A PC in your entertainment center

TiVo and its brethren get credit for introducing the average consumer to the concept of the digital video recorder (DVR) and opening the door to bigger and better things. The Home Theater PC (HTPC) is the computer enthusiast's answer to all the things that a DVR generally does, with the potential to do everything a full-fledged computer does. The concept had a bit of a slow start until Microsoft's release of Windows XP Media Center Edition (MCE) 2005, which gave the very familiar Windows a living room interface and the hardware support that HTPCs needed.

No matter what operating system you use for your HTPC, the same general concepts exist: recording and time-shifting TV are the device's most basic functions; playback and recording of DVD and Blu-ray are secondary but (perhaps) no less critical, followed by distribution of audio content and, in more ambitious setups, serving up digital media in its capacity as the whole home network's media storage center. And don't forget the ability to do mundane things like browsing the web from ten feet away on a shiny new 1080p HDTV.

The newest evolution in the HTPC is the continuing development of HDMI (High Definition Multimedia Interface). HDMI allows a protected connection that carries both audio and video over a single cable, and in the current version, 1.3a, HDMI is finally established enough that it now just works. . . most of the time. When the last update was published, HDMI for content-protected video was working fairly well in the HTPC arena, but HDMI for content-protected audio was not yet working very well. That has changed in the past few months, as AMD, NVIDIA, and Intel have all made substantial improvements in getting full-blown HDMI working. Things are now solid enough to make HDMI a vital part of the HD-capable HTPC.

It has been over three and a half years since the HTPC has gone mainstream. Today, the HTPC front-end is fairly well established, with a slick interface and a compact, living-room-friendly form factor, and it's reliable enough that you rarely notice it's there. Toss in working HDMI for both audio/video signals, and it's possible to fit an HTPC in your entertainment center with even fewer cables strewn about than ever before.

Going beyond the DVR

Though it has made great strides in the past few years, the HTPC is still fundamentally a geek endeavor. An off-the-shelf DVR is almost certainly going to be cheaper, use less power, and be easier to setup than an HTPC. Using an Xbox 360, PS3, AppleTV, or something else as a Media Center Extender to get content to your TV will also be cheaper (and probably easier). If you can skip recording and just playback recorded content, the Western Digital WD TV is cheap and effective. As Mythtv.org points out, lots of solutions exist, almost all of them cheaper than building your own HTPC.

You get lots of potential for additional capability with an HTPC, capabilities like massive amounts of storage space: There's nothing stopping you from building an HTPC with a few terabytes of hard disk space, assuming you're willing to deal with the cost and power consumption. You won't find that in an off-the-shelf DVR. (Of course, with an off-the-shelf DVR, you can call technical support when it breaks; or, more appropriately, when your family's DVR breaks and they live 300 miles away, they can call tech support so you can continue watching The Office, uninterrupted.)

Have a standard-definition DVR already and want to go high-definition (HD)? Sure, it would be cheaper to buy an HD-capable DVR, but what if you want Blu-ray, too? A Sony PlayStation 3 might be able to do the Blu-ray part, but with only 80GB max, it's severely lacking in space. Hence, for those with needs desires beyond the average DVR user, the HTPC starts to make sense.

The fact that you can do it all in one box with an HTPC is the real reason for building one. The HTPC can handle DVR duties, HD playback, and even gaming (now that finding fast yet quiet video cards for 1920x1080 gaming is no longer the chore it once was).

Evolution in the HTPC: proper HDMI support

The biggest change since the last update is the ability to implement the fully protected content path in an HTPC necessary to play HD content (both audio and video).

On the video hardware side, HDCP (high-bandwidth digital content protection), AACS (Advanced Access Content System), and the other mechanisms for the Protected Video Path have worked for the last generation or two of computer hardware. To get full-resolution protected content output on your monitor or TV, both the video source (the video card in your HTPC) and the display (monitor/TV) must support HDCP. Today, most do.

To play protected audio has been a bit more difficult until very recently, as no current video or sound card (no matter which hardware it has) supports the Protected Audio Path needed to get compressed multichannel audio (Dolby TrueHD or DTS-HD MA) from your Blu-ray to your speakers via HDMI. The fix, as Anandtech and others discovered, is to let your HTPC decompress the multichannel audio, and send it over HDMI as uncompressed 8-channel LPCM. The hangup then became that hardware did not incorporate enough bandwidth to accommodate uncompressed 8-channel audio over HDMI, or if it did, the drivers or something else didn't work.

Redemption (or at least a workable fix) finally arrived in summer, 2008. AMD's Radeon HD 4000-series graphics cards, NVIDIA's GeForce 8200/8300 chipset, and Intel's G45 chipset all support 8-channel LPCM and actually work. Technically, Intel's G965 and G35 chipsets also support 8-channel LPCM, but the drivers never made it a pleasant experience.

ASUS's brand-new soundcard, the Xonar HDAV 1.3 would also work if you really needed to get an existing system with only video-over-HDMI to contain audio, but one look at the price of the Xonar HDAV 1.3 (almost $200), plus the thought of cramming another card into an already-crowded HTPC case, makes it a less than ideal solution for a new build.

Anandtech has considerable discussion on this in several recent articles, including one on 8-channel LPCM over HDMI and two more on chipsets with integrated video.