Alan Freedman -- The Computer Language Company - Computer Desktop Encyclopedia
Computer Desktop Encyclopedia
Longest-Running Tech Reference on the Planet

A CDE Definition

You'll love The Computer Desktop Encyclopedia (CDE) for Tech Term of the Day (TTOD)

LOOK UP ANOTHER TERM


DFF

See DSD.



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 Millions of 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.

Even Higher Sampling Rates
No longer confined to a physical disc, DSD resolutions have gone beyond SACD (see table below). The DSD's one-bit sampling generates a very low signal-to-noise ratio, and "noise shaping" shifts the noise to a high frequency that is filtered out before the final output. The advantage to higher sampling is that the noise is spread out over a wider frequency band, and the filtering can be relaxed. High-end DSD players offer multiple filtering modes to accommodate high-res DSD files. See SACD, DSD DAC, DXD, signal-to-noise ratio and high-resolution audio.


            Multiples
 DSD          of CD        Number of
 Format      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)





Personal Use Only

Before/After Your Search Term
BeforeAfter
device networkingDFP
device resolutionDfs
device serverDFSMS
device syncingDFT
device vendor controlDFT mode
DeviceNetDG
Devices Profile for Web ServicesDG/UX
DevOpsDGPS
devsDHCP
DeXDHCP autoconfiguration addressing

Terms By Topic
Click any of the following categories for a list of fundamental terms.
Computer Words You Gotta KnowSystem design
Job categoriesUnix/Linux
Interesting stuffPersonal computers
InternetIndustrial Automation/Process Control
Communications & networkingAssociations/Standards organizations
HistoryDesktop publishing
Audio/VideoGraphics
MainframesSecurity
ProgrammingHealthcare IT
System design