Effect Parameters

To set or retrieve parameters of sound effects, you must first obtain the appropriate interface to the buffer that contains the effect. The following interfaces give you access to parameters of the standard DMOs available on all systems.

• IDirectSoundFXChorus8
• IDirectSoundFXCompressor8
• IDirectSoundFXDistortion8
• IDirectSoundFXEcho8
• IDirectSoundFXFlanger8
• IDirectSoundFXGargle8
• IDirectSoundFXI3DL2Reverb8
• IDirectSoundFXParamEq8
• IDirectSoundFXWavesReverb8

To obtain one of these interfaces, pass the corresponding IID to the QueryInterface method of the buffer containing the effect. For a list of IIDs, see DirectSound Interface GUIDs.

Changes in effect parameters do not always take place immediately. For efficiency, DirectSound processes 100 milliseconds of sound data in a buffer, starting at the play cursor, before the buffer is played. This preprocessing happens after all of the following calls:

• IDirectSoundBuffer8::SetCurrentPosition
• IDirectSoundBuffer8::SetFX
• IDirectSoundBuffer8::Stop
• IDirectSoundBuffer8::Unlock