private static bool openVideoStream(string videoFile, 
            out MediaDetClass mediaDetClass, out _AMMediaType aMMediaType)
{
    MediaDetClass mediaDet = new MediaDetClass();
    
    //loads file
    mediaDet.Filename = videoFile;

    //gets # of streams
    int streamsNumber = mediaDet.OutputStreams;

    //finds a video stream and grabs a frame
    for (int i = 0; i < streamsNumber; i++)
    {
        mediaDet.CurrentStream = i;
        _AMMediaType mediaType = mediaDet.StreamMediaType;

        if (mediaType.majortype == JockerSoft.Media.MayorTypes.MEDIATYPE_Video)
        {
            mediaDetClass = mediaDet;
            aMMediaType = mediaType;
            return true;
        }
    }

    mediaDetClass = null;
    aMMediaType = new _AMMediaType();
    return false;
}