How to Build a DVR

The digital video recorder (DVR) is a wonderful piece of
modern technology. While the VCR may have freed us from the
rigid schedules of TV programming, the DVR has freed us from
having to learn how to program our VCRs, not to mention
trying to figure out what's on that pile of unlabelled video
tapes.

But DVRs have two major flaws -- you have to pay for the
privilege of using one, and you're stuck with whatever
capabilities the DVR you purchase happens to come with. If
you want to expand the space on your DVR for storing
additional programs, or want to tweak your user interface,
there isn't much you can do about it.

If you build your own DVR, you sidestep both problems. You
won't have to buy the hardware or sign up for a contract with
your satellite or cable company for the device, you won't
have to pay for the service, and you can modify and expand
your DVR all you want. And it turns out a DVR isn't very
complicated -- you can easily build one with off-the-shelf
technology. That's because a DVR is basically a hard drive
with a way to interface with your TV signal, plus some
software to control it. If you have an old desktop computer
lying around, you're already halfway there.

Laying the Foundation for Your 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.

TV Capture Cards

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.