Note: in this document, the terms 'VGA' and 'SVGA' are used somewhat interchangeably. However, strictly speaking:
There are boards for your PC that will take NTSC/PAL and put it into a window.
There are also stand-alone boxes that will allow you to view NTSC/PAL on a VGA computer monitors. One example is the Z64 V-Box. I have no idea how well it performs. However, from the specs, it would appear to have a limited color resolution (only Y:U:V 4:2:2) so while adequate for some games, it may display annoying contours for continuous tone images.
What you may find in the end is that your $150 TV gives you a better picture.
(The following from: Stan Rohrer For cards as well that take NTSC and put it into a window on your PO:
Check in the PC mail-order catalogs and your local PC parts outlets.
There are a number of TV boards and frame grabber boards that do what you
want. Prices start (I think) around $150. Professional level conversion
boxes soar above there somewhere.
I've just started investigating such devices. PC Zone (800-258-2088
for orders/catalog) and MicroWarehouse (800-367-7080) carry Computer Eyes
and TelevEyes by Digital Vision. Prices here range from $300 to $600 with
the highest reported to include genlock and overlay capability.
PC Zone has an AITech TV board for $150. I don't know if it will take
NTSC video input or not. One of the guys I work with just bought an (unknown
brand) TV board that takes NTSC but he doesn't have it installed yet.
While VGA usually expects separate H and V sync - it looks like SCART
has them only in combined (composite) form but many monitors and video
projectors will accept either.
(From: Someone who wishes to remain anonymous.)
I just bought a box that lets me view PAL/NTSC output from a VCR or
DVD player on an old (but big) VGA monitor I had spare.
It's called the Gamars V-box. (Gamars
and
Gamars Europe) Inside
it has a Philips SAA7111 and an Averlogic AL250 IC. Inputs are composite
video and S-video, autodetecting PAL or NTSC. Output is VGA.
The quality is great. The only problem is that playing an NTSC disc
in my PAL DVD player causes the DVD player to output PAL at 60 Hz. This
fools the V-box into engaging NTSC mode, which results in a black and white
picture.
The box was inexpensive, about $40 or so. Cheap importer:
Golden
Shop VGA Box Page.
(From: Jerry Penner (jpenner@sentex.net).)
You want to connect a Herc Mono TTL monitor to a composite video signal?
Can you say 'Big Waste of Time and Effort'? If you want a black and orange
or black and green TV screen, connect your RCA video output on your VCR
to the input of a composite CGA monitor. These monitors were used on Sanyo
MBC computers, and early Apple clones as well as some XT's. Colour composite
CGA monitors used to be used on C-64 and Vic-20 computers. Their usefulless
as TV/game monitors is legendary, and you'll be lucky to find a used one
for under CDN$80.
I have a Magnavox CM8762-074T RGB Color Monitor which accepts both CGA
TTL and NTSC color composite video inputs. Locating monitors of this type
may be an alternative to video format conversion. These may be available
for next to nothing as the owners have upgraded and are often not interested
in (or aware of) their present utility. They are often of relatively high
quality and display a very nice picture since their original intended resolution
is similar to that of NTSC. I use the Magnavox CM8762-074T for testing
of VCRs and other baseband video sources.
Some (mostly older high-end) monitors will accept multiple input types
like VGA, EGA, and composite. Some examples are: Mitsubishi AUM1371/81,
Tatung CM1495, Princeton Ultra-14, and NEC MultiSync. These can select
between VGA and EGA input (either a switch or cable) and the Mitsubishi
(at least) will also accept composite (NTSC) video.
The scan rates differ by a significant factor. If you can program your
VGA card for the monitor's horizontal scan rate (around 15.734 Hz - similar
to NTSC in the case of CGA), then the remaining problem is converting from
analog to TTL. This will require some high speed comparators and logic.
If it's a true CGA monitor, there simply is no practical way to use
it with a VGA card. Period. If it's one of the original multisyncs that
happens to work with CGA, then there's some hope. However, these weren't
so common: Sony 1302, Mitsubishi AUM1381 or Diamond Scan, plus a few others).
In this case, you just need the proper cable and the appropriate switch
settings for the monitor.
Well, what happens is that the display is quite acceptable other than
the fact that there are two of everything on the screen indicating timing
problems. Covering the right side of the screen with a sheet of paper works
to cure the problem but a more acceptable solution is needed.
Adjustments to the monitor frequency, width, phase, H-hold, etc. don't
help." Note that CGA outputs TTL level signals (0 to 3-5V) and VGA outputs
analog levels (.7 V p-p). Therefore, what you have done may not work in
any case if the monitor expects strictly a TTL input. However, your monitor
must be compatible with the VGA levels.
The monitor would have to sync at double its normal scan rate for the
picture to properly fill the screen. First, it would be difficult to modify
the monitor for such a substantial change in horizontal scan rate. Second,
and more importantly, any such change could compromise the safety - stressing
the monitor's circuitry - increasing the risk of failure and the possible
fire hazard. Therefore, I would not recommend even making the attempt unless
you are quite knowledgeable in the design of monitor deflection circuits
and power supplies.
One other option other than replacing the video card or the monitor
would be to determine if your PC is capable of putting out CGA scan rate
video. Many video cards do have this capability not so much for CGA as
for NTSC/PAL compatibility. However, some programming or use of special
video drivers (software) may be required.
Alternatively, you may be able to find an inexpensive card that would
be able to provide the correct timing or even some old CGA cards that no
one wants anymore. Also, monochrome video rates are 18.43 kHz. If you can
find some MGA cards, you may be able to tweek the monitor that far.
Actually, for your intended application, painting over one half of the
screen isn't such a bad idea. :-)
A scan converter can be used on the analog signals once they are generated
to adapt the video to your monitor. However, I don't know if scan converters
with suitable input and/or output capabilities exist.
The digital to analog conversion can be done with a few resistors if
you are not terribly fussy about the quality. For example, the following
circuit should be able to generate a reasonable VGA signal from a 2 bit
input (e.g., MGA or one of the EGA color channels):
I have not tested this circuit. Using low value pullups on the TTL signals
(say 220 ohms) should help improve the high level consistency.
(From: Jack Schidt (jack@wintel.net).)
Most questions regarding changing or using VGA signals in non-standard
(PC) methods, is answerable only by consulting either:
However, this is not always simple! You will have to obtain the specs to have any idea of whether what you
want to do is possible. These are very often high resolution with a typical
horizontal scan rate of 64 kHz.
There are several issues:
If it is fixed frequency, you will be able to use it only in your high
resolution (probably) applications. Booting the PC will require a normal
VGA monitor for the messages to be seen.
You need to determine what its expected H and V rates are to see if
they fall within the range of the video card. Some internal twiddling may
be possible depending on the monitor. Also, the software size adjustment
in the ATI Install program also affect rates so that adds another couple
of degrees of freedom.
If you need to combine the H and V sync, a TTL gate, single transistor
circuit, or sometimes just a couple of resistors will do it.
For example, if you are able to program your video card for negative
sync polarity, then an AND gate (which will act as an OR for negative logic)
should do it. For positive sync polarity, a NOR gate or NPN transistor
will work. It is also possible to build an auto-polarity switching circuit
to accommodate any combination of positive and negative sync polarities.
In some cases, just using a resistor in series with each sync line will
be enough.
(From: Exar (exar@aol.com).)
For any type of video converters call ALTINEX,INC. in California 714-524-5400
they make a device that will combine sync, separate sync, put it on Green,
shift image left or right. Product name is DA1910SX. I have several of
them for my PC, MAC SGI and SUN.
See the documents: "Fixed Frequency Monitor FAQ" and "Sync-On-Green
PC Video FAQ" for details.
Some monitors have the required circuitry to accept separate sync internally
that is not brought out for a particular model. In this case, some careful
exploration may reveal hidden treasures. There are video cards designed for just this purpose. Whether the investment
is worth it compared with a new PC compatible monitor is questionable IMO.
See the document: Notes
on Approaches to Using Fixed Frequency Monitors on PCs for additional
information and names of companies who manufacture the special video adapters.
Has anyone ever managed to do this? Any opinions on whether or not it
is possible?" This would require changing the horizontal scan rate by a large amount
and is unlikely to be easily accomplished without extensive modifications
to the monitor's circuitry. This should not even be attempted unless you
are knowledgeable in the design of monitor deflection circuits and power
supplies.
For other Apple (MacIntosh) monitors, see the section: VGA
to Fixed Frequency Monitor (3, 4, or 5 BNC Connectors) as most of these
run at a fixed frequency. For example, the Mac II rate is 35.0 kHz H and
66.67 Hz V.
(From: James Willcox (jwillcox@spitfire.net).)
Boca makes an adapter. I have one and it works fine. It has little switches
on it to select resolution and refresh rate.
The most important thing is to get the sync pin(s) connected and the
horizontal scan rate as close to the required value.
There is much more info and links at:
It is a CGA frequency only monitor. It has an 8 pin analog jack on the
back and may have a 5 pin ttl jack and ttl to analog converter inside for
standard CGA, you can use a cable for the analog plug to a 9 pin d plug
for MCGA and get 320 x 200 by 16 Million colors. Some IBM cards will put
out the correct frequency and analog signal, most won't. I used an ATI
Wonder VGA card that would work correctly *if* manually configured.
Otherwise you need a VGA to NTSC converter. See the section:
VGA
to TV - NTSC or PAL for more information.
(From: Jon Jenkins (jenkinsj@ozy.dec.com).)
I use standard 74HC DIP gates available from any electronics store.
I use a 14 pin DIP socket originally so that I could change gate types
(OR/XOR/AND) easily. 74HC86 (XOR) works just great with the VR320 (I am
using it now can also use OR, don't understand why ??).
The VN10KM is a small signal N channel enhancement mode MOSFET also
available from most electronics store.
If the video card you are using is a standard VGA output (I'm using
a diamond stealth 64 VRAM):
Just a note, when you set up your video card in Windows (or Win95) set
it to 1280x1024x72|66 or whatever is closest. I use a VR260 (1024x864)
at 1027x768@66Hz (check with your manual DA or D4 are 72Hz) your VGA will
not like this frequency so either disconnect it quickly or before you actually
set the video card to this mode (i.e. put the OK as the active control
in Windows and then connect the VR320 and hit return) My diamond setup
gives me 10 seconds to do this adjustment When you exit you will probably
have to select the 1280x1024 mode with your old VGA connected again and
from then on every time you start Windows you will be able to view it in
"big" colour mode. Note the vr320 will not work in DOS mode as it is not
an auto-scan monitor so all you see when you boot up is garbage until Windows
starts, I put "win" in my autoexec.bat file.
Note there is a danger here: I had set up the monitor and for some reason
it did not work so I couldn't see what was going on: my old VGA wouldn't
work and the VR wouldn't work either so I had to find the cards .ini files
and edit by hand to get back to usable video!!
For FreeBSD/XF86 the lines are:
Notes:
Gate type=LS or HC types, HC preferred:
Use XOR gate with DEC monitors and as a first shot with others, then
OR gate then NAND gate.
Get an oscilloscope and adjust porch levels to 0.3V and 0 level (sync
level) to 0.0V
For example:
(From: Brian B Some other possibilities may be: ADV7175/ADV7176, UPC1352 (ECG/NTE1416). You can also buy little boxes to do this. Quality is general not great
as you are seriously limited by the NTSC/PAL standards. Even with S-video
inputs to a TV or and S-VHS VCR played on a high-end TV, don't expect to
be able to throw away your computer monitor!
