This can cause confusion because the ' DVD+RW Alliance' logo is a stylized 'RW'. Thus, "R" format discs are only suited to non-volatile data storage, such as audio or video. "R" format DVDs can be written once and read arbitrarily many times, whereas "RW" formats can be written to repeatedly. R and RW formats DVD-RW discs on a spindle The dyes used in each case are different as they are optimized for different wavelengths. This is used in conjunction with a higher numerical aperture lens. The smaller focus is possible with a shorter wavelength 'red' laser of 640 nm, compared to CD-R's wavelength of 780 nm. These two changes allow more pits to be written in the same physical disc area, giving higher data density. The larger storage capacity of a DVD-R compared to a CD-R is achieved by focusing the laser to a smaller point, creating smaller 'pits' as well as a finer track pitch of the groove spiral which guides the laser beam. Burned DVDs have a higher failure-to-read rate than pressed DVDs, due to differences in the reflective properties of dye compared to the aluminum substrate of pressed discs.Ĭomparing recordable CDs and DVDs Since written tracks are made of darkened dye, the data side of a recordable DVD has a distinct color. By varying the laser intensity quickly, high density data is written in precise tracks. During the burning of a single bit, the laser's intensity affects the reflective properties of the burned dye. Like CD-Rs, DVD recordable uses dye to store the data. Pressing is used in mass production, primarily for the distribution of home video. Data is written (' burned') to the disc by a laser, rather than the data being 'pressed' onto the disc during manufacture, like a DVD-ROM. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. High-Definition Versatile Multilayer Disc (HD VMD)ĭVD recordable and DVD rewritable are optical disc recording technologies.HD DVD: HD DVD-R, HD DVD-RW, HD DVD-RAM.Blu-ray Disc ( BD): BD-R & BD-RE, Blu-ray 3D, Mini Blu-ray Disc, 4K Blu-ray ( Ultra HD Blu-ray).DVD: DVD-R, DVD+R, DVD-R DL, DVD+R DL, DVD-R DS, DVD+R DS, DVD-RW, DVD+RW, DVD-RAM, DVD-D, DVD-A, DVD-Video, HVD, EcoDisc, MiniDVD.Compact disc ( CD): CD-DA, CD-ROM, CD-R, CD-RW, 5.1 Music Disc, Super Audio CD ( SACD), Photo CD, CD Video ( CDV), Video CD ( VCD), Super Video CD ( SVCD), CD+G, CD-Text, CD-ROM XA, CD-i, MIL-CD, Mini CD.
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