Work items for Vfw capture driver wrapper


1) Support IOverlay
  No work has been done yet to support overlays.
  the thunks should already exist. refer to
  motown\avicap.32\*.c to see how avicap manages overlays
  the thunks from avicap.32 are already in place in this
  filter

2) Support IReferenceClock slaved to the VSYNC clock.
  the _vsyncmem structure in vidx.h is the structure
  that will be shared with the driver.  the driver will
  update this struture with a QPC value and with a VSYNC
  count on each vsync.  we will expose a clock that
  periodically checks this memory and keeps it's own clock
  (based on QPC from drifting relative to this memory)
  the thunks for this have been written but not tested.
  (see vidxSetupVsyncMem)

3) Complete work to support IPropertyPage. the thunking
  for videoDialog is complete.  No new thunks should
  be necessary here, just expose editing of _vfwcaptureoptions.
  A new thunk to enum video capture drivers may make life easier.
  one caveat here:  VfwCapDriverDialog currently works only
  when the filters is Paused (because only then does it have
  the driver open).

4) Expose Line21 (closed caption) and SMPTE timecode streams.
  Thunks for these are complete (these streams are returned
  as extra fields in the VIDEOHDREX for each frame captured).

5) Support variable frame rate capture (for video conferencing).
  preferably some form of frame-on-demand rather than doing
  this by munging frame rates on the fly.

6) Port to NT.  all of the vidxZZZ functions are part of the
  thunking layer.  equivalents will have to be written for NT.
  (some of this work has aleady been done in the NT version
  of avicap32.