Video Connections Demystified
Submitted by Midnight on Fri, 08/10/2007 - 7:57am.
When I first started learning about audio and video with my Playstation 2, which was super cool in 2000 because it doubled as a DVD player, I was rather intimidated by all the terminology involved with gaming and home theater audio/video. Only through constant internet forum perusing have I been able to keep semi-knowledgeable on the subject, and the problem has only gotten worse with the addition of tons of new connections/formats/signals since then. In an effort to help those who may be starting the venture fresh, this article seeks to demystify one of the main sources of confusion: connections and cables. I shall start with video connections. A small amount of basic knowledge may be required when we get into resolutions, HDTV, and bandwidth, but I will try to keep this as entry level as possible. Unfortunately, breaking down the many video formats is outside the scope of this article (the definition of 480i, 480p, 720p, 1080i, and 1080p). However, I have linked you to the wiki on each topic, and there are plenty of resources available on the net to better understand video formats. The title of each section also links to the relevant wiki. Without further ado, the following is a comprehensive description of all video connections you are likely to encounter in North America in the year 2007.
[Disclaimer to video geeks: I am trying to make this easy for a beginner, so I am going to present some facts in a way that may not be 100% technically correct (e.g. 480p is SDTV at twice the speed). I am also going to ignore PAL. Spare me the nasty comments on what an ignoramus I am and try to understand the intent. If you think I am genuinely wrong then please point it out and we'll discuss.]
Click 'read more' for the full scoop.
Analog. Old faithful. You may know it by the name "RCA," which is the commonly used term for the connector on the end of the cable. This is probably the video connection you are most accustomed to. Video is transferred via one "hot" wire in the center with some wire mesh shielding that acts as the "ground." Can transmit 480i video, which is standard definition TV programming, but nothing better.
Analog. The slightly better looking sister of composite video. S-Video is short for "separate video." It transmits the video via two separate signals: one for color and the other for brightness. This keeps the signals from becoming intermingled and interfering with one another. Can transmit 480i and nothing more. In the late 90s S-Video was the cat's pajamas for home theater enthusiasts because of it's superior signal to composite video. I have read that S-Video is 20% better than composite. I don't know how the author of that statistic defined "better." S-Video is almost a bastard step-child these days because it was originally meant for getting the most out of your standard definition TV (SDTV), but nobody cares about pushing SDTV to the limit anymore because HDTV is so much better. You will find it on many video sources in your house, but it will probably rarely be used.
Analog. Don't confuse "component" with "composite." If S-video is the slightly better looking sister to composite, component is an even better looking set of triplets next door. Yeah, it's that good. Component is essentially the current station wagon for video sources of all kinds. It supports 480i, 480p, 720p, 1080i, and 1080p. Yes, you read that correctly. Component video has the bandwidth to support 1080p. Finding devices that accept 1080p via component inputs is the issue, not the cable's ability to transmit the format. Even before the HDTV revolution component video became the way to go because it supported 480p (progressive scan SDTV, essentially SDTV at twice the frame rate) from DVD players. It then became the new standard for HDTV once 720p and 1080i came on the scene. Component video breaks the video signal into three different parts, so it has the bandwidth to transmit a lot of information. This makes it very useful, and you'll find it on almost all new standard and high-definition sources and displays. Reminder: all three cables transmit video, and you'll need an additional audio connection for sound.
Analog. Stands for "video graphics array." You've seen this on your computer, as it's the most popular way to get video from your PC to its monitor. Beware: VGA is also the common term for the resolution 640x480, but the VGA "connection" can do much more than that. Supports resolutions from 480i all the way up to 1080p and beyond. It's pretty versatile, but finding a consumer display (excluding computer monitors) that accepts VGA may be an issue. Even if your TV has a VGA input, it may not support a HDTV resolution via VGA. You just have to check the manufacturer's specs on your TV to know for sure. Recently I know that some Sony DLP HDTVs accept up to 720p via VGA, Toshibas usually don't accept any widescreen resolutions, and Samsungs accept up to 1080p. I use my Xbox 360 at 1080p on my Samsung DLP HDTV. VGA is great for computer monitors, and a capable input for TVs, but with the latter you have to do your homework to ensure it will function as you desire.
Digital or Analog. Stands for "digital visual interface" or "digital video interface" depending on who you ask. DVI is the much better looking and more capable cousin of VGA, kind of like Tasha Yar from Star Trek The Next Generation (VGA) and Seven of Nine from Star Trek Voyager (DVI). You might have seen this on computer monitors and video cards, as it is most often used for PCs and LCD monitors. Can support all currently encoded high definition resolutions and more (1080p, 1440p, etc). Directly compatible with HDMI (to be discussed below). All it takes to turn a DVI connection into a HDMI connection is a cheap adapter, but be careful, DVI comes in many different flavors (outside the scope of this article, but here's a link), and you'll need the right one for a DVI/HDMI conversion (no DVI-A). Like VGA, it is uncommon to see DVI as part of the average home theater setup, but it has its uses,
especially as a tool to get video from a PC to a HDTV via a DVI/HDMI converter.
