Direct Stream Digital represents audio as a 1-bit pulse-density modulation (PDM) signal sampled at 2.8224 MHz or higher. Unlike PCM, which encodes amplitude values per sample, DSD represents changes in amplitude through pulse density.
The result is exceptionally wide dynamic range and frequency response, but with challenges in editing and processing due to its 1-bit nature. DSD is primarily used in SACD and high-resolution archival systems, valued for its analogue-like smoothness and transient accuracy.