static int ffm_write_write_index(int fd, int64_t pos) { uint8_t buf[8]; int i; for(i=0;i<8;i++) buf[i] = (pos >> (56 - i * 8)) & 0xff; lseek(fd, 8, SEEK_SET); if (write(fd, buf, 8) != 8) return AVERROR(EIO); return 8; }