CD Storage Capacity
One thing about the CD's sampling rate and precision is that it produces a lot of data. On a CD, the digital numbers produced by the ADC are stored as bytes, and it takes 2 bytes to represent 65,536 gradations. There are two sound streams being recorded (one for each of the speakers on a stereo system). A CD can store up to 74 minutes of music, so the total amount of digital data that must be stored on a CD is:
44,100 samples/(channel*second) * 2 bytes/sample * 2 channels * 74 minutes * 60 seconds/minute = 783,216,000 bytes
That is a lot of bytes! To store that many bytes on a cheap piece of plastic that is tough enough to survive the abuse most people put a CD through is no small task, especially when you consider that the first CDs came out in 1980. Read How CDs Work for the complete story!
For more information on analog/digital technology and related topics, check out the links below.
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More Great Links
- Thomas Edison's Phonograph
- Whatis.com: Analog-to-digital conversion
- Whatis.com: Digital-to-analog conversion
- Audio Compact Disc - An Introduction - one of the best descriptions ever of the laser lens system and the tracking methods used in CD drives
- MPEG Pointers and Resources - details on MPEG compression used in DVD