If you have read the HowStuffWorks article How CDs Work (as well as How Analog and Digital Recording Works), then you know that CDs store music as digital samples. The sampling rate is 44,100 samples per second, and the analog signal is converted to a 16-bit binary number at each sample. The sampling is done on two channels (one for each speaker in a stereo system).
If you have read How DVDs Work, you know that DVDs are very similar to CDs, but they hold more data -- 4.7 gigabytes for a DVD compared to 650 megabytes for a CD. Two-layer DVDs can store twice that.
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The DVD-audio standard uses the extra data space on a DVD to do two things:
- Increase the sampling rate and quantization levels dramatically Although there are a number of options, DVD-audio typically uses 96,000 samples per second and 24 bits per sample. In other words, there are more than twice as many samples per second and 256 times more quantization levels.
- Record in surround sound (six channels instead of two)
DVD-audio has the potential to replace CDs because of the higher quality of the sound. However, there are several things that might prevent widespread acceptance of DVD-audio:
- The standard has taken some time to gel, and it came some time after DVD-video and its players were released. Many people with DVD players today would have to replace their players to listen to DVD-audio discs.
- It is not clear that most consumers care about the difference in sound quality, since it is fairly subtle.
- There is a competing standard from Sony/Philips called the Super Audio CD that claims to have even better sound quality.
For more information about sound and recordings, take a look at the next page.
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