Building a Basic HTPC February 03, 2004

Introduction

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The problem with having a HTPC doing multiple tasks is that it becomes more difficult to integrate the software and yet your wallet gets thinner and thinner. Instead of starting off with a full-fledged HTPC, we're going to start with a very introductory approach to the HTPC and then through follow-up articles, add more features.

For this introductory HTPC article, we have two very specific tasks: DVD upsampled to HDTV resolutions, and a personal TV recorder. Since we're "lazy," our HTPC needs to perform like a real piece of home theater equipment as much as possible. The system should integrate itself seamlessly, and shouldn't force the user to think about it as a computer. The HTPC also has to have an advantage over a similar dedicated component – there's no point in reinventing the wheel unless you can make it faster, smaller, and cheaper.

Why these two tasks?

We've designed this system as an ideal starting point for anyone with a "HDTV ready" television.

Having a PC-based TIVO is ideal for a number of reasons. The most important factor is cost. Both TIVO and ReplayTV charge a subscription fee and ridiculous premiums for larger hard drives. With a PC, you can add and replace IDE hard drives on a whim and also enjoy free TV listings. In addition, it is possible to enjoy higher quality video through a PC-based system through improved video scaling than would otherwise be possible with a standard unit.

Finally, ATI and other third-party software applications have media server applications that will allow their multimedia products to stream video to client systems on your desktop, and NVIDIA is expected to add this capability to its Personal Cinema line in the near future.

The upsampled DVD is the more important feature in our HTPC today. Even if cost is no object, the HTPC approach to DVD can offer better picture quality than any stand-alone unit. DVDs are recorded with 480 lines of resolution, however it turns out that upsampling the video to a 720p or 1080i resolution for HDTV and HDTV-ready televisions will offer the best quality.


SIDEBAR: "But why is the rum gone?"

Making something out of nothing

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It's a real phenomenon

One of the most often confused concepts is the idea that upsampling DVDs to HDTV resolutions will make DVDs look as good as HDTV. It doesn't seem as if this is possible -- the data is not present to begin with. The real answer is that while an upsampled DVD isn't as good as true HDTV, it will look better than a straight 480 progressive lines of resolution. Here's why…

HDTV-ready CRT

Like a CRT PC monitor, an HDTV-ready CRT can sync at multiple resolutions. The catch is that the electron beam is not designed to change in size depending on the resolution (it changes but not by design). Suppose you have a 19" monitor running at 1280x1024 or 1600x1200. While reading this webpage, look at the white background. Get as close to the screen as you can to study the white. Now, change your monitor to 640x480 or 800x600 (if you want 640x480 in WinXP, go to Control Panel, Display, Settings, Advanced, Adapter, List All Modes…). Now look carefully at the white background – you'll see horizontal black lines. Ok you can go back to your original resolution.

The white background of the webpage does not have any detail. However the monitor is designed to resolve a higher resolution than the 640x480 you were testing. The space between one horizontal line to the next is greater than the distance that the closest two lines the monitor can reproduce. At a higher resolution, your monitor produces a more film-like picture because you are reducing the dead space. This is true even though you are dealing with two progressive signals.

This is to say that irrespective of detail, since 480p is typically below the maximum displayed resolution of the TV, upsampling can provide improved picture quality even if there is no change in actual picture content. This is why you do not want to have your HDTV displaying a true 480 lines.

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Upsampling Continued…

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The other argument for upsampling

Manufacturers realize the scanline phenomenon and so some TVs will double the 480p signal to 960p lines of resolution. Plasma, LCD, or DLP TV's are fixed array screens and MUST do this. Does this mean that upsampling is useless for these TVs? The answer is still no. PCs can offer a higher quality upsample.

