Window Callback Services

[The feature associated with this page, Audio Mixers, is a legacy feature. It has been superseded by Volume Controls. Volume Controls has been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use Volume Controls instead of Audio Mixers, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The mixer services provide window callback services so that your application can process messages from mixer drivers. To use these services, specify the CALLBACK_WINDOW flag in the fdwOpen parameter and a window handle in the dwCallback parameter of the mixerOpen function. Driver messages are sent to the window procedure function for the window identified by the handle in dwCallback. The messages are specific to the audio device type.