-x. The demo came from a company that rents them, so depending how much you need to use it, it might be worth renting it and having it shipped fed-x. I don't know the name of the rental co, so try calling Lyon Lamb. `Tyson Henry (henry@cs.arizona.edu)
yeidel@tomar.accs.wsu.edu (Joshua Yeidel) (06/01/91)
Another scan converter in the same general class as the Lyon-Lamb: Chromatek 9120 Down Converter sold in the USA by: Qutron PO Box 105 Allendale,NJ 07401 (201) 327-3259 This is also a multi-sync autosync wide-range (15khz-128khz) scan converter. The main difference between this $24K machine and the lower-priced ones (about $15K) is the pan and zoom flexibility. This machine has similar capabilities to the Lyon-Lamb, but is smaller, draws 2 amps rather than 10, and has 1 fan instead of six. I have no connection with Chromatek or Qutron except that we just bought one and are happy with it so far.
siri@otc.otca.oz (Siri Hewa) (06/03/91)
> >PS anyone, correct me if I'm wrong, I just going through all this >myself. Anyone care to explain the difference between a sync signal >and a BB (blackburst) signal. > >// Drew Whitehouse, E-mail: drw900@anusf.anu.edu.au >// Visualization Group, Fax : +61 (0)6 247 3425 >// Australian National University, Phone : +61 (0)6 249 5985 >// Supercomputer Facility. >// GPO Box 4, Canberra ACT Australia 2601. BB signal is as it indicated,Black composite signal with no Luminance, and Chroma signal. You need this signal for Genlock if there is no internal SPG (Sync Pulse Genarater).What it does is take the subcarrier/ Horizonatal Phase relation to derive the required sync,and phase values. I try to explain this simply as I could, but it is not easy to explain how Pal signal is constructed with few lines. BB signal got subcarrier as well. But sync signal may not have subcarrier signal. Siri Hewa. |||| OTC || Network R&D
tegen@isy.liu.se (Claes Tegenf{lt) (06/03/91)
henry@cs.arizona.edu (Tyson R. Henry) writes: >There are several ways to convert computer screens into video. Many vendors >sell boards that output NTSC video. For example, I think you can get one for I think it could be worth the effort to take a look on the Amiga, it was built around video signals... It has several broadcast quality video boards, including the amazing Video Toaster! (It's one of a kind). It all depends on what the demands are. But if you are talking about $20000 as some do, then you could buy a couple of Amigas with Video Toaster, genlocks and ... and still have some dollars left to take a vacation for! /Clas -- ------------------------------------------------------------------------- | Clas Tegenfeldt | tegen@isy.liu.se | "Magic cooking software". | -------------------------------------------------------------------------
sbarrkum@csserv2.ic.sunysb.edu (Sereno A.Barr Kumarakulasinghe) (06/05/91)
Here are the replies (in no particular order) that I recieved and that were
posted in reply to my query as to how Id record what was on a computer screen
directly onto a VCR.
Thanks everbody and sorry that I could not thank everyone individually.
___________________________________________________________________________
From: drw900@viz.anu.edu.au ("Drew R Whitehouse")
In article <1991May30.084541.1@happy.colorado.edu>, kskelm@happy.colorado.edu writes:
|> In article <1991May30.072153.17869@sbcs.sunysb.edu>, sbarrkum@csserv2.ic.sunysb.edu (Sereno A. Barr Kumarakulasinghe) writes:
|> >
|> > I want to record whats on a computer screen directly onto a VCR.
|> > If the output is in RGB or mono output how would I get about
|> > doing this.
|> >
|> > Would one of those thingys that take the computer output and enable it
|> > to be viewed on a TV screen do the trick (what are they called).
|>
|> A GenLock, and YES.
You wouldn't happen to an amiga person, or maybe SGI ? In
general a genlock is NOT all you need, unless you happen to be lucky
enough to have a machine that already can generate NTSC/PAL signal. If
you are, you need an RGB->composite covertor (and possibly a genlock
).