In the first example, I did a simple line double. Instead of leaving the black space, I copied the line directly above it. In real-life, upsampling incorporates more advanced algorithms. Unsurprisingly, PC video cards are among the best scalers because they are developed with the mindset that people sit only a foot or two from a monitor. If I gave a school child this picture interlaced close up and asked him to figure out the pattern, he'd be able to fill in the blanks and "guess" what could have been present in the image. Video cards with good multi-tap scalers are able to do the same thing and maximize the resolution possible. In the future, we'll probably see more DVD players and TVs incorporating PC-like graphics processing.

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Security

The final advantage is security -- not security against hackers, but security in your purchase. DVD upsampling is available in commercial players from Samsung, V Inc., and LG, however due to piracy concerns, these features are only possible on the DVI outputs, making them ill suited for many HDTV/HDTV-ready displays on the market. Second, some DVDs have additional copy protection which will prevent upsampling on these machines. With a PC, it is much easier to circumvent these restrictions, especially when dealing with analog outputs such as component video. This allows you to get the best quality out of your equipment, although without question, circumventing these restrictions for piracy is illegal.



SIDEBAR: "A red sun rises, blood has been spilled this night."

The chassis

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An HTPC should fit in with the décor. Many enthusiasts have turned to small form factor systems such as the Shuttle SFF. While the SFF works well, we argue that for a HTPC, you should consider a micro-ATX or full ATX solution to keep your options open. To start, your selection for mini-ITX and even microATX motherboards is limited. Going with a standard ATX motherboard gives you the option to pick out the right motherboard for your budget and wishes. More importantly, most SFF systems have support for a single PCI add-on card and an AGP card with only two IDE channels. In a "flagship" HTPC, you might find yourself needing more HDDs and more add-in cards.

1) AGP graphics card (+1 if you want a larger heatsink for silent operation)
2) HDTV tuner (or P-I-P tuner to complement the primary tuner)
3) Sound card
4) Wi-Fi 802.11G
5) Dedicated deinterlacer/ scaler
6) Video capture

Though we're not building a flagship HTPC today, we'll still go with a full ATX setup so that we can continue to upgrade the system in future articles. In our system, we went with an Antec Overture with the built-in TruePower 380W power supply.

Antec Overture

First and foremost, we wanted a case that looked nice. Then we needed a power supply that met our criteria put forth in our Power Supply Guide. The Overture scores well in both regards with the glossy black finish and TruePower 380W. Although Antec claims this is a piano quality finish and includes a microfiber cleaning cloth, the finish does have a textured appearance to it. It's great for a computer case, but nowhere near the quality of the piano-black finish on the Swans T200A speakers we’ve discussed earlier.

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CPU	Page:: ( 5 / 10 )

In other system building guides, this would be the point where we talk about the Intel versus AMD debate. As we always say, choosing the right CPU depends on the right task. A HTPC is unique because it is possible to have "too much CPU power." When it came to building workstations it was important to have a fast CPU for rendering images, or running numerical computations, and for file servers, it was important to have a powerful enough CPU to meet the unpredictable demands of the clients – the proverbial "100 toilets flushing at once." For an HTPC it's different – the tasks are fixed. Your DVD-Video is always going to be 720x480 at 24-30fps. HDTV will never exceed 1920x1080 resolution. Analog cable TV will never require more than 2 channels of audio. So here's our simple formula:

Upsampled DVD-Video: 1 GHz is plenty

High-Quality Digital Video Recording: P4 2.0 GHz or Athlon XP 2400+

Windows Media HD 1080p: Athlon64 3000+ or P4 3.0+GHz

The Pentium 4 has the advantage over the Athlon XP when it comes to multimedia encoding thanks to SSE2 (as evidenced by our recommendation to go with an Athlon 2400+ for maximum quality MPEG-2 recording). Nonetheless, keep in mind that from 2.0 to 2.8GHz, the P4 won't buy you better digital video recording, and you won't be able to do 1080p Windows Media HD reliably until you hit 3 GHz. By then, the Athlon64 offers an equally tempting product. A 2.4GHz P4 would give you 720p Windows Media HD support and by then, we'd want to move onto the Athlon64.

