HDMI to DVI to VGA

R

rcrez

Limp Gawd
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May 22, 2005
Messages
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I have a large 21" CRT that I would like to show HD video on from a HDMI source.

I know there are HDMI to DVI adapters out there.

I also knwo that there are DVI to VGA adapters out there.

Can I chain the two together to generate a nice signal on my VGA only CRT???
 
Nope, HDMI uses something called HDCP that is meant for copy protection. The HDMI device talks with the Display (over HDMI) and then receives the correct HDCP signal which tells both devices that it's okay to talk with each other, for what you'll be doing there is no other end to tell the HDMI device that it's okay to talk so it's going to send out the signal.
 
Is this true for a non-encrypted HDMI signal?

Using a Samsung HDTV tuner box with a DVI-HDCP port, I can connect a standard computer 17" LCD to it using DVI and I still get the signal.

I suspect this is the case because the over the air signal does not have HDCP so it will still work with non HDCP devices.

If this is the case, then shouldn't HDMI behave similarily?
 
i'm not sure but from what i understand, an hdmi cable only carries a digital signal, whereas certain dvi cables bypass them with extra analog pins built into the cable. There is no actual "conversion" that happens within the cable, or those passive adapters. can anyone back this up?

And not all dvi cables can carry an analog signal either, only dvi-i and dvi-a can (not dvi-d)

and once again pls, somebody correct me if i'm wrong.
 
SJetski71 said:
i'm not sure but from what i understand, an hdmi cable only carries a digital signal, whereas certain dvi cables bypass them with extra analog pins built into the cable. There is no actual "conversion" that happens within the cable, or those passive adapters. can anyone back this up?

And not all dvi cables can carry an analog signal either, only dvi-i and dvi-a can (not dvi-d)

and once again pls, somebody correct me if i'm wrong.
Click to expand...

Yep, that's right. DVI-VGA adapters simply pass the analog signal to the right pins on a VGA connector, without doing any conversion. *edit* (had signal flow backwards)--if the signal starts VGA (analog), nothing is going to show up at the HDMI end (digital)
 
Cax6ton said:
Yep, that's right. DVI-VGA adapters simply pass the analog signal to the right pins on a VGA connector, without doing any conversion. If the signal starts HDMI, then nothing is going to show up on the VGA end,
Click to expand...
Yup, some devices support it (early HDMI stuff) so they might ask for an HDCP signal but if it does your not going to get anything.
 
if it was possible, you would loose all benefits going from hdmi to vga as well as dvi to vga. therefore if you can, use straight dvi (upgrade vid card) or use a hdtv (vid card) to component adapter. the leadtek 6200 agp vid cards come with dvi, svga and hdtv out.

the hdtv out comes with an adapter for component or svideo which is cool. i'm going to use straight dvi though with my samsung hdtv from circuit city (i mention it since i got a sweet deal there).
 
HDCP is a choice that is dictated by the SOURCE MATERIAL. However, HDMI must natively support it. Therefore SOURCE and DESTINATION must support HDMI but only the MATERIAL can turn on or off the flag.

But as for your question. Yes...HDMI is digital only. Therefore a dongle chain will not work. DVI-I is bascially DVI-D (digital signal) + VGA/RGB in the same cable. It was meant as a "stepping stone".

What you need is a DVI-D to VGA converter. They cost a few $100 typically ($200 to $400). Sorry to burst your bubble :(

-tReP
 
Thanks guys. It all makes sense now.

I guess I will have to get something with at least DVI inputs in order to watch HDMI.

It seems like the Apple Cinema Display's have DVI-I inputs instead of DVI-D which are on most LCDs. This allows allows them to consolidate both VGA and DVI into one port to support most video cards. This is also why apple has VGA to DVI converters (which really are just passing the pins through like you guys said). Is this right?
 
yup, DVI-I carries both analog and digital signal, so PC video card DVI adapters just use the pins for analog HD15
 
Does the HD source also have component out? You can find component->vga cables.

peace.
unloaded
 
UnLoadeD said:
Does the HD source also have component out? You can find component->vga cables.

peace.
unloaded
Click to expand...

What...where? I don't believe you. You needa transcoder to go from component to VGA. Cables just won't do it.

-treP
 
There are cables which will convert vga to RGsB which is RGB with sync on green. The only way to go from VGA to component is via a transcoder of some sort, wether a stand alone peice or part of larger box.
 
Ya Bighitter is right, you may already know this but the key term to look for is SOC "sync on green" and many front projectors are capable of doing it. Those funny looking vga~component cables only work on displays that are capable of soc. Some lcd monitors are also capable but they're a bit uncommon and they're descriptions often vague. People often resort to calling mfr technicians to see if their displays are capable of soc.
 
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many PC video cards produced by the major name brands now have component out adapters available, but check before you buy the card.

SOC is hopefully a dead or dying standard hearkening back to Analog days. Glory to the digital era!
 
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