The wave/in/out device class consists of full duplex audio devices. You access these devices by using the wave functions, which are described in the Platform Software Development Kit (SDK). Devices in this class are associated with line devices that support the LINEMEDIAMODE_AUTOMATEDVOICE media type, which is specified in the dwMediaModes member of the LINEDEVCAPS structure for the line device.
DWORD DeviceInId; // identifier of wave in audio device DWORD DeviceOutId; // identifier of wave out audio device
The DeviceInId and DeviceOutId members are identifiers of a closed audio device. You use these identifiers in a call to the waveOutOpen function to open the device for output. You can use the resulting device handle to play digitized audio data at the line or phone device.