Here's one link to check:
(From: Tomi Holger Engdahl (then@neppari.cs.hut.fi).)
There is all sorts of information relevant to video at:
Homebuilt circuit persons should take a look at:
For introduction to scan conversion, check
NTSC/PAL system limit the bandwidth which makes picture to loose some
details. The picture is usually even worse than that, because of the cheap
video encoding chips used in many converters.
(From: Bill Sloman (sloman@sci.kun.nl).)
Try the Analog Devices AD721 and AD722. When I used the AD720, I had
to add a National Semiconductor LM1881 sync separator, and black-level
clamps on the red, green and blue inputs to get the right DC levels.
Check them out at Analog Devices.
(From: Leon Heller (leon@lfheller.demon.co.uk).)
Raytheon has a chip which produces broadcast quality PAL/NTSC from VGA.
I think that Harris does one, as well.
There are a couple of VGA-to-TV converter boxes that also output an
NTSC RGB signal. I own one from UMAX - I think it's called the TV-Mini.
I bought it from Global Computer Supplies for about $175. I also think
that MicroWarehouse sells this product. There's a model sold by AVer also
that has RGB out... but it's over $300.
The UMAX TV-Mini is a small box that plugs into your VGA card... it
also has a female VGA connector on it so you can display images on your
computer monitor and television monitor at the same time. The TV-Mini is
powered by the PC's keyboard connector. It has an RCA jack for composite
NTSC, an S-Video jack for S-video output and a Mini-8-DIN for RGB output...
if you go to UMAX's web page, they'll talk about how the TV-Mini comes
with an RGB SCART cable (SCART is a strange looking connector that's used
on many European televisions) - but it doesn't come with this cable.
I was able to build a small adapter cable with some parts from Digi-Key.
The TV-Mini manual provides the Mini-9-DIN pinouts.
(From: Jerry G. (jerryg@total.net).)
I have played around with a few. The ones in the upper $300 to $400
are not too bad. You will get a reasonable picture. I found the cheap ones
are extremely poor.
The best way to do it is with a video display card that has it built
in. These cards are expensive because the scan rate must be changed. There
is a lot of high speed ram and processing involved to do it right.
It is not a question of movement involved. It is a question of scan
rate conversion that makes things complex. With this conversion there is
the requirement of some complex quantizing to also convert the characters
to match as well. In a lower priced card that I have seen good results
is the ATI card with the NTSC output. I don't know the price of the card,
but it is not cheap...! There is a Targa card that is excellent, but the
price is too high unless you are in the business... But like I said, the
higher the price, I found the pictures get better.
Also, the bandwidth for the fonts, and data comming through the conversion
is extremely wide. It is wider than off of a conventional TV broadcast,
or what comes out of a VCR. The TV set that you use must have a Video Component
input, and be able to handle at least 600 lines resolution or better. If
not, you will be cutting the performance of the signal right at the end!
If your TV has S-Video capability, get the card with that option. It is
better than using encoded NTSC or PAL. The S-Video mode keeps the color
information separate for processing. This allows for a better signal to
noise in the luminance signal, thus rendering cleaner pictures.
Please note, that you will never get the same picture out of a TV video
monitor as your computer monitor. They are based on very different processing
and CRT design. There are VGA Monitor projectors on the market, and I would
consider renting one for the casual use. It will certainly do a much better
job. This is what I recommend and do for my clients. Don't even think about
buying such a projector unless you have a lot of use for it. They are extremely
expensive, and require periodic maintenance.
(From: E. Abel (EugeneA1@worldnet.att.net).)
I've used an ATI 3D Expression+ PC2TV. The S-Video output is not bad,
although text is really not very crisp.
Surprisingly, the TV output from the Canopus Pure 3D card is much better.
Text is actually readable. (this is on a 27" Sony trinitron TV.) The Canopus
card uses a Chrontel chip to do the conversion.
Of course, at $190 the card is a little pricy.
If the game outputs VGA, Raytheon has a chip, the TMC2360, which converts
it to broadcast quality PAL/NTSC video.
"I managed to construct a VGA to RGB converter so far, so I'm almost
halfway there, all I believe I need now is an RGB to NTSC converter circuit,
although i was trying to avoid the cost of buying one they sell in the
PC catalogs."
Can you program your video card to output 15,734 Hz H interlaced scan?
If so, you will have a lot less hassle.
"Is there a minimum & maximum resolution for a TV , or does that
depend on the size of the TV?" If you mean scan lines, that is pretty much fixed at 525 total interlaced
2:1 at 60/30 Hz (625 at 50/25 Hz for PAL 50 Hz systems) with about 420
(540) actually visible on a typical TV. TV's are not auto-scan - they are
designed to run at a single scan rate.
Therefore, even displaying easily viewable VGA resolution will be tough.
A TV with an S-video input may do somewhat better.
(Remember when you had at most 40 characters across on a Commodore?)
(From: FoulDragon (fouldragon@aol.com).)
I'll warn you: You can get a box that will make your PC display on a
TV, but it will not be worth your while. We use them at our school, they
cost from US $100 and up, and the picture, even on a good TV is very poor.
If you can afford one of those boxes, buy a used VGA [even monochrome]
and use that as you will be much happier.
(From: Terry Lin (tlin@servtech.com).)
I find that with the ATI PC2TV, on a S-Video hookup on a Sony XBR, the
image quality is pretty decent. The flicker removal makes even a full white
screen easy to look at (provided you have the contrast turned down, which
should be done on every set). I have seen what poor external boxes can
do, they give me adaches with the flicker and blurriness. Just make sure
your setup is right before evaluating the entire PC to TV monitor thing.
You are much better off getting a bottom-end SVGA monitor for your PC.
As noted, the resolution of a TV or composite monitor is not even good
enough to do justice to VGA (640x480) when using the composite video input.
Direct RGB can be better but the pitch of the CRT relatively coarse dot
or slot mask or aperture grill is then likely to be the limiting factor.
A composite monitor or TV will give you approximately 480-490 lines vertically
but 10 to 15 percent of these may be hidden by the CRT bezel due to overscan.
However, horizontal resolution is much worse. You will be lucky to get
half the VGA resolution (300 to 350 lines). For SVGA, there is simply no
way to display 800 x 600 without expensive scan conversion on such a tube
and you will not be able to read text or display clear graphics. In addition,
since the composite monitor or TV is interlaced, there will be annoying
flicker of graphics with thin horizontal lines.
Save your pennies - prices for basic monitors are dropping. Your Apple
monitor may work fine on your VCR, however.
(From: Jerry Roush (roush_jerry@htc.honeywell.com).)
There is an "inexpensive" device available from JDR Microdevices that
works fairly well, called the AVerKey (JDR part no. VGA-NTSC) They are
about $100. It also has S-video output.
If you would like to experiment, here is a really simple circuit that
may work well enough for combining Hsync, Vsync, and one of the VGA color
signals, say green, into a composite video.
If the monitor sense lines on the VGA connector are tied MS1 (pin 12)
= GND, MS0 (pin 11) = no connect, then some programs will default to monochrome
and use a reasonable color map. I don't know how you will get a reasonable
mapping to monochrome for the others.
All you will need are 4 resistors.
I am calling your connector on the monitor 'Composite Video In'.
Set monitor video termination for Hi-Z. R4 provides the cable termination
to minimize reflections and ghosting of the green video signal.
Set your video card for negative sync polarity.
You may need to tweak these values for best results. This will depend
on your actual signals. The variable R3 may provide enough range for this.
However, some CGA monitors have internal NTSC composite inputs and in
that case, it is simply a matter of flipping the appropriate switch.
See: Tomi Engdahl's (then@neppari.cs.hut.fi) Video chips and circuits
page:
One example is the
Motorola
MC44011.
This part can be used without an external delay line (for PAL to RGB)
but a delay is recommended. The chip also provides an A/D sampling clock
output for video digitizing applications.
It is possible to search the Motorola site from for other parts or application
notes from their Search
Page.
(From: Julie Porter (Julie.Porter@efi.com).)
I was able to get my Sony PVM Monitor to successfully take a YC input
on the RGB port. I used the MC44011 and it worked! However be advised.
The MC44011 has just been announced for last buy this month! March of 1999.
There are no other non digital solutions. The TDA3330 has been unavailable
for some time. There is some additional information on my
Video
Animation Web site. I urge people to call Motorola and ask that this
component, not be discontinued as there are many web references designs
that use it. There are no substitutes. It should also be noted that if
people are considering these designs then they should get the parts soon.
The part will go out of production this fall (1999).
(From: Jeremy Todd (bulb@cix.compulink.co.uk).)
Sony makes at least two PAL decoder chips - CXA1621S and V7021.
It looks like you'd need a separate sync stripper (LM1881 or EL4581CN)
Brooktree's Bt812KHF is a much fancier thing for video processing and
multimedia stuff.
From RS(UK) both the Sony chips are 10UKP each for 1 off's. The Bt812KHF
is 107UKP!!
(From: Sam).
Also, some questions are along the lines of the following:
The answer is: MC44011 by Motorola, cost $28(Can). It requires some
sort of a micro to program it (PIC or the like will do).
There is no external critical components except for a 14.318MHz crystal
(found on any PC motherboard).
About the old TV single-chip decoders. This is not true, I've been working
with those things for 15 years, and in 70-80s the decoders were much more
complicated than they are now (each decoder, actually, requires a delay
line (sometimes more than one) and a bunch of various filters). Yes, you
had one chip and half a dozen of coils, trim-caps to tune (that required
some equipment and knowledge).
Sorry, the chip I suggest has 44pins :-( but little hassle :-)
Is there the possibility to convert a video to a VGA signal? My NEC
has only a VGA input. Or: Are there any monitors available which have both
inputs (like my old Mitsubishi)?"
"I have a VGA monitor That I want to use to watch TV. I want to be able
to maybe build a box that will let me plug a vcr video out into the monitor.
I do not want to spend tons of $$$$$. Can anyone tell me if there is a
way to do this??"
"I have a HI-FI VHS that is attached to my stereo. Therefore, my audio
needs are well taken care of. I now need the video. I had to sell my TV
a little while ago so I do not have a T.V. at this point. I have recently
acquired a 20" monitor for my PC (DFI brand.) It has the RGB (red-green-blue)
connectors on the back along with a Horizontal and Vertical cable connections.
So I have a cable that plugs into my video board on my PC that turns into
5 connectors at the end that connects to the monitor."
"Does anyone have any information on viewing composite video on SVGA
type monitors. I have a MAGNAVOX SVGA monitor and if possible I'd like
to feed composite video from my VCR and Sony PSX and PANASONIC 3D0 to it.
Rather than getting a Toshiba TIMM monitor there has to be some kind of
blackbox that will allow someone to do this...Please send info to the address
provided or post here." If your PC monitor scans down to 15.734 kHz, then all you need to do
is convert the line level NTSC composite to RGB and sync. Some older auto-scan
monitors like the Mitsubishi AUM1381 even have a composite NTSC input jack.
Conversion requires a single chip and a few discrete components. Commercial
converter boxes are also available.
However, if it is a modern SVGA/auto-scan that does not go below 31.4
kHz, then it is a non-trivial problem requiring a video A/D, frame memory,
readout electronics, video D/A, etc. This is called a scan converter and
is not an afternoon project even for an experienced design engineer.
