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IPerChannelDbLevel::SetLevelAllChannels

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IPerChannelDbLevel::SetLevelAllChannels

The SetLevelAllChannels method sets the volume levels, in decibels, of all the channels in the audio stream.

HRESULT SetLevelAllChannels(
  float  aLevelsDB[],
  ULONG  cChannels,
  LPCGUID  pguidEventContext
);

Parameters

aLevelsDB

[in]  Pointer to an array of volume levels. This parameter points to a caller-allocated float array into which the method writes the new volume levels, in decibels, for all the channels. The method writes the level for a particular channel into the array element whose index matches the channel number. If the audio stream contains n channels, the channels are numbered 0 to n – 1. To get the number of channels in the stream, call the IPerChannelDbLevel::GetChannelCount method.

cChannels

[in]  The number of elements in the aLevelsDB array. If this parameter does not match the number of channels in the audio stream, the method fails without modifying the aLevelsDB array.

pguidEventContext

[in]  Context value for the IControlChangeNotify::OnNotify method. This parameter points to an event-context GUID. If the SetLevelAllChannels call changes the state of the level control, all clients that have registered IControlChangeNotify interfaces with that control receive notifications. In its implementation of the OnNotify method, a client can inspect the event-context GUID to discover whether it or another client is the source of the control-change event. 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 cChannels does not equal the number of channels.
E_POINTER Pointer aLevelsDB is NULL.
E_OUTOFMEMORY Out of memory.

Remarks

If the specified level value for any channel is beyond the range that the IPerChannelDbLevel::GetLevelRange method reports for that channel, the SetLevelAllChannels call clamps the value to the supported range and completes successfully. A subsequent call to the IPerChannelDbLevel::GetLevel method retrieves the actual value used for that channel.

Requirements

Client: Windows Vista

Header: Include Devicetopology.h.

See Also

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