SD / SD2

The Sound Designer .SD was introduced by Digidesign's Sound Designer, originally from the Mac initially introduced in 1985. It is a 16-bit mono format for shorter length sounds.

The Sound Designer II .SDII is a sample format that extends the .SD format to 24-bit and can be used for sampling longer length sounds. Each Sound Designer II file contains two "Forks", the "resource fork" and "data fork", the data fork only contains the sample data and the resource fork all sound parameters.