le32_set
le32_set(&hdr.riff.size, f->endpos - sizeof(hdr.riff));
le32_set(&hdr.fmt_hdr.size, sizeof(hdr.fmt));
le32_set(&hdr.fmt.rate, f->rate);
le32_set(&hdr.fmt.byterate, f->rate * f->par.bps * f->nch);
le32_set(&hdr.data_hdr.size, f->endpos - f->startpos);