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"  Shrink to Fit You&amp;#039;ve mentioned using zipped and compressed files in many of your columns. How do the various compression programs shrink your data and how does the process affect a file? Without getting into the down-and-dirty math, one can lump file compression into two classes: lossless and lossy. (The language may sound clumsy, but then computer scientists and poets rarely hang out together.) Something compressed losslessly can be uncompressed to its exact original state. A file that&amp;#039;s undergone lossy compression can never be restored exactly to its former self. You use both lossy and lossless compressed files all the time, often without even thinking about it. For example, the JPEG images your browser downloads while surfing the Internet are lossy files. The difference between a JPEG and, say, a program downloaded as a lossless ZIP file is that you probably won&amp;#039;t mind if a few pixels of the JPEG image are gone. However, you&amp;#039;d likely be pretty upset if a line of essential code went missing from your program. Why use lossy compression? Because most lossy formats allow you to achieve very high rates of compression. For example, a 10MB CD track can be compressed into a 1MB MP3 file without much loss of quality. But that doesn&amp;#039;t mean you&amp;#039;re getting a perfect copy. By definition, lossy compression tosses out information from the original file. In the common WMA, MP3 or AAC music file formats, for instance, audio information at the limits of human hearing may be eliminated. In a video file such as WMV or DivX (see &amp;quot;Three Things You Need to Know About DivX,&amp;quot; next page), color information and frames may be sacrificed. In a digital image file such as JPEG or TIFF, some color and pixels might be ignored. If, however, your file is a work document or executable program and you absolutely, positively must keep every last bit of data, you&amp;#039;ll want lossless formats such as ZIP, RAR and Stuffit. (For music purists, there are also lossless audio formats such as Apple Lossless and FLAC.) How does compression work? There are a variety of ways, but most involve finding patterns within the data and removing redundant information. For example, in my second paragraph I used the term &amp;quot;JPEG&amp;quot; three times. A compression program might replace the word &amp;quot;JPEG&amp;quot; with the number 1, then add &amp;quot;1=JPEG&amp;quot; to the compressed file&amp;#039;s internal translation table. By assigning every word or letter pattern a code number, the number of characters it takes to save the information is greatly reduced--it&amp;#039;s just not very nice to read. Things become problematic, however, when a compressed file, such as a JPEG, gets opened, edited and then saved again as a compressed file. After repeated compressions, the data loss begins to show. DivX is the MP3 of video. Although it got its start as the Internet video format of choice for the, ahem, adult entertainment industry, DivX is now showing up in a surprising number of places. Everything from portable media players to the newest DVD players are trumpeting DivX file-reading capabilities. This computer video-compression program has gained popularity because of its ability to shrink movies and recorded TV programs to up to one-tenth their size without losing visible video quality. This makes it perfect for sending videos over the Internet or burning up to 9 hours of DVD-quality video on a single 4.7GB DVD. It&amp;#039;s easy to use. You can find the DivX player and converter for Windows and Mac OS X at divx.com. (The player is free; the converter is free for a 15-day trial, then costs $20.) The player will allow you to view DivX movies on your computer. The converter uses a drag-and-drop interface to convert DVD files, as well as almost any other video format, into DivX files. The beauty of DivX is that the resultant file can be optimized to whatever medium you want to view your video on. For instance, if you plan to watch your movie on an HDTV, there is a high-quality setting. If you&amp;#039;d rather watch on a Sony PlayStation Portable, there is a setting that maximizes compression. The conversion is processor-intensive, so it&amp;#039;s best to avoid using other programs while the converter is running to prevent errors in the compressed file. (One common hiccup is the sound file being out of sync with the video.) There&amp;#039;s a free alternative. If you&amp;#039;re against paying for software on principle, there is a free open-source DivX-style format, cleverly named XviD. Like DivX, XviD is a codec based on the MPEG-4 video standard. Although there is no official XviD player or converter, the codec, which is available at xvid.org, can enable third-party software to convert to and view the format. Many of the new portable media and DVD players that play DivX also play XviD, but you should check before you buy.   