livetrax/gtk2_ardour/engine_dialog.cc

/*
    Copyright (C) 2010 Paul Davis

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include <exception>
#include <vector>
#include <cmath>
#include <fstream>
#include <map>

#include <boost/scoped_ptr.hpp>

#include <gtkmm/messagedialog.h>

#include "pbd/error.h"
#include "pbd/xml++.h"
#include "pbd/unwind.h"
#include "pbd/failed_constructor.h"

#include <gtkmm/alignment.h>
#include <gtkmm/stock.h>
#include <gtkmm/notebook.h>
#include <gtkmm2ext/utils.h>

#include "ardour/audio_backend.h"
#include "ardour/audioengine.h"
#include "ardour/mtdm.h"
#include "ardour/rc_configuration.h"
#include "ardour/types.h"

#include "pbd/convert.h"
#include "pbd/error.h"

#include "ardour_ui.h"
#include "engine_dialog.h"
#include "gui_thread.h"
#include "utils.h"
#include "i18n.h"

using namespace std;
using namespace Gtk;
using namespace Gtkmm2ext;
using namespace PBD;
using namespace Glib;

static const unsigned int midi_tab = -1; /* not currently in use */
static const unsigned int latency_tab = 1; /* zero-based, page zero is the main setup page */

static const char* results_markup = X_("<span foreground=\"red\" style=\"italic\" size=\"larger\">%1</span>");

EngineControl::EngineControl ()
	: ArdourDialog (_("Audio/MIDI Setup"))
	, basic_packer (9, 4)
	, input_latency_adjustment (0, 0, 99999, 1)
	, input_latency (input_latency_adjustment)
	, output_latency_adjustment (0, 0, 99999, 1)
	, output_latency (output_latency_adjustment)
	, input_channels_adjustment (0, 0, 256, 1)
	, input_channels (input_channels_adjustment)
	, output_channels_adjustment (0, 0, 256, 1)
	, output_channels (output_channels_adjustment)
	, ports_adjustment (128, 8, 1024, 1, 16)
	, ports_spinner (ports_adjustment)
	, control_app_button (_("Device Control Panel"))
	, lm_measure_label (_("Measure"))
	, lm_use_button (_("Use results"))
	, lm_back_button (_("Back to settings ... (ignore results)"))
	, lm_button (_("Calibrate..."))
	, lm_table (12, 3)
	, have_lm_results (false)
	, lm_running (false)
	, midi_refresh_button (_("Refresh list"))
	, ignore_changes (0)
	, _desired_sample_rate (0)
	, no_push (true)
	, started_at_least_once (false)
{
	using namespace Notebook_Helpers;
	vector<string> strings;
	Label* label;
	AttachOptions xopt = AttachOptions (FILL|EXPAND);
	int row;

	set_name (X_("AudioMIDISetup"));

	/* the backend combo is the one thing that is ALWAYS visible 
	 */

	vector<const ARDOUR::AudioBackendInfo*> backends = ARDOUR::AudioEngine::instance()->available_backends();

	if (backends.empty()) {
		MessageDialog msg (string_compose (_("No audio/MIDI backends detected. %1 cannot run\n\n(This is a build/packaging/system error. It should never happen.)"), PROGRAM_NAME));
		msg.run ();
		throw failed_constructor ();
	}

	for (vector<const ARDOUR::AudioBackendInfo*>::const_iterator b = backends.begin(); b != backends.end(); ++b) {
		strings.push_back ((*b)->name);
	}

	set_popdown_strings (backend_combo, strings);
	backend_combo.set_active_text (strings.front());
	backend_combo.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::backend_changed));

	/* setup basic packing characteristics for the table used on the main
	 * tab of the notebook
	 */

	basic_packer.set_spacings (6);
	basic_packer.set_border_width (12);
	basic_packer.set_homogeneous (false);

	/* pack it in */

	basic_hbox.pack_start (basic_packer, false, false);

	/* latency tab */

	/* latency measurement tab */
	
	lm_title.set_markup (string_compose ("<span size=\"large\" weight=\"bold\">%1</span>", _("Latency Measurement Tool")));
	
	row = 0;
	lm_table.set_row_spacings (12);
	lm_table.set_col_spacings (6);
	lm_table.set_homogeneous (false);
	
	lm_table.attach (lm_title, 0, 3, row, row+1, xopt, (AttachOptions) 0);
	row++;

	Gtk::Label* preamble;

	preamble = manage (new Label);
	preamble->set_width_chars (60);
	preamble->set_line_wrap (true);
	preamble->set_markup (_("<span weight=\"bold\">Turn down the volume on your audio equipment to a very low level.</span>"));

	lm_table.attach (*preamble, 0, 3, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);
	row++;

	preamble = manage (new Label);
	preamble->set_width_chars (60);
	preamble->set_line_wrap (true);
	preamble->set_markup (_("Select two channels below and connect them using a cable."));

	lm_table.attach (*preamble, 0, 3, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);
	row++;

	label = manage (new Label (_("Output channel")));
	lm_table.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);

	Gtk::Alignment* misc_align = manage (new Alignment (0.0, 0.5));
	misc_align->add (lm_output_channel_combo);
	lm_table.attach (*misc_align, 1, 3, row, row+1, xopt, (AttachOptions) 0);
	++row;

	label = manage (new Label (_("Input channel")));
	lm_table.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);

	misc_align = manage (new Alignment (0.0, 0.5));
	misc_align->add (lm_input_channel_combo);
	lm_table.attach (*misc_align, 1, 3, row, row+1, FILL, (AttachOptions) 0);
	++row;

	xopt = AttachOptions(0);

	lm_measure_label.set_padding (10, 10);
	lm_measure_button.add (lm_measure_label);
	lm_measure_button.signal_clicked().connect (sigc::mem_fun (*this, &EngineControl::latency_button_clicked));
	lm_use_button.signal_clicked().connect (sigc::mem_fun (*this, &EngineControl::use_latency_button_clicked));
	lm_back_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (notebook, &Gtk::Notebook::set_current_page), 0));
	
	lm_use_button.set_sensitive (false);

