For a description of the error return values from DriverProc, see the discussion of installable drivers in the Microsoft Windows Software Development Kit. The following table lists the general error return values from auxMessage, wodMessage, widMessage, midMessage, and midMessage.
MMSYSERR_ALLOCATED | Requested device is already allocated. |
MMSYSERR_ERROR | Unspecified error. |
MMSYSERR_NOERROR | No error. |
MMSYSERR_NOMEM | Memory allocation error. |
MMSYSERR_NOTENABLED | Driver is not enabled. |
MMSYSERR_NOTSUPPORTED | Driver does not support specified operation. |
In addition to these general error return values, there are error return values unique to each type of audio device. The following table lists these device-specific error return values.
MIDIERR_NOTREADY | MIDI output hardware is busy. |
MIDIERR_STILLPLAYING | Driver is still playing MIDI data. |
MIDIERR_UNPREPARED | MIDI data block has not been prepared. |
WAVERR_BADFORMAT | Unsupported waveform data format. |
WAVERR_STILLPLAYING | Driver is still playing waveform data. |
WAVERR_UNPREPARED | Specified waveform data block has not been prepared. |