StreamTime method retrieves the current stream time.
virtual HRESULT StreamTime( [ref] CRefTime &rtStream );
Reference to a CRefTime object that receives the current stream time.
Returns an HRESULT value. Possible values include those listed in the following table.
||No reference clock is available.
Stream time is defined as the current reference time (as given by the reference clock) minus the start time (specified by CBaseMediaFilter::m_tStart). A media sample's time stamp specifies the stream time when it should be rendered. If a sample with a time stamp less than the current stream time has not yet been rendered, it is late.