If you don't have a machine that produces video signal you
need a "scan covertor" that filters a hires signal down to video
resolution and put's it in a NTSC/PAL format. (quite a bit more
expensive than a genlock). Sometimes another alternative (depending on
your application) is to buy another framebuffer for your machine that
produces video (eg Vista boards for PC's).
Drew
PS anyone, correct me if I'm wrong, I just going through all this
myself. Anyone care to explain the difference between a sync signal
and a BB (blackburst) signal.
// Drew Whitehouse, E-mail: drw900@anusf.anu.edu.au
// Visualization Group, Fax : +61 (0)6 247 3425
// Australian National University, Phone : +61 (0)6 249 5985
// Supercomputer Facility.
// GPO Box 4, Canberra ACT Australia 2601.
________________________________________________________________________
From: siri@otc.otca.oz (Siri Hewa)
First you have to find out about your computer o/p got TTL RGB, or Linear RGB(1
volt pp).
If you got linear, then to transfer that into composite video,which you can
record on a vcr, you need a Encoder. Encoder can be NTSC, or PAL. Depend on what
format you want to record.
If you want good quality, then buy a industrial Video Encoder. Otherwise you
can design one by your self. There are lots of video encoder IC,s on the
market.
TTL RGB, only need to cut down to 1 volt level,before you feed into a video
encoder.
Siri Hewawitharana.
|||| OTC ||
Network R&D
Australia.
siri@otc.otca.oz.au
_____________________________________________________________________________
From: chughes@unix1.tcd.ie (Conrad Hughes)
Message-ID: <chughes.675656609@unix1.tcd.ie>
Modulator? Yep. The one problem you may find is that the modulator outputs
at the same frequency as your VCR, in which case you may see a perfect
image on the TV, thru the VCR, but the VCR itself is not tuned to the
modulator correctly, and so it records an untuned image. There's generally
a twiddly bit somewhere which changes the frequence your VCR / the modulator
works on.
If the mono is composite video (or are you in the states - dunno what
output you use if you are), you may be able to plug that straight into
your VCR - have a look in the VCR manual if you have a SCART (or any
other) socket on the VCR; it might tell you.
What I'd love is the circuit for an RGB -> UHF / CVBS modulator, I
hear they're trivialish, but they're quite expensive to buy... I'd also
want to hook sound into the UHF o/p...
posted on behalf of Merlin Hughes (hughesmp@vax1.tcd.ie)
--SICK--
You suffer... But why?
___________________________________________________________________________
From: henry@cs.arizona.edu (Tyson R. Henry)
Message-ID: <3779@optima.cs.arizona.edu>
There are several ways to convert computer screens into video. Many vendors
sell boards that output NTSC video. For example, I think you can get one for
the mac for hundreds of dollars and one for the Iris for about a thousand.
There are also some new VCRs and laserdisk recorders that have RGB input. One
possible problem with these is that they have to match the scan rate of your
computer (while RGB is a standard, the rate at which screens are drawn is
NOT a standard, everything is different). I have not tried contacting the
manufacturers of these machines. It would be best to get a demo and make
sure it works with YOUR computer before you buy one. I think these machines
start about $1-2k.
There are different grades of NTSC video. For example the board that plugs
into the mac does not produce very good video. Once again, try to get a
demo so you know what you are getting into.
There are several companies that make general scan converters that claim to
be able to take any RGB input and produce NTSC. Some names:
RGB Spectrum -- $14,995
2550 9th St.
Berkeley, CA 94710
TEL: (415) 848-0180
FAX: (415) 848-0971
Lyon Lamb Video Animation Systems, Inc. -- $24,950
4531 Empire Ave.
Burbank, CA 91505
Tel: (818) 843-4831
Fax: (818) 843-6544
Folsom Research Inc.
