DSD64

DSD64 is a common name for 2.8224 MHz, 1-bit Direct Stream Digital (DSD) audio, whose sampling frequency is exactly 64 times that of 44.1 kHz. This term is primarily used to distinguish this specification from higher-speed DSD formats; SACD literature typically refers to it simply as DSD or 2.8224 MHz.

The raw bit rate is 2.8224 Mbit/s for mono and 5.6448 Mbit/s for stereo, excluding overhead for encapsulation, error correction, or compression. DSD relies on oversampling and noise shaping to shift a significant amount of quantization noise to high frequencies, requiring low-pass filtering on the playback end. One-bit DSD cannot be directly compared to PCM bit depths, nor can its dynamic range be inferred based on the “1-bit” designation.

The high-density layer of an SACD stores stereo or multichannel programs as DSD64 and may use DST lossless compression. DSD64 can also be found in files such as DSF, DSDIFF, or WavPack; the file format DSD64 is not synonymous with SACD, as the former does not include the physical layer, program area, or protection scheme of an optical disc.

Players may decode DSD64 natively, or they may first convert it to high-sampling-rate PCM before applying volume adjustment, crossover, or room correction. DoP can package DSD64 data into 176.4 kHz, 24-bit PCM transport frames, with the payload remaining DSD. The way the device interface displays the data does not, by itself, prove that no conversion occurred during the entire internal processing.