| Microsoft DirectX 8.1 (C++) | 
The Lock method acquires or releases a lock on the DMO. Call this method to keep the DMO serialized when performing multiple operations.
Syntax
HRESULT Lock(
    LONG bLock
);
Parameters
bLock
Value that specifies whether to acquire or release the lock. If the value is non-zero, a lock is acquired. If the value is zero, the lock is released.
Return Value
Returns an HRESULT value. Possible values include those in the following table.
| Return Code | Description | 
| E_FAIL | Failure | 
| S_OK | Success | 
Remarks
This method prevents other threads from calling methods on the DMO. If another thread calls a method on the DMO, the thread blocks until the lock is released.
See also