You can of course buy PC cards that will enable you to watch TV in a
window on you PC.
There are also external boxes that will accept antenna/cable or NTSC/PAL
composite input and drive a VGA monitor. One such unit is the 'Proview'
(Proview Technology, Garden Grove, CA). This is reviewed in Popular Electronics,
June, 1997. It appears to be quite capable with its own internal 181 channel
tuner and IR remote control. It accepts both RF (antenna or cable) and
composite inputs and can select between the video source or computer to
drive the monitor (but does no processing of the computer's VGA signal
- full screen only). With a suggested list price of $119, the Proview could
represent a cost effective alternative to a new TV if you have a VGA monitor
sitting around collecting dust.
Some others can be found at:
In any case, a $150 TV may actually produce a better picture. This is
because the CRT/electronics in a computer monitor is optimized for focus
at the expense of brightness. Therefore, sharpness may actually be excessive
and brightness may be inadequate except under subdued lighting conditions
(especially on a well worn monitor!).
(From: Helmut Weber (Helmut.Weber@hamburg.sc.philips.com).)
There are some companies that have boards ready, which you only have
to buy and plug into your PC. Try:
There are lots of video cards that have video capture and real time
display from RCA phono and S-Video inputs, Matrox Rainbow Runner (which
requires a Matrox Millenium/Mystique 220/G200) or the upcoming Marvel,
the ATI All-In-Wonder and it's decendents.....
There are several other cards that fill this bill. There are external
devices that attach to your parallel ports, or USB port, or Firewire port
which can also do this. Some of the older Diamond monitors also had video
input as well as a computer input but they were quite expensive.
There are chips to do RGB to NTSC or PAL color encoding but not, as
far as I know, scan conversion. For your needs, look into Sony, Philips,
and Analog Devices, Motorola, and others.
See: Tomi Engdahl's (then@neppari.cs.hut.fi) Video chips and circuits
page:
As has been pointed out, using the strict definition of NTSC to PAL
as referring only to the color encoding, all you need is a couple of chips
for NTSC to RGB and then RGB to PAL, maybe even a single chip. However,
for the very common interpretation of NTSC to PAL (IMHO, maybe a little
USA-biased) is with respect to US NTSC 525 line 60 Hz systems to PAL 625
50 Hz systems which is where the non-trivial part comes in.
If what you really mean is NTSC 525/60 Hz to PAL 625/50 Hz, it's not
trivial.
The usual way is to use a scan converter. Essentially, an NTSC color
decoder/A-D feeds a frame buffer (approximately VGA size). The frame buffer
is then read out at PAL rates and the necessary interpolation is performed
using digital processing to go from 525 (480 or so active) to 625 (580
or so active) lines. The output is sent to a video DAC and then color encoded
for the PAL system. Everything all happens in real-time.
Needless to say, this is not your basic hobbiest afternoon project.
Here are some additional comments:
(From: Clive Tobin (tobin@nwus.com).)
Conversion is not a trivial matter, involving interpolating scanning
lines, changing the field rate, and changing the color encoding scheme.
I am not aware of a simple chip set that will do it. There are several
ways of doing it with bought equipment, listed in order of increasing price:
Editor's note: Not all multi-standard VCRs do what you want. Some/many
simply convert the color encoding between NTSC and PAL without affecting
the scan rate (which is much more difficult/expensive). A wide vertical
range TV or monitor might produce a viewable picture with these but at
the wrong speed (off by 5/6 or 6/5 including the sound)! Unless the product
specifications clearly state 'full conversion' or 'scan rate conversion'
or something similar, you can probably assume they take the cheap way out!
Make sure you can return the VCR if it doesn't meet your needs! --- sam. (From: Geoffrey S. Mendelson (geoffm@pita.cs.huji.ac.il).)
There are digital converters that do this "on the fly". Akai (and Radio
Shack in the US) sell a VCR for $500-600 (US) that works well. Panasonic
sells the AG-W1 (NV-W1) that is an excellent VCR and a much better converter
for about $1800.
You can also buy just the converters.
Avoid VCR's that claim to play PAL tapes on NTSC TVs. They convert the
color signal from PAL to NTSC (well enough for the kiddies to watch tapes),
but assume you can "stretch" the sync of your tv to work with 50Hz video.
(From: Tim Jacobs (timothy.jacobs@gecm.com).)
The output from these PAL VCRs won't always record properly, because
they take advantage of the fact that the TV can put up with some signal
variations that a low-bandwidth VCR (such as an ordinary VHS machine) can't.
The other big problem is the higher frame rate of NTSC as opposed to
PAL. In NTSC you have 30 frames per second against PAL's 25. PAL frames
have 100 more lines than NTSC frames. So to convert, you have to drop 5
frames each second, add 100 lines every frame, and then you have to worry
about the Colour!
This is very complicated if you want good quality.
Here in the UK, there is a VCR available from, IIRC, Panasonic, that
will convert between PAL, NTSC, and SECAM (French system). You chose your
input system which is either from socket inputs or the tape play-back,
and your output system which is to socket outputs or tape record. The machine
then does the conversion for you.
The only problems I see with this VCR are, no TV Tuner, and they cost
around 1000 UKPounds.
(From: Chris Hall christopher.hall@bbc.co.uk).)
At a broadcast level, probably the best known TV standards converters
are made by Snell and Wilcox. I have also used a Barco unit. At a PC level,
Vine Micros made a number of boxes for much less money than broadcast kit
which do the conversions between PC (and Mac) video standards and broadcast
ones. (From: Steve Darsey, N5PMB (sdarsey@yahoo.com).) We use a Sony DSC1024G
everyday, does what you ask. Up to 1024x768 to NTSC or PAL video in composite,
component (RGB or Y,RY,BY) and S. It will also go the other way. NTSC or
PAL to a computer monitor. Also does NTSC to/from PAL. It will also do
aspect ratio conversion. Did a letter box from a 16x9 source, no sweat.
I have also seen it used to down-convert HD to SD TV.
The Hyperconverter is very comparable, at the time of our purchase,
it did not do much more than pure scan conversion from the PC to video.
I have no knowledge of their current model.
If price is no object, look for the Fulsom 9000 series boxes. Those
machines can deal with much larger (over 1600x1200) pixel rates and will
probably walk your dog and water the plants. :)
Find an AV rental or convention show production facility and see if
they rent one. We use Alford Media, they have a few locations around the
country.
The typical scan converter must implement the following functions. (This
example applies to a unit designed to convert from SVGA or workstation
video format to NTSC):
For more information on features and selections of scan converters,
try:
Implementing a system of this type is a challenging task even for an
experienced engineer with extensive design experience with both analog
and digital systems.
(From: Derek Roberts (der@cam-orl.co.uk).)
If you really want to do this properly, check out the Genesis Microchip
gmVLD8 which uses DSP techniques to do the un-interlacing. Of course you
need to add an A-D, field or frame store and some control, But this is
the basis of a decent quality scan converter.
The following is described for NTSC; A similar approach can be taken
with PAL 625/50 to SVGA at 800x600, 50 Hz.
To convert NTSC interlaced at 30 frames/second 60 fields per second
to VGA which is at 60 complete non-interlaced frames per second requires
a simple scan converter. This is basically an NTSC color decoder and video
A/D feeding a full frame memory storing RGB (probably at 24 bits), and
VGA video D/A. I say simple to compare it to the general case where in
addition to frame store, you need a high speed interpolator to convert
between resolutions. VGA is close enough to NTSC resolution (at least in
terms of the number of active video lines) that no interpolation is needed.
See the section: What is a Scan Converter?. In either
case, this is a non-trivial project. IMHO, this is a poor use of an expensive
monitor. A $200 TV will likely look better.
An even simpler approach is possible as well which only requires a one
or two line buffers instead of a full frame store. Each input line is read
in and reformatted to the appropriate VGA line (even or odd) depending
on which field is being displayed. The other lines are blanked (i.e., display
even lines and blank the odd lines during the even field display). This
would only require enough buffer memory for one or two scan lines (depending
on whether the implementation uses a double buffer or more sophisticated
write and read timing) which would be a significant cost and complexity
savings compared to a full frame store. The disadvantage is that since
half the lines are by necessity left blank, the maximum possible brightness
of the display will be reduced. It is not possible to use the blank lines
as the interleaving of the even and odd fields will be incorrect and result
in a poor display.
Inexpensive scan doublers do exist. For example:
(From: Jeffrey Kessler (kessler@fas.harvard.edu).)
I picked up a device called the "Video Cheese Box" from a company called
TVOne.
This is a $70 box that acts as a rudimentary line doubler. It takes a composite
or S-Video input and outputs a 640 X 480 60 Hz VGA signal.
The picture is dramatically better than on a regular TV.
I'm in no way affiliated with this company except for having purchased
one of their products.
(From: Richard Birchall (birchallr@aecl.ca).)
AverLogic has a chip that makes
the task of implementing a scan doubler almost trivial. From their product
description: "The
AL250
is a 64 pin single chip scan doubler/de-interlacer. It converts interlaced
TV signals (e.g., NTSC or PAL) into non-interlaced RGB format for output
to a PC monitor or LCD panel. The single device also corrects color accuracy
on different types of CRT and removes jagged edge artifacts from motion
pictures. To allow a regular PC monitor to display television or video
input you just need to add a de-coder and the AL250."
Philips has chips, as does Raytheon, these would take digital RGB and
convert to oversampled PAL output.
(From: Mike Diack (moby@kcbbs.gen.nz).)
Analog devices does a chip (AD720) which has the delay & filter
elements on the chip itself.
The IC is a Video Interlace Processor (VIP), part number VIP-01033.
It converts 16-bit digital VGA video (5:6:5, R:G:B) to similarly formatted
NTSC/PAL compatible video.
The IC can also be bought as part of a circuit board with additional
components, producing composite, Y/C, and SCART analog RGB outputs, in
three different configurations:
This is actually a very interesting subject. Assuming you have a constant
video level (or AGC), a simple diode clamp on the horizontal sync tips
(diode clamp the sync so that the black level is where you want it) is
actually a high quality black level clamp. The sync level is constant after
all. I use this method in accurate video digitizers for DC restoring the
video before putting it into an A/D converter. The cool thing about simple
diode DC restorers is that the capacitance is usually much less than that
of the analog switches needed in other types. For example one of the best
analog switches is the readily available 74HC4316, but even this has 40pF
(if memory serves) on its pins.
The really hard part is finding a high quality large-signal linear video
amplifier. If the video is capacitor coupled to the video amp, then the
average brightness level will change the voltage of the black and sync
levels seen by the amplifier. This is ok if the video amp is linear, but
most aren't so the sync amplitude ends up changing depending on brightness.
I.e., the black level will change depending on the brightness of the image
(this is completely unacceptable for medical image capturing devices, for
example).
The way linearity is measured for video amplifiers is the term "differential
gain". It gives the largest difference in percent between a constant small
amplitude signal (traditionally the color carrier is used for this) measured
at different voltage levels (hopefully which sweep the entire output swing
of the video amplifier).
