IChannelAudioVolume::SetAllVolumes

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IChannelAudioVolume::SetAllVolumes

The SetAllVolumes method sets the individual volume levels for all the channels in the audio session.

HRESULT SetAllVolumes(
  UINT32  dwCount,
  const float  *pfVolumes,
  LPCGUID  EventContext
);

Parameters

dwCount

[in]  The number of elements in the pfVolumes array. This parameter must equal the number of channels in the stream format for the audio session. To get the number of channels, call the IChannelAudioVolume::GetChannelCount method.

pfVolumes

[in]  Pointer to an array of volume levels for the channels in the audio session. The number of elements in the pfVolumes array is specified by the dwCount parameter. The caller writes the volume level for each channel to the array element whose index matches the channel number. If the stream format for the audio session has n channels, the channels are numbered from 0 to *n *– 1. 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 code Description
E_INVALIDARG Parameter dwCount does not equal the number of channels in the stream format for the audio session, or the value of a pfVolumes array element is not in the range 0.0 to 1.0.
E_POINTER Parameter pfVolumes is NULL.
AUDCLNT_E_DEVICE_INVALIDATED 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.
AUDCLNT_E_SERVICE_NOT_RUNNING The Windows audio service is not running.

Remarks

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

Requirements

Client: Windows Vista

Header: Include Audioclient.h.

See Also

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