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PVRs - The basics of recording TV shows on your PC

by Marty Winston

What do we mean by PVR?

See how quickly confusion starts? PVR may stand for Personal Video Recorder or PC Video Recorder or sometimes Programmable Video Recorder. Sometimes the acronym becomes DVR for Digital Video Recorder.

We’re not here to fight over definitions. So let’s just agree that this is all about using your PC the way you’re used to using your VCR. A few things are different, but that’s a good starting place.

One more point. We’ll mostly be discussing PC-based PVR. There are some set-top PVR boxes you can buy, and they work the same way, only with their own built-in computer, hard drive and TV electronics. Some satellite or cable boxes also include PVR features.

Since you already own a computer and hard drive (we’re not just guessing, because, after all, you are reading this on the Web), we’ll assume that you want us to focus on PC-based PVR.


No cassettes

If you eavesdrop in the stores, one of the first things many people ask about those set-top PVR boxes is, where does the cassette go? PVR doesn’t use standard videocassettes; instead, it uses a hard disk (the one already in your PC with us, the one inside the box with those set-top units).

That can be better, or worse, depending on why you make video recordings.

If you have a huge library of videocassettes and you watch many of them all the time, a PVR may not be as good a solution – though it can be. While you will almost always make your recordings onto the hard disk, you don’t have to leave them there. If your computer has the ability to record onto a CD or a DVD, you can easily transfer your video recordings onto a disk (and a recordable DVD may even cost you less than a videocassette). You can even edit the video (to remove those repetitive shots of Aunt Marge, for example) before making the transfer and (because it’s digital) not lose any playback quality.

It’s also possible to make or move recordings onto high-capacity removable storage, like a Zip disk. You’ll want to read the section ahead on the trade-off between space and playback quality.

If you normally just “time shift” (record shows that appear at inconvenient times so you can watch them once at a convenient later time), a PVR can be a wonderful solution.

You won’t need a pocket protector to make it all happen, either. A spate of new online EPG (electronic program guide) such as TitanTV.com and PC scheduling utilities make it easier to automate PVR settings on most PCs than it is to set the time of day on most VCRs.


Where will the TV signal come from?

Do you have cable TV? How about the new digital cable, with hundreds of channels? Do you have satellite TV? Are you using a classic antenna to receive local broadcasts? How about DTV broadcasts? While we’re at it, do you have a video camera?

One way or another, you can record any or all of these with a PVR (one at a time, of course).

If your computer has a WinTV-PVR or WinTV, you’re already ahead of the game. The built-in tuner on WinTV's is ready to receive antenna-fed broadcasts, standard cable channels and video feeds from cameras or satellite boxes.

There’s a great resource at http://www.TitanTV.com that can tell you what kinds of program sources are available where you live (in the US at least). There may be more than you knew about.

So getting the program you want to record into your computer is about as easy as getting it to a TV set or a VCR. And whether or not you decide to make your PC also act as your PVR, it’s a great way to have a new place to watch your favorite shows.


Transforming the TV show into data

Remember phonograph records? They’re analog; their digital counterparts are music CDs. MP3 players are the digital counterparts to analog cassette players. Did you ever scan an old photo? The photo is analog, the scanned image is digital.

With luck, and good equipment, your enjoyment of sounds and images is unchanged (and perhaps improved) by whatever method transfers them from analog to digital. For example, the CD got rid of the scratches, pops and hisses of vinyl records, and MP3 players are both smaller and more capacious than their cassette ancestors.

The work of converting something analog into something digital is called encoding. It has to happen somewhere, and for a PVR, that somewhere can be located either in the system hardware or in the system software.

Hauppauge WinTV-PVR cards, for example, include specialized encoding hardware, while most other WinTV cards do not, (though all WinTV's can record TV shows, WinTV-PVR's have special hardware for video recording, making them the best choice for recording TV shows) but not to worry.

There are at least three add-on Windows software products that include support of WinTV-PVR for TV recording as well as playback convenience features.

§ Click http://www.intervideo.com/jsp/Product_Profile.jsp?p=WinDVR to learn about WinDVR from InterVideo.