Now you have to be very careful about manufactures differential gain
measurements. Many of them play games to get even a mediocre 3% - 1% differential
gain. Typically they specify this parameter with a reduced output range
(when you really want the parameter to apply to rail-to-rail output swings
so you can get a 2V signal needed for most A/D converters) or limit the
input range, the gain or flat out lie (I have no idea where comLinear got
the specs for their clc520/522 variable gain amplifier, for example. It
says .5% in the datasheet, but I measure it to be more like 5%).
All older video amplifier ICs (like the uA722 and NE592) are really
lousy. Discrete transistor amplifiers also suck (many monitors use a cascode
amplifier which is very bad). Most new ICs suck too- especially those which
are labeled as video amplifiers. The only ones which I have been satisfied
with are the newest current feedback OP-amps (the + side is high-impedance,
but the - side is zero ohms. Usual op-amps are linear, but have a limited
bandwidth because the - input is high impedance). These have enough open-loop
gain so that they really are linear. One that I really like is the AD9617:
.01% differential gain (!), 160MHz bandwidth, immense slew rate (settles
to less than 1% of final value within 10ns or so) and only costs about
$10.
If you need variable gain (for AGC perhaps), the best chip to use the
AD834 500MHz multiplier. This little 8-pin chip is expensive (like $40)
but it is the only thing that even approaches being linear (and even it
is quite a bit worse than the AD9617).
(From: Brian Campanotti (bcampano@toronto.cbc.ca).)
Look at the Clamping ICs from Gennum Corp (part numbers GB4550 and GB4551).
They do input buffering and clamping. They are a good front end to any
video project.
(From: Mika Iisakkila (iisakkil@alpha.hut.fi).)
Since your application probably needs some kind of an input/output buffer
anyway, you might consider some integrated DC restored video amplifier.
Elantec makes excellent such chips; data sheets are available on their
web site EL2090 is really good as far as video quality goes, but a bit expensive
for applications that don't need 100 MHz bandwidth and near-zero droop.
EL4089 is simpler and cheaper, but not quite "broadcast" quality. There's
also some new chip, but I haven't looked into it yet.
For both chips, you'll need to get the sample pulse from somewhere,
so you can't lose the LM1881. I've used the burst gate output from it to
control 2090's sample input, and quality of the result far surpasses my
measuring instruments.
If you want to also invert the colors, then you have to decode the chrominance
to RGB, invert these, reencode, recombine, etc.
The assumption here is that the input is an NTSC or PAL composite video
signal and that the desired output is a valid composite waveform with negative
sync tips. In this case, what is required is as follows:
For monochrome video, the conversion steps would be replaced with a
simple inverting amplifier and possibly an analog switch to merge the sync.
There may be some shortcuts one can take but you get the picture (no
pun).
(From: Joel Kolstad (kolstadj@CSOS.ORST.EDU).)
Also note that straight video signal inversion will produce some...
interesting... color changes, but not the same changes as you get from
photographic film. For monochrome video, the end result will look like
a photographic negative.
These are also available from surplus electronics outlets for under
$5 or as generic replacements for VCR servicing for $12 to $20.
The only connections required to make them work are a source of regulated
power - 5 to 12 V depending on model and possible s control voltage to
select output instead of pass-through mode.
Most any multisync "VGA" style monitor will work with the GX, TX or
CG3/CG6 frame buffers on a Sun Sparc. Commercial 13W3 cables and adapters
are available or you could get the instructions from a couple of places
on the net.
I use my ViewSonic 17s on both Macs and Suns.
You should have a copy of Birdsall's Sun FAQ and you may wish to join
the Suns-at-Home mail list, for all Sun self-maintainers. Use a search
engine for these and they should vector you to the cable pinouts as well.
Usually the chroma line (C) is passed through a capacitor and tied to
the luma line (Y) after it is passed through a resistor. Usually 470 pF
and 100 ohms.
VGA monitor pinout can be found at:
Composite is better than using an RF modulator and feeding the signal
into the TV tuner but is otherwise the worst of them all.
S-video uses two signal paths, luma and chroma. It's better than composite
video, which mix both together into a single signal.
But component video is better than S-video. With component, you have
three separate signals - usually Y, R-Y, and B-Y. This bypasses the subcarrier
encode/decode process entirely, and gives better quality.
There's also RGB, which is potentially just a bit better than Y/R-Y/B-Y,
but can also be considered a different type of "component".
Here is an example of a homebuilt video digitizer:
If this is not possible then (assuming two sources):
The delay would need to be anywhere up to 1/2 frame (or 1 frame if only
one of the sources can be delayed). Not an afternoon project. For N sources,
you would need N-1 0 to full frame delay units. Also note that commercial
broadcasts will sometimes shift frame reference when cutting between remote
locations which are not genlocked. If these sources are to be supported,
you will need an automatic adjustment scheme to maintain synchronization. This depends on whether they are shooting on video or film. There are
display cards for PC which allow you to dial up the vertical output rate,
which you want to match to either 30Hz( NTSC frame rate) or 24Hz (typical
film frame rate). Multiples are fine, i.e. 60 or 48Hz respectively.
But that isn't the end of it. You may have (approximately) matched the
frame rate of the camera, but you have to also lock them together as there
will be a certain amount of drift due to slight differences in the two
scan (frame) rates. For film there are devices called a Computach or a
Synclock, which attach to the movie camera and take a video input (you
can just feed it sync from your PC card but you may need to fiddle the
level or polarity).
On set, they roll the camera and adjust the shutter phase so the vertical
blanking bars on the PC fall in between movie frames. The synclock then
keeps the camera perfectly synchronized to the PC sync.
If you're shooting on video it's a bit harder. You need to genlock the
video camera to the PC, which can be awkward as the PC sync may not be
quite steady enough (directors HATE having to lock to ANYTHING).
The hardest thing to do is run several PC's in the same shot, because
they won't be scanning in sync; you can lock your camera to only one at
a time. If anyone knows of PC videocards that can be genlocked together
I'd be very interested.
We do a lot of this kind of work and at the end of the day, particularly
if there is more than one PC in shot, we record the computer graphics to
video and use Amiga monitors, because they look like PC monitors but take
video input. We use Umatic or Betacam tapes because the playback machines
can be drum locked together. Obviously though, if you need a high degree
of interactivity with the actor, this won't work too well.
The vertical blanking bar on a PC is quite fine so if they aren't in
the foreground you can usually get away with just matching the vertical
rate of the PC as close as possible to that of the video/film camera. You
won't see flicker, just a fine dark line moving up or down the picture
slowly.
That is about the sum total of my experience but if anyone else has
better suggestions I'd be very interested. I have seen some TV/movies with
multiple computers in shot with no sign of flicker or blanking bars; maybe
the bars are just too fine to show up?
(From: falcon@tao.agoron.com (Tom Strano)
In my personal experience, I've found that simply setting the video
mode on a PC to 640*480, any color depth, and a 60 Hz refresh rate, results
in a very stable picture, even when taped with a cheap consumer camcorder
and no attempt at synchronization. I've done this with at least 3 different
computers, all with different monitors and video cards, and it always works
fine. Perhaps I'm just luckier than some technicians...
One source for info on timing specs is the data sheet for a video DAC
or RAMDAC. They will usually define all of these parameters.
DigiKey lists 74ACT715PC-ND as "Video Synchronous Generator NEW!" It
is a 20 pin DIP and costs $17.50 each for small quantities. The surface-mount
version is SC instead of the PC in the above number. You have to pay an
extra $1 for the datasheet if you want one. 1-800-DIGI-KEY is their order
line. http://www.digikey.com/ is their web address.
(From: (opal@opal.co.il).)
Try philips SAA1101.
Try using the National Semiconductor LM1881 It's a 8 pin DIP that does
exactly what you need.
I think it costs @ $8.00 and you only need a couple of caps externally.
(From: Jan Arvidsson (janarv@algonet.se).)
The EL4583C from Elantec has a dedicated HSYNC output in addition to
CSYNC and VSYNC outputs, available on the less expensive LM1881 (National).
It is of course very easy to derive a pure HSYNC signal from the CSYNC
output!
If you have a composite monitor (probably gathering dust at this point),
then this in conjunction with the otherwise useless VCR will result in
quite a nice TV. Many CGA monitors as well as early auto-scan or multi-scan
monitors have NTSC (or possibly PAL) compatible composite inputs. Some
even have built in speakers. A set of RCA patch cables and you are all
set. Since they were designed for high resolution (at the time) computer
applications, the quality is generally excellent. (Note: I do not make
the same quality claims for modern SVGA monitors as their display is optimized
for high scan rate computer video and not CGA or NTSC). In addition, controls
are usually accessible to permit any desired degree of underscan or overscan.
It may even be possible to use the VCR's timer to turn your rig on and
off automatically! (It just requires faking out the record/cassette interlock
and locating a signal that can be used to control a power relay.
Conserve your landfills - save a VCR!
Sync: separate horizontal and vertical TTL signals. May be either polarity.
It is relatively easy to combine the H and V syncs together and then
combine these with the video (usually the green signal for 'sync-on-green')
but most low cost VGA monitors do not support this mode and you would then
need to separate the signals at the far end. You could come up with alternative
ways of combining the signals to save on cables but these will all complicate
your circuitry at the monitor end. There are multiple coax cables inside
a single sheath for just this purpose.
The five coaxial cables (75 ohm, RG59 typical) are wired as shown in
the table. The corresponding VGA connector pin numbers are in ().
Make sure that the lengths of the cables are fairly well matched - to
within a couple of inches - to assure that the 3 color channels line up
precisely. (One foot of cable is about 1.5 to 2 ns of delay which is significant
for a 10 ns dot clock!).
Also note that you will lose your 'Plug-and-Play' capabilities without
the direct control connections to the monitor (or for monitors without
these features).
That's it!
You will wish that your fingers were about 10 times smaller than they
are, however. :-)
If you insist, the adjustment would be called something like horizontal
oscillator, horizontal frequency, or horizontal hold. If you do tweak,
mark everything beforehand just in case you need to get back to the original
settings.
WARNING: Make sure you understand the issues involved in working inside
a monitor! Something that looks innocent can really ruin your whole day!
There is also some risk to the monitor - changing it too far may result
in damage either immediately (the horizontal output transistor or power
supply may blow) or increase component stress reducing reliability and
shortening its life. There is no way to know without looking at the design.
However, these are digital (TTL) monitors with respect to the video
inputs and proper linear video amplifiers may not even be present. Therefore,
you may need to implement both the NTSC or PAL decoding as well as boosting
the signal levels to the hundred volts or so needed to drive the CRT.
The scan rate of CGA is the same as NTSC so deflection is not a problem.
For PAL (625/50) instead of NTSC, the vertical rate will need to be
reduced to 50 Hz but this should not be a problem. The horizontal scan
rate is close enough (15.625 kHz).
Similar comments apply to EGA monitors that have a compatible scan rate.
EGA represents a range of scan rates between 15.75 kHz and 21.85 kHz so
this should not be a problem.
You cannot even safety test scan rates on all monitors - some will blow
up or be damaged by being driven with incorrect video.
For a monitor that you already have, posting the model number or looking
it up is really the only way to be sure of its capabilities.
Quicky tests:
The following URLs provide quick access to the general specifications
of many common PC and MAC compatible video monitors:
I have a copy of a very detailed book on using old 19" monitors for
VGA:
I have not tried his kits but the book is very good. BTW if you pay
much more than $300 for a 19' surplus monter you have been moderately had.
I do not have any other connection with this person, I just think his book
is very good if you are even thinking of using a "non-VGA" monitor with
a VGA card.
