This is a library that implements a proposed digital audio intermediary format, called DXD-e, that allows audio player and workstation applications to handle DSD (Direct Stream Digital) audio with only minor modifications to their input and output plugins. This is accomplished by embedding the original 1-bit DSD audio stream, along with a digital pilot signal, into a conventional decimated 24-bit PCM version of the DSD stream (which is known otherwise as DXD). This embedding consumes the 9 LSBs of each 24-bit sample (8 for the DSD and 1 for the pilot) while noise-shaping filters are employed to completely bury the resulting noise underneath the existing high-frequency DSD quantization noise always found in a DXD stream. In short, the DXD stream is made to hold a lossless copy of the original DSD stream without any degradation.

github.com/dbry/DXD-e
hydrogenaudio.org/index.php/topic,129787.0