Video cables

[J. P. Gilliver (John)]

I once bought an HDMI to VGA cable - being puzzled even at the
time, as AIUI one is digital and the other analogue! It didn't
work, of course. I haven't thrown it out!

Well, this could be interesting.
Did you pay $100 (active) or $10 (surely not passive) ?
Those would be old pricing.
The active ones have dropped considerably in price.
https://www.amazon.com/Moread-Gold-Plated-Projector-Chromebook-Raspberry
/dp/B00SW9JI9A
They can run off the +5V pin on the HDMI connector.
I don't know what the current flow limit is on that
pin, as it's probably intended for powering the
SDA/SCL/CEC plane.
Loading Image...

My cable looks something like
https://www.ebay.co.uk/itm/3m-HDMI-male-to-VGA-SVGA-D-Sub-male-Video-Ad
apter-Cable-for-1080p-HDTV-Monitor/132496128620?epid=7014465649&hash=item
1ed9627a6c:g:1QwAAOSwwZtaecem:rk:33:pf:0
, other than mine says it is 2.5m not 3; I still have the bag. I
bought it at a computer fair: I think I paid less than shown,
possibly less than 2 pounds. It certainly doesn't _look_ as if it has
_any_ electronics in it, though you never can tell with moulded plugs
these days (and the industry referring to _anything_ as a "cable" or
"lead", even power supplies, these days doesn't help).
I was interested that the above one specifically says in the text
lower down the listing that it isn't for laptops etc.; but it does
specifically mention HDTV receivers, which is what I wanted it for (to
connect one to a VGA monitor [which came as part of an analogue-only
TV, but has higher resolution than SD TV]). What the listing actually
says: "This HDMI to VGA HD15 (Male) connects your HDMI-equipped
device, HDTV (NOT FROM COMPUTER OR LAPTOP) to your monitor. The
HDMI-equipped devices include high-definition DVD player, HDTV
receiver, projector, Playstation system. It is used to connect your
HDMI-equipped devices including DVD player, HDTV receiver, projector
and playstation system to your monitor."

Since the output is unprotected, the dongle is not
allowed to "support" HDCP. If the OS has an issue with
lack of proper HDCP support at 1920x1080 or higher,
it has the option of "making the image fuzzy" during
Hollywood movie playback. (The player program likely
requests protection.)
This is also why HDMI capture cards aren't supposed
to support HDCP, and the front end chip is not
supposed to have HDCP keys installed in it to make
encrypted content capture possible.
Paul

Your second link doesn't show any lines that look like analogue
signals - well, I don't know what SCL and SDA are, but they certainly
aren't the three that'd be needed for RGB, even if one included sync..
If, as I suspect, these cables are truly passive, I just wonder how
they can get away with selling them! I might have expected a few,
fly-by-night, but it is many months (I think more like two years)
since I bought these, and I can still see them for sale on ebay. UK
seller, too.
Ah, I was going to say there are others: looking at one of those
(also UK seller), it says: "VGA to HDMI connector cable not an
Analogue to Digital Converter. This is a VGA to HDMI cable; this does
not convert Analogue signals to Digital.
For this cable to work your video card must support Digital signal
output through the VGA port. Please check your laptop, computer or
other device user manual to see whether it will support Digital
output through VGA."
I suppose that just might let them off the hook - _if_ any device
exists that outputs digital signals through the VGA connector. Have
you ever heard of such? It wouldn't excuse the other one, though -
which specifically says (going the other way) HDTV receiver to monitor!
JPG

OMG. You're kidding. VGA to HDMI passive ?
There aren't enough controlled impedance signals on VGA to do that.

Well, _one_ of the cable descriptions did imply that some (I suspect
only one, and a very rare one!) graphics cards output HDMI signals via
an (S)VGA connector!

Most of the HDMI to VGA I can see here, have the "box with VGA" on the
end, and that's probably where the converter chip is located.

Indeed. That's what I would guess, too.

