const AVOption *av_set_string(void *obj, const char *name, const char *val);
const AVOption *av_set_double(void *obj, const char *name, double n);
const AVOption *av_set_q(void *obj, const char *name, AVRational n);
const AVOption *av_set_string(void *obj, const char *name, const char *val);
const AVOption *av_set_double(void *obj, const char *name, double n);
const AVOption *av_set_q(void *obj, const char *name, AVRational n);