Types of Audio Devices

The following types of audio devices can be accessed by applications using API functions provided by the Windows NT Win32 subsystem:

• Waveform input devices that convert analog audio signals into digital information.

• Waveform output devices that convert digital audio information into analog audio signals.

• MIDI input ports that receive MIDI messages from external MIDI devices, such as keyboards.

• MIDI output ports that send MIDI messages to external MIDI devices, such as keyboards and drum machines.

• Internal MIDI synthesizers, which are internal MIDI output devices that synthesize music from MIDI messages sent by applications.

• Auxiliary audio devices such as CD players, which do not require data transfers but whose output can be mixed with MIDI and waveform audio, and whose volume can be controlled by a driver.

• Mixer devices that control multiple audio lines.

Combination drivers are audio device drivers that can support several of these types of audio devices. The standard audio driver, mmdrv.dll, is a combination driver.