DVI, HDMI and 1394 connectors:

DVI connector
DVI is Video only. DVI is used on Computers, STB's (Set Top Boxes) , Display devices such as HDTV's, LCD's, Projectors, Plasmas and the latest DVD players with upconversion to HD resolution.

HDMI has Video, Audio and Control Signals. HDMI is used on STB's (Set Top Boxes) , Receivers, Display devices such as HDTV's, LCD's, Projectors, Plasmas and at least one of the latest DVD players with upconversion to HD resolution.

There are 6-pin and 4-pin connectors.
Laptops and Video camcorders generally use the 4-pin connectors, Desktop computers and peripherals usually uses the 6-pin connector.
Home Theater components usually use 4-pin i.Link connectors, although there are some, especially Pro level devices which use the 6-pin connector. The difference between the 6-pin and 4-pin connectors, besides the connectors themselves is that the 6-pin has power lines for powering devices.

Capabilities, Advantages and Disadvantages:
Connection Type
Digital Video connection*, Excellent connection for HDTV's and Set Top Boxes/Receivers that support it. Video is compatible with HDMI provided both devices are HDCP compatible. DVI carries uncompressed video data. Point to point interface - connects only two devices at a time.
Used on only some HDTV's, Projectors, STB's and Receivers. Limited length unless you use very expensive special cables. DVI will be replaced by HDMI for Home Theater applications.
Digital connection for Video and Audio**, device control features. 1394 carries compressed video and audio data. 1394 is a bi-directional interface designed for connecting multiple devices. When used as a Digital Audio connection (generally called i.LINK) , it allows transfer of very high sampling rate (up to 192kHz) PCM multichannel digital audio for DVD-Audio and SACD discs, as well as regular digital audio from DVD-Video, CD, Video CD/Super VCD and MP3 discs. 1394 has its own form of copy protection called 1394/5C.
Found on few Home Theater Devices at this point. Often only supports Digital Audio, not video.
HDMI Digital connection for Video and 8-channels of Digital Audio as well as device control features. Video portion is compatible with DVI devices if they are HDCP enabled. HDMI carries uncompressed video data. HDMI will replace DVI eventually for Home Theater connectivity. Point to point interface - connects only two devices at a time. Brand new and still not available on many devices.
*Almost all DVI connections include DVI-D, which is the digital version of DVI. Some, especially Computer Video cards, support DVI-I, which supports analog video as well.
** Many 1394 (i.LINK) devices such as DVD/SACD players will only support audio, not video.

Frequently Asked Questions (FAQ)
Questions and Answers:
Q1) Can I connect from HDMI to DVI?
A1) Yes. You will only have the video functionality however. The video portions of HDMI and DVI are "pin compatible". You can use an HDMI to DVI cable or a HDMI to DVI Adapter. Whether or not it will actually work or not requires a bit more complex of an answer. Why? HDCP. HDCP stands for "High-bandwidth Digital Content Protection" (HDCP). It is meant to prevent you from copying content you are not "allowed" to copy.
see here. Generally HDMI connectors all use HDCP. They don't technically "have to", but it would be pretty silly to use an HDMI connector without it having HDCP. DVI connections on the other hand, may or may not have HDCP. Computers and LCD monitors for example, can have DVI connections which do not have, or "need" HDCP. Many of the early HDTV's to include DVI connectors do not have HDCP. Some projectors, especially non-Home Theater oriented ones with DVI connectors do not have HDCP. Generally you will need to be sure that both devices use HDCP in order to connect together an HDMI device and a DVI device.

Q2) Can I connect any two HDMI devices together?
A2) Yes. This should work. Some early devices do not have the HDMI connection enabled or may have problems due to imperfect implementation.

Q3) Can I connect any two DVI devices together?
A3) Maybe. If both devices have HDCP the connection should work. If both devices do not have HDCP the connection generally should work. If one supports HDCP and one does not then the connection will generally be disabled by HDCP*. Besides the possibility of HDCP issues there are also three types of DVI. DVI-D is a digital only connection. DVI-A is an analog (VGA compatible video signal) connection. DVI-I has both the Digital connection as well as the analog connection within the same cable. In addition to these three types of DVI there are also two types of DVI-D. Dual link and Single link. Single link supports HD (High Definition) resolutions while Dual link can support resolutions greater than that. Since we are talking about HD usage here, we can forget about dual link for our purposes.

Q4) Can I connect 1394 (DTVLink/Firewire/i.Link) to HDMI?
A4) No.

Q5) Can I connect 1394 (DTVLink/Firewire/i.Link) to DVI?
A5) No.

Q6) Can I connect any two 1394 devices together?
A6) Yes. 1394 has two different uses in Home Theater gear - Audio/Video or just Audio. You should check whether or not your device supports both or just audio. There may be issues connecting devices supporting 1394 Audio/Video with devices that only support 1394 Audio. There is also the copy protection issue (1394/5C) which would not let you record material that you are not "supposed" to.


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