The WODM_GETPLAYBACKRATE message requests a waveform output driver to return the current playback rate multiplier value for the specified device.
The driver should return MMSYSERR_NOERROR if the operation succeeds. Otherwise it should return one of the MMSYSERR or WAVERR error codes defined in mmsystem.h. See waveOutGetPlaybackRate return values in the Win32 SDK.
A client sends the WODM_GETPLAYBACKRATE message by calling the user-mode driver’s wodMessage entry point, passing the specified parameters.
Support for the WODM_GETPLAYBACKRATE message by user-mode drivers is optional. If a driver supports the WODM_SETPLAYBACKRATE message, it must also support WODM_GETPLAYBACKRATE.
Typically, the user-mode driver calls DeviceIoControl to send the kernel-mode driver an IOCTL_WAVE_GET_PLAYBACK_RATE control code.