The contemporary Microsoft Windows operating systems can be called "multimedia" systems. They support many sound and video features which now are standard parts of the OS. Among numerous sound interfaces available, there are three well-documented, having many examples, and freely distributed interfaces from Microsoft: Direct Sound, Multimedia Control Interface (MCI), and WaveForm Audio.
Direct Sound is a component of Microsoft DirectX - the set of object multimedia libraries. DirectX consist of several components used widely in modern computer games, graphical applications and multimedia programs. Direct Sound has many advanced capabilities including multi-channel mixing and 3D sound. This system could be used successfully in multimedia terminal, but it has a few disadvantages that made the author give up:
It is object library, so it requires object-oriented coding style in sound modules and C++ compiler.
DirectX is not a standard element of early Windows NT and Windows 95 versions. If DirecX has not been installed in such systems, DirectX-dependent programs would not work.
The latest version of DirectX for Windows NT does not support capturing (recording) of sound. Other mechanisms must be used to make full-duplex programs.
Multimedia Control Interface (MCI) is a standard component of Windows systems. It is very simple in use: programmer calls functions with char* parameter, which is a shell-like command. This is the only advantage of making use of this mechanism in multimedia terminal. It neither supports real-time continuous recoding nor playing, and it seems to be slower than system calls, because of parsing commands. It made the author give up.
In the author's opinion the most suitable mechanism in this case is the Waveform Audio mechanism, described in details in the next chapter.