Your cable with the molded ends, it would have to be an amazing
miniaturization job, to fit everything and include an active IC
for the conversion. Of course there's no way to do HDMI to
VGA passively. Why would anyone make a royal mess of the HDMI
connector on some device, in an attempt to make it dual
purpose ?
Since your cable works, you're going to have to wait a
few minutes and "feel for heat" to locate the IC. Some of
these adapters actually overheat, because their cooling
isn't good enough. Some of the heat can go into the connector,

No, it _didn't_ work. For the use I wanted, from an HDTV tuner to a
monitor. Note that one of the cables above specifically says "This HDMI
to VGA HD15 (Male) connects your HDMI-equipped device, HDTV (NOT FROM
COMPUTER OR LAPTOP) to your monitor. The HDMI-equipped devices include
high-definition DVD player, HDTV receiver, projector, Playstation
system. It is used to connect your HDMI-equipped devices including DVD
player, HDTV receiver, projector and playstation system to your
monitor." Which did _not_ work with the one I bought (I didn't expect it
to; it was just cheap enough for a punt).

or down the cable itself. The molding around the PCB, might
not carry much of the head away.
Paul

In practice, I obtained a small cheap SCART-to-VGA converter box, and
have been using that monitor with a - non-HD - DTV box ever since. (It's
only my bedroom telly, so doesn't need the HD really.) That box has been
on power - except for power cuts - for some years now, and never given a
moment's trouble.


Visit 255soft.uk if you find petitions unfair (and please *pass it on*, too).

[Phi]

I once bought an HDMI to VGA cable - being puzzled even at the time,
as AIUI one is digital and the other analogue! It didn't work, of
course. I haven't thrown it out!

Well, this could be interesting.
Did you pay $100 (active) or $10 (surely not passive) ?
Those would be old pricing.
The active ones have dropped considerably in price.
https://www.amazon.com/Moread-Gold-Plated-Projector-Chromebook-Raspberry
/dp/B00SW9JI9A
They can run off the +5V pin on the HDMI connector.
I don't know what the current flow limit is on that
pin, as it's probably intended for powering the
SDA/SCL/CEC plane.
http://unitedtechnologies.com.pk/Nti/image/10ci.png

My cable looks something like
https://www.ebay.co.uk/itm/3m-HDMI-male-to-VGA-SVGA-D-Sub-male-Video-Ad
apter-Cable-for-1080p-HDTV-Monitor/132496128620?epid=7014465649&hash=item
1ed9627a6c:g:1QwAAOSwwZtaecem:rk:33:pf:0
, other than mine says it is 2.5m not 3; I still have the bag. I bought
it at a computer fair: I think I paid less than shown, possibly less
than 2 pounds. It certainly doesn't _look_ as if it has _any_
electronics in it, though you never can tell with moulded plugs these
days (and the industry referring to _anything_ as a "cable" or "lead",
even power supplies, these days doesn't help).
I was interested that the above one specifically says in the text lower
down the listing that it isn't for laptops etc.; but it does
specifically mention HDTV receivers, which is what I wanted it for (to
connect one to a VGA monitor [which came as part of an analogue-only TV,
"This HDMI to VGA HD15 (Male) connects your HDMI-equipped device, HDTV
(NOT FROM COMPUTER OR LAPTOP) to your monitor. The HDMI-equipped devices
include high-definition DVD player, HDTV receiver, projector,
Playstation system. It is used to connect your HDMI-equipped devices
including DVD player, HDTV receiver, projector and playstation system to
your monitor."

Since the output is unprotected, the dongle is not
allowed to "support" HDCP. If the OS has an issue with
lack of proper HDCP support at 1920x1080 or higher,
it has the option of "making the image fuzzy" during
Hollywood movie playback. (The player program likely
requests protection.)
This is also why HDMI capture cards aren't supposed
to support HDCP, and the front end chip is not
supposed to have HDCP keys installed in it to make
encrypted content capture possible.
Paul

