How do CD/DVDs work? How are we able to get sound and pictures from a disk?

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How do CD/DVDs work? How are we able to get sound and pictures from a disk?

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2 Answers

Anonymous 0 Comments

Most music these days (unless you are getting vinyls or something) is digital in format, meaning it’s stored in binary (aka ‘1’s and ‘0’s). Optical media (CDs/DVDs/Blu-ray) work by encoding those bits as a physical change in the disk.

The exact process varies by the type of disk. These can be physical pits (CD-ROM), darkening a pre-applied dye (CD-R), or by turning a normally-reflective material opaque (CD-RW). These are simplifications, but should for the most part get the point across.

Anonymous 0 Comments

So you break pictures and sound into chunks – spatial chunks for pictures and time chunks for sound. You then quantized that information – capture some discrete levels of color or sound and apply a number to it. That’s digital media.

So then you got a string of numbers that make up pictures or sound. You burn that information into a thin layer of aluminum. Every time your data switches from a 1 to a 0 or back again, you burn a little pit in the disc.

On read, the disc reader uses it’s spin speed and position of laser to start generating bits. Every time a pit comes, the laser is scattered, this is detected, and internally your string of numbers generate inverts.