Direct Stream Digital

From Free net encyclopedia

Direct-Stream Digital (DSD) is a name used by Sony and Philips for pulse-density modulation, an encoding technology to store audio signals on digital storage media and is used for the super audio compact disc (SACD). The signal is stored as delta-sigma modulated digital audio, a sequence of single bit values at a very high frequency sampling rate of 64 times of normal CD sampling rates of 44.1 kHz or 2.8224 MHz (1 bit times 64 times 44.1 kHz). Noise shaping are used by the 64x oversampled signal to reduce distortion caused by the very high quantization of the audio signal to a single bit. Due to the high sampling rate the bandwidth and therefore the audio quality can be higher than is possible with the 44.1 kHz (16 bits times 44.1 kHz) PCM format used for normal audio CDs.

There is much debate over whether DSD or PCM is ultimately the better digital encoding format, as can be seen in the format war between SACD and DVD-Audio.

Practical DSD converter implementations were pioneered by Ed Meitner, an Austrian sound engineer and owner of EMM Labs. Global DSD technology was developed by Sony and Philips, the designers of the audio CD. Philips' DSD tool division was transferred to Sonic Studio, LLC in 2005 for on-going design and development.

DSD technology may also have potential for video applications. A similar structure based on pulse-width modulation, which is decoded in the same way as DSD, has been used in Laserdisc video. Template:Tech-stubde:Direct Stream Digital ja:Direct Stream Digital pl:DSD ru:DSD