526 East Bidwell St.
Folsom, CA 95630
Tel: (916) 983-1500
FAX: (910) 997-0955
I have seen a demo of the Lyon Lamb converter. It produces broadcast
quality NTSC and can pan and zoom across the screen. Since NTSC is
such a poor standard it is important to be able to pan and zoom so you can
zoom in to show details. The pan and zoom can be change under program
control through an RS232 port.
I have not seen demos of the other machines, but I have heard that they
are not as good as the Lyon Lamb--they do not produce "broadcast quality."
We got an on site demo of the Lyon Lamb, all we had to pay was the federal-x.
The demo came from a company that rents them, so depending how much you need
to use it, it might be worth renting it and having it shipped fed-x. I don't
know the name of the rental co, so try calling Lyon Lamb.
`Tyson Henry (henry@cs.arizona.edu)
____________________________________________________________________________
From: tmkk@uiuc.edu (K. Khan)
Message-ID: <1991May31.153543.14820@ux1.cso.uiuc.edu>
In article <chughes.675656609@unix1.tcd.ie> chughes@unix1.tcd.ie (Conrad Hughes) writes:
>In <1991May30.072153.17869@sbcs.sunysb.edu> sbarrkum@csserv2.ic.sunysb.edu (Sereno A. Barr Kumarakulasinghe) writes:
>
>Modulator? Yep.
Nope. A modulator takes a COMPOSITE NTSC video signal and modulates it
with a carrier for a particular TV channel, e.g. channel 3 or 4. The
original poster wants to convert an RGB video signal, which requires
somethig considerably different than a modulator.
What Sereno really wants is a scan converter which turns the RGB signal
into a composite NTSC signal which can then be piped driectly into the
input on the VCR (no RF modulator is necessary; in fact, the use of a
modulator will lessen the picture quality).
Sereno, if you give us more specifics as to what type of computer and
video display you want to record, I or others might be able to give you
more specific pointers to devices which will help you.
___________________________________________________________________________
From <@CUNYVM.CUNY.EDU:CDO@IBM-B.RUTHERFORD.AC.UK> Thu May 30 07:54 EDT 1991
There's been a lot on this in the last couple of months.
Briefly, the options:
1. Use a camera; loads of quality problems.
2. Use a standards convertor; loads of money.
3. Use a system that produces an NTSC (US,Japan) or PAL
(rest of the world) compatible RGB signal and put it through
an NTSC/PAL convertor.
4. Use a system that produces an NTSC or PAL composite signal
direct.
A plea for sanity on this: the majority of output viewed on
a high-res screen IS NOT SUITABLE for recording onto videotape.
Realize that to get a watchable sequence (as opposed to a session
transcript) you will almost certainly need
(a) to junk most of the text
(b) to alter the colours to less saturated ones
(c) to thicken or junk loads of thin lines
(d) to reduce the usual multi-focus arrangement of windowed
screens down to one where there is a single area of interest.
Cheers
Chris Osland
Head of Computer Graphics
Rutherford Appleton Laboratory, UK
_____________________________________________________________________________
From sbender@dsd.es.com
At the very least, you will need to get your hands on an NTSC encoder which
combines RGB component video into NTSC composite video... If you're expecting
to buy one of these, prices vary greatly (as does quality) from about $1500
to $20000 (wow!).
Additionally, most NTSC encoders will only accept RS-170/RS-170A (USA) or PAL/
SECAM (europe) signals which are 640x484, 30 Hz, interlaced (horizontal timing
of 15.7 KHz, or pixel frequency of 12.2 MHz).
If you are using a higher resolution monitor and/or one that uses a 60 Hz. non-interlaced signal, your problem becomes much more difficult to solve.
Commercial boxes exist to solve this problem but they are difficult to come
by and quite expensive.
E-mail me if you need more specific information and I'll try and dig it up.
Best Wishes!
