media.rs

        let mut fileio = sf::SF_VIRTUAL_IO {
            get_filelen: Self::vio_get_filelen,
            seek: Self::vio_seek,
            read: Self::vio_read,
            //write: unsafe { std::mem::transmute(std::ptr::null::<libc::c_void>()) },
            write: Self::vio_write,
            tell: Self::vio_tell,
        };