DSD

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DSD

(Direct Stream Digital) The sampling technique used in Sony's high-resolution SACD music format. Although SACD discs never took off and new ones are few and far between, the DSD format is used to encode music for high-quality downloads. Increasingly, Blu-ray players and music servers can decode the format. Digital DSD files use DFF and DSF extensions, the latter holding meta-data.

From 44 Thousand to 3 Million Samples
For standard CDs, music is digitized 44.1 thousand times per second, producing 16-bit PCM samples. In contrast, DSD uses pulse density modulation (PDM) to encode 2,822,400 1-bit samples per second (64 times the CD sampling rate). Each DSD sample is a 1 or 0 (either up or down from the previous sample). Compared to CDs, DSD boosts frequency response from 20 kHz to 100 kHz and dynamic range from 96 to 120 db. See PCM, PDM and CD.

Beyond the Original
No longer confined to a physical disc, DSD resolutions have evolved beyond the original SACD format (see table below). See SACD, DSD DAC, DXD and high-resolution audio.
           MultiplesDSD          of CD        Number ofFormat      Samples  ---1-Bit Samples---

 SACD
 (DSD64)        64    2,822,400 (2.8 MHz)

 Double-rate
 (DSD128)      128    5,644,800 (5.6 MHz)

 Quad-rate
 (DSD256)      256   11,289,600 (11.2 MHz)

 Octuple-rate
 (DSD512)      512   22,579,920 (22.5 MHz)