title: Can I safely assume that the destination Sample received by my DirectShow Transform Filter will have memory already allocated to it?
body: <p>I've written a DirectShow Transform filter using Delphi 6 and the DSPACK library.  I've examined the DSPACK base Filter classes and the code belonging to their 'WAV Dest' sample app, which is a Transform filter example.  As far as I can tell, memory is not allocated by the receiving Filter for either the Transform filter's source IMediaSample or the destination IMediaSample parameters, although I do see the destination IMediaSample's length potentially adjusted using IMediaSample.SetActualLength().</p>
  
  <p>I just want to make sure that I can rely on the code calling my Transform filter having already allocated memory for those two parameters so I don't have to, if that is indeed part of the DirectShow API specification.  Otherwise, I assume I would need to do that allocation myself using CoTaskMemAlloc().  Can someone give me the definitive answer here?</p>