Your second link doesn't show any lines that look like analogue
ignals - well, I don't know what SCL and SDA are, but they certainly
aren't the three that'd be needed for RGB, even if one included sync..
If, as I suspect, these cables are truly passive, I just wonder how
they can get away with selling them! I might have expected a few,
fly-by-night, but it is many months (I think more like two years) since
I bought these, and I can still see them for sale on ebay. UK seller,
too.
Ah, I was going to say there are others: looking at one of those (also
UK seller), it says: "VGA to HDMI connector cable not an Analogue to
Digital Converter. This is a VGA to HDMI cable; this does not convert
Analogue signals to Digital.
For this cable to work your video card must support Digital signal
output through the VGA port. Please check your laptop, computer or other
device user manual to see whether it will support Digital output through
VGA."
I suppose that just might let them off the hook - _if_ any device
exists that outputs digital signals through the VGA connector. Have you
ever heard of such? It wouldn't excuse the other one, though - which
specifically says (going the other way) HDTV receiver to monitor!
JPG

OMG. You're kidding. VGA to HDMI passive ?
There aren't enough controlled impedance signals on VGA to do that.

Well, _one_ of the cable descriptions did imply that some (I suspect only
one, and a very rare one!) graphics cards output HDMI signals via an
(S)VGA connector!

Most of the HDMI to VGA I can see here, have the "box with VGA" on the
end, and that's probably where the converter chip is located.

Indeed. That's what I would guess, too.

Your cable with the molded ends, it would have to be an amazing
miniaturization job, to fit everything and include an active IC
for the conversion. Of course there's no way to do HDMI to
VGA passively. Why would anyone make a royal mess of the HDMI
connector on some device, in an attempt to make it dual
purpose ?
Since your cable works, you're going to have to wait a
few minutes and "feel for heat" to locate the IC. Some of
these adapters actually overheat, because their cooling
isn't good enough. Some of the heat can go into the connector,

No, it _didn't_ work. For the use I wanted, from an HDTV tuner to a
monitor. Note that one of the cables above specifically says "This HDMI to
VGA HD15 (Male) connects your HDMI-equipped device, HDTV (NOT FROM
COMPUTER OR LAPTOP) to your monitor. The HDMI-equipped devices include
high-definition DVD player, HDTV receiver, projector, Playstation system.
It is used to connect your HDMI-equipped devices including DVD player,
HDTV receiver, projector and playstation system to your monitor." Which
did _not_ work with the one I bought (I didn't expect it to; it was just
cheap enough for a punt).

or down the cable itself. The molding around the PCB, might
not carry much of the head away.
Paul

In practice, I obtained a small cheap SCART-to-VGA converter box, and have
been using that monitor with a - non-HD - DTV box ever since. (It's only
my bedroom telly, so doesn't need the HD really.) That box has been on
power - except for power cuts - for some years now, and never given a
moment's trouble.
Visit 255soft.uk if you find petitions unfair (and please *pass it on*, too).
--
"Everyone is entitled to an *informed* opinion." - Harlan Ellison

That is similar to the mini firewire (IEEE 1394) to USB cables that are on
sale, as far as I know, the data stream is not compatible.

a.. 4 feet USB Data cable Firewire IEEE 1394 for MINI DV HDV camcorder to
edit pc c17
b.. SHARP FIRE WIRE 4 PIN DATA CABLE TO EDIT PC
c.. use this cable to download videos and pictures from your camcorders
its a 4pin firewire to usb
d.. check camcorder for the firewire port its quicker and super fast
e.. will work with JVC,SONY,PANASONIC and many more camcorders

It would be interesting to get a definitive comment on this.

[Paul]

Post by Phi
That is similar to the mini firewire (IEEE 1394) to USB cables that are
on sale, as far as I know, the data stream is not compatible.

A $2 passive device cannot do that, no.

https://www.amazon.ca/1-8m-IEEE-1394-FireWire-Cable/product-reviews/B00OCS8X8C/ref=dpx_acr_txt?showViewpoints=1

"but I get windows error message
damaged or unrecognisable USB device"

You could design a device to do this conversion,
using effectively a double-buffered frame buffer
between sides, and UVC class USB at the destination,
but you wouldn't sell enough of them to pay for the
chip engineering.

You could do the conversion with an FPGA and
and an external static RAM. And the circuit board
would run you at least $100 when you were finished.
I doubt anyone would buy at that price. (Electronic
toys are quite sensitive to price, no matter what
valuable function it does.)

Since putting a Firewire card in your desktop PC
costs $25, a custom chip solution would have to be
many times cheaper to compete. And there isn't the
sales volume to drive down the price.