Memory

Upsampled DVD-Video or DVR: 256MB

Windows Media HD 1080p support: 512MB

Our memory recommendation may seem incredibly aggressive given our 1GB and 2GB in our workstations, however it's important to remember that you won't be multitasking or dealing with anything more complex than a 2-megapixel image. As always, we recommend going with high-quality RAM such as that from Corsair or OCZ. Generic RAM is OK too, as long as you stay vigilant and recognize the gamble – when your hardware is unstable and you've got a quality power supply, check the RAM next.


SIDEBAR: Tell me how he died.

I will tell you how he lived.

Graphics

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We've gone with Quadro's and GeForce FX's in our gaming and server systems, but for this HTPC, we went with ATI.

ATI’s Multimedia Legacy

ATI’s multimedia tradition goes back to the 1996 with the launch of the ATI Video Xpression graphics card. This product featured the mach64-VT graphics chip, the first consumer graphics chip with a high-performance video scaler, and introduced the AMC (ATI Multimedia Channel).

Before the advent of AMC, if you wanted to watch TV on your computer, you only had two options. You could go with a TV card with an analog VGA pass-through cable which would deteriorate picture quality, or you could use the internal “VESA Feature Connector” which allowed an internal connection between the TV tuner card and the video card.

Unfortunately, the VESA Feature Connector limited desktop resolution to 256 colors and so again, you’d be sacrificing picture quality. ATI’s AMC technology allowed you to attach a TV tuner daughterboard to your PC without any sacrifices in resolution or color.

Over the years, ATI has continued to improve the technology in their multimedia and video perspectives, and for our HTPC, we're building it around the ATI All-in-Wonder 9600 and the component video adapter. If DVI output is important, you would need the All-in-Wonder 9800.

The component video adapter from ATI supports 480p, 720p, and 1080i resolutions. At 480p and 1080i, overscan can be a problem with CRT-based television. ATI does offer a 1770x1000 scan mode, which syncs to 1080i televisions and offers reduced overscan. The overscan is the fault of the television, however other than the one reduced-1080i scan mode, ATI offers little in the way of addressing this issue.

Picture quality at 480p

Compared to the native tuner on my HDTV-ready 27” Samsung 2796 TV (which was last years top of the line 27” Samsung HDTV), the ATI shows a reduction in signal noise in all channels. The drawback to this effect is that it makes the picture look a little soft, this is similar to the pictures from the early progressive scan TVs. It can be argued about which picture is preferable, the slightly noisier but sharper or the noiseless, softer picture. (It's worth pointing out that it is true detail as opposed to noise masquerading as detail).
The ATI tuner is stronger than that from my old Sony XBR, with improved picture on weaker cable channels. At times, there appears to be some pixelation artifacts with the ATI.

Some cheap TV tuners take a long time to switch channels, but the ATI changes channels very quickly. Compared to previous computer TV solutions, the picture has been improved and has less of a “processed” look, although personally it is not as pleasing as the native TV tuner. For most purposes, you probably won’t be using a computer to watch cable TV on your TV. The HD output will be used to playback HD videos that may be more readily available on a computer as opposed to another source.


SIDEBAR: The Last Samurai

Picture Quality (cont’d)

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Going to 1080i

When watching TV at 480p, the ATI doesn’t improve upon the standard TV tuner. Things change at 1080i. Some would argue that there is no reason to upsample cable TV to higher resolutions, since the source data is not there. Those in the know (i.e. those who read this article without skipping around!) already recognize that this upsampling step is one of the key components to optimizing your video quality. This is why the Runco and Faroujda can charge a premium for their products. Theory aside, watching cable TV at 1080i is a marked improvement over standard 480p. It isn’t going to fool anyone into thinking that it is HD, but it allows you to use your HDTV at it maximal capability for more programs.

Usability

The TV software through "EazyView" resembles what you would see on a digital cable box. With an internet connection, you can have instant access to TV listings and the current program and channel ID are automatically displayed. You won’t make the mistake of calling Little House on the Prairie a John Wayne flick.

