IDirect3DDeviceManager9::LockDevice method

Gives the caller exclusive access to the Direct3D device.


HRESULT LockDevice(
  [in]  HANDLE           hDevice,
  [out] IDirect3DDevice9 **ppDevice,
  [in]  BOOL             fBlock


hDevice [in]

A handle to the Direct3D device. To get the device handle, call IDirect3DDeviceManager9::OpenDeviceHandle.

ppDevice [out]

Receives a pointer to the device's IDirect3DDevice9 interface.

fBlock [in]

Specifies whether to wait for the device lock. If the device is already locked and this parameter is TRUE, the method blocks until the device is unlocked. Otherwise, if the device is locked and this parmater is FALSE, the method returns immediately with the error code DXVA2_E_VIDEO_DEVICE_LOCKED.

Return value

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return codeDescription

The method succeeded.


The device handle is invalid.


The Direct3D device manager was not initialized. The owner of the device must call IDirect3DDeviceManager9::ResetDevice.


The device is locked and fBlock is FALSE.


The specified handle is not a Direct3D device handle.



When you are done using the Direct3D device, call IDirect3DDeviceManager9::UnlockDevice to unlock to the device.

If the method returns DXVA2_E_NEW_VIDEO_DEVICE, call IDirect3DDeviceManager9::CloseDeviceHandle to close the handle and then call OpenDeviceHandle again to get a new handle. The IDirect3DDeviceManager9::ResetDevice method invalidates all open device handles.

If fBlock is TRUE, this method can potentially deadlock. For example, it will deadlock if a thread calls LockDevice and then waits on another thread that calls LockDevice. It will also deadlock if a thread calls LockDevice twice without calling UnlockDevice in between.


HRESULT LockDevice(
    IDirect3DDeviceManager9 *pDeviceManager,
    BOOL fBlock,
    IDirect3DDevice9 **ppDevice, // Receives a pointer to the device.
    HANDLE *pHandle              // Receives a device handle.   
    *pHandle = NULL;
    *ppDevice = NULL;

    HANDLE hDevice = 0;

    HRESULT hr = pDeviceManager->OpenDeviceHandle(&hDevice);

    if (SUCCEEDED(hr))
        hr = pDeviceManager->LockDevice(hDevice, ppDevice, fBlock);

    if (hr == DXVA2_E_NEW_VIDEO_DEVICE)
        // Invalid device handle. Try to open a new device handle.
        hr = pDeviceManager->CloseDeviceHandle(hDevice);

        if (SUCCEEDED(hr))
            hr = pDeviceManager->OpenDeviceHandle(&hDevice);

        // Try to lock the device again.
        if (SUCCEEDED(hr))
            hr = pDeviceManager->LockDevice(hDevice, ppDevice, TRUE); 

    if (SUCCEEDED(hr))
        *pHandle = hDevice;
    return hr;


Minimum supported client

Windows Vista [desktop apps only]

Minimum supported server

Windows Server 2008 [desktop apps only]



See also

Direct3D Device Manager