If you have read How DVDs and DVD Players 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.
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)
- 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.