How to Build a DVR

The most basic element of a homemade DVR is a computer. You could technically use any computer for this, but you'll be installing some new internal components, including a new hard drive, so a desktop is a better bet than a laptop. You could use a Mac, but you'll generally find that you have more options with a PC.

How powerful of a computer will you need? Well, that depends on what you want to do with your DVR. If you're just recording TV shows and movies in standard definition, then you don't need anything very powerful. If you'll be recording and playing back high-definition (HD) programming or want to watch Blu-ray discs, then you're going to need a computer with a little more horsepower. There are five things to watch for when buying or setting up the computer that you'll use for your DVR:

Processor - You don't need a top-of-the-line quad-core processor to run a DVR. In fact, for basic DVRing, older and slower processors will work fine, especially since the encoding will be handled by a separate component (the TV capture card). The bottom line here is that the processor should be powerful enough to run a modern operating system. If you're stuck running Windows 95 or earlier, you may have a harder time finding compatible software.

Hard Drive - You'll be surprised how quickly hard drive space gets eaten up by recorded TV shows. A single movie in HD can use up several gigabytes of drive space by itself. Hard drive prices have dropped considerably in the last five years, so if you're repurposing an old computer, you'll want to swap out the old drive for something larger. Remember, you can't have too much hard drive space, so buy as much as you can afford. You'll want a speedy drive to avoid problems with video quality. Keep in mind that you can always expand later by adding an additional drive.

Video Card - It's going to take a fairly powerful video card to process the video signal and send it to your TV. If we're talking about HD and Blu-ray, the video card will need even more power. This is the part of the DVR that's going to matter most to what you actually see on-screen, so if you're going to splurge on any part of your project, this should be it. There are many video cards to choose from, with new ones coming out all the time, so your best bet is to check audio/visual message boards for tips on which card is best suited to your purpose.

Memory - A minimum of two gigabytes of RAM will help your DVR run smoothly, although upgrading to four gigabytes won't hurt (and, again, might be necessary if HD is involved). Memory is inexpensive these days, and more RAM is almost always better.

Power Supply - A high-end video card and an extra hard drive can draw a lot of power, so you'll need a power supply that can provide it. A good way to get a rough idea of how much power you'll need is with an online power supply calculator like the one Journey Systems provides.

Next, we'll choose and install a TV capture card.

A typical computer doesn't have a video input that can accept a signal from a antenna or a set-top cable or satellite box. You'll need a TV capture card, which has its own tuner to receive television signals, to take the incoming signal and read it. Better capture cards have onboard processors that handle the encoding of the signal into the digital format the show will be saved as. A capture card that does its own encoding takes a lot of stress off the computer's main processor. In fact, if you use this type of card, you won't need a powerful main processor.

One important thing to look for in a video capture card is the ability to accept an MPEG-2 transport stream in both DBV and ATSC, sometimes referred to as digital hardware cards. That technical jargon simply refers to the format that TV shows are transmitted in over digital broadcasting networks. With the United States and many other countries switching to all-digital broadcasting, you'll want to avoid older capture cards that only accept analog signals. Many cards can handle both analog and digital signals.

A typical capture card will allow a user to record up to two programs at the same time while watching a third. If you want to record even more programs simultaneously, you'll need to install an additional capture card. But remember to make sure your power supply can handle the extra load.

Installing a video capture card isn't difficult. Most cards are PCI or PCI-Express cards -- they fit into slots on the motherboard of your computer. After removing the cover of your computer, the card is installed by pressing it firmly into the appropriate slot. The card is then secured with a single screw. There are also video capture devices available that are even easier to install. They plug into to any available USB 2.0 port.

In the next section, we'll find out what software you can use to watch and record TV programs.

There are several DVR software packages available, and some of them are even free. Some video capture cards come packaged with free DVR software as well, so if you like the program your card came with, you won't have to buy any additional software.

The specific software you choose comes down to personal preference and the operating system on your DVR computer. If you're running Linux, you can use Freevo or MythTV, which are free, or SageTV, which is a commercial application -- that is, you have to pay for it. SageTV is a popular choice because in addition to Linux, it also runs under Windows, along with GB-PVR (free) and BeyondTV (commercial). Mac users can try Elgato's EyeTV or Miglia's EvolutionTV (both commercial).

The main differences between the programs lie in their interfaces and how customizable they are. Some programs use a dedicated server to send programming information to your DVR computer (which will have to be connected to the Internet, of course), while others use a Web browser to access program data. Additional features include online services, weather reports and the ability to convert video files to portable formats.

There is one other interesting option: you could use Microsoft Windows Media Center to run your DVR. You could even integrate a computer running Windows Media Center with an Xbox 360 using Windows Media Extender. This way, you control the on-screen functions through the Xbox, which solves the remote control problem (which we'll address shortly). You can even purchase a special Media Center remote for use with the Xbox, but newer universal remotes can be programmed to work with the Xbox just as well. It's even possible to have your DVR computer in another room, as long as both the computer and Xbox are connected to your home network.

Once all the internal components have been connected and the software is installed, it's time to hook your DVR computer to your TV. First, attach your cable connection or satellite cable to the video capture card's input.

Next, connect the DVR computer's video card to your TV. If you plan to watch HD, you'd probably use an HDMI connection, although component, S-Video or VGA are also possibilities, depending on your particular system.

To get sound, you'll have to connect the audio output of your computer to the inputs on your home theater system, or your TV if you don't have a home theater system.

Finally, connect the computer to the Internet, turn everything on and let the program list load. You should be ready to watch and record TV shows with your own home-built DVR.

For more information on DVRs and other related topics, skip on over to the next page.