IChannelAudioVolume::SetChannelVolume method

The SetChannelVolume method sets the volume level for the specified channel in the audio session.


HRESULT SetChannelVolume(
  [in]       UINT32  dwIndex,
  [inconst float   fLevel,
  [in]       LPCGUID EventContext


dwIndex [in]

The channel number. If the stream format for the audio session has N channels, the channels are numbered from 0 to N– 1. To get the number of channels, call the IChannelAudioVolume::GetChannelCount method.

fLevel [in]

The volume level for the channel. Valid volume levels are in the range 0.0 to 1.0.

EventContext [in]

Pointer to the event-context GUID. If a call to this method generates a channel-volume-change event, the session manager sends notifications to all clients that have registered IAudioSessionEvents interfaces with the session manager. The session manager includes the EventContext pointer value with each notification. Upon receiving a notification, a client can determine whether it or another client is the source of the event by inspecting the EventContext value. This scheme depends on the client selecting a value for this parameter that is unique among all clients in the session. If the caller supplies a NULL pointer for this parameter, the client's notification method receives a NULL context pointer.

Return value

If the method succeeds, it returns S_OK. If it fails, possible return codes include, but are not limited to, the values shown in the following table.

Return codeDescription

Parameter dwIndex is set to an invalid channel number, or parameter fLevel is not in the range 0.0 to 1.0.


The audio endpoint device has been unplugged, or the audio hardware or associated hardware resources have been reconfigured, disabled, removed, or otherwise made unavailable for use.


The Windows audio service is not running.



This method, if it succeeds, generates a channel-volume-change event regardless of whether the new channel volume level differs in value from the previous channel volume level.


Minimum supported client

Windows Vista [desktop apps only]

Minimum supported server

Windows Server 2008 [desktop apps only]



See also

IAudioSessionEvents Interface
IChannelAudioVolume Interface