Direct Stream Digital™

: A proprietary CD/DVD data format proposed by Sony and Philips for use in the SACD . DSD bandwidth is normally 2.844Mb per channel (64 times 44.1kHz), with optional sampling rates of 32 or 128 times 44.1kHz,yielding a slightly higher data rate than that required by 24-bit/96 kHz resolution conventional A/D-D/A systems. DSD uses a delta modulated ADC to generate a 2.8224MHz, 1-bit signal, a rate chosen as a simple multiple of the lowest common high-fidelity PCM sampling rate, 44.1kHz. The 1-bit datastream is recorded directly to disk, avoiding the decimation and oversampling stages, inherently improving the resultant audio quality, simplified error protection, and there is no need to frame the data into words. Sony claims that the sampling rate is so high that it more nearly approximates the original analog signal, allowing equalizers and other effects processors to better simulate analog effects. It is claimed that DSD can have frequency response up to 1MHz, or up to a dynamic range (within the audio bandwidth) of 120dB, equivalent to about a 20-bit resolution. A number of DSP algorithms are available which allow the optimization of either bandwidth or dynamic range.

[Note that these benefits apply only to those players which support the DSD standard, as a replay on any conventional CD, DVD or another digital format would require the decimation and framing steps.]

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