public static extern sbyte *av_get_string(void *obj, string name, libavutil.AVOption **o_out, System.Text.StringBuilder buf, int buf_len);
public static extern long av_get_int(void *obj, string name, libavutil.AVOption **o_out);
public static extern double av_get_double(void *obj, string name, libavutil.AVOption **o_out);
public static extern libavutil.AVRational av_get_q(void *obj, string name, libavutil.AVOption **o_out);
public static extern int av_set_string3(void *obj, string name, string val, int alloc, libavutil.AVOption **o_out);