	/* Increase the default spacing around the labels of these three
	 * buttons
	 */

	Gtk::Misc* l;

	if ((l = dynamic_cast<Gtk::Misc*>(lm_use_button.get_child())) != 0) {
		l->set_padding (10, 10);
	}

	if ((l = dynamic_cast<Gtk::Misc*>(lm_back_button.get_child())) != 0) {
		l->set_padding (10, 10);
	}

	preamble = manage (new Label);
	preamble->set_width_chars (60);
	preamble->set_line_wrap (true);
	preamble->set_markup (_("Once the channels are connected, click the \"Measure\" button."));
	lm_table.attach (*preamble, 0, 3, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);
	row++;

	preamble = manage (new Label);
	preamble->set_width_chars (60);
	preamble->set_line_wrap (true);
	preamble->set_markup (_("When satisfied with the results, click the \"Use results\" button."));
	lm_table.attach (*preamble, 0, 3, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);

	++row; // skip a row in the table 
	++row; // skip a row in the table 

	lm_table.attach (lm_results, 0, 3, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);

	++row; // skip a row in the table 
	++row; // skip a row in the table 

	lm_table.attach (lm_measure_button, 0, 1, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);
	lm_table.attach (lm_use_button, 1, 2, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);
	lm_table.attach (lm_back_button, 2, 3, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);

	lm_results.set_markup (string_compose (results_markup, _("No measurement results yet")));

	lm_vbox.set_border_width (12);
	lm_vbox.pack_start (lm_table, false, false);

	/* pack it all up */

	notebook.pages().push_back (TabElem (basic_vbox, _("Audio")));
	// notebook.pages().push_back (TabElem (midi_vbox, _("MIDI")));
	notebook.pages().push_back (TabElem (lm_vbox, _("Latency")));
	notebook.set_border_width (12);

	notebook.set_show_tabs (false);
	notebook.show_all ();

	notebook.set_name ("SettingsNotebook");

	/* packup the notebook */

	get_vbox()->set_border_width (12);
	get_vbox()->pack_start (notebook);

	/* need a special function to print "all available channels" when the
	 * channel counts hit zero.
	 */

	input_channels.signal_output().connect (sigc::bind (sigc::ptr_fun (&EngineControl::print_channel_count), &input_channels));
	output_channels.signal_output().connect (sigc::bind (sigc::ptr_fun (&EngineControl::print_channel_count), &output_channels));

	control_app_button.signal_clicked().connect (mem_fun (*this, &EngineControl::control_app_button_clicked));
	manage_control_app_sensitivity ();

	cancel_button = add_button (Gtk::Stock::CANCEL, Gtk::RESPONSE_CANCEL);
	ok_button = add_button (Gtk::Stock::OK, Gtk::RESPONSE_OK);
	apply_button = add_button (Gtk::Stock::APPLY, Gtk::RESPONSE_APPLY);

	/* Pick up any existing audio setup configuration, if appropriate */

	XMLNode* audio_setup = ARDOUR::Config->extra_xml ("AudioMIDISetup");

	ARDOUR::AudioEngine::instance()->Running.connect (running_connection, MISSING_INVALIDATOR, boost::bind (&EngineControl::engine_running, this), gui_context());
	ARDOUR::AudioEngine::instance()->Stopped.connect (stopped_connection, MISSING_INVALIDATOR, boost::bind (&EngineControl::engine_stopped, this), gui_context());
	ARDOUR::AudioEngine::instance()->Halted.connect (stopped_connection, MISSING_INVALIDATOR, boost::bind (&EngineControl::engine_stopped, this), gui_context());

	backend_changed ();

	if (audio_setup) {
		set_state (*audio_setup);
	}

	/* Connect to signals */

	driver_combo.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::driver_changed));
	sample_rate_combo.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::sample_rate_changed));
	buffer_size_combo.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::buffer_size_changed));
	device_combo.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::device_changed));
	midi_option_combo.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::midi_option_changed));

	input_latency.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::parameter_changed));
	output_latency.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::parameter_changed));
	input_channels.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::parameter_changed));
	output_channels.signal_changed().connect (sigc::mem_fun (*this, &EngineControl::parameter_changed));

	notebook.signal_switch_page().connect (sigc::mem_fun (*this, &EngineControl::on_switch_page));

	no_push = false;
 }

 void
 EngineControl::on_response (int response_id)
 {
	 ArdourDialog::on_response (response_id);

	 switch (response_id) {
	 case RESPONSE_APPLY:
		 push_state_to_backend (true);
		 break;
	 case RESPONSE_OK:
		 push_state_to_backend (true);
		 hide ();
		 break;
	 case RESPONSE_DELETE_EVENT: {
		 GdkEventButton ev;
		 ev.type = GDK_BUTTON_PRESS;
		 ev.button = 1;
		 on_delete_event ((GdkEventAny*) &ev);
		 break;
	 }
	 default:
		 hide ();
	 }
 }

 void
 EngineControl::build_notebook ()
 {
	 Label* label;
	 AttachOptions xopt = AttachOptions (FILL|EXPAND);