Paul

[John Williamson]

Post by Phi
That is similar to the mini firewire (IEEE 1394) to USB cables that are
on sale, as far as I know, the data stream is not compatible.
 a.. 4 feet USB Data cable Firewire IEEE 1394 for MINI DV HDV camcorder
to edit pc c17
 b.. SHARP FIRE WIRE 4 PIN DATA CABLE TO EDIT PC
 c.. use this cable to download videos and pictures from your
camcorders its a 4pin firewire to usb
 d.. check camcorder for the firewire port its quicker and super fast
 e.. will work with JVC,SONY,PANASONIC and many more camcorders
It would be interesting to get a definitive comment on this.

You'd need to check, but what it may do is have some smartness in the
cable to convert IEEE 1394 data levels and format to USB. It may need a
driver to install a virtual firewire port.

I've just solved the same problem. I bought a fairly old (2009) Canon
type X-HA1 Mini DV, HDV camcorder, and found that (a) it needs the right
program to download the HD format data via Firewire, as Windows only
natively supports SD, and (b) the cables are about as common as hens'
teeth. The laptop I am using has a 4 pin Firewire port built in.
Luckily, it didn't need the 800 MHz version, which is 9 pins.

The same setup also works with a Panasonic domestic one I picked up for
less than a tenner including a soft case and a dodgy cassette. (The shop
guy said the battery was duff, but it turned out the cassette was
jamming, causing a reset loop every time it tried to load. I'm happy
with the picture quality, and it plays back SD tapes from the big
camera, saving head wear.)

An alternative, if you have the right slot free (PCI, PCI card or the
express versions), is to buy a 400MHz capable IEEE 1394 card, and the
right cable.

4 to 6 pin are common, but 4 to 4 are not so easy, and it took me a few
minutes to find one online (At CPC, as it happens.) 4 to 6 pin cables
are available from RS Online.

[Paul]

Post by John Williamson

Post by Phi
That is similar to the mini firewire (IEEE 1394) to USB cables that
are on sale, as far as I know, the data stream is not compatible.
a.. 4 feet USB Data cable Firewire IEEE 1394 for MINI DV HDV
camcorder to edit pc c17
b.. SHARP FIRE WIRE 4 PIN DATA CABLE TO EDIT PC
c.. use this cable to download videos and pictures from your
camcorders its a 4pin firewire to usb
d.. check camcorder for the firewire port its quicker and super fast
e.. will work with JVC,SONY,PANASONIC and many more camcorders
It would be interesting to get a definitive comment on this.

You'd need to check, but what it may do is have some smartness in the
cable to convert IEEE 1394 data levels and format to USB. It may need a
driver to install a virtual firewire port.
I've just solved the same problem. I bought a fairly old (2009) Canon
type X-HA1 Mini DV, HDV camcorder, and found that (a) it needs the right
program to download the HD format data via Firewire, as Windows only
natively supports SD, and (b) the cables are about as common as hens'
teeth. The laptop I am using has a 4 pin Firewire port built in.
Luckily, it didn't need the 800 MHz version, which is 9 pins.
The same setup also works with a Panasonic domestic one I picked up for
less than a tenner including a soft case and a dodgy cassette. (The shop
guy said the battery was duff, but it turned out the cassette was
jamming, causing a reset loop every time it tried to load. I'm happy
with the picture quality, and it plays back SD tapes from the big
camera, saving head wear.)
An alternative, if you have the right slot free (PCI, PCI card or the
express versions), is to buy a 400MHz capable IEEE 1394 card, and the
right cable.
4 to 6 pin are common, but 4 to 4 are not so easy, and it took me a few
minutes to find one online (At CPC, as it happens.) 4 to 6 pin cables
are available from RS Online.

So are you saying the source device supports two protocols
on the same connector ?

That's possible, but if so, the manual should mention it.

AFAIK four pin Firewire would have TX+/TX-/RX+/RX- and no power.
You don't want Firewire bus power near the camcorder, and on
desktops at least, people use 6-to-4 passive converters so
the power isn't on the cable or near the camcorder.

It's not that there is a direct danger, but VBUS has leaked
by stuff getting bent in the connector on previous occasions.
And blown out the Firewire on the camcorder end.