§ Click http://www.freytechnologies.com/ to learn about SageTV from Frey Technologies.

§ Click http://www.snapstream.com/Products/newProductPage.asp to learn about Personal Video Station from SnapStream.

§ Click http://www.gocyberlink.com/english/products/product_main.jsp?ProdId=20 to learn about Power VCR II from CyberLink.

One advantage of software encoding is that it tends to be less expensive to implement; one disadvantage is that it consumes some of the available computing power.

The alternative is hardware encoding, which means adding electronic devices to the computer. It costs a little more but uses fewer of the computing resources and tends to work a little faster or a little more smoothly under difficult conditions. The WinTV PVR card, for example, uses hardware encoding.

In a moment, we’ll take a look at what encoding standards are involved, and how they differ in terms of what you see and how much space it takes to store it.


Playing back

We absolutely do not want to confuse you, though there are several elements to using a PVR that can change. We’ll try to address them simply, one at a time.

Some of these things aren’t really about playing back what you recorded. They may involve choices you make when setting up a PVR, or your options for making the recording. Whenever and however they came about, playback time is when you’ll notice them or think of them.

Where do you want to watch shows you record? If you’re OK with watching them on your PC, no problem, any WinTV card lets you do that. If you want to watch them on a TV set, you need a way to get to it. You can select the newest WinTV card (the WinTV-PVR-350) with both advanced PVR features and its own video and audio output connectors which connect to the audio/video jacks on most TV sets. Also, many PC graphics cards have a “TV out” feature that lets you connect your PC to a TV monitor and show everything on your PC on the TV screen. You can also buy a separate “TV out” card.

Do you need the best possible picture quality? The better the picture you want to see, the more disk space you’ll use recording it. Another way to say that is, the better the picture you want to see, the less recording time you’ll get for a stated amount of disk space. For example, at its highest quality image (as good as a DVD), a WinTV PVR card will use 4GB to record a 2-hour movie; it can also record the same 2-hour movie at about the same quality as a videocassette using just 1.5 GB of disk space.

Do you want to watch a big picture? You might be surprised how viewable a TV show can be in a space as small as a business card on your PC screen (which is, after all, about the same size as those pocket TV screens). If you’re recording an interview show, for example, a little less image quality or a smaller image size may be perfectly acceptable, and you may be able to fit an hour-long recording on something as small as a 100MB Zip disk. If you want to watch a sports or entertainment show on your TV set, you’ll probably want something closer to at least VCR quality. If it’s a movie and a big screen TV, go for the DVD quality. One nice thing about PC-based PVR is that it gives you these choices.


A look at quality versus recording time

Let’s start with our best stuff.

High: The image on the left shows the PVR image you see at our highest quality setting. The image on the right is a 20x magnified view of a portion of the image on the left. This is the same quality image a DVD player puts on your TV screen. An hour-long program will use 2GB of disk space at this quality setting. This is an uncompromising setting for recording feature films from digital cable or digital satellite channels.

Moderate: The image on the left shows what you see at a moderate setting, with about the same quality as a VCR. Again, the image on the right is a 20x magnified view of the image on the left. An hour-long program will use 750MB of disk space at this quality setting. This is a great choice for normal time-shift viewing of a favorite show.


Low: The image on the left shows what you see at a lower setting, with about the same quality as an out-of-town station. Again, the image on the right is a 20x magnified view of the image on the left. An hour-long program will use 250MB of disk space (a Zip disk) at this quality setting. It’s a very good setting for watching shows or movies broadcast in black & white. It’s also a good setting for watching interview (“talking head”) shows.


Lowest: The image on the left shows what you see at a compromise setting, with about the same quality as a VCR. Again, the image on the right is a 20x magnified view of the image on the left. An hour-long program will use 100MB of disk space at this quality setting (the capacity of an older or smaller Zip disk). This is better than the quality of most Web streaming video feeds. It’s absolutely appropriate for keeping logs of program content. It’s a cool way to make videos you can send in an envelope, or to record videos at home to watch on a laptop later.


