if (fmt1->extensions) {
if (fmt1->read_probe) { score = fmt1->read_probe(pd); } else if (fmt1->extensions) {
static AVInputFormat *probe_input_format(AVProbeData *pd, int is_opened){    AVInputFormat *fmt1, *fmt;    int score, score_max;    fmt = NULL;    score_max = 0;    for(fmt1 = first_iformat; fmt1 != NULL; fmt1 = fmt1->next) {        if (!is_opened && !(fmt1->flags & AVFMT_NOFILE))            continue;        score = 0;        if (fmt1->extensions) {            if (match_ext(pd->filename, fmt1->extensions)) {                score = 50;            }        } else if (fmt1->read_probe) {            score = fmt1->read_probe(pd);        }        if (score > score_max) {            score_max = score;            fmt = fmt1;        }    }    return fmt;}