High Definition Connections: What's the Difference Between HDMI and DVI?
High definition viewing calls for high-def digital cables, but when it comes to choosing between DVI and HDMI for your HDTV, things can get a little confusing – especially with all those acronyms. CableOrganizer.com explains what the mystery abbreviations stand for and what they can tell you about a cable, then looks at the similarities and differences between these two popular digital connection options.
What Their Names Can Tell You
DVI stands for digital visual interface, with the key word being “visual.” DVI cables transmit high definition video, which is terrific in and of itself, but that's as far as DVI capabilities go – alas, audio isn't part of the deal. It's perfectly fine to use DVI cables for video signals (many people do, since they hit the market before HDMI), but keep in mind that separate audio cables will be necessary.
On the other hand, when you're talking HDMI (or high definition multimedia interface), “multimedia” is the operative word, because it signifies that this cable type carries not only high-resolution video signals, but audio as well. As a matter of fact, HDMI cables have the capacity to handle just about any home theater audio system, up to and including Surround Sound 7.1.
Same Technology, Two Different Cables
HDMI and DVI use the same technology to transfer video signals: a low voltage, three-channel format known as TMDS, or transmission minimized differential signaling. TMDS delivers outstanding video images by encoding signals to protect them against degradation as they travel between devices. TMDS uses a single twisted pair of copper wires for each data channel; one wire carries the signal in standard format, while the other one transmits an inverted version of the same signal. When the video signals reach their destination, the device decodes them, measures one against the other, and compensates for any loss that may have happened along the way.
Because HDMI and DVI are both built on TMDS, they can be used interchangeably with HDMI-to-DVI or DVI-to-HDMI adapters, provided that you use the appropriate audio cables in addition. Although some users may say that they're able to detect slight differences between different brands/makes of cables, remember that HDMI and DVI share the same video technology, and should deliver virtually identical picture quality.
The Difference Between Connectors
While HDMI and DVI share the same technology, their connector designs are very different. Within the scope of HDMI, there are only two connector styles: the single link, 19-pin “Type A” (the standard and most widely used HDMI connector) and “Type B,” a dual-link miniature 32-pin connector that's used to relay video signals between smaller devices.
When it comes to DVI connector types, the spectrum is a little broader, with not only single and dual-link options, but three different signal types as well: DVI-A (for analog), DVI-D (for digital), and DVI-I (an integrated version that accommodates both analog and digital signals). And unlike HDMI, DVI connectors can vary greatly in number of pins, depending on which combination of link and signal they are. DVI connectors also have the benefit of added support and stability, thanks to two built-in screws that hold them in place while they're plugged in.
Cable Quality Counts in Home Theater Systems
If you are investing in a home theater system, you want the best performance possible. Cable quality counts a great deal in how well your home theater will perform. It is very tempting to re-use old cables to hook up your new equipment, but that will only result in less than optimal performance. In fact, often the cables provided in the boxes with home theater system components are not the best cables for optimal performance.
S Video Cable
The S-Video cable quality you use in your high-resolution home theater system will determine the quality of video provided. Cables with 24 karat gold contact connectors allow the signal transferred to be optimized and gold resists corrosion better than other connector metals. Look for cables that have heavy-duty strain relief to keep the cable connected to the end connector properly. All interior connector pins should be bonded to their conducting wires with high grade silver solder. Cables should provide low capacitance design so that your video signal remains perfect even for long cables. Also, choose a cable that has a high quality, flexible jacket so that flexing the wire around furniture or other components will not result in internal wiring breaks.
Component Video Cables
Component video cables used in your home theater system to connect DVD players, satellite receivers and television with other video components should also be of the finest quality. Low-loss component video cables allow the best possible picture to arrive at your output device. These cables should be multi-stranded, copper construction for optimal performance. Look for 24 karat gold RCA connectors on the ends of the component video cables for the best possible conductivity.
Speaker Wire Cables
Speaker wire is another place that quality counts. The speaker cable you choose will determine the clarity of sound and how natural music reproduction sounds to your ear. Avoid the temptation to use old speaker cable because you need to have high-performance cable with large copper conductor areas for proper power transfer and to allow the full dynamic range, including the bass response of sound to transfer. Quality speaker cable that is constructed with Linear Polyethylene (LPE) insulation will reduce signal loss so that even the true audiophile will be satisfied with the sound reproduction.
It doesn't matter if you use in-wall speaker cable or speak cable that is run along the outside of the wall. It doesn't matter if you place the cable into conduits for neatness and extra protection or place it at the bottom of the baseboard, it is still necessary to select the best quality speaker cable to ensure you get to hear the sound your fine home theater system is capable of producing.
It is also a good idea to protect your quality speaker cable in a conduit or transit cover if you are not planning for in-wall wiring. These transit covers or conduits are available at very little expense and in a variety of colors and shapes so that you can route your home theater speaker cable to any area of the room or even to other rooms in the house to ensure that cables do not become tripping hazards, and are not damaged by pets or household cleaning.