MXDM_GETDEVCAPS

Sent to an audio mixer device driver to request the capabilities of a specific mixer device. This message is normally sent to an audio mixer driver in response to a mixerGetDevCaps call.

The return value is an error code, or zero (MMSYSERR_NOERROR) if the operation is successful. Possible error codes are:

MMSYSERR_NOTENABLED

The driver failed to load or initialize.

dwParam1: For Plug and Play drivers, specifies a pointer to an MDEVICECAPSEX structure. The driver fills this structure with the capabilities of the device.
For non-Plug and Play drivers, specifies a pointer to a MIXERCAPS data structure. The driver fills this structure with the capabilities of the device.
dwParam2: For Plug and Play drivers, specifies a device node.
For non-Plug and Play drivers, specifies the size, in bytes, of the MIXERCAPS data structure.

For non-Plug and Play drivers, the driver should only write dwParam2 or less bytes to the location pointed to by dwParam1. If dwParam2 is zero, write nothing and return MMSYSERR_NOERROR. The Mixer Manager handles this case for your driver.

An audio mixer driver must support this message. The Mixer Manager will validate the following parameters for the MXDM_GETDEVCAPS message before calling the driver. Your driver does not need to check for the following conditions:

dwParam1 contains a valid pointer to a MIXERCAPS. This structure will be at least large enough to hold the specified number of bytes passed in dwParam2.
dwParam2 must be non-zero. If the caller requests zero bytes of mixer device capabilities, the mixer manager handles this case for your driver.