One problem is that if you are using the channel browser to read through the TV listings, it won’t loop through the listings. For example, if you go all the way to channel 82, it won’t advance or loop to channel 2. You will need to go backwards through the listings again. When advancing channels manually, you do not have this problem. Second, despite living the major metropolitan city of San Francisco and despite ATI's choice of GuidePlus (owned by TV Guide) for their listings, there are a few major channels such as the Travel Channel not tracked by the software, and occasional errors in the schedule (listings for one channel only have been off by 1-2 hours).

One nice feature is the integration of this channel guide with the recording capability. While watching TV, you can still scroll through the listings for other channels and in the future. Once you find a show that you want to record, you can just press the record button on the remote, and it will be recorded at the appropriate time. Tap it another time and you can set it to record every weekday or every week. The GuidePlus listings are updated weekly, but the update must be done manually. This is a major error on GuidePlus and ATI, and it will need to be fixed before the TV becomes seamless.

There is digital video recording and time shift functionality built into the ATI program, but we found it to be a little buggy. When time shifting, the TV software would sometimes crash out. There is also a noticeable drop in image quality when used in this mode due to the MPEG-2 encoding. We can say that the crashes are much less frequent with the latest Catalyst 4.1 drivers, but that further driver updates would be useful. We are not sure where the error stems from as we've had no luck on multiple systems with clean WinXP installs and multiple sound cards. That said, recording works excellently and while recording image quality remains at full resolution.

New since Catalyst 3.10 is EazyShare. In theory, this would allow you to use your ATI Radeon powered desktop PC watch live TV, timeshifted TV, or recordings streamed from the All-in-Wonder server. Our initial impressions are that the software still needs some debugging, but we will have to focus on EazyShare in a future article.

Aspect Ratio Conversion

One of the nice things about the ATI is that it supports aspect ratio conversion. This is helpful if you have a 4:3 ratio HDTV. When running 1080i, the ATI is sending an anamorphic widescreen signal. For widescreen sources such as your desktop or DVD, it's possible to use the anamorphic squeeze feature of your TV. For televisions, the squeeze would result in a black frame around your video. The ATI multimedia center can correct this by outputting the TV as an anamorphic signal as well, which becomes normal on a 4:3 TV.

When recording in MPEG-2, the anamorphic aspect ratio is preserved. This makes the TIVO/TV experience almost seamless. It's possible to leave the TV application running at all times – when the HDTV display is turned on, it is as if you were using the native tuner. One caveat is that ATI does not provide the same aspect ratio correct when recording to MPEG-4. This is also an error on ATI's part and we hope it is corrected soon. Second, although the TV application supports multiple aspect ratios, the ATI file player does not. There needs to be better integration with ATI's development teams.





SIDEBAR: Now he's using the Schilder technique.

The versatile DVD

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DVD Quality Second to None

With the VGA output, it is possible to scale to DVD to any resolution. With the component video output however, the ATI DVD player only allows for 480p output with Macrovision-protected DVDs out of the box. This is the case for the other upsampling DVD players on the market – these DVDs only output DVI.

In the case of titles such as Finding Nemo, the set top players will be unable to upsample to 1080i. This is where the strength of the HTPC comes in. By running 3rd party software wrappers such as DVD Region Free will remove the Macrovision protection on DVDs on-the-fly. This allows you to run any DVD at the higher 1080i resolutions through the component video connector – no other platform can do that.

Another advantage to using this setup for DVD playback is the lighting fast layer changes and chapter seeking due to the higher speed DVD-ROM drives in computers. The transition between the first and second layer is impossible to identify with any of today's current DVD-ROMs. Even layer changes with old 2x drives are virtually indetectable. Playback of “non-standard” DVDs is also easier on the computer such as your travel videos put on DVD+/-RW.

ATI definitely knows how to make quality video playback chips. They were one of the first to incorporate 2:3 pulldown support in their DVD player and Samsung will be using ATI chips in their next generation of TVs. We did not notice any lip sync errors during playback, but we would like ATI to add a software option to correct for this if it ever showed up. Some high-end receivers have this function.

