How It Works: DVD
Same-size disc, seven times more data: This primer explains how DVD works and how you can get it.
Michael Gowan, special to PCWorld.com
Coming Soon to a PC Near You
DVD's time has come--almost. According to analysts at International Data Corporation, DVD-ROM drives are expected to overtake CD-ROM drives as standard equipment on home and notebook PCs by 2001. But in the meantime, CD-ROM drives are still expected to outsell DVD-ROM drives 105 million to 22 million this year.
DVD-ROM drives fit into the same PC drive bays as CD-ROM drives. They have been optional in new PCs from just about every PC maker for the past year. Vendors including Hi-Val, Philips, and Sony sell external models; kits that include software and hardware decoders for MPEG-2 video run about $200 to $300. In 1999 PC makers started shipping more notebook computers with DVD-ROM drives, as fixed or removable devices. You can also buy third-party drives for notebooks that connect through the PC Card slot.
DVD-ROM drive read speeds--or "X" speeds--differ from those of CD-ROM drives. A first-generation 1X DVD-ROM drive reads discs at about 1.3MB per second and reads CD-ROMs at roughly the same speed as an 8X or 9X CD-ROM drive. The 4X and faster DVD-ROM drives commonly sold today read CD-ROMs at about the same speed as a 32X CD-ROM drive. Because of the paucity of DVD-ROM apps, the biggest benefit of buying a faster DVD-ROM drive is better CD-ROM performance.
If you have a processor slower than 300 MHz, you may want to get an MPEG-2 decoder card to watch DVD movies and run multimedia apps. Video is stored on DVDs with MPEG-2 compression. For the video to run, the data must be decoded, which requires lots of processing power; too little can mean dropped frames. An MPEG-2 card, which sells for $25 to $50, takes over the decoding work for the processor, allowing the video to play smoothly.
MPEG-2 decoders also typically offer a TV-out connector, which lets you watch DVD movies on a TV. Some new PCs include these decoder cards, while others include a TV connection jack on their video cards. If you want to watch full-screen movies on an underpowered notebook equipped with a DVD-ROM drive, you might need a PC Card MPEG-2 decoder like Margi's DVD-to-Go.
While DVD-ROM drives are positioned to replace CD-ROM drives, recordable DVD faces a stiff challenge from recordable CD formats, especially CD-RW. Drive vendors have divided into four camps, each supporting one of the four standards for recordable DVD. DVD-R hardware is sold exclusively by Pioneer, and the drives cost about $5000; DVD-R blanks, made by Pioneer and TDK, cost about $45 a pop. DVD-RAM drives from Panasonic, Toshiba, and Hitachi cost $300 to $700 and the discs sell for $25 each. DVD-RW drives from Pioneer have appeared only as consumer-electronics devices costing about $2400, with discs running $30. Finally, Sony, HP, Yamaha, and Philips back DVD+RW but haven't yet released products.
At the moment, DVD-RAM is leading the recordable race. However, only users who need storage with extremely high capacity are turning to it. Most consumers who need optical storage find that CD-RW drives fit their needs much more affordably. According to IDC analysts, recordable DVD drive sales won't pick up until more drives capable of reading recordable DVDs hit the market.
- DVD Forum
- The DVD FAQ
- A Closer Look at DVD
Additional Resources:
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