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?

In: Technology

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.

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.