Audio Line and Control Queries

[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 It has been superseded by Volume Controls.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 functions for determining information about audio lines, audio-line controls, and control details. The services also provide functions for setting control details.

You can use the mixerGetLineInfo function to retrieve information about a specified audio line. This function fills the MIXERLINE structure for a specified source audio line, destination audio line, or line identifier. The structure includes the destination line number, the number of channels in the audio line, as well as a short and a long name for the audio line.

The mixerGetLineControls function retrieves general information about one or more controls associated with an audio line. This function fills the MIXERLINECONTROLS structure with information about the specified control or controls. You can use mixerGetLineControls to retrieve control properties for one of the following:

• All controls for a specified source line
• A specified control for a specified source line
• The first control of a specific class for a specified source line

The mixerGetControlDetails function retrieves properties of a single control associated with an audio line. This function fills the MIXERCONTROLDETAILS structure with the current values for a control.

The mixerSetControlDetails function uses the contents of the MIXERCONTROLDETAILS structure to set the properties of the specified control. You must ensure that all members of this structure are filled before you call mixerSetControlDetails.