Cooperative Levels

Because Windows is a multitasking environment, more than one application can be working with a device driver at any one time. Through the use of cooperative levels, DirectX makes sure that each application does not gain access to the device in the wrong way or at the wrong time. Each DirectSound application has a cooperative level that determines the extent to which it is allowed to access the device.

After creating a device object, you must set the cooperative level for the device by using the IDirectSound8::SetCooperativeLevel method. Unless you do this, no sounds will be heard.

The following example sets the cooperative level for the DirectSound device represented by the IDirectSound8 interface at lpDirectSound. The hwnd parameter is the handle to the application window.

HRESULT hr = lpDirectSound->SetCooperativeLevel(hwnd, DSSCL_PRIORITY);
if (FAILED(hr))
{
  ErrorHandler(hr);  // Add error-handling here.
}

DirectSound defines three cooperative levels for sound devices, specified by the values DSSCL_NORMAL, DSSCL_PRIORITY, and DSSCL_WRITEPRIMARY. These levels are explained in the following topics:

• Normal Cooperative Level
• Priority Cooperative Level
• Write-primary Cooperative Level

Note   The DSSCL_EXCLUSIVE cooperative level is obsolete. It is no longer possible for a DirectX application to mute other applications. Applications that request the exclusive level are granted the priority level instead.