Parametric Equalizer
[The feature associated with this page, DirectSound, is a legacy feature. It has been superseded by WASAPI and Audio Graphs. Media Casting have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use Media Casting instead of DirectSound, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
A parametric equalizer amplifies or attenuates signals of a given frequency.
Parametric equalizer effects for different pitches can be applied in parallel by setting multiple instances of the GUID_DSFX_STANDARD_PARAMEQ effect on the same buffer. In this way, the application can have tone control similar to that provided by a hardware equalizer.
This effect is represented by the IDirectSoundFXParamEq8 interface. Its parameters are contained in the DSFXParamEq structure.