	 /* clear the table */

	 Gtkmm2ext::container_clear (basic_vbox);
	 Gtkmm2ext::container_clear (basic_packer);

	 label = manage (left_aligned_label (_("Audio System:")));
	 basic_packer.attach (*label, 0, 1, 0, 1, xopt, (AttachOptions) 0);
	 basic_packer.attach (backend_combo, 1, 2, 0, 1, xopt, (AttachOptions) 0);

	 lm_button.signal_clicked.connect (sigc::mem_fun (*this, &EngineControl::calibrate_latency));
	 lm_button.set_name ("record enable button");
	 if (_have_control) {
		 build_full_control_notebook ();
	 } else {
		 build_no_control_notebook ();
	 }

	 basic_vbox.pack_start (basic_hbox, false, false);

	 if (_have_control) {
		 Gtk::HBox* hpacker = manage (new HBox);
		 hpacker->set_border_width (12);
		 hpacker->pack_start (control_app_button, false, false);
		 hpacker->show ();
		 control_app_button.show();
		 basic_vbox.pack_start (*hpacker);
	 }

	 basic_vbox.show_all ();
 }

 void
 EngineControl::build_full_control_notebook ()
 {
	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
	 assert (backend);

	 using namespace Notebook_Helpers;
	 Label* label;
	 vector<string> strings;
	 AttachOptions xopt = AttachOptions (FILL|EXPAND);
	 int row = 1; // row zero == backend combo

	 /* start packing it up */

	 if (backend->requires_driver_selection()) {
		 label = manage (left_aligned_label (_("Driver:")));
		 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
		 basic_packer.attach (driver_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
		 row++;
	 }

	 label = manage (left_aligned_label (_("Device:")));
	 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
	 basic_packer.attach (device_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
	 row++;

	 label = manage (left_aligned_label (_("Sample rate:")));
	 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
	 basic_packer.attach (sample_rate_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
	 row++;


	 label = manage (left_aligned_label (_("Buffer size:")));
	 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
	 basic_packer.attach (buffer_size_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
	 buffer_size_duration_label.set_alignment (0.0); /* left-align */
	 basic_packer.attach (buffer_size_duration_label, 2, 3, row, row+1, SHRINK, (AttachOptions) 0);
	 row++;

	 input_channels.set_name ("InputChannels");
	 input_channels.set_flags(Gtk::CAN_FOCUS);
	 input_channels.set_digits(0);
	 input_channels.set_wrap(false);
	 output_channels.set_editable (true);

	 label = manage (left_aligned_label (_("Input Channels:")));
	 basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
	 basic_packer.attach (input_channels, 1, 2, row, row+1, xopt, (AttachOptions) 0);
	 ++row;

	 output_channels.set_name ("OutputChannels");
	 output_channels.set_flags(Gtk::CAN_FOCUS);
	 output_channels.set_digits(0);
	 output_channels.set_wrap(false);
	 output_channels.set_editable (true);

	 label = manage (left_aligned_label (_("Output Channels:")));
	 basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
	 basic_packer.attach (output_channels, 1, 2, row, row+1, xopt, (AttachOptions) 0);
	 ++row;

	 input_latency.set_name ("InputLatency");
	 input_latency.set_flags(Gtk::CAN_FOCUS);
	 input_latency.set_digits(0);
	 input_latency.set_wrap(false);
	 input_latency.set_editable (true);

	 label = manage (left_aligned_label (_("Hardware input latency:")));
	 basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
	 basic_packer.attach (input_latency, 1, 2, row, row+1, xopt, (AttachOptions) 0);
	 label = manage (left_aligned_label (_("samples")));
	 basic_packer.attach (*label, 2, 3, row, row+1, SHRINK, (AttachOptions) 0);
	 ++row;

	 output_latency.set_name ("OutputLatency");
	 output_latency.set_flags(Gtk::CAN_FOCUS);
	 output_latency.set_digits(0);
	 output_latency.set_wrap(false);
	 output_latency.set_editable (true);

	 label = manage (left_aligned_label (_("Hardware output latency:")));
	 basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
	 basic_packer.attach (output_latency, 1, 2, row, row+1, xopt, (AttachOptions) 0);
	 label = manage (left_aligned_label (_("samples")));
	 basic_packer.attach (*label, 2, 3, row, row+1, SHRINK, (AttachOptions) 0);

	 /* button spans 2 rows */

	 basic_packer.attach (lm_button, 3, 4, row-1, row+1, xopt, xopt);
	 ++row;

	 label = manage (left_aligned_label (_("MIDI System")));
	 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
	 basic_packer.attach (midi_option_combo, 1, 2, row, row + 1, SHRINK, (AttachOptions) 0);
	 row++;
 }

 void
 EngineControl::build_no_control_notebook ()
 {
	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
	 assert (backend);

	 using namespace Notebook_Helpers;
	 Label* label;
	 vector<string> strings;
	 AttachOptions xopt = AttachOptions (FILL|EXPAND);
	 int row = 1; // row zero == backend combo
	 const string msg = string_compose (_("The %1 audio backend was configured and started externally.\nThis limits your control over it."), backend->name());

	 label = manage (new Label);
	 label->set_markup (string_compose ("<span weight=\"bold\" foreground=\"red\">%1</span>", msg));
	 basic_packer.attach (*label, 0, 2, row, row + 1, xopt, (AttachOptions) 0);
	 row++;

	 if (backend->can_change_sample_rate_when_running()) {
		 label = manage (left_aligned_label (_("Sample rate:")));
		 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
		 basic_packer.attach (sample_rate_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
		 row++;
	 }

	 if (backend->can_change_buffer_size_when_running()) {
		 label = manage (left_aligned_label (_("Buffer size:")));
		 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
		 basic_packer.attach (buffer_size_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
		 buffer_size_duration_label.set_alignment (0.0); /* left-align */
		 basic_packer.attach (buffer_size_duration_label, 2, 3, row, row+1, xopt, (AttachOptions) 0);
		 row++;
	 }

	 connect_disconnect_button.signal_clicked().connect (sigc::mem_fun (*this, &EngineControl::connect_disconnect_click));

	 basic_packer.attach (connect_disconnect_button, 0, 2, row, row+1, FILL, AttachOptions (0));
	 row++;
 }

 EngineControl::~EngineControl ()
 {
	 ignore_changes = true;
 }

 void
 EngineControl::disable_latency_tab ()
 {
	 vector<string> empty;
	 set_popdown_strings (lm_output_channel_combo, empty);
	 set_popdown_strings (lm_input_channel_combo, empty);
	 lm_measure_button.set_sensitive (false);
	 lm_use_button.set_sensitive (false);
 }

 void
 EngineControl::enable_latency_tab ()
 {
	 vector<string> outputs;
	 vector<string> inputs;

