try {
Glib::Threads::Mutex::Lock lm (AudioEngine::instance()->process_lock ());
r->input()->ensure_io (_master_out->output()->n_ports(), false, this);
try {
Glib::Threads::Mutex::Lock lm (AudioEngine::instance()->process_lock ());
r->input()->ensure_io (_master_out->output()->n_ports(), false, this);