Video Inputs on an A/V Receiver
When connecting video devices in a home theater, it's generally best to connect them directly to the A/V receiver's video inputs and let the receiver switch (that is, select) which video source goes to the display. If you try to connect video devices directly to the TV or display instead, you'll discover that most displays have a rather limited set of inputs on the back (though some do have a ton).
Analog video inputs
There are four common types of analog video connections (in order of best to worst):
Component: Component video connections can be found on DVD players, HDTV tuners, gaming consoles such as the PS3, Xbox 360, and Nintendo Wii, and on many PVRs (such as TiVo and those built-in to high-definition set-top boxes for cable and satellite TV).
S-video: S-video connections can be found on better VCRs (the S-VHS models), most DVD players, DSS receivers, digital cable set-top boxes, PVRs, and older gaming consoles (Xbox, PlayStation 2, and Nintendo GameCube, for example).
Composite: Not a great choice, relative to S-video and component; use it only for low-resolution video sources, such as low-end VCRs.
Coaxial (also called baseband — rarely found in a receiver): Coaxial is the pits, so the less said about it the better.
What you want to look for in a receiver are both S-video connections and component video connections for your analog video sources. The picture quality you get when using these connections is almost always better than what you get with a composite video connection.
HDTV signals need a special kind of component video connection called a wideband component video connection. Some receivers have component video connections but can’t handle the higher frequencies of HDTV. If a specification is given, look for something higher than 25 MHz.
Many otherwise excellent displays have only a single-component video input, and few displays have enough S-video inputs for everything you might want to connect to them. This is a strong argument for finding a receiver that has a sufficient number of inputs. Count up what you have that uses S-video or component video and focus your search on A/V receivers that have what you need.
Digital video inputs
Digital HDMI audio/video connections are used for both audio and video — all over a single cable. Here’s an overview of how HDMI fits into the receiver world:
HDMI is still a relatively new technology in the receiver market — it’s become pretty much the go to video connection technology for HDTVs and for high-definition sources feeding into those TVs (such as DVD, Blu-ray disc, and set-top boxes).
Most mid-priced (or better) receivers have at least a few built-in HDMI inputs (and one HDMI output). Many of the less expensive receivers have just component video inputs and no HDMI. Over time, HDMI will become standard on just about all receivers.
HDMI has become the primary means of connecting high-definition source devices, so you’ll want to have as many HDMI inputs on your receiver as you can. Expensive receivers often top out at three HDMI inputs (which would allow, for example, a Blu-ray disc player, a high-definition gaming console, and a TV set-top box to connect through your receiver).
If you don’t have enough HDMI inputs on your receiver, you can use HDMI cables to connect some sources directly to the TV, and then connect the audio outputs of those sources to your receiver using digital audio connections. If you have a Blu-ray disc player, make sure you connect it directly to the receiver using HDMI, to ensure that you’ll be able to get the highest quality surround-sound audio using DTS-HD Master Audio or Dolby True HD.