/// <summary>Initialize a VideoStream for an existing stream</summary>
/// <param name="aviFile">The file that contains the stream</param>
/// <param name="aviStream">An IAVISTREAM from [aviFile]</param>
public VideoStream(int aviFile, IntPtr aviStream)
{
this.aviFile = aviFile;
this.aviStream = aviStream;
Avi.BITMAPINFOHEADER bih = new Avi.BITMAPINFOHEADER();
int size = Marshal.SizeOf(bih);
Avi.AVIStreamReadFormat(aviStream, 0, ref bih, ref size);
Avi.AVISTREAMINFO streamInfo = GetStreamInfo(aviStream);
FrameRate = (float)streamInfo.dwRate / (float)streamInfo.dwScale;
Width = (int)streamInfo.rcFrame.right;
Height = (int)streamInfo.rcFrame.bottom;
FrameSize = bih.biSizeImage;
CountBitsPerPixel = bih.biBitCount;
FirstFrame = Avi.AVIStreamStart(aviStream.ToInt32());
CountFrames = Avi.AVIStreamLength(aviStream.ToInt32());
}