if (url_is_streamed(&s->pb)) {
if (asf->is_streamed) {
static int asf_write_trailer(AVFormatContext *s){    ASFContext *asf = s->priv_data;    INT64 file_size;    /* flush the current packet */    if (asf->pb.buf_ptr > asf->pb.buffer)        flush_packet(s);    if (url_is_streamed(&s->pb)) {        put_chunk(s, 0x4524, 0, 0); /* end of stream */    } else {        /* rewrite an updated header */        file_size = url_ftell(&s->pb);        url_fseek(&s->pb, 0, SEEK_SET);        asf_write_header1(s, file_size, file_size - asf->data_offset);    }    put_flush_packet(&s->pb);    return 0;}