This section gives the required and optional messages for waveform output device drivers. For detailed information on these messages, see the reference section later in this chapter.
The wodMessage entry-point function for waveform output drivers must support the following messages.
WODM_BREAKLOOP | Breaks a playback loop. |
WODM_CLOSE | Closes and deallocates a waveform output device. |
WODM_GETDEVCAPS | Requests the capabilities of a waveform output device. |
WODM_GETNUMDEVS | Requests the number of waveform output devices a driver supports. |
WODM_GETPOS | Requests the current playback position for a waveform. |
WODM_OPEN | Opens and allocates a waveform output device. |
WODM_PAUSE | Pauses waveform playback on a waveform output device. |
WODM_RESET | Stops playback and returns all data blocks to the client application. |
WODM_RESTART | Continues playback after playback has been paused. |
WODM_WRITE | Sends a data block for playback. |
The wodMessage entry-point function for waveform output drivers can optionally support the following messages, depending on the capabilities of the target hardware.
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.
WOM_CLOSE | Notifies a client application when a device is closed. |
WOM_DONE | Notifies a client application when the driver is finished with a data block and is returning it to the client. |
WOM_OPEN | Notifies a client application when a device is opened. |