	 ARDOUR::AudioEngine::instance()->get_physical_outputs (ARDOUR::DataType::AUDIO, outputs);
	 ARDOUR::AudioEngine::instance()->get_physical_inputs (ARDOUR::DataType::AUDIO, inputs);

	 if (inputs.empty() || outputs.empty()) {
		 MessageDialog msg (_("Your selected audio configuration is playback- or capture-only.\n\nLatency calibration requires playback and capture"));
		 lm_measure_button.set_sensitive (false);
		 notebook.set_current_page (0);
		 msg.run ();
		 return;
	 }

	 if (!outputs.empty()) {
		 set_popdown_strings (lm_output_channel_combo, outputs);
		 lm_output_channel_combo.set_active_text (outputs.front());
		 lm_output_channel_combo.set_sensitive (true);
	 } else {
		 lm_output_channel_combo.set_sensitive (false);
	 }

	 if (!inputs.empty()) {
		 set_popdown_strings (lm_input_channel_combo, inputs);
		 lm_input_channel_combo.set_active_text (inputs.front());
		 lm_input_channel_combo.set_sensitive (true);
	 } else {
		 lm_input_channel_combo.set_sensitive (false);
	 }

	 lm_measure_button.set_sensitive (true);
 }

 void
 EngineControl::setup_midi_tab_for_backend ()
 {
	 string backend = backend_combo.get_active_text ();

	 Gtkmm2ext::container_clear (midi_vbox);

	 midi_vbox.set_border_width (12);
	 midi_device_table.set_border_width (12);

	 if (backend == "JACK") {
		 setup_midi_tab_for_jack ();
	 }

	 midi_vbox.pack_start (midi_device_table, true, true);
	 midi_vbox.pack_start (midi_refresh_button, false, false);
	 midi_vbox.show_all ();

	 midi_refresh_button.signal_clicked().connect (sigc::mem_fun (*this, &EngineControl::refresh_midi_display));
 }

 void
 EngineControl::setup_midi_tab_for_jack ()
 {
 }	

 void
 EngineControl::refresh_midi_display ()
 {
	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
	 assert (backend);

	 vector<string> midi_inputs;
	 vector<string> midi_outputs;
	 int row  = 0;
	 AttachOptions xopt = AttachOptions (FILL|EXPAND);
	 Gtk::Label* l;

	 Gtkmm2ext::container_clear (midi_device_table);

	 backend->get_physical_inputs (ARDOUR::DataType::MIDI, midi_inputs);
	 backend->get_physical_outputs (ARDOUR::DataType::MIDI, midi_outputs);

	 midi_device_table.set_spacings (6);
	 midi_device_table.set_homogeneous (true);
	 midi_device_table.resize (midi_inputs.size() + midi_outputs.size() + 3, 1);

	 l = manage (new Label);
	 l->set_markup (string_compose ("<span size=\"large\" weight=\"bold\">%1</span>", _("MIDI Inputs")));
	 midi_device_table.attach (*l, 0, 1, row, row + 1, xopt, AttachOptions (0));
	 l->set_alignment (0, 0.5);
	 row++;
	 l->show ();

	 for (vector<string>::iterator p = midi_inputs.begin(); p != midi_inputs.end(); ++p) {
		 l = manage (new Label ((*p).substr ((*p).find_last_of (':') + 1)));
		 l->set_alignment (0, 0.5);
		 midi_device_table.attach (*l, 0, 1, row, row + 1, xopt, AttachOptions (0));
		 l->show ();
		 row++;
	 }

	 row++; // extra row of spacing

	 l = manage (new Label);
	 l->set_markup (string_compose ("<span size=\"large\" weight=\"bold\">%1</span>", _("MIDI Outputs")));
	 midi_device_table.attach (*l, 0, 1, row, row + 1, xopt, AttachOptions (0));
	 l->set_alignment (0, 0.5);
	 row++;
	 l->show ();

	 for (vector<string>::iterator p = midi_outputs.begin(); p != midi_outputs.end(); ++p) {
		 l = manage (new Label ((*p).substr ((*p).find_last_of (':') + 1)));
		 l->set_alignment (0, 0.5);
		 midi_device_table.attach (*l, 0, 1, row, row + 1, xopt, AttachOptions (0));
		 l->show ();
		 row++;
	 }
 }

 void
 EngineControl::update_sensitivity ()
 {
 }

 void
 EngineControl::backend_changed ()
 {
	 if (ignore_changes) {
		 return;
	 }

	 string backend_name = backend_combo.get_active_text();
	 boost::shared_ptr<ARDOUR::AudioBackend> backend;

	 if (!(backend = ARDOUR::AudioEngine::instance()->set_backend (backend_name, "ardour", ""))) {
		 /* eh? setting the backend failed... how ? */
		 return;
	 }

	 _have_control = ARDOUR::AudioEngine::instance()->setup_required ();

	 build_notebook ();
	 setup_midi_tab_for_backend ();

	 if (backend->requires_driver_selection()) {
		 vector<string> drivers = backend->enumerate_drivers();

		 if (!drivers.empty()) {
			 {
				 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
				 set_popdown_strings (driver_combo, drivers);
				 driver_combo.set_active_text (drivers.front());
			 }

			 driver_changed ();
		 }

	 } else {
		 driver_combo.set_sensitive (false);
		 /* this will change the device text which will cause a call to
		  * device changed which will set up parameters
		  */
		 list_devices ();
	 }

	 vector<string> midi_options = backend->enumerate_midi_options();

	 if (midi_options.size() == 1) {
		 /* only contains the "none" option */
		 midi_option_combo.set_sensitive (false);
	 } else {
		 if (_have_control) {
			 set_popdown_strings (midi_option_combo, midi_options);
			 midi_option_combo.set_active_text (midi_options.front());
			 midi_option_combo.set_sensitive (true);
		 } else {
			 midi_option_combo.set_sensitive (false);
		 }
	 }

	 maybe_display_saved_state ();
 }

 bool
 EngineControl::print_channel_count (Gtk::SpinButton* sb)
 {
	 uint32_t cnt = (uint32_t) sb->get_value();
	 if (cnt == 0) {
		 sb->set_text (_("all available channels"));
	 } else {
		 char buf[32];
		 snprintf (buf, sizeof (buf), "%d", cnt);
		 sb->set_text (buf);
	 }
	 return true;
 }

 void
 EngineControl::list_devices ()
 {
	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
	 assert (backend);

