Q35Blue-ray and HD DVD technologies Competition for the next-generation digital versatile disc (DVD) standard is between blue-ray discs (BDs) and high-definition (HD) DVDs. How much information-storage capacity does a single BD have?
(a) 20 gigabytes
(b) 30 gigabytes
(c) 50 gigabytes

A35 The BD, which is mainly being promoted by Sony Corp. and Matsushita Electric Inc. has information storage capacity of 25 gigabytes for single-layer recordable discs, and 50 gigabytes for dual-layer discs. The correct answer is (c), which is the equivalent
storage capacity offered by some 70 compact discs (COs) each with 700-megabyte capacity, or 10 DVDs each with 4.7-gigabyte capacity. A 25-gigabyte BD can record two hours of HD TV broadcasts, while a 50-gigabyte BD can record up to seven hours of such broadcasts if the data is compressed.

Meanwhile, HD DVDs which Toshiba Corp. and NEC Corp. are promoting have an information storage capacity of 15 giga-bytes for single- and 30 gigabytes for dual-layer recordable discs.

The new triple-layer recordable disc has a capacity of 45 gigabytes. Currently, DVDs can record two hours of standard-resolution TV images, while HD DVDs can record 48 hours of images. The 15-gigabyte HD DVDs can record a little less than two hours ofHD images, while 30-gigabyte discs can record these images for about 3 hours 50 minutes. Read/write HD DVDs can record about five and a half hours of compressed HD images.