if (size <= len) return 1;
if (!ffm_nopts) {  if (size <= len) return 1; }
static int ffm_is_avail_data(AVFormatContext *s, int size){    FFMContext *ffm = s->priv_data;    offset_t pos, avail_size;    int len;    len = ffm->packet_end - ffm->packet_ptr;    if (size <= len)        return 1;    pos = url_ftell(&s->pb);    if (pos == ffm->write_index) {        /* exactly at the end of stream */        return 0;    } else if (pos < ffm->write_index) {        avail_size = ffm->write_index - pos;    } else {        avail_size = (ffm->file_size - pos) + (ffm->write_index - FFM_PACKET_SIZE);    }    avail_size = (avail_size / ffm->packet_size) * (ffm->packet_size - FFM_HEADER_SIZE) + len;    if (size <= avail_size)        return 1;    else        return 0;}