	 /* now fill out devices, mark sample rates, buffer sizes insensitive */

	 vector<ARDOUR::AudioBackend::DeviceStatus> all_devices = backend->enumerate_devices ();

	 /* NOTE: Ardour currently does not display the "available" field of the
	  * returned devices.
	  *
	  * Doing so would require a different GUI widget than the combo
	  * box/popdown that we currently use, since it has no way to list
	  * items that are not selectable. Something more like a popup menu,
	  * which could have unselectable items, would be appropriate.
	  */

	 vector<string> available_devices;

	 for (vector<ARDOUR::AudioBackend::DeviceStatus>::const_iterator i = all_devices.begin(); i != all_devices.end(); ++i) {
		 available_devices.push_back (i->name);
	 }

	 if (!available_devices.empty()) {

		 update_sensitivity ();

		 {
			 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
			 set_popdown_strings (device_combo, available_devices);
			 device_combo.set_active_text (available_devices.front());
		 }

		 device_changed ();

		 ok_button->set_sensitive (true);
		 apply_button->set_sensitive (true);

	 } else {
		 sample_rate_combo.set_sensitive (false);
		 buffer_size_combo.set_sensitive (false);
		 input_latency.set_sensitive (false);
		 output_latency.set_sensitive (false);
		 input_channels.set_sensitive (false);
		 output_channels.set_sensitive (false);
		 ok_button->set_sensitive (false);
		 apply_button->set_sensitive (false);
	 }
 }

 void
 EngineControl::driver_changed ()
 {
	 if (ignore_changes) {
		 return;
	 }

	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
	 assert (backend);

	 backend->set_driver (driver_combo.get_active_text());
	 list_devices ();

	 maybe_display_saved_state ();
 }

 void
 EngineControl::device_changed ()
 {
	 if (ignore_changes) {
		 return;
	 }

	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
	 assert (backend);
	 string device_name = device_combo.get_active_text ();
	 vector<string> s;

	 {
		 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);

		 /* don't allow programmatic change to combos to cause a
		    recursive call to this method.
		 */

		 /* sample rates */

		 string desired;

		 vector<float> sr;

		 if (_have_control) {
			 sr = backend->available_sample_rates (device_name);
		 } else {

			 sr.push_back (8000.0f);
			 sr.push_back (16000.0f);
			 sr.push_back (32000.0f);
			 sr.push_back (44100.0f);
			 sr.push_back (48000.0f);
			 sr.push_back (88200.0f);
			 sr.push_back (96000.0f);
			 sr.push_back (192000.0f);
			 sr.push_back (384000.0f);
		 }

		 for (vector<float>::const_iterator x = sr.begin(); x != sr.end(); ++x) {
			 s.push_back (rate_as_string (*x));
			 if (*x == _desired_sample_rate) {
				 desired = s.back();
			 }
		 }

		 if (!s.empty()) {
			 sample_rate_combo.set_sensitive (true);
			 set_popdown_strings (sample_rate_combo, s);

			 if (desired.empty()) {
				 sample_rate_combo.set_active_text (rate_as_string (backend->default_sample_rate()));
			 } else {
				 sample_rate_combo.set_active_text (desired);
			 }

		 } else {
			 sample_rate_combo.set_sensitive (false);
		 }

		 /* buffer sizes */

		 vector<uint32_t> bs;

		 if (_have_control) {
			 bs = backend->available_buffer_sizes(device_name);
		 } else if (backend->can_change_buffer_size_when_running()) {
			 bs.push_back (8);
			 bs.push_back (16);
			 bs.push_back (32);
			 bs.push_back (64);
			 bs.push_back (128);
			 bs.push_back (256);
			 bs.push_back (512);
			 bs.push_back (1024);
			 bs.push_back (2048);
			 bs.push_back (4096);
			 bs.push_back (8192);
		 }
		 s.clear ();
		 for (vector<uint32_t>::const_iterator x = bs.begin(); x != bs.end(); ++x) {
			 s.push_back (bufsize_as_string (*x));
		 }

		 if (!s.empty()) {
			 buffer_size_combo.set_sensitive (true);
			 set_popdown_strings (buffer_size_combo, s);

			 buffer_size_combo.set_active_text (bufsize_as_string (backend->default_buffer_size()));
			 show_buffer_duration ();
		 } else {
			 buffer_size_combo.set_sensitive (false);
		 }

		 /* XXX theoretically need to set min + max channel counts here
		  */

		 manage_control_app_sensitivity ();
	 }

	 /* pick up any saved state for this device */

	 maybe_display_saved_state ();

	 /* and push it to the backend */

	 push_state_to_backend (false);
 }	

 string
 EngineControl::bufsize_as_string (uint32_t sz)
 {
	 /* Translators: "samples" is always plural here, so no
	    need for plural+singular forms.
	 */
	 char buf[32];
	 snprintf (buf, sizeof (buf), _("%u samples"), sz);
	 return buf;
 }

 void 
 EngineControl::sample_rate_changed ()
 {
	 if (ignore_changes) {
		 return;
	 }

	 /* reset the strings for buffer size to show the correct msec value
	    (reflecting the new sample rate).
	 */

	 show_buffer_duration ();
	 save_state ();

