General Question

8lightminutesaway's avatar

Is hdmi higher quality than dvi?

Asked by 8lightminutesaway (1424points) December 26th, 2008

Can I get the same hd quality out of my graphics card’s dvi port with an internal blu ray reader as with a normal blu ray player with hdmi?

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6 Answers

RandomMrdan's avatar

Yes, they should both be HDCP compatible. The only difference is that HDMI if bridged with a sound card inside your computer can transfer sound through a single cable. Where as if you use a DVI cable, you will have to find a second cable for sound. I’d find it easier to just use a DVI to HDMI cable, and use a separate sound cable (most sound cards are surround sound for home theater), and find a 10 dollar 3.5mm cable to RCA composite cables (red and white).

To answer your question…Yes the quality for video will be the same. Any questions pertaining to setting up a media center, give me a buzz, I have set my own up, and have helped many customers in my place of work to set up theirs as well. I work at a microcenter and sell anything my customers may want that we carry.

pascal_cuoq's avatar

HDMI is not better quality than DVI (DVI is already a digital signal, for up to 1920×1200 for single-link DVI, more for dual-link DVI. From a technical standpoint, there is nothing to improve in DVI at this time).

However, DVI does not carry the encrypted signal that is the only thing allowed to come out from blu-ray drives. As a consequence, you will not get HD at all if you watch a blu-ray disk on a graphic card with only a DVI port, only purposefully downgraded DVD-like quality.

Buying a DVI -> HDMI adapter won’t help. The whole chain has to be able to carry the encrypted signal in order to get HD on the screen. You need a new video card with HDMI or DisplayPort, and a new screen with the same. Welcome to the wonderful world of HDCP, where you need to buy again (and pay more) for devices that limit what you can do with them. If you do not like it, vote with your wallet and postpone your transition to blu-ray.

Lightlyseared's avatar

HDMI and DVI are interchangable. The signal is the same only the connector is different. Having said that some moitors with a DVI input can’t display HDCP but that is a limitation of the monitor not the cable.

pascal_cuoq's avatar

> Having said that some moitors with a DVI input can’t display HDCP but that is a
> limitation of the monitor not the cable.

And (all?) current DVI video cards are unable to carry HDCP to the monitor through
a DVI port, but you can see that as a limitation of the video cards :)
Seriously, DVI is a non-encrypted standard. Although it is digital, it actually contains
“red”, “blue” and “green” wires. The fact that people later chose to define HDMI as
an extension of DVI and optionally re-use the wires in the DVI connector for
carrying something else does not change the fact that a
device (monitor or video card) with the DVI label does not need to know
anything about HDCP.

From http://en.wikipedia.org/wiki/Digital_Visual_Interface (the rest of the page
is also very interesting):

Some new DVD players, TV sets (including HDTV sets) and video projectors have DVI/HDCP connectors; these are physically the same as DVI connectors but transmit an encrypted signal using the HDCP protocol for copy protection. Computers with DVI video connectors can use many DVI-equipped HDTV sets as a display; however, due to Digital Rights Management, it is not clear whether such systems will eventually be able to play protected content, as the link is not encrypted.

See also http://en.wikipedia.org/wiki/High-Definition_Multimedia_Interface

Lightlyseared's avatar

1. Don’t believe everything g you read in wikipediea.

2. The first revision of the HDCP specs were only compatible with DVI connectors. HDMI connectors were only added to later revisions of the specs.

3. All HDMI devices support HDCP but for DVI devices it is only optional. The cable can transmit the signal (the signal is exactly the same as the one HDMI transmits) the only difference is manufactures aren’t forced to include HDCP decoding if the device only has a DVI input.

4. Nvidia graphics cards that have purevideo HD transmit HDCP from the DVI connector. I think we can safely assume ATI’s later cards do the same.

5. Don’t believe everything you read on wikipedia. I know I said this already but I figured it was important enough to mention again.

8lightminutesaway's avatar

I have nvidia 9800 gtx (has 2 dvi outputs) , which has purevideo HD and is supposed to support HDCP. Thanks for the responses.

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