Cambiar el directorio de carga de imágenes predeterminado

function custom_upload_dir($path) {
    $upload_dir = wp_upload_dir();
    $path['path'] = $upload_dir['basedir'] . '/custom';
    $path['url'] = $upload_dir['baseurl'] . '/custom';
    return $path;
}
add_filter('upload_dir', 'custom_upload_dir');