USB would have its own +5V, D+, D-, GND in place of the
Firewire signals, if such a dual personality was being
contemplated. The camcorder doesn't need to touch +5V
if it doesn't want to, but it would need D+ and D-.
Perhaps wiring up just three of the wires would be sufficient

So at least the signaling could fit. I don't know if
the voltage levels of the two technologies are compatible
on the signal pins.

Reading the camcorder manual would reveal whether any
whizzy capabilities exist, and you can work from there.
A little Googling on the camcorder model number, might
dig up a solution or give a pinout.

There are other examples out there, like seeing a
headphone jack on a laptop, and when you happen to
stare into the barrel of the headphone jack, you're
greeted by red LED light. That's a TOSLINK
output for a plastic fiber TOSLINK cable. All fitted
into the headphone jack for dual-output. And I don't
think that was mentioned in the manual either. You
were just supposed to guess as to what that was.

Paul

[John Williamson]

Post by Paul
So are you saying the source device supports two protocols
on the same connector ?
That's possible, but if so, the manual should mention it.

The transfer protocols for data and control signals are the same, laid
down in the standard, but without the right codec installed on the
computer, it won't download the HD video. Install the codec (Mine came
with a high definition editing program), and the process is transparent,
with full control over the tape transport (And, if you work out how,
basic camera controls) from the computer. I can even mix HD and SD takes
on the same tape, and the computer sorts out which is which, and treats
them accordingly. Or I can downres the HD to SD in the camera...

Post by Paul
AFAIK four pin Firewire would have TX+/TX-/RX+/RX- and no power.
You don't want Firewire bus power near the camcorder, and on
desktops at least, people use 6-to-4 passive converters so
the power isn't on the cable or near the camcorder.

They actually just don't connect the power pins in the 6 pin plug. No
conversion is needed. A decent cable would have the pins cut off inside
the 6 pin plug. I'd use a converter on a fly lead on a desktop, though,
as the plugs on the PC are usually a right faff to reach.

Post by Paul
It's not that there is a direct danger, but VBUS has leaked
by stuff getting bent in the connector on previous occasions.
And blown out the Firewire on the camcorder end.

Yerss. The PC end is capable of providing up to 30 Volts at well over an
Amp on the 6 pin connectors.

Post by Paul
USB would have its own +5V, D+, D-, GND in place of the
Firewire signals, if such a dual personality was being
contemplated. The camcorder doesn't need to touch +5V
if it doesn't want to, but it would need D+ and D-.
Perhaps wiring up just three of the wires would be sufficient

For conversion from Firewire to USB, you would need power for the
conversion circuitry, which doesn't need to go anywhere near the input
pins. Without a converter, you have two devices speaking different
languages.

Post by Paul
So at least the signaling could fit. I don't know if
the voltage levels of the two technologies are compatible
on the signal pins.

The signal voltage levels are not compatible, the one may damage
equipment designed for the other, and the encoding and data transmission
schemes are definitely not compatible. The USB system uses differential
transmission along the data lines, while Firewire uses D/S encoding,
with the data on one line, and a strobe on the other. Firewire also
permits more than one master on a connection, with arbritation
protocols, which USB doesn't, only permitting one master device per
connection. They are like chalk and cheese.

Post by Paul
Reading the camcorder manual would reveal whether any
whizzy capabilities exist, and you can work from there.
A little Googling on the camcorder model number, might
dig up a solution or give a pinout.

The pinouts for USB and Firewire connections are laid down in the
standard, as are the voltages and signalling formats. The only
non-standard pinouts will be on the composite output (Where the
connections for the video vary between makers, with the audio
connections being standard. Some makers put the video signal on the
second ring, and earth on the sleeve, some put the earth on second and
the video on the sleeve. The plug is always of TRRS format, and may be
2.5mm or 3.5mm diameter), and component analogue outputs, which vary
from S-VHS to full on balanxced lines for each component and a multiway
connection..

The basics are simple, though. My Canon also has a Mini USB connector to
access the SD card used for still pictures, as does the domestic one,
but the USB ports can not be used to transfer video, even at SD. Both
USB ports show up on the computer as an external hard drive.