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.
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:
1 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.
2 dwParam2 must be non-zero. If the caller requests zero bytes of mixer device capabilities, the mixer manager handles this case for your driver.