Backup tapes are good news for video pirates

时间:2019-02-27 10:07:01166网络整理admin

By Barry Fox MANY computer owners back up the contents of their hard discs onto digital tape. Now Philips, the Dutch electronics giant, is launching a high-density version that can back up many times as much data. The snag is that it could be a video pirate’s dream. Standard QIC and Travan backup tapes typically hold a gigabyte of data. But the tapes of the Digamax system being launched at next week’s PC Expo in New York by Philips and the American computer firm Exabyte can store 13 times as much. Compressing data by reducing the amount of repetitition, such as spaces between text, doubles the capacity to 26 gigabytes. This is equal to 7 hours of high-quality digital video or five feature-length movies on a digital video disc. The Digamax drives will also play QIC and Travan cartridges. A demonstration by Philips last week showed Digamax can reproduce DVD-quality video. The jump in capacity has been achieved using new tape positioning techniques. The Eagle cartridges used by the new system contain 300 metres of 8-millimetre video tape “embossed” with a low-frequency guide signal deep in its magnetic coating. This keeps the recording heads aligned with the tape to an accuracy of 1 micrometre. This precision is vital because data is recorded over the guide signal in very narrow, parallel tracks. Eight tracks are recorded simultaneously across the width of the tape. At the end of the tape the heads are stepped a small distance sideways to record another eight tracks running in the opposite direction. This happens 24 times to lay down 192 parallel tracks. Philips will make the Digimax drive,