(From the Editor).
A circuit to perform the automatic sync polarity correction is shown
at:
Note: I believe there may be a problem with the use of normal or LS
TTL for the sync buffers of this circuit due to their sourcing of current
when the input is LOW. A gate with a Low Level Input Current of less than
.2 mA should be used. (--- sam)
You have two problems: compressing the signals to 1/4 screen and synchronizing
them. The straightforward (though not simple) approach is to digitize each
at 1/4 resolution into a frame buffer which is read out at NTSC rates.
This overcomes the issues of genlocking and timing of the 4 quadrants.
When you are looking for something for the consumer marketplace, Look
toward Mt. Fuji :-).
The MB88303 from fujitsu is an "NMOS Television Display Controller"
And the NJM 22075 is a "Sync & Video SuperImposer". These two chips
and very little else form a complete on screen text & Min graphics
system. Add a uC and you are in business. Also low cost and easy to implement.
Have hardware & software someplace if needed.
(From: Winfield Hill (hill@rowland.org))
This isn't an easy thing to do, as quite a bit of electronics is required.
Fortunately, this function is needed for TV sets, VCRs etc and several
manufacturers have created custom VLSI chips to do the task, which is called
On Screen Display or OSD. For example, Phillips, SGS-Thompson, Rohm, and
NEC, etc. all make OSD chips. Some, like Motorola, include the OSD function
within a microprocessor.
I like the NEC uPD6464A chip.
Using an OSD chip, you can roll your own design (e.g. see Sept and Oct
1996 Electronics World, which uses a discontinued chip!), but it's still
a non-trivial task! One easy solution is to purchase an OSD already on
a pcb, with all the extra circuitry and C source code software. E.g. BOB-1
from Decade Engineering in Turner, Oregon (503-743-3194). It uses the Rohm
BU5963AS chip and cost $169 each ($200 with the software).
Check out:
Vertical luminance resolution in the monitor or TV is determined by
the video standard (NTSC, PAL) and the quality of the monitor or TV. Specifically,
for NTSC (525 total lines for NTSC) there can be a maximum of 482 or so
active video lines and something like 580 for PAL (625 line). The remaining
lines are for blanking and sync during retrace. These are physical scanning
lines.
Vertical luminance resolution for the VCR is determined only by the
number of active video scan lines for each standard.
Factors which reduce the effective vertical resolution are CRT focus
(spot size) and stability of the interlace, and Kell factor. (See the section:
What
is Kell Factor with Respect to Interlaced Displays?.
Depending on the video standard, vertical color resolution may be less.
Depending on the video source, there will be a variety of other factors
which reduce the effective resolution horizontally and vertically.
The Kell factor - which has to do with the fact that we're often undersampling
an image from the standpoint of the Gospel According to St. Nyquist - IS
a factor in the reduction of vertical resolution, but interlacing plays
a part as well. This comes from at least two factors:
Also see the connector info at:
Original VGA (31.5 kHz - 640x480)/SVGA (35-37 kHz - 800x600) 15 pin
sub D:
Mono VGA is similar using only the Green Video and Return.
Note that many of the pins shown above as "no connects" (actually, these
were sometimes used as monitor ID bits by many manufacturers) are now defined
under the VESA Display Data Channel standard. This standard provides two
protocols for display ID and control, including support for the full ACCESS.bus
interface. The current definition of the "VGA" pinout per the DDC standard
is:
This defined several protocols for digital communications between a
host system and its display. DDC provides 3 different modes:
I used a multimeter to determine this on the VGA to 9 pin adapter for
a NEC Multisync II.
BTW, don't use an EGA 9 pin extension cable to connect it to VGA. While
this will work, the wires are not shielded or the wrong wires and you will
get ghosting and ringing at vertical edges. I constructed mine using proper
75 ohm coax for the RGB and H and V sync as well (though it is not needed
for the sync).
(From: Carl Mueller).
If you're sure it's a VGA monitor (not CGA or EGA, which are not compatible
with VGA), then there are two possible likely pinouts for the plug. I believe
they are both detailed in the ibm PC hardware FAQ. One possibility is the
CGA pinout, and the other is the 9-pin VGA pinout. Check the grounds to
find out.
(From: Chris Lawson (lawsonc@micron.net).)
Note that the Apple 16" monitor is a fixed frequency display - i.e.,
it only works at one resolution and scan frequency. Here are the partculars:
(From: Tony Matt (tonym@world.std.com).)
Cable for Mitsubishi Diamond Scan 20M (Model HC3925ETK)
Pin A1: Red
Pin A2: Green
Analog: 13W3 connector:
Sense table - 1=nc, 0=strap to gnd
This is a good SVGA monitor (same as Sony Multiscan GDM-17SE). The Sun
version doesn't connect the H and V sync lines to the video connector.
If you open it, on the the video board there will be a 3 pin connector
labeled H sync, V sync, and ground. All you have to do is connect these
to some unused wires in the video cable. There will be several wires going
to a small board which I think is used for monitor detection, or other
functions only used by a sun station. You can just cut any two of these
and use them for sync. Cut off the 13W3 and attach a HD15 connector, remembering
which pins are used for sync.
If you're not into soldering, I'm fairly sure there is an adapter fit
this that just converts the separate sync to sync on green. If I remember
correctly, the web site that was selling it incorrectly identified it as
a fixed frequency monitor and said you needed one of their special video
cards. It is NOT fixed frequency.
I have the pinouts for the RGB connectors on newer Sony monitors (specifically,
the PVM-2030 and PVM-2530 Profeel Pro monitors). These pinouts are directly
from the owner's manual. The connector used is a DB25 female.
The Sony RGB Multi Input pinout is also valid for the kV-25XBR; it should
also work with the kV-20XBR and KX-1901, and I know it works with a KX-2501.
(The KX series monitors are the original Sony Profeel monitors from about
1983, and they are very common.)
A female 34-pin floppy connector will mate with the Sony connector just
fine. I was able to use the analog RGB input on a KX-2501 to display VGA
PC video using a sync level converter circuit and drivers from:
I am trying to connect a Silicon Graphics (SGI) 17" screen display to
an SGI Octane CPU. I would like to build my own HD15 to 13W3 cable.
The monitor is standard SVGA with the VESA Display Data Channel (DDC)
and works fine on a PC.
SGI OCTANE CPU video pinout (13W3):
1 Monitor ID bit 3 (TTL)
-- end V1.88 --
W3PM End of File
SCART to VGA
This will only be possible without a lot of work if the VGA compatible
monitor or video projector can sync at the PAL (or whatever) scan rate.
If so, this may be possible with just a special cable. If available, use
an oscilloscope to confirm that your equipment produces the relevant signals
(not all SCART connectors have all the signals). See the document:
Pinouts
for Various Connectors in Real Life(tm) for the SCART pinouts.
TV to Fixed Frequency Monitor
The hardware needed to watch TV on a typical high resolution fixed frequency
monitor would cost more than a nice large TV. In two words, forget it!
In addition to decoding the NTSC/PAL to RGB, the scan rates are SO different
that the only hope would be to build a full blown scan converter.
TV to MGA
"How hard would it be to make my amber Hercules monitor display
the output from my VCR? the VCR has a RCA video output and a coaxial RF
output and I want to use the monitor as an orange TV."
This is almost certainly not worth the effort as the monitor accepts TTL
(2 bits) and can display at most 4 gray (well, amber) levels without extensive
modifications. In addition, the scan rates differ substantially between
NTSC or PAL and the Hercules standard. As noted below and elsewhere in
this document, a CGA monitor with a composite video input would be a better
choice.
TV to CGA
"I have a RGB CGA monitor and would like to use it to display
a composite or S-video signal from a VCR. I was wondering if anyone knows
how to accomplish this or knows of any economical products that will be
able to do this. Any info on S-video pinouts would also be greatly appreciated."
Is it strictly CGA? If so, that is TTL and you can forget about displaying
VCR S-video without extensive and not worth-it modifications. Some CGA
monitors have composite inputs or analog RGB inputs. With analog RGB inputs,
you need an NTSC to RGB converter. These can be built with a single chip
and some discrete components. There are probably converter boxes available
as well. If it accepts composite, then just use the normal video out from
your VCR. S-video won't gain you anything unless the monitor has separate
Y and C inputs as well. If all it has is S-video in, then you can combine
the Y and C signals with a resistor and capacitor. See the section:
S-Video
to Composite.
PC VGA/SVGA to/from TTL
VGA to TTL (MGA, CGA, EGA)
Both the signal format and scan rates are incompatible. Therefore, simple
conversion between analog VGA/SVGA and any of the TTL formats - Mono, CGA,
and EGA - is generally not realistically possible.
VGA to CGA1
The following applies with minor changes (scan rates, number of bits) to
MGA, CGA, EGA, and most other TTL video signal formats as well.
"I am trying to use an old Sony monitor, (PVM-1342Q), which
only accepts a CGA video signal through a 9 pin connector. My output is
SVGA via a HD15 pin connector. Any suggestions on pin assignments or existing
converters to do the job?"
Assuming the monitor is actually CGA, it is probably not worth it. CGA
is TTL and SVGA is analog - you would need a converter and then only end
up with CGA's 8 colors or whatever.
VGA to CGA 2
For the general case of desiring to drive a true CGA-TTL monitor from a
VGA card, there are three options:
If the monitor accepts analog RGB, it may be possible to program you VGA
card to put out the CGA (15.734 kHz) horizontal scan rate to be compatible
with a CGA monitor of this type. Your hardware and software may or may
not support this easily or at all.
VGA to CGA 3
"We are trying to upgrade our print servers and have a lot
of CGA monitors and a lot of PS2 computers with VGA cards. We don't need
more than 2 colors (mono) but when we make an adapter to connect the R
to R, G to G, B to B, H to H, V to V, Ground to Ground and the rest NC
we don't really get what is wanted.
This is not surprising as the horizontal scan rates for VGA and CGA differ
by about a factor of two. This is much too large change for the monitor
to accommodate.
TTL to VGA/Analog
This requires matching the scan rates and implementing a suitable digital
to analog converter to take the TTL data and produce analog signals.
450 ohms
Bit 1 (MSB) o--------/\/\/------------+
|
900 ohms |
Bit 0 (LSB) o--------/\/\/------------+-------+----o Analog video signal
|
/
\ 75 ohms (termination, may
/ be inside monitor).
\
|
Ground o--------------------------------------+----o Monitor Ground
This assumes the H and V sync are separate signals. If this is not the
case, these will need to be combined into this signal (at least one of
the channels) as well.
CGA to VGA
There are two problems:
In general, where only 1 (or a few) of these are needed, locating true
CGA monitors at used computer stores or thrift shops is definitely the
easier way to go!
VGA to Analog RGB
Note that in some cases, no actual hardware is needed - the video adapter
may be programmed to do what you want either using existing or special
driver software or at a low level by directing controlling the video chipset:
If you are lucky, you can reach an apps engineer in either case who has
knowledge of your requirements, and has the means to supply you a solution.
Otherwise, you need to write a short assembly language program to stuff
the VGA controller registers with the correct parameters for what you are
trying to do.
VGA to Fixed Frequency Monitor (3, 4, or 5 BNC Connectors)
Questions about this specific problem are among the most common as low
cost fixed frequency monitors become available when their workstation hosts
are decommissioned due to the march of progress.