Upsampling Quality

The upsampling/deinterlacing to either 1080i or 480p was done without any artifacts and the 1080i output definitely showed more subjective detail than the 480p -- we did not have the hardware to test the 720p outputs. Our TV had no problem recognizing the HD signals that the ATI broadcasted. With HD resolution sources played back on the ATI, the image was as would be expected from a 1080i source.




SIDEBAR: Finding Nemo

Choosing the Sound Card

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While sound is essential to creating a theater experience, we don’t necessarily need all the bells and whistles in our HTPC. With an HTPC, most of the audio decoding and processing will be done by your receiver rather than internally by the computer. This means that we don’t really need a card with many analog outputs, all you really need is a good digital out, either optical or coaxial. Good software compatibility is also needed to ensure that DTS and Dolby Digital signals can be passed through the card. Ideally we would have a card that can convert all analog inputs into a digital out. If this is not possible, then we need a clean analog output stage to get MP3s and CD audio to our receiver.

In using our system as a digital video recorder, the audio is usually received in analog from the TV tuner module, so your sound card should have a good analog input stage, meaning it should have low noise levels with good sensitivity and bandwidth. With over the air broadcasts, the quality of the source material will not exceed the recording capabilities of any sound card. As we move to HDTV, then the audio will be in the digital domain, so shouldn’t need to go through the analog inputs of a sound card at all.

When playing back DVDs, you just need to be able to pass the DTS or Dolby Digital signal through the sound card’s SPDIF output. The ATI All-in-Wonder has its own SPDIF output, however we had little luck getting this to work flawlessly. We'd encounter "pops" and episodes where the Denon receiver lost sync with the Dolby Digital bitstream.

So what did we choose?

We initially chose the Via chipset powered, Mad Dog Entertainer 7.1 DSP card. This choice was not based upon the 7.1 feature, but rather the card’s 24bit DSP, SPDIF connections, and bargain cost. Home theaters are already a tangled mess of wires, if we can keep the connections from the HTPC to the receiver down to a single digital audio cable, this would be a good thing. The Envy24-HT chip used in this sound card has hardware support for digitization of the line-in, allowing us to use the SPDIF out for TV audio as well. The feature is not yet properly implemented in the Via drivers.

This brought us to our second go-to-guy, the SB Live. The SB Live has a tried and true digitization of the analog inputs. Moreover, after good success with the Envy24-HT and even my M-Audio Audiophile USB DVD SPDIF out, I expected Sound Blaster support to be a no-brainer as it was one of the earliest and most popular SPDIF-out capable cards. Unfortunately, luck was not with me. The ATI DVD player refused to pass the AC3/DTS signal through my SB Live. As ATI officially only supports SPDIF through the All-in-Wonder, I'm out of luck.

Doh!

We'd like to keep the sound card under $50 and so we ultimately decided to stick with the Envy24-HT. While we must switch audio inputs on our receiver when choosing between a DVD and TV (something you'd have to do with most TVs anyway), we do get the high-quality 24-bit audio and ability to pass 96 kHz PCM audio.



SIDEBAR: For relaxing times, make it Santori time.

Conclusion

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Unlike our other system building articles, it's clear that we've spent much less time going over the hardware. Time and time again, we've said the most important thing about building a specialized system is to know your task. We went all out for our Dual Opteron system using nothing but the best. We explained why storage server and RAID were not synonymous. For the HTPC article, we hope that you've learned a little bit about signal processing, but also showing you that you don't need the fastest CPUs or the most RAM all the time, and that sometimes the simplest solution such as an All-in-Wonder can make for the best solution.

So far we’ve taken a rather simplistic view of the HTPC, there are other software solutions besides ATI’s MultiMedia Center such as Snapstream’s BeyondTV and SageTV from Frey Technologies. We’ll be going into more detail on the world of HTPC’s in a follow-up article, so stay tuned!


SIDEBAR: Lost in Translation