IChannelAudioVolume::SetChannelVolume method (audioclient.h)

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

Syntax

HRESULT SetChannelVolume(
  [in] UINT32      dwIndex,
  [in] const float fLevel,
  [in] LPCGUID     EventContext
);

Parameters

[in] dwIndex

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.

[in] fLevel

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

[in] EventContext

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.

Remarks

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.

Requirements

See also

IAudioSessionEvents Interface

IChannelAudioVolume Interface

IChannelAudioVolume::GetChannelCount