Assuming you are willing to use something else to boot and only run at
a single resolution, then the last hurdle is sync:
So, check your scan rate. If that is not compatible, then you will need
a new display board anyway. If it is compatible, then you will just need
the sync combiner. Then there is the problem of booting DOS or Windows
- these usually want 640x400 at boot.
VGA to Apple RGB
"Is there any way to modify an Apple 12-inch RGB color monitor
so that it can display 640x480 (instead of 512x384)?
I assume you want VGA resolution - 31.4 kHz horizontal.
VGA to Mac (Monitor) Conversion
I have no idea of what this gadget actually does but it may be worth checking
out:
VGA to Sun/Sony GDM1960
(From: Flupke ut Warns (P.O.Langemeijer@student.utwente.nl).)
VGA to Amiga 1024
From: jcaldwel@iquest.net (Mr. Caldwell)
VGA to SCART
SCART is basically an analog RGB + composite sync interface found mostly
on PAL (and maybe other European standard) TVs but rarely on TVs in the
U.S. Signal conversion from VGA to SCART is straightforward - just a matter
of generating composite sync and making the proper cable. However, it has
the same problems as the others with respect scan rates unless you are
running an O/S like Linux or an X-server - for the latter case, see:
X
on TV.
Notes on VGA to RGB Conversion
See the document: Approaches
to Using Fixed Frequency Monitors on PCs for an adapter using a programmable
logic device to implement conversion from separate H and V sync to sync-on-green.
Or, here is a solution using discrete logic:
Pin 1: Red video
I join all the "returns" together with the ground on the small PCB and
use that as a common ground for the RGB cable to the monitor. You can use
separate if you want to but you should join the green return and sync returns
together. I did find some small shadowing if I didn't group them all together.
Pin 2: Green video
Pin 3: Blue video
Pin 4: Monitor ID bit 2
Pin 5: Ground
Pin 6: Red return
Pin 7: Green return
Pin 8: Blue return
Pin 9: NC
Pin 10: Sync return
Pin 11: Monitor ID bit 0
Pin 12: Monitor Id bit 1
Pin 13: H sync
Pin 14: V sync
Pin 15: NC#VR260 monitor is 70MHz 1024x864
The circuit to do this is as follows:
#VR320/319 monitor is 130MHz 1280x1024
Modeline "1280x1024" 130.81 1280 1312 1472 1696 1024 1027 1030 1063
+hsync +vsync
Modeline "1024x864" 69.2 1024 1040 1168 1272 864 864 867 904 +hsync
+vsync
+5 V
o
|
/
\ VR1 (1k carbon mini pot)
/ (Warning: don't let this go near zero!)
\
33uF tantalum | ~0.3V DC in porch area
GREEN o----+----||-----+----------------------+---o GREEN to monitor
+----||-----+ |
.1-.01uF ceramic |
|
Gnd |
o |
| |
/ |
\ 47k |
| _|
HSYNC o-+----|-------\ |
| GATE |------CSYNC----+----|| VN10KM or similar small
VSYNC o-+----|-------/ | |_ N channel enhancement MOSFET
| \ |
\ / 47K o
/ \ Gnd
\ 47K /
/ |
| o
gnd gnd
HSYNC, VSYNC and CSYNC are grounded with 47k carbon resistors
Capacitors are optional, I don't use them.
VGA to TV - NTSC or PAL
"I am interested in converting a signal from my video card
to a signal that can be taken into the video in on my vcr. I realize that
it is not going to be easy. Still I would appreciate how to do it."
You are correct - this is not easy.
For the special case of VGA to NTSC or PAL, you may be able to get away
with something less than a full blown scan converter. See the section:
What
is a Scan Divider?".
"In the July 1996 issue of Electronics Now, a MC1377P (Motorola)
is used to convert RGB to NTSC/PAL. The chip can be purchased through the
Newark catalog. This chip is very easy to use and should make your circuit
simple." (See the wiring instructions, below. --- sam.)
(From: Quick Fix (iradg@guru.nu).)
"The MC1377 is a 20 pin all-in-one chip. Connect the following:
+12 VDC to pin 14 and ground to pin 15, composite sync to pin 2, RGB to
pins 3, 4, and 5, respectively. Put a 3.58 MHz xtal between pins 17 and
18. Optional Y delay pin 6 to 8. Video output at pin 9. I have made and
sold many of these. If you have any more questions, you can visit the Motorol
Website and search for: "MC1377".
VGA to TV Converter Boxes, Adapters, and Boards
(From: Kevin Centanni (kpc@panix.com).)
VGA to NTSC/PAL Chip
"I am trying to build a circuit to convert the RGB output of
a video game to my large screen TV."
(From: Leon Heller (Leon@lfheller.demon.co.uk).)
Questions and Answers on VGA to NTSC Considerations
This dialog resulted from the desire to construct a VGA to NTSC converter
to output PC video to a TV or VCR.
"I figure the odds are in my favor by creating one myself,
and as far as I know, no harm could come to my computer by attempting it
since the VGA/RGB is and output only and not and I/O. Now since I already
manged to convert my VGA to RGB, hopefully you might be able to answer
some specific questions for me?"
If you mean resolvable spots on the TV screen, realistically, it is about
half VGA horizontally and perhaps a little more than half vertically or
about 320x300 give or take.
"Assuming the construction of this circuit would only allow
a maximum output from my VGA card, what resolution would that be? 640x480
or 800x600? (I have no expectations of anything higher)"
As noted, for a regular TV, you can send it 640x480 but it will be somewhat
fussy. 800x600 is really out of the question. A high quality TV-monitor
might do VGA ok. The actual number of lines on a TV is, of course, only
about 480 active with perhaps only 420 visible due to the CRT bezel. Unlike
an auto-scan monitor, you don't get easy control of this and no control
of the number of lines.
"Finally, taking into consideration the limitations of such
a device, I only intend for this to be used for full motion video playback,
as my current video capture card, as well as all other cards currently
on the market, lack the ability to output the video back to the original
source (i.e. a VCR or camcorder)."
Unfortunately, even expensive solutions are still limited by NTSC. However,
since your playback is often at reduced resolution (e.g., MPEG) to begin
with, this may be acceptable.
VGA to Composite Video
Realize that no matter what you do, the quality you get on the TV/VCR is
not going to be anywhere near what you see on the computer screen. You
must keep this in mind when designing layouts, selecting text fonts and
font sizes, etc. The new video cards with on-board NTSC/PAL output should
be better than your average cheap converter but don't expect miracles.
"I need a bit of advice on converting VGA or SVGA to output
suitable for a color composite monitor and/or a regular NTSC standard television.
I have seen add on cards or outboard boxes that will convert VGA to standard
TV but I am not sure if this will have the same effect on a Color Composite
Monitor. You see I am wondering if it would be more cost effective to keep
my old Apple Color Composite Monitor and buy the necessary hardware to
convert VGA output from my IBM clone or to just go ahead and buy a bottom
end 14" VGA monitor? Can I even get true 24 bit 800 x 600 color performance
out of a TV or a color composite monitor?"
A color composite monitor may be somewhat better than a good TV but it
is still limited by the NTSC standard - mainly horizontal resolution but
color rendition as well. There is no way to get even basic VGA performance
(640 x 480) from a TV or composite monitor.
VGA to Grayscale Composite Monitor
This will only work if you can program the video card to produce a compatible
resolution and scan rate.
R1
Hsync o--------/\/\/------------+
|
R2 |
Vsync o--------/\/\/------------+
|
R3 |
Green Video o----+---/\/\/--+---------+--------o Composite Video In
| ^ | (Termination = Hi Z)
\ +----+
/ +--------o GND of monitor
\ R4 |
/ |
| |
GND (shield) o----+--------------------+
It is essential that all this be built as close to the monitor as possible
for best signal quality.
TV or Composite Video to RGB (Analog or Digital)
NTSC to CGA
"Does anyone know how to convert a video out signal into a
signal usable by a CGA monitor (RGB + H and V sync)?"
If your CGA monitor is TTL, then it may not be possible, at least not without
modifications to the monitor. You need to convert from NTSC to RGB. There
are single chips (with a few external components) solutions to this. Try
Sony, Philips/Signetics, and Analog Devices (I think) as well as others.
These take NTSC (or PAL) and output RGB and sync. CGA is not analog (continuous
range of video values). It is TTL with Red, Green, and Blue signals as
well as a separate Intensity signal. Unless your CGA monitor can take analog
video (.7 V p-p) inputs, you will still only be able to get 8 or 16 colors
- not a normal TV picture. (And even for that, you will need external circuitry
to convert the analog output of the decoder chip to TTL.)
Composite Video (NTSC/PAL) to RGB
Several companies provide single ship solutions requiring only the addition
of a few discrete components to convert NTSC or PAL to RGB and H+V or C
sync. Some have options for YIQ, S-Video, and other formats at the input
or output in as well.
"I looked at several chip manufacturers. Most have extensive
documentation on their chips in PDF format. Again, most of the chips currently
available convert Y/C to digital RGB, and have a lot of extra brightness/sharpness
control built in. Too complex- the simplest chip I came across was 18 pins
and still required two dozen external components."
(From: Eugene (eugenek@istar.ca).)
Watching TV on a PC Monitor - NTSC/PAL to VGA
Questions are along the lines of the following:
"I'm wondering whether I could use my NEC Multisync as a TV.
Long ago I had a Mitsubishi Colour Monitor which could also be directly
connected to the videorecorder. Sure, I could use cards in my PC like "WIN/TV",
but then every time I want to look TV I have to switch on the PC as well.
It depends on your monitor:
For PAL (625/50) the relevant resolution is closer to 800x600.
"I want to display output of VCR on my computer monitor. Is
there a video card that has Video In (such as RCA in)? Would you tell me
which video cards they are? Or does anyone know any other way to display
VCR out on a computer monitor? Or Is there a PC monitor exist that has
RCA input jacks?"
(From: Todd McCormick (todd@galstar.com).)
Comments on TV to VGA/SVGA Conversion
You need a lot more than cables. Here are some comments:
Video Standards Conversion
NTSC to PAL
"Does anyone know of a simple way to convert NTSC signals produced
by American video equipment to UK PAL signals."
If you simply mean the color conversion, then a couple of chips will do
it.
If you simply want to watch an NTSC tape on a PAL TV it may work but not
with proper color if the vertical has a wide enough range to sync or you
have a vertical hold control with enough range. If your intent is to put
it into a VCR, you can safely forget it.
The cheapest of all, if you can stand to see the image in black and white
with the vertical size off, would be to plug it into the video input jack
of a PAL monitor that has a wide-range vertical hold control. Don't use
the RF (antenna) input of a regular TV as it may not work at all because
of the different carrier frequencies. (You did buy one with video and audio
jacks, didn't you?)
What is a Scan Converter?
A scan converter accepts video of one format - say SVGA - and outputs it
to some other format - say NTSC. Some are designed for fixed input format
while others can adapt - possibly automatically like an auto-scan monitor
- to a wide range of input scan rates and resolutions. Output format is
most often selectable between NTSC and PAL scan rates (or those of other
TV formats) with a variety of output options such as composite, RGB, SCART,
and S-Video.
However, in the end, no matter how the scan converter is implemented, if
the ultimate destination is an NTSC or PAL TV, the resulting picture quality
will be very limited. Even a $20,000 professional scan converter may not
be able to display fully legible VGA on an NTSC or PAL TV.
