function AverageTimePerFrameForFile(const Filename: string): int64;
var
  dshow: TIEDirectShow;
begin
  Result := -1;
  dshow := TIEDirectShow.Create;
  try
    dshow.FileInput := AnsiString(FileName);
    dshow.EnableSampleGrabber := true;
    dshow.Connect;
    dshow.Pause;

    dshow.TimeFormat := tfTime;
    if dshow.Duration = 0 then
      exit;
    Result := dshow.GetAverageTimePerFrame;
    dshow.Disconnect;
  finally
    FreeAndNil(dshow);
  end;
end;

  // fills video formats list box
  ListBox1.Clear;
  with ImageEnView1.IO.DShowParams do
    for i := 0 to VideoFormatsCount - 1 do
    begin
      with VideoFormats[i] do
        begin
          s := SysUtils.Format('%s %dx%d %.0f MB/s', [Format, BitmapWidth, BitmapHeight,    BitRate / 1048576]);   
          s := s + ' '+inttostr(10000000 div GetAverageTimePerFrame);
          ListBox1.Items.Add(s);
        end;
    end;