Not just for watching

Just like a VCR, you may want to use a PVR for reasons beyond just watching shows later. Here are a few examples:

§ The lowest quality viewing on a PVR means the most hours per Gigabyte of free hard disk space, which makes a PVR an easy, low-cost way (with an inexpensive video camera) to provide full-time video security, using a PC already on site.

§ Have a recordable DVD drive? Use the highest-quality settings to capture movies from a digital cable or digital satellite station, transfer them to DVD and watch them anywhere you have a DVD player, any time. (Of course, this is only legal for personal use).

§ Have a CDR or CDRW drive? You can save a favorite program to a video CD (most DVD players will play it) and view it at about the same quality as a videotape.

§ Have a video camera? Transfer your video through the PVR, edit it digitally, then save the result on CD, DVD or videotape. You’ll find a variety of powerful “prosumer” video editing software available today, at prices from free to reasonable.

§ Want to just say hello, face to face? If your video clip is short enough and your Internet connection fast enough, you can send the clip as an e-mail attachment. You can also transfer it to a CD, DVD, videotape or Zip disk and mail it (a great way to stay in touch with kids away at college).

§ Thought about adding streaming video to a Web site? A PVR is a great way to capture all the pieces for editing. It lets you work with higher-quality video before converting to the lower-quality streaming standards, meaning more professional results.

With a little of your own imagination, you might easily come up with other ways to take advantage of PVR in ways that we have yet to imagine.


Tech talk

If you don’t like jargon, you can quit reading now and be confident that you already know enough of the basics of PVR to make good decisions about it.

If you’re curious about technology and standards, we won’t go too deeply, and we will give you enough information to get you started.

The first thing we want to talk about is compression, which has to do with squeezing all the data that’s in original video down into something smaller that your consumer can handle.

Studio-quality video represents 270MB of data every second. In the early 1990s, the film and broadcast industries were looking for ways to make that smaller so they could put some video onto a CD. That meant fitting everything into about 1.6MB/sec.

The Motion Picture Expert Group (note their initials, MPEG) came up with an answer, introduced it in 1992 and won an Emmy for their efforts. It reduced the picture resolution to 352 dots on each of 240 lines (written as 352x240), which is about as good as a consumer VHS videocassette playback.

If that’s an appropriate quality level for your purposes, this standard, now called MPEG﷓1, can records 1 hour 24 minutes in one Gigabyte (1GB) of disk space (or 21 minutes on a single 250MB Zip disk).

The 352x240 Video CD (MPEG﷓1) standard was an admitted compromise, especially in an era when DVD players were appearing everywhere. They wanted to be able to support a higher-quality Super Video CD (480x480) mode, a full-quality (US NTSC) broadcast TV (704x480, exactly 4 times the detail of MPEG﷓1) mode and a full-quality DVD (720x480) mode. (We won’t discuss here but will note that the highest current resolution of images in the US is in HDTV mode, at 1920x1080, with about 25 times the resolution of the original Video CD).

In 1994, MPEG-2 arrived. It brought a variety of the higher resolutions and a variety of compression ratios (think of it as how much disk space to record how much show). MPEG﷓2 works, in part, by recognizing and noting (instead of recording again) those parts of the TV picture that have not changed during the latest tiny slice of a second. The MPEG﷓2 standard is at work in DVD players, digital cable TV, digital satellite TV and elsewhere. Where the MPEG﷓1 standard was based on handling data at 1.6MB/sec, the MPEG﷓2 standard is designed for rates around 5MB/sec.

But those last numbers are misleading. We won’t go into the math here; we’ll just note that a WinTV-PVR card captures MPEG﷓1 video at the Video CD rate of 1.15MB/sec and MPEG﷓2 video at a variety of rates from 2-12MB/sec.

By comparison, streaming Web video involves 0.02-0.03MB/sec, which helps explain why their size and quality are limited and their motion is visibly jerky.

Naturally, we think our WinTV-PVR products represent your best choice for full-performance MPEG-1 and MPEG-2 recordings. Now that you’ve read our PVR Primer, you know enough to decide whether or not you agree.

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