Direct Stream Digital（DSD）是一项属于Sony和飞利浦的专利，利用脉冲密度调制（pulse-density modulation）编码将音频信号保存在数字媒体上的科技，这项技术的应用对象是SACD。

信号本身以ΔΣ调制后的数字音频保存，连续单一个比特的串行以64倍于CD采样率（44.1 kHz）的频率来采样，即2.8224 MHz。借由64倍过采样（oversample）来达成noise shaping，把以往由于量化不精确的声音频号而造成的噪音和失真，减少至一个比特以内的误差。可议的是，1-bit Sigma-Delta运算是否真的可能解决失真问题。由于1-bit Sigma-Delta转换的运作方式，以DSD编码的声音在低频上有着比标准CD更好的分辨率，然而在较高的频域比CD差，因而它的保真性也较低。

Direct-Stream Digital (DSD) is the trademark name used by Sony and Philips for their system of digitally recreating audible signals for the Super Audio CD (SACD).

DSD uses pulse-density modulation encoding—a technology to store audio signals on digital storage media that are used for the SACD. The signal is stored as delta-sigma modulated digital audio; a sequence of single-bit values at a sampling rate of 2.8224 MHz (64 times the CD Audio sampling rate of 44.1 kHz, but only at ⁄₃₂₇₆₈ of its 16-bit resolution). Noise shaping occurs by use of the 64-times oversampled signal to reduce noise/distortion caused by the inaccuracy of quantization of the audio signal to a single bit. Therefore, it is a topic of discussion whether it is possible to eliminate distortion in one-bit Sigma-Delta conversion.