Paper Trail Whenever I print from the Internet, I get an extra page with little to no type on it. This seems wasteful. Is there any program or setting that stops this? Doesn&amp;#039;t that drive you nuts? It&amp;#039;s almost like the Web authors purposely put in just too much information to fit on a page. Why do Web designers hate trees, huh? There&amp;#039;s no program or setting that&amp;#039;s going to work in every situation--no computer knows whether that last page is useless drivel or the critical last steps of your map&amp;#039;s directions--but there is one way you can save that paper if it really irks you. In both Internet Explorer and Firefox for Windows, there is an option in the File menu called Print Preview. (The File/Print menu in OS X offers similar options.) If you select that instead of just Print, you&amp;#039;ll see a visual representation of what you&amp;#039;re about to print and be able to discern if it&amp;#039;s a useless footnote that takes up a whole page. Then, if you hit Print from the Print Preview screen, you can select a page range to be printed. Just take off the last page listed (or more, if you feel like it) and the extra page will remain in the digital realm. Cable Conundrum I bought an HDTV last year with one HDMI input, which I plug my cable box into. Now my new DVD player has an HDMI output, too. Are there any switchers on the market I can use? Considering that the format has been around since 2002, you&amp;#039;d think that HDMI switchers would be more common. But it&amp;#039;s only recently that HDMI switchers--devices that let you take multiple video sources and route them over a single output--have become readily available. Prices vary wildly. On the high end, there are options such as the PureLink HDS-41R, a &amp;quot;4x1&amp;quot; (four inputs into one output) that retails for $550. It includes a remote control, and has discrete channel selection codes that can be used with a universal, programmable remote. For my money, I&amp;#039;d suggest the 5x1 Enhanced HDMI Switch available at monoprice.com. It also includes a remote control and has codes that can be used with a universal remote--but it offers one more channel than the PureLink. And, it&amp;#039;s only $133 plus shipping. Why the huge price difference? Besides the PureLink&amp;#039;s slightly nicer-looking chassis, there really doesn&amp;#039;t seem to be a difference between the products beyond the typical AV song and dance. After all, these switchers aren&amp;#039;t doing anything too fancy--just passing on digital signals in a way that Ethernet and USB switchers have been doing for decades. Powerline networking has played second fiddle to wireless networking for years. In true plug-and-play form, powerline devices use your existing electrical outlets and wiring to extend your Ethernet network. Although easy to use, older powerline products have a comparatively slow maximum speed of 14 megabits per second (much slower if you turned on a hair dryer), and they tether laptop users to the nearest outlet. But a new generation of powerline products can stream data at up to 200Mbps--fast enough for four hi-def video streams. Netgear&amp;#039;s new Powerline HD Ethernet Adapter ($250 for a two-adapter system; additional adapters cost $130) is based on the OPERA standard. Products based on the HomePlug AV standard (which is, you guessed it, incompatible) should arrive later this year. In our tests, the electrical-interference slowdowns seemed to have been worked out, making powerline a faster, more reliable way to stream video than even next-gen wireless equipment.   Cellular Sellers I&amp;#039;m looking for a new cellular carrier, and I&amp;#039;ve seen third-party Internet sites that will sign you up for a wireless plan, but charge less for the phones than the carriers do. Are these sites on the level? I can&amp;#039;t vouch for every site out there trying to sell you phones, but some of the deals are legit. If you&amp;#039;re actually in need of new cellphone service, they can save you some cash. There is, however, generally a hitch--which most commonly comes in the form of a mail-in rebate. For example, at the time of this writing, Amazon.com--no fly-by-night retailer--is offering $155 in mail-in rebates on T-Mobile&amp;#039;s Motorola RAZR. Mail-in rebates are already a hassle, but a look at the fine print reveals that you aren&amp;#039;t eligible for this particular rebate until you&amp;#039;ve used T-Mobile&amp;#039;s service for 181 consecutive days--six months! That&amp;#039;s not to say these sorts of deals aren&amp;#039;t worth your trouble. In the above case, rebates put the final price of the phone at minus $100. You&amp;#039;ll make money by purchasing the phone. But considering you&amp;#039;ll have to have the service for six months to qualify (and your contract--which must be at least $39.99 per month to qualify--will last at least a year), these deep discounts aren&amp;#039;t going to net you a bunch of free phones to turn around on eBay. "^^<http://www.w3.org/2001/XMLSchema#string>
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