1982, Philips and Sony formulated the red book standard for CD-DA laser discs. Thus, a new type of CD was born. The recording method of CD-DA laser disc is different from LD system. The CD-DA laser video disc system first digitizes the analog audio signal by PCM (pulse code modulation), and then records it on the optical disc after being encoded by EFM(8~ 14 bit modulation).
In the mid-1980s, the development of optical disks was very rapid, and new varieties such as WORM, CD-ROM, magneto-optical disk (MOD) and phase change disk (PCD) were introduced one after another. The appearance of these CDs has brought great impetus to the information revolution.
Extended data:
Some classifications of optical discs:
1, CD: (CD) CD. A CD consists of liad-in (the location where data is recorded); Then there is the directory area, which records data from the inside out; After recording, add the export track end recording mark. On the optical disk, the analog data is engraved on the optical disk with a large burner, and many small pits are not visible to the naked eye.
2.CD-DA: (CD-Audio) An optical disk for storing digital sound effects. 1982, Sony and Philips formulated the red book standard to store sound data in the form of audio tracks. The CD has the ability to be compatible with music movies of this specification.
3. CD-G: (compact-disc-graphics) CD-DA has added graphics to become another format, but it has not been popularized. This is an attempt at multimedia computer.
4.CD-ROM: CD-ROM player. 1986, Sony and Philips formulated the yellow book standard and defined the file format. Two types are defined, namely, mode 1 for computer data storage and mode 2 for compressed video image storage, which makes the optical disc a universal storage medium. And add error detection code, error correction code and other bits to ensure that computer data can be read completely and correctly.
Baidu encyclopedia-CD