 }

 void 
 EngineControl::buffer_size_changed ()
 {
	 if (ignore_changes) {
		 return;
	 }

	 show_buffer_duration ();
	 save_state ();
 }

 void
 EngineControl::show_buffer_duration ()
 {

	 /* buffer sizes  - convert from just samples to samples + msecs for
	  * the displayed string
	  */

	 string bs_text = buffer_size_combo.get_active_text ();
	 uint32_t samples = atoi (bs_text); /* will ignore trailing text */
	 uint32_t rate = get_rate();

	 /* Translators: "msecs" is ALWAYS plural here, so we do not
	    need singular form as well.
	 */
	 /* Developers: note the hard-coding of a double buffered model
	    in the (2 * samples) computation of latency. we always start
	    the audiobackend in this configuration.
	 */
	 char buf[32];
	 snprintf (buf, sizeof (buf), _("(%.1f msecs)"), (2 * samples) / (rate/1000.0));
	 buffer_size_duration_label.set_text (buf);
 }

 void
 EngineControl::midi_option_changed ()
 {
	 if (!ignore_changes) {
		 save_state ();
	 }
 }

 void
 EngineControl::parameter_changed ()
 {
	 if (!ignore_changes) {
		 save_state ();
	 }
 }

 EngineControl::State*
 EngineControl::get_matching_state (const string& backend,
				    const string& driver,
				    const string& device)
 {
	 for (StateList::iterator i = states.begin(); i != states.end(); ++i) {
		 if ((*i).backend == backend &&
		     (*i).driver == driver &&
		     (*i).device == device) {
			 return &(*i);
		 }
	 }
	 return 0;
 }

 EngineControl::State*
 EngineControl::get_saved_state_for_currently_displayed_backend_and_device ()
 {
	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();

	 if (backend) {
		 return get_matching_state (backend_combo.get_active_text(),
					    (backend->requires_driver_selection() ? (std::string) driver_combo.get_active_text() : string()),
					    device_combo.get_active_text());
	 }


	 return get_matching_state (backend_combo.get_active_text(),
				    string(),
				    device_combo.get_active_text());
 }

 EngineControl::State*
 EngineControl::save_state ()
 {
	 if (!_have_control) {
		 return 0;
	 }

	 bool existing = true;
	 State* state = get_saved_state_for_currently_displayed_backend_and_device ();

	 if (!state) {
		 existing = false;
		 state = new State;
	 }

	 store_state (*state);

	 if (!existing) {
		 states.push_back (*state);
	 }

	 return state;
 }

 void
 EngineControl::store_state (State& state)
 {
	 state.backend = get_backend ();
	 state.driver = get_driver ();
	 state.device = get_device_name ();
	 state.sample_rate = get_rate ();
	 state.buffer_size = get_buffer_size ();
	 state.input_latency = get_input_latency ();
	 state.output_latency = get_output_latency ();
	 state.input_channels = get_input_channels ();
	 state.output_channels = get_output_channels ();
	 state.midi_option = get_midi_option ();
 }

 void
 EngineControl::maybe_display_saved_state ()
 {
	 if (!_have_control) {
		 return;
	 }

	 State* state = get_saved_state_for_currently_displayed_backend_and_device ();

	 if (state) {
		 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);

		 if (!_desired_sample_rate) {
			 sample_rate_combo.set_active_text (rate_as_string (state->sample_rate));
		 }
		 buffer_size_combo.set_active_text (bufsize_as_string (state->buffer_size));
		 /* call this explicitly because we're ignoring changes to
		    the controls at this point.
		 */
		 show_buffer_duration ();
		 input_latency.set_value (state->input_latency);
		 output_latency.set_value (state->output_latency);

		 if (!state->midi_option.empty()) {
			 midi_option_combo.set_active_text (state->midi_option);
		 }
	 }
 }

 XMLNode&
 EngineControl::get_state ()
 {
	 XMLNode* root = new XMLNode ("AudioMIDISetup");
	 std::string path;

	 if (!states.empty()) {
		 XMLNode* state_nodes = new XMLNode ("EngineStates");

		 for (StateList::const_iterator i = states.begin(); i != states.end(); ++i) {

			 XMLNode* node = new XMLNode ("State");

			 node->add_property ("backend", (*i).backend);
			 node->add_property ("driver", (*i).driver);
			 node->add_property ("device", (*i).device);
			 node->add_property ("sample-rate", (*i).sample_rate);
			 node->add_property ("buffer-size", (*i).buffer_size);
			 node->add_property ("input-latency", (*i).input_latency);
			 node->add_property ("output-latency", (*i).output_latency);
			 node->add_property ("input-channels", (*i).input_channels);
			 node->add_property ("output-channels", (*i).output_channels);
			 node->add_property ("active", (*i).active ? "yes" : "no");
			 node->add_property ("midi-option", (*i).midi_option);

			 state_nodes->add_child_nocopy (*node);
		 }

		 root->add_child_nocopy (*state_nodes);
	 }

	 return *root;
 }

 void
 EngineControl::set_state (const XMLNode& root)
 {
	 XMLNodeList          clist, cclist;
	 XMLNodeConstIterator citer, cciter;
	 XMLNode* child;
	 XMLNode* grandchild;
	 XMLProperty* prop = NULL;

	 if (root.name() != "AudioMIDISetup") {
		 return;
	 }

	 clist = root.children();

	 states.clear ();

	 for (citer = clist.begin(); citer != clist.end(); ++citer) {

		 child = *citer;

		 if (child->name() != "EngineStates") {
			 continue;
		 }

		 cclist = child->children();

		 for (cciter = cclist.begin(); cciter != cclist.end(); ++cciter) {
			 State state;

			 grandchild = *cciter;

			 if (grandchild->name() != "State") {
				 continue;
			 }

			 if ((prop = grandchild->property ("backend")) == 0) {
				 continue;
			 }
			 state.backend = prop->value ();