The output of the interpolator is typically 6 to 10 bits of data for each
color channel.
What is a Scan Doubler?
This is a special case of a scan converter where the output format has
roughly twice the number of lines as the input format and runs at twice
the horizontal scan rate. Various scan doubler boxes are available commercially.
For example, check out the offerings from Harmonic
Reseach. (I have no idea of whether they are any good - just an example.)
Scan Doubler Chips
Several companies now provide single chip (or minimal chip) solutions to
a major part or all of this problem. For example, Siemans has just announced
the SDA9400 Scan Rate Converter which appears to includes nearly everything
required - even the buffer memory - to convert from interlaced to progressive
(i.e., non-interlaced) scan in Y-U/V format.
What is a Scan Divider?
For the special case of converting from VGA at 640x480 (31.4 kHz H, 60
Hz V) to NTSC or SVGA at 800x600 (31.4 kHz H, 50 Hz V) to PAL, something
simpler than a full blown scan converter may be satisfactory. In this case,
it is only necessary to provide storage for a single scan line (rather
than an entire frame store) since the input horizontal frequency is (almost)
exactly twice that of NTSC (15.734 kHz) or PAL (15.625 kHz). A double buffer
where one buffer is storing while the other is reading out at approximately
half the VGA pixel rate should work. With appropriate timing, even lines
become the even field and odd lines become the odd field (I may have this
backwards). It is still not a trivial undertaking. Keep in mind that the
quality you will get on NTSC or PAL will be poorer than the VGA due to
fundamental NTSC or PAL bandwidth limitations. Also, flicker for line graphics
will be significant due to the interlacing at 30 Hz.
RGB to PAL Converter Chips
(From: Gary L. Sanders (75052.2665@CompuServe.COM).)
Digital Video Conversion Chips
"I'd appreciate on an Integrated Circuit (IC) made by a Hong
Kong company called Display Research Laboratory."
(From: Philip Decker (pdecker@lds.loral.com).)
Black Level Clamp
"I'm looking for a simple GOOD black level clamp circuit for
clamping a video signal."
(From: Joseph H Allen (jhallen@world.std.com).)
Inverting an Analog Video Signal
Inverting a video signal means doing something to both the luminance (intensity)
and chrominance (assuming a color signal). This is not totally trivial
(at least, it is more than just putting it through an op amp). You would
have to convert to baseband, strip off the sync and invert the signal,
recombine with sync, remodulate to channel 3 or 4.
Bypassing the conversions would be messy as you would be dealing the chroma
phase space - I wouldn't even want to risk a wild guess as to what would
be involved.
Miscellaneous Video Conversion Topics
CGA Boards with NTSC Output
Old CGA cards had RCA outputs. Usually those cards had one monochrome monitor
output and other output was composite video (usually NTSC).
CGA to VGA
This requires both converting the signal levels from TTL to analog as well
as doubling the scan rate since modern VGA monitors will not go down below
31 kHz H. CGA is around 15.7 kHz. If you aren't fussy about how the colors
map, the signal level conversion may be just some resistors. However, the
scan rate conversion requires capturing the data on each line and spitting
it out twice in one line time, and providing the proper H sync to match.
This would consist of a double buffer digital line memory (for the CGA
TTL bits) and timing logic to store line n while reading out line n-1 twice
at double the rate. It's all doable but not a project for a digital novice.
NTSC/PAL to RF (Channel 3/4) Output
This is called an RF modulator. Every VCR in the universe has one of these
and the vast majority are in self contained modules that can be reused.
It will be the silver colored metal box that has the two RF (antenna and
TV) connectors.
SVGA Monitor on Sun Sparc
This question comes up somewhat less frequently than the opposite (Sun
fixed or dual frequency monitor on PC SVGA):
(From: jmz@southwind.net).
S-Video to Composite
(From: David Kuhajda (dkuhajda@locl.net).)
Items of Interest
Various Video Standards
General VGA Information
(From: Tomi Holger Engdahl (then@tinasolttu.cs.hut.fi).)
Comparison of Composite, S-Video, Component Video,
and RGB
(From: Dave Martindale (davem@cs.ubc.ca).)
TV Capture Cards for PCs
Here are some Web sites of companies who market various video products
for PCs.
But be careful, what they say is not always the reality...
Mixing of Independent Video Sources
If they are truly independent, then this is a non-trivial problem. You
will need to either:
For info on the availability of commercial devices, you may want to post
to one of the video newsgroups - rec.video.production,
for example.
Studio Video Recording or Filming Directly from Monitors
"I'm designing graphics for a computer that is used on a the
set of a TV show. When the camera operators shoot the screen, horizontal
lines roll up and down. I assume it has something to do with the scan rates.
I know there is a small program for the Macintosh that corrects this, but
I know of nothing for the PC. Does anyone know?"
(From: Dic (dic@werple.mira.net.au).)
Video Controller Timing
"I wonder if anyone could tell me a good reference on how CRT
controllers operate. Specifically, how do the HSYNC, VSYNC, BLANK, and
dot clocks interact. Or, would some kind soul like to explain it? Thanks."
I am not exactly sure what you really want but here are some simple descriptions:
For RGB, some monitors will want 'sync on green' which is this type of
signal only for the green video. R and B and just the straight video. Mono
composite is this signal. NTSC/PAL: RGB color encoded and modulated. Composite
video is used for the luminance (intensity) with the color information
modulated on a subcarrier (which is ignored by a B/W TV).
Sync Generator Chips
(From: Rob-L (rob-l@mars.superlink.net).)
Sync Separators
(From: Myron Brookshire (harris.mbrooksh@ic1d.harrris.com).)
Dead VCRs and Composite Monitors
Most VCRs go to their graves not because of electronics problems but because
of the death of the tape transport. Or, perhaps, because the owner was
not willing to spend the money or take the time to resuscitate (or has
killed it due to improper servicing). Of course, it might just need a 50
cent rubber tire (but that is for another FAQ). What this means is that
the tuner and video circuitry is generally as good as the day the VCR rolled
off the assembly line.
Video Cables
"Does anyone know about the specifications of the video and
sync signals for VGA monitors?"
Video: .7 V p-p, (more positive is brighter).
"I am trying to send VGA signals over some 180 feet of cable,
I'd especially be interested in the required line impedance of the cable."
Line impedance: 75 ohms terminated at both ends.
"Is it possible to produce a Composite Sync signal (or maybe
even a composite video signal) that could be fed into an off-the-shelf
VGA monitor, so I could use only 3 instead of 5 coaxial wires in parallel?"
RG59U 75 ohm coax is what is normally used, but you will need a good quality
cable to go 180 feet without too much signal degradation. Of course, it
also depends on what resolution and thus what video bandwidth you need
and how much dispersion (signal delay as a function of frequency) you can
tolerate.
Building a 5 BNC Cable
This is straightforward, if time consuming and tedious.
Coax Center Coax Shield
---------------------------------------
Red Video (1) Red Return (6)
Green Video (2) Green Return (7)
Blue Video (3) Blue Return (8)
H Sync (13) Ground (5,10)
V Sync (14) Ground (5,10)
Tie pin 11 (ID0) to Ground to indicate a color monitor. Leave pin 12 (ID1)
open.
Tweaking the Deflection Rates of a Fixed Frequency
Monitor
Pulling a fixed frequency monitor by more than a few percent will likely
be a problem. I know this is not the answer you were looking for but getting
a new inexpensive video card, video card designed for fixed frequency monitors,
or new monitor, may be a better solution.
Modifying a CGA (or EGA) Monitor for NTSC or PAL
Input
These are often high quality monitors and would make nice TV displays -
especially as there are many no doubt gathering dust on their way to the
dumpster!
How Can I Determine Monitor Specifications or Whether
It Supports SVGA?
There is no easy way to tell by just examining the monitor visually. Even
those with only a 9 pin rather than a 15 pin connector are sometimes SVGA
(e.g., Mitsubishi AUM1381 and NEC Multisync II which will do 800x600 at
56 Hz V non-interlaced and 1024x768 interlaced at 43 Hz V).
While not conclusive, positive results on the first 3 of these tests definitely
increases the likelihood that it supports at least some SVGA modes. Of
course, if you recognize a model number, you have dramatically increased
your odds of success - assuming it works!
Low Cost VGA Hacking
Typical question:
"I have an old mitsubishi monitor, model number C3919N, Scan
rate is 15.5-23.5kHz horizontal, analog. I want to run video from my pc
svga card into this monitor. I found the correct video mode, resolution,
etc. in which it works, but have one problem. I get two perfect images
displayed on this screen."
(From: Martin Moeller (mmoeller@delphi.com).)
This book contains a lot of good information and advice. He also sells
kits for less than $50 (see comment below --- sam) to make the sometimes
needed sync inversion from VGA. (VGA cards invert H and V sync depending
on mode to tell the monitor what rate to go to. As far as I know only IBM
ever used this.)
Self Published by a Michael Johnson, Esoteric Electronics
35-R Derryfield Road
Derry, NH 03038
Night only Phone: 1-603-434-8494
Real Time Multi-Screen Displays
These are the type of displays used to view multiple video inputs simultaneously
on a single screen - security monitoring, for example.
On-Screen Display Implementation
"I am looking for chips that do on-screen display of text and
simple graphics. I've got some information about a Philips chip PCA8516
which seems to be a pretty nice complete chip for doing everything I want.
Are there other chips out there that do this as well?"
(From: Jack Climent (rocket5@haven.ios.com).)
SCART Site
Video Resizing
"I'm looking for a device to do resize (in horizontal direction
only) of a video signal. Basically I need a fractional decimator (in this
case 2:3). Harris has some stuff that might be useful, and Phillips has
some devices but I think they're more geared towards NTSC/PAL (data rate
here is around 20 MHz, but, then again, isn't the luminance typically sampled
at a pretty high rate?). Anyway, I also know I could do it in an FPGA with
bit-serial arithmetic, but I'd rather buy something."
(From: David L. Tosh (dlt@earthlink.net).)
Video Resolution of Various VCR Formats
Luminance Specifications:
The above refers to resolvable horizontal resolution - the maximum number
of vertical lines that can be seen using an arbitrary high quality monitor
to view the VCR's output. Also, this applies only to luminance - intensity,
not color. The color resolution is much lower and in the particular case
of SVHS vs. VHS at least, not improved over VHS since it is recorded in
exactly the same way. Also, I don't know whether this is a just noticeable
difference (JND) or percent response type of spec where the lines are really
just resolvable.
What is Kell Factor with Respect to Interlaced Displays?
(From Bob Myers (myers@fc.hp.com).)
Interlace is particularly troublesome on moving images, where you will
often perceive momentarily "missing" details. There was a LOT of discussion
regarding the gory details of interlacing in the recent HDTV debates within
SMPTE and other groups.
Common PC Video Connector Pinouts and Assorted Monitor Info
Many of these are also available at the
Sci.Electronics.Repair
FAQ site (and its mirror sites) in the document:
Pinouts
for Various Connectors in Real Life(tm).
Video Graphics Adapter (VGA)
Note that IBM called VGA 'Video Graphics Array' probably in reference to
the video memory. However, we will use the more popular terminology since
it agrees with the naming conventions of the other PC standards.