-Steve Bender: Evans & Sutherland-
___________________________________________________________________________
From: "Dwight D. Moore" <DWIGHT@geohub.gcn.uoknor.edu>
They are called scan converters and there are different types depending on what
you want,
how much you can spend and what type of computer you are using. For PC's, there
is
ususally a board you can by and install to do the trick. For workstations, you
can either
buy a board (sometimes the workstation maker has this type of add on board) or
you
can buy a scan conversion box that sits between the computer and the monitor
that
sends a signal to the monitor and another device, i.e. the VCR. (of course these
are more
expensive). One word of warning, standard VHS taping, as opposed to beta or
Super-VHS
is much like a TV monitor in that the resolution is low (~524 scan lines) and
recording off
of a higher resolution monitor, much detail is lost, especially in text and thin
lines.
----------------------------------------------------------------------------
Dwight D. Moore
Geosciences Computing Network
University of Oklahoma
dwight@geohub.gcn.uoknor.edu (129.15.40.10)
disclaimer ()
{
if ((fp = fopen("mail", "w+")) == NULL) exit (1);
fprintf (fp, "This is my opinion.\n");
fprintf (fp, "This does not represent the opinion of OU or the GCN\n");
fclose (fp);
}
----------------------------------------------------------------------------
From: sundare@SPUNKY.CS.NYU.EDU (Venkataraman Sundareswaran)
What you need is a box that takes RGB input and converts it into
NTSC (the video transmission standard).
-Sundar
____________________________________________________________________________
From: John T. West <surfer@ERC.MsState.Edu>
WARNING!
>From the tone of your message, you appear to think that this will be
simple. To reproduce high quality computer graphics on video tape
requires money and patience. It is not easy!
Of course, if quality is not a big deal, you simply get a camera,
position it the proper distance away from the screen, and start
recording.
hangin' ten:
-John West- MSUNSFERC4CFS surfer@erc.msstate.edu
Engineering Research Center for Computational Field Simulation
Mississippi State University ***** National Science Foundation
P.O. Box 6176 (601) 325-2904 (my voice) x8278 (secretary)
Mississippi State, MS 39762 (601) 325-7692 (fax)
Street address: 2 Research Boulevard, Starkville, MS 39759
..............................................................
"Ours is not to reason why, but just to do and die"
"`forward,' he cried from the rear, and the front rank died"
- the appropriate sources
hangin' ten:
-John West- MSUNSFERC4CFS surfer@erc.msstate.edu
Engineering Research Center for Computational Field Simulation
Mississippi State University ***** National Science Foundation
P.O. Box 6176 (601) 325-2904 (my voice) x8278 (secretary)
Mississippi State, MS 39762 (601) 325-7692 (fax)
Street address: 2 Research Boulevard, Starkville, MS 39759
..............................................................
"Ours is not to reason why, but just to do and die"
"`forward,' he cried from the rear, and the front rank died"
- the appropriate sources
______________________________________________________________________
From: Eddie McCreary <acsls@Menudo.UH.EDU>
RBG to NTSC converters and yes they would do the trick. Unfortunately
I hear they cost on the order of $ 10k-12k.
--
Eddie McCreary |In the midst of the word he was trying to say,
EMcCreary@uh.edu, Internet|In the midst of his laughter and glee,
EMcCreary@UHOU, BITNET |He had softly and suddenly vanished away--
University of Houston |For the Snark _was_ a Boojum you see.
__________________________________________________________________________lew@debra.doc.ca (Lew Stelmach) (06/06/91)
When confronted with the same problem we purchased a VGA board that has an NTSC output in either RGB, NTSC composite, or S-VHS. The board is cheap ($800 Canadian) and works very well. It is called the Willow TVGA board. It will also overlay your VGA video on top of an incoming NTSC video signal. Highly recommended. Lew Stelmach -- --------------------------------------------------------------------- Lew Stelmach, Ph.D. | Communications Research Centre (613) 998 2005 voice | 3701 Carling Ave.