| WODM_GETPITCH | Requests the current pitch rate setting. |
| WODM_GETPLAYBACKRATE | Requests the current playback rate setting. |
| WODM_GETVOLUME | Requests the current volume level setting. |
| WODM_PREPARE | Requests that the driver prepare a data block for playback. |
| WODM_SETPITCH | Sets the pitch rate. |
| WODM_SETPLAYBACKRATE | Sets the playback rate. |
| WODM_SETVOLUME | Sets the volume level. |
| WODM_UNPREPARE | Requests that a driver clean up the preparation previously done on a data block. |
In addition to receiving messages, drivers must notify clients when certain events occur. Waveform output drivers notify clients by sending one of the following messages using the DriverCallback function.