			 if ((prop = grandchild->property ("driver")) == 0) {
				 continue;
			 }
			 state.driver = prop->value ();

			 if ((prop = grandchild->property ("device")) == 0) {
				 continue;
			 }
			 state.device = prop->value ();

			 if ((prop = grandchild->property ("sample-rate")) == 0) {
				 continue;
			 }
			 state.sample_rate = atof (prop->value ());

			 if ((prop = grandchild->property ("buffer-size")) == 0) {
				 continue;
			 }
			 state.buffer_size = atoi (prop->value ());

			 if ((prop = grandchild->property ("input-latency")) == 0) {
				 continue;
			 }
			 state.input_latency = atoi (prop->value ());

			 if ((prop = grandchild->property ("output-latency")) == 0) {
				 continue;
			 }
			 state.output_latency = atoi (prop->value ());

			 if ((prop = grandchild->property ("input-channels")) == 0) {
				 continue;
			 }
			 state.input_channels = atoi (prop->value ());

			 if ((prop = grandchild->property ("output-channels")) == 0) {
				 continue;
			 }
			 state.output_channels = atoi (prop->value ());

			 if ((prop = grandchild->property ("active")) == 0) {
				 continue;
			 }
			 state.active = string_is_affirmative (prop->value ());

			 if ((prop = grandchild->property ("midi-option")) == 0) {
				 continue;
			 }
			 state.midi_option = prop->value ();

			 states.push_back (state);
		 }
	 }

	 /* now see if there was an active state and switch the setup to it */

	 for (StateList::const_iterator i = states.begin(); i != states.end(); ++i) {

		 if ((*i).active) {
			 ignore_changes++;
			 backend_combo.set_active_text ((*i).backend);
			 driver_combo.set_active_text ((*i).driver);
			 device_combo.set_active_text ((*i).device);
			 sample_rate_combo.set_active_text (rate_as_string ((*i).sample_rate));
			 buffer_size_combo.set_active_text (bufsize_as_string ((*i).buffer_size));
			 input_latency.set_value ((*i).input_latency);
			 output_latency.set_value ((*i).output_latency);
			 midi_option_combo.set_active_text ((*i).midi_option);
			 ignore_changes--;
			 break;
		 }
	 }
 }


 int
 EngineControl::push_state_to_backend (bool start)
 {
	 if (no_push) {
		 return 0;
	 }

	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();

	 if (!backend) {
		 return 0;
	 }

	 /* figure out what is going to change */

	 bool restart_required = false;
	 bool was_running = ARDOUR::AudioEngine::instance()->running();
	 bool change_driver = false;
	 bool change_device = false;
	 bool change_rate = false;
	 bool change_bufsize = false;
	 bool change_latency = false;
	 bool change_channels = false;
	 bool change_midi = false;

	 uint32_t ochan = get_output_channels ();
	 uint32_t ichan = get_input_channels ();

	 if (_have_control) {

		 if (started_at_least_once) {

			 /* we can control the backend */

			 if (backend->requires_driver_selection()) {
				 if (get_driver() != backend->driver_name()) {
					 change_driver = true;
				 }
			 }

			 if (get_device_name() != backend->device_name()) {
				 change_device = true;
			 }

			 if (get_rate() != backend->sample_rate()) {
				 change_rate = true;
			 }

			 if (get_buffer_size() != backend->buffer_size()) {
				 change_bufsize = true;
			 }

			 if (get_midi_option() != backend->midi_option()) {
				 change_midi = true;
			 }

			 /* zero-requested channels means "all available" */

			 if (ichan == 0) {
				 ichan = backend->input_channels();
			 }

			 if (ochan == 0) {
				 ochan = backend->output_channels();
			 }

			 if (ichan != backend->input_channels()) {
				 change_channels = true;
			 }

			 if (ochan != backend->output_channels()) {
				 change_channels = true;
			 }

			 if (get_input_latency() != backend->systemic_input_latency() ||
			     get_output_latency() != backend->systemic_output_latency()) {
				 change_latency = true;
			 }
		 } else {
			 /* backend never started, so we have to force a group
			    of settings.
			 */
			 change_device = true;
			 if (backend->requires_driver_selection()) {
				 change_driver = true;
			 }
			 change_rate = true;
			 change_bufsize = true;
			 change_channels = true;
			 change_latency = true;
			 change_midi = true;
		 }

	 } else {

		 /* we have no control over the backend, meaning that we can
		  * only possibly change sample rate and buffer size.
		  */


		 if (get_rate() != backend->sample_rate()) {
			 change_bufsize = true;
		 }

		 if (get_buffer_size() != backend->buffer_size()) {
			 change_bufsize = true;
		 }
	 }

	 if (!_have_control) {

		 /* We do not have control over the backend, so the best we can
		  * do is try to change the sample rate and/or bufsize and get
		  * out of here.
		  */

		 if (change_rate && !backend->can_change_sample_rate_when_running()) {
			 return 1;
		 }

		 if (change_bufsize && !backend->can_change_buffer_size_when_running()) {
			 return 1;
		 }

		 if (change_rate) {
			 backend->set_sample_rate (get_rate());
		 }

		 if (change_bufsize) {
			 backend->set_buffer_size (get_buffer_size());
		 }

		 post_push ();

		 return 0;
	 } 

	 /* determine if we need to stop the backend before changing parameters */

	 if (change_driver || change_device || change_channels || change_latency ||
	     (change_rate && !backend->can_change_sample_rate_when_running()) ||
	     change_midi ||
	     (change_bufsize && !backend->can_change_buffer_size_when_running())) {
		 restart_required = true;
	 } else {
		 restart_required = false;
	 }

	 if (was_running) {

		 if (!change_driver && !change_device && !change_channels && !change_latency && !change_midi) {
			 /* no changes in any parameters that absolutely require a
			  * restart, so check those that might be changeable without a
			  * restart
			  */

