if( mpeg->get_video_info(track, pid, framerate, width, height) ) return 1;
if( pid < 0 || framerate <= 0 ) return 1;
double position = framenum / framerate;
if( mpeg->get_video_info(track, pid, framerate, width, height) ) return 1;
if( pid < 0 || framerate <= 0 ) return 1;
double position = framenum / framerate;