In addition to handling all your audio signals, many receivers these days are designed to process and route your video signals. This can be especially helpful if, for example, your TV doesn't have enough of a certain kind of video input to accommodate all your gear. And as you'll see in our descriptions below, it may also help reduce the total number of cables you have to run to your TV, depending on your receiver's capabilities.
Basic video switching
Virtually all home theater receivers, as well as some stereo models, offer some form of basic video switching. These models allow you to switch easily between sources, but in some cases, they can only pass along a video signal to your TV via the same type of connection that it came in on. For example, if you connected two components via component video, one via HDMI, and one by composite video, you'd need to run another one of each of those types of cables between your receiver and TV.
Video conversion — more convenient switching
Some home theater receivers offer "video conversion" — the ability to accept a variety of incoming video connections from the components in your system and pass them all to your TV through a different type of video connection. For example, if your Wii™ is hooked up to your receiver via S-video, but your receiver has a higher-quality output like HDMI, and offers HDMI video conversion, you'll be able to send that video signal (plus all your other video sources) to your TV via a single HDMI connection. Now, you'll still be seeing the lower-quality S-video picture, but it means you won't have to switch inputs on your TV every time you want to watch a different source — the main benefit here is convenience.
Video upconversion — get the best signal possible
Along with video conversion, some receivers offer video upconversion, or "scaling." These receivers can upgrade any video source to a superior high-resolution video signal that more closely matches the capabilities of your HDTV. Your DVDs and older video sources will look cleaner and more detailed. However, there are limits — don't expect your VHS tapes to look high-def.
(It's worth noting that some manufacturers may use the term "video upconversion" to describe video conversion. But unless your receiver's manual includes instructions on setting the resolution you'd like to upconvert your signals to, it's not video upconversion.)
What we recommend
As you can see in the descriptions above, you get the biggest advantage when your receiver offers video conversion or upconversion. Both offer a streamlined, one-cable connection to your TV, plus upconversion gives you the added benefit of improved video performance. In fact, we generally don't recommend routing video signals through a receiver with basic video switching. For more info, watch our short video on conversion and upconversion.