A word about digital versus analog connections: Digital is better. Why? Because it's much more difficult for a digital signal to get distorted or "misunderstood." It's a sequence of 1s and 0s. It either gets there or it doesn't. Analog signals are susceptible to many types of interference from other electronic signals, and while shielding on the cable reduces this greatly, there's just no better way to transmit the signal perfectly than through a digital connection. Analog connections work great--they've been used with great success for years, but if you have a choice then digital is the way to go. Oh, and by the way, don't ever pay Best Buy, Circuit City, or anyone else for an expensive digital cable (DVI, HDMI, digital optical audio, digital coax audio). As I said, the signal either gets there or it doesn't. A $100 digital cable from Monster will perform exactly the same as my $5.18 digital cable from a bargain basement internet retailer. It used to make a difference with analog connections, but not with digital.
Digital. Stands for "high definition multimedia interface." In 2002 a bunch of smart Japanese guys got together and said "This is frickin ridiculous. Have you looked at the back of our entertainment centers lately? There's 12 different types of cables carrying 8 different types of signals, and if something goes wrong our wives aren't even going to try to troubleshoot...they'll just take the credit card and go shopping. Something's got to be done." As described above, there are many limitations on what type of signal each connection can carry and how prevalent it is among consumer electronics. HDMI was created as a new standard to unite everyone, like the Big Three should have done with oil filters 70 years ago. It was created to carry signals digitally, support every current conceivable HDTV resolution (even 1440p, which doesn't really exist yet), be expandable, and also carry audio on the same connection! HDMI is the new one-stop connection for home theater goodness. The future will work like this: Buy a video source (game console, HD-DVD player, etc), plug it in, connect its HDMI cable to your TV, you're done. You'll probably
want to use an A/V receiver for the sound, but you won't be required to, or even use a separate cable. HDMI already has substantial market penetration, and many consumers who have bought devices in the past two years have an HDMI connection. Whether they are using it is a different story.
Side note on HDMI: there are several point release versions of HDMI (1.0, 1.1, 1.2, 1.3). Unless you are on the bleeding edge of A/V technology it does not make any difference right now. HDMI 1.3 is much touted right now in high end A/V advertisements, but as of today I know of no A/V equipment that can take advantage of it better than HDMI 1.2 In five years maybe it will matter.
So there it is, a roundup of all the video connections you're likely to see on consumer devices in North America in the year 2007. I hope this helps demystify the subject and bring a little more clarity to discussions of connecting high definition video gear. Hit me with questions, and feel free to add to the discussion or point out anything that could be explained better.
I wish they could agree on what format to use for production of new TVs. It would probably make for cheaper products. I'd almost rather have 5-7 hdmi connections on the back of my TV than a choice of a bunch of different ones.
Unfortunately, the market doesn't agree on which format to use so it's practically a necessity to have a connection panel like the one in the picture at the top.
Hopefully I'll have to worry about this problem one day. As for now, I'll just stick with my trusty dual purpose computer / 360 monitor (vga).
A tip for those that have a new TV and an "old" 360 without the hdmi connection: try out the vga cable, it just might look better than component depending on your TV. This all depends on the quality of the chip that decodes the different signals.
Midnight, something I'm kind of curious about: I wonder what the average response time is per connection format. Of course it's different for each TV, but I wonder if there's a reliable format one could usually fall back on for gaming performance.
Since the data in each type of connection travels at the speed of light, connection type is not a factor in response time. Processing on each end of the connection is the limiting factor, which is usually determined by the TV technology.
LOL, no, I meant is there a trend with the chips and technology to decode each signal. I should have been more clear. I didn't know if you'd come across any such info finding that say.. dvi tends to run fastest, or analog vs digital. That's all.
Don't have much direct knowledge of that. As I mentioned to JDogg in the HD-DVD thread, one thing you can do is ensure the video format stays in "native" form throughout as much of the transition as possible. For instance, the Xbox 360 renders most games at 720p. If you have your 360 set to output 720p then there is no conversion going on inside the 360. If you have it set to 1080i then there is a conversion to do. It's not a difficult conversion, and the time required is probably on the order of micro or nano seconds, but it is a conversion nonetheless.
When that signal gets to your TV your TV must display it. If you TV is 720p native and it receives a 720p signal then there's no conversion. If it's 1080i/p native then the TV must do a conversion.
If you are a perfectionist you want to render, output from the device, and display on the TV the same signal so that as little processing as possible takes place. Again, the processing time involved is essentially negligible, and I don't think anyone can perceive it as lag. We're really just discussing semantics.
One recent advance in this area related to home theater is 120 Hz displays. Many new TVs can output 120 Hz. Movies are filmed at 24 Hz. If you have a device capable (right now the PS3 and Blu-Ray discs are about the only game in town) you can output 1080p @ 24Hz to the TV. Since 120 is evenly divisible by 24, the TV can display the frames without any significant conversion (each frame 5 times). This is much different than the 3:2 pulldown your DVD player usually does, which converts the 24fps to 30 or 60 fps. That's a nasty algorigthm that involves splicing and creating frames that didn't previously exist. The technology is pretty good, but it's not "pure." Viewing a movie at 1080p24 is the closest you can come to the theater experience, and possibly better (no scratched film) if your home theater is well equipped.
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