Section 6.1. Determining Functional Requirements


6.1. Determining Functional Requirements

We started our design of the media center PC by pretending that we were heavy consumers of audio and video media and deciding which functions were essential or desirable. Our goal was to design a media center PC that we could build for about the same price as a commercial Windows MCE PC, but with additional features and functionality.

Here's the list of functional requirements we came up with:


Analog cable-ready, 125-channel tuners

Our cable TV service is standard analog that uses no channels above 99, but our televisions can tune channels through 125. Because our cable company sometimes adds channelsand sometimes adds higher-numbered channels while leaving lower channels unusedwe need tuners that support analog cable channels at least through Channel 125.


Digital OTA tuner

Although we don't yet own an HDTV, that could change at any time. We want our media center PC to record OTA (over-the-air) digital broadcasts, which requires a digital tuner. Also, with Broadcast Flag legislation looming, we wanted to acquire a DRM-free digital tuner card while they were still available. Most digital tuner cards can also tune digital cable signals, but only those that use unencrypted QAM-64 or QAM-256, which is usually limited to local channels, if that.


Time-shifted video recording

We use our DVD recorders primarily for time shifting. Other than sporting events, news, weather, and similar live programming, we haven't watched a program in real time for 15 years or more. We record everything and zap the commercials, if any. It is essential that the media center PC provide similar functionality, including commercial zapping.


Video recording quality

We record everything in DVD-quality mode unless we're recording a movie that requires higher compression to fit on one disc. Accordingly, although lower-quality recording modes are desirable for additional flexibility, DVD-quality mode is essential.


Capacity

We tend to accumulate recorded programs and watch them in batches. For example, if "Masterpiece Theatre" is running a four-part series, we don't begin watching the series until we've recorded all four episodes. Sometimes we don't watch a series until months after we recorded it. We decided we needed an absolute minimum of 100 hours of DVD-quality video storage, and 250 hours or more would be better.


Watch-while-record

The system must allow us to watch one live analog program while recording another analog and/or digital program.


Record multiple programs simultaneously

The system must allow us to record two analog programs simultaneously. We decided to settle for the ability to record only one digital program at a time, because to do otherwise would require additional digital tuners. That would be overkill for our system, but perhaps not for yours.


Live-pause and real-time commercial zapping

The system must allow us to "live-pause" a program while it is being recorded. That is, if we begin watching a program in real time, the system must allow us to press a pause button when the phone rings and continue recording the program. When we have dealt with the interruption, the system must allow us to resume watching the program at the point we paused it. Because live-pause buffers video for later viewing, this feature also allows us to zap commercials in a live program by waiting several minutes after the program starts to begin watching it.


Online program guide

The system must feature a free, interactive program guide, customized to the channels provided by our cable system. Selecting a program to be recorded should be a simple matter of pointing to that program on the guide menu and pressing a button. Ideally, the program guide should be customizable to hide channels we never watch.


Video archiving

The media center PC must make provision for archiving recorded programs to writable DVD discs that can later be played back in the media center PC or on an ordinary DVD player.


Standard file formats

The media center PC must record video data as standard file formats without DRM copy protection or other impediments to copying and editing those recordings. Ideally, the media center PC would also be able to translate various standard file formats to other file formats.


CD and DVD player

The media center PC must function as a standard CD player and DVD player, capable of playing CD-DA audio discs and DVD-Video discs. Ideally, the media center PC should also be capable of ripping the content of CD and DVD discs to its hard drive.


Media library and audio/video server

The media center PC should provide a media library management function, allowing us to store, organize, and play back video and audio data, including the MP3, OGG, FLAC, and WAV audio file formats, as well as digital camera images in JPEG and RAW formats and DV camcorder video. The media center PC should also function as a multimedia server for other systems throughout the house, by allowing those other systems to access stored audio/video via a network share.


Gaming console replacement

The media center PC should function as a gaming PC, within the limitations of using a standard television for display. We're only casual gamers, so even an entry-level 3D graphics card suffices for our needs. Dedicated gamers can install the latest fire-breathing gaming video card instead.


Casual PC replacement

The media center PC should be usable for casual PC functions such as checking email or browsing the Web, again within the limitations of using a television as a display device. Don't overestimate the abilities of a standard-definition TV. Our 27" CRT standard-definition TV supports 640 x 480 resolution at best, which makes it marginally usable for web browsing and email. When we replace that old 27" Panasonic, we'll choose a 32" or 35" LCD model that supports at least 720p, if not 1080p. Such a display has sufficient resolution to use for any PC function, including gaming.


Extensibility

As we thought about the functions a media center PC could provide, we realized that it could support other unrelated functions in the future. For example, we may eventually use the media center PC to control a home weather station or provide automated attendant and voice mail functions for our home telephone system. Because the media center PC is a standard PC, making provision for these possible future functions is a simple matter of making sure that the media center PC has plenty of processor, memory, hard drive capacity, USB ports, and so on.


Ease of use

Although the media center PC is a PC and will sometimes be used as such, ease-of-use is a major consideration for the core multimedia functions. For example, scheduling a program to be recorded or playing a DVD should be a matter of punching a few buttons on a remote control rather than navigating menus with keyboard and mouse.


Upgradable to HD-DVD and/or Blu-Ray

Consumers initially ignored the rollout of high-definition video discs based on the competing HD-DVD and Blu-Ray standards, and rightly so. The first players were slow, crash-prone, and overpriced by an order of magnitude. Only a handful of titles were available, and they sold at a 50% to 100% premium over standard DVDs. Still, those initial teething pains will eventually be dealt with, and either HD-DVD or Blu-Ray (not both) will become the new standard. We wanted our media center PC to be easily upgradable to support whichever HD standard eventually wins.

At first glance, it might seem that adding high-definition support would be as easy as replacing the existing optical drive with an HD-DVD or Blu-Ray model. There's more to it than that, though. HD playback requires a lot of processing power, memory, and video bandwidth, which is why early Blu-Ray players were essentially thinly disguised Pentium 4 PCs. We'll design our media center PC to have sufficient resources to be easily upgradable to support high-definition optical discs. At most, we'll need to upgrade the optical drive and video adapter.

That laundry list is a lot to ask of a system, but even at that one of our original wish-list items didn't make the final cut:


Streaming video/RF-out

We originally intended to design a media center PC capable of outputting an RF signal that could be received by any television in the house. We concluded that, although it was possible to do that, it would require significant cost and effort for little return. As an alternative, we decided it would be easy enough to burn any programs we wanted to watch elsewhere to a DVD and watch them on a standard DVD player.




Building the Perfect PC
Building the Perfect PC, Second Edition
ISBN: 0596526865
EAN: 2147483647
Year: 2006
Pages: 84

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