6
1 Red (Analog) 6 Red Return 11 (ID0) GND (Color) 11. . . 1
2 Green (Analog) 7 Green Return 12 (ID1) NC (Color) . . .
3 Blue (Analog) 8 Blue Return 13 Horizontal Sync . . .
4 Reserved 9 No Connect 14 Vertical Sync . . .
5 Ground 10 Ground 15 No Connect . . .
15 10 5
Note: Monitor ID Lines ID1,ID0=NC,G for color; G,NC for Mono. ID0 only
may be used.
VGA (VESA Standard)
(From: Bob Myers (myers@fc.hp.com).)
6
1 Red (Analog) 6 Red Return 11 Monitor ID0 (opt.) 11. . . 1
2 Green (Analog) 7 Green Return 12 Data (SDA) . . .
3 Blue (Analog) 8 Blue Return 13 Horizontal Sync . . .
4 Reserved 9 +5 VDC (frm host)* 14 Vertical Sync . . .
5 Return 10 Sync return 15 Data clock (SCL)* . . .
15 10 5
Those signals marked with an asterisk would be supplied by the host only
if the host supports the DDC2 protocol (I2C or ACCESS.bus).
VESA Display Data Channel Standard
(From: Bob Myers (myers@fc.hp.com).)
DDC was the first and only definition of the 15-pin D-subminiature video
output connector which VESA has provided. No further definitions on this
connector will be made, as VESA is instead concentrating on the new Enhanced
Video Connector standard which is due out later this year. This will define
a completely new connector which will include support for DDC and separate
syncs as in the 15-pin D-sub, and will also include support for audio I/O,
video input, and the USB and P1394 serial interfaces.
VGA - 9 Pin
This is pretty standard as the NEC Multisync II, Tatung CM1495, and others
use the same pinout. However, there is at least one other pinout that has
been used which is similar to the CGA pinout. Also see the document:
Pinouts
for Various Connectors in Real Life(tm).
Pin 1: Red Video Pin 2: Green Video Pin 3: Blue Video Pin 4: H Sync
Pin 5: V Sync Pin 6: Red Return Pin 7: Green Return Pin 8: Blue Return
Pin 9: Ground
Note: IBM PGC assigns pin 4 to Composite Sync and pin 5 is a no-connect.
Enhanced Graphics Adapter (EGA)
p> EGA - TTL (15.74-21.85 kHz) 9 pin:
1 GND 6 Secondary Green Video/Intensity
2 Secondary RED Video 7 Secondary Blue Video
3 Primary RED Video 8 H Sync TTL Positive
4 Primary GREEN Video 9 V Sync TTL Negative
5 Primary BLUE Video
Color Graphics Adapter (CGA)
CGA - TTL (15.75 kHz - 320x200 or 640x200) 9 pin:
1 GND 6 Intensity
2 Unused 7 Unused
3 RED Video 8 H Sync TTL Positive
4 GREEN Video 9 V Sync TTL Positive
5 BLUE Video
Dell UltraScan 17ES
This pinout may be used by a number of Dell monitors. The connector looks
like a standard VGA/SVGA HD15 but is wired differently (for some unfathomable
reason).
Pin 1: Gnd Pin 2: Red video Pin 3: Gnd Pin 4: Green video Pin 5: Gnd
Pin 6: Gnd Pin 7: NC Pin 8: VSync Pin 9: HSync Pin 10: Blue video Pin 11:
NC Pin 12: NC Pin 13: NC Pin 14: NC Pin 15: NC
Monochrome Graphics Adapter (MGA)
MGA - TTL (18.43 kHz - 720x350) 9 pin:
1 GND 6 Intensity
2 Unused 7 Video
3 Unused 8 H Sync TTL Positive
4 Unused 9 V Sync TTL Negative
5 Unused
MacIntosh Video
Mac II - analog (35 kHz H, 66.67 Hz V - 640x480) 15 pin. Mac II and Quadra
- analog (49.7 kHz H, 74.55 Hz V - 832x624) 15 pin.
1 Red Ground 9 Blue Video
2 Red Video 10 Sense 2
3 Composite Sync 11 Ground
4 Sense 0 12 Vertical Sync
5 Green Video 13 Blue Ground
6 Green Ground 14 Ground
7 Sense 1 15 Horizontal Sync
8 Reserved (+12)
Mac (16") Monitor Info
(From: Dale Adams (adams9@apple.com).)
Here's the pinout for the Apple DB15 video connector:
Pin Signal Description
----- ----------- ----------------------------------------
1 RED.GND Red Video Ground
2 RED.VID Red Video
3 CYSNC~ Composite Sync
4 MON.ID1 Monitor ID, Bit 1
5 GRN.VID Green Video
6 GRN.GND Green Video Ground
7 MON.ID2 Monitor ID, Bit 2
8 nc (no connection)
9 BLU.VID Blue Video
10 MON.ID3 Monitor ID, Bit 3
11 C&VSYNC.GND CSYNC & VSYNC Ground
12 VSYNC~ Vertical Sync
13 BLU.GND Blue Video Ground
14 HSYNC.GND HSYNC Ground
15 HSYNC~ Horizontal Sync
Shell CHASSIS.GND Chassis Ground
You can pretty much ignore the ID bits. You can try the following cable
pinouts to match to a VGA connector.
Mac Video DB15 VGA Connector HD15
---------------- --------------------
2 ------------------- Red Video ------------ 1
1 ------------------- Red Ground ----------- 6
9 ------------------- Blue Video ----------- 3
13 ------------------- Blue Ground ---------- 8
5 ------------------- Green Video ---------- 2
6 ------------------- Green Ground --------- 7
15 ------------------- Hsync ---------------- 13
12 ------------------- Vsync ---------------- 14
14 ------------------- Sync Ground ---------- 10
Mitsubishi Diamond Scan Monitors
These monitors accept PC video (at least standard VGA - 640x480 at 60 Hz
- but have non-standard connectors. Here are two types - there may be others.
Pin Function PC Connector Monitor Connector
Red (Analog) 1 2
Green (Analog) 2 4
Blue (Analog) 3 10
Reserved 4 6
Return 5 6
Red Return 6 1
Green Return 7 3
Blue Return 8 5
Sync Return 10 6
Monitor ID0 11 6
Horzontal Sync 13 9
Vertical Sync 14 8
Cable for 13" Mitsubishi Diamond Scan (Model AUM1391A)
Pin Function PC Connector Monitor Connector
HD DB-15 male DB-25 male
Red (Analog) 1 2
Green (Analog) 2 4
Blue (Analog) 3 14
Red Return 6 3
Green Return 7 5
Blue Return 8 15
Sync Return 10 1
Monitor ID0 11 1
Horzontal Sync 13 16
Vertical Sync 14 17
Sun 13W3
This was introduced by Sun Microsystems and is a nice compact robust connector.
Other manufacturers have copied it.
Pin 1: NC
The following I picked off the net so I do not know the accuracy of the
resolution table.
Pin 2: NC
Pin 3: Sense 2
Pin 4: SRTN
Pin 5: CSYNC
Pin 6: NC
Pin 7: NC
Pin 8: Sense 1
Pin 9: Sense 0
Pin 10: CRTN
Pin A3: Blue +----------------- * gnd
| +------------- * vertical sync
| | +--------- sense 2
| | | +----- sense common (gnd)
| | | | +- composite sync
| | | | |
| | | | | grey
red | | | | | green blue
| 1o 2o 3o 4o 5o | |
(O) (O) (O)
6o 7o 8o 9o 10o
| | | | |
| | | | +--- composite common (gnd)
| | | +------- sense 0
| | +----------- sense 1
| +--------------- * gnd
+------------------- * horizontal sync
* May be NC. My spies tell me Sun considers these obsolete. The green video
input is used by grayscale monitors.
Sense Type/scan rate
-------------------------------------------
0 TBD (?))
1 Reserved
2 1280x1024, 76Hz
3 1152x900, 66Hz
4 1152x900, 76Hz, 19"
5 Reserved
6 1152x900, 76Hz, 16 or 17"
7 Nothing (no monitor connected)
Sun/Sony GDM17E10
(From: Andy Cuffe (baltimora@psu.edu).)
Sony PVM-2030 and PVM-2530 Profeel Pro Monitors
(From: Rob Myers (myer3812@nova.gmi.edu).)
Note On Pins 3,4,5,6,11:
Pin Signal Descr
---------------------------------------------------------------
1 IBM Select High: IBM mode (RGBI)
Low: 3 Bit TTL (RGB)
2 Audio Select High: Audio input from pin 13
Low: Audio input from LINE A/B/VTR jacks
3 HSync/CSync Horizontal or Composite Sync, Negative Pol.
4 Blue Input Video Inputs: Positive Pol.
5 Green Input (Sync on green optional in analog mode)
6 Red Input
7 NC
8 NC
9 Analog/Digital High: Analog mode
Low: Digital mode
10 RGB/Normal High: RGB input selected
Low: LINE A/B/VTR input selected
11 VSync Vertical Sync, Negative Pol.
12 Blanking High: Video input from RGB input only
Low: LINE A/B/VTR signal is superimposed over
signal from RGB input
13 Audio Input -5 dB / 100% mod.
14 NC
15-24 Ground
25 intensity Positive Pol.
These monitors are regular NTSC monitors, but I'm sure they can be connected
to computers the same way I connected the KX-2501... using a simple buffer
circuit and special video drivers. Another possibility is to build a component-to-RGB
converter for really high quality DVD playback (better than S-Video)...
the blanking feature seems interesting but the RGB source would have to
be synchronized with the composite source. I think the KX's/XBR's have
the blanking input, too.
SGI Octane to Sony GDM-17E21 Cable
(From: Yves DELAY (yves.delay@imag.fr).)
A1 Red (analog)
Below is the pinout of the SGI 13W3 to HD15 cable, part number: 018-0500-001,
Rev. E VIST 9717, obtained after a phone call to the SGI hotline.
A2 Green (analog)
A3 Blue (analog)
2 Monitor ID bit 0 (TTL)
3 Composite sync (active low), TTL
4 Horizontal drive (active high), TTL
5 Vertical drive (active high), TTL
6 Monitor ID bit 1 (TTL)
7 Monitor ID bit 2 (TTL)
8 Gnd
9 Gnd
10 Gnd Signal SGI OCTANE (13W3) Monitor: GDM-17E21 (HD15 male)
----------------------------------------------------------------------------
Red A1 1 Red
Red Gnd A1 Gnd 6 Red Gnd
Green A2 2 Green (+ composite sync)
Green Gnd A2 Gnd 7 Green Gnd
Blue A3 3 Blue
Blue Gnd A3 Gnd 8 Blue Gnd
Pins 6, 7, and 8 tied together, along
with both connectors metallic shell
and cable shield.
Notes:
S-Video Note that this is often called S-VHS. I
don't know whether this is correct. I assume that S-Video refers to the
use of separate luminance (intensity) and chrominance (color) signals and
that S-VHS refers to a modified recording standard for the VHS tape format
to achieve higher resolution on special S-VHS tape. S-VHS may or may not
use S-Video signals and vice-versa.
In any case, S-Video uses a 4 pin mini-DIN connector. Viewing from the
female-end with the key at the bottom:
Pin 1 (lower right): Y Ground
Pin 2 (lower left): C Ground
Pin 3 (upper right): Y (Intensity/Luminance)
Pin 4 (upper left): C (Color/Chrominance)
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