error = mlt_frame_get_image( frame, image, format, &iwidth, &iheight, writable );
if ( !error ) {
GlslManager::get_instance()->lock_service( frame );
error = mlt_frame_get_image( frame, image, format, &iwidth, &iheight, writable );
if ( !error ) {
GlslManager::get_instance()->lock_service( frame );