When we talk about the speed of writers, we usually say how many Xes, but what does X stand for?
One X for CD is 150KB per second. So for a fully loaded CD-ROM with 650MB, it will take about 87 seconds for a 52X writer to complete the burning. The formula is 650 x 1024 ÷ 150 ÷ 52 = 87. As far as a DVD, one X represents 1380KB/sec. With this rate, a fully loaded DVD master with 4.7GB will requires about 893 seconds (about 15 minutes) for a 4X writer to complete the burning. Again, the formula is 4.7 x 1024 x 1024 ÷ 1380 ÷ 4 = 892.8. But note that the actual time will be longer because of the lead-in and lead-out. On the other hand, most of the time the master is not fully loaded so the numbers above are the extreme cases. Your burning time will be a function of how full the master is and what type of media you are using. Some media, although advertised for a certain speed, may not be able to attain the rates advertised and the duplicator will try to burn at a lower speed to ensure its integrity.