			 if (change_rate && !backend->can_change_sample_rate_when_running()) {
				 /* can't do this while running ... */
				 restart_required = true;
			 }

			 if (change_bufsize && !backend->can_change_buffer_size_when_running()) {
				 /* can't do this while running ... */
				 restart_required = true;
			 }
		 }
	 }

	 if (was_running) {
		 if (restart_required) {
			 if (ARDOUR_UI::instance()->disconnect_from_engine ()) {
				 return -1;
			 }
		 }
	 }


	 if (change_driver && backend->set_driver (get_driver())) {
		 error << string_compose (_("Cannot set driver to %1"), get_driver()) << endmsg;
		 return -1;
	 }
	 if (change_device && backend->set_device_name (get_device_name())) {
		 error << string_compose (_("Cannot set device name to %1"), get_device_name()) << endmsg;
		 return -1;
	 }
	 if (change_rate && backend->set_sample_rate (get_rate())) {
		 error << string_compose (_("Cannot set sample rate to %1"), get_rate()) << endmsg;
		 return -1;
	 }
	 if (change_bufsize && backend->set_buffer_size (get_buffer_size())) {
		 error << string_compose (_("Cannot set buffer size to %1"), get_buffer_size()) << endmsg;
		 return -1;
	 }

	 if (change_channels || get_input_channels() == 0 || get_output_channels() == 0) {
		 if (backend->set_input_channels (get_input_channels())) {
			 error << string_compose (_("Cannot set input channels to %1"), get_input_channels()) << endmsg;
			 return -1;
		 }
		 if (backend->set_output_channels (get_output_channels())) {
			 error << string_compose (_("Cannot set output channels to %1"), get_output_channels()) << endmsg;
			 return -1;
		 }
	 }
	 if (change_latency) {
		 if (backend->set_systemic_input_latency (get_input_latency())) {
			 error << string_compose (_("Cannot set input latency to %1"), get_input_latency()) << endmsg;
			 return -1;
		 }
		 if (backend->set_systemic_output_latency (get_output_latency())) {
			 error << string_compose (_("Cannot set output latency to %1"), get_output_latency()) << endmsg;
			 return -1;
		 }
	 }

	 if (change_midi) {
		 backend->set_midi_option (get_midi_option());
	 }

	 if (start || (was_running && restart_required)) {
		 if (ARDOUR_UI::instance()->reconnect_to_engine()) {
			 return -1;
		 }
	 }

	 post_push ();

	 return 0;
 }

 void
 EngineControl::post_push ()
 {
	 /* get a pointer to the current state object, creating one if
	  * necessary
	  */

	 if (_have_control) {
		 State* state = get_saved_state_for_currently_displayed_backend_and_device ();

		 if (!state) {
			 state = save_state ();
			 assert (state);
		 }

		 /* all off */

		 for (StateList::iterator i = states.begin(); i != states.end(); ++i) {
			 (*i).active = false;
		 }

		 /* mark this one active (to be used next time the dialog is
		  * shown)
		  */

		 state->active = true;

		 manage_control_app_sensitivity ();
	 }

	 /* schedule a redisplay of MIDI ports */

	 Glib::signal_timeout().connect (sigc::bind_return (sigc::mem_fun (*this, &EngineControl::refresh_midi_display), false), 1000);
 }


 float
 EngineControl::get_rate () const
 {
	 float r = atof (sample_rate_combo.get_active_text ());
	 /* the string may have been translated with an abbreviation for
	  * thousands, so use a crude heuristic to fix this.
	  */
	 if (r < 1000.0) {
		 r *= 1000.0;
	 }
	 return r;
 }


 uint32_t
 EngineControl::get_buffer_size () const
 {
	 string txt = buffer_size_combo.get_active_text ();
	 uint32_t samples;

	 if (sscanf (txt.c_str(), "%d", &samples) != 1) {
		 throw exception ();
	 }

	 return samples;
 }

 string
 EngineControl::get_midi_option () const
 {
	 return midi_option_combo.get_active_text();
 }

 uint32_t
 EngineControl::get_input_channels() const
 {
	 return (uint32_t) input_channels_adjustment.get_value();
 }

 uint32_t
 EngineControl::get_output_channels() const
 {
	 return (uint32_t) output_channels_adjustment.get_value();
 }

 uint32_t
 EngineControl::get_input_latency() const
 {
	 return (uint32_t) input_latency_adjustment.get_value();
 }

 uint32_t
 EngineControl::get_output_latency() const
 {
	 return (uint32_t) output_latency_adjustment.get_value();
 }

 string
 EngineControl::get_backend () const
 {
	 return backend_combo.get_active_text ();
 }

 string
 EngineControl::get_driver () const
 {
	 return driver_combo.get_active_text ();
 }

 string
 EngineControl::get_device_name () const
 {
	 return device_combo.get_active_text ();
 }

 void
 EngineControl::control_app_button_clicked ()
 {
	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();

	 if (!backend) {
		 return;
	 }

	 backend->launch_control_app ();
 }

 void
 EngineControl::manage_control_app_sensitivity ()
 {
	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();

	 if (!backend) {
		 return;
	 }

	 string appname = backend->control_app_name();

	 if (appname.empty()) {
		 control_app_button.set_sensitive (false);
	 } else {
		 control_app_button.set_sensitive (true);
	 }
 }

 void
 EngineControl::set_desired_sample_rate (uint32_t sr)
 {
	 _desired_sample_rate = sr;
	 device_changed ();
 }

 void
 EngineControl::on_switch_page (GtkNotebookPage*, guint page_num)
 {
	 if (page_num == 0) {
		 cancel_button->set_sensitive (true);
		 ok_button->set_sensitive (true);
		 apply_button->set_sensitive (true);
	 } else {
		 cancel_button->set_sensitive (false);
		 ok_button->set_sensitive (false);
		 apply_button->set_sensitive (false);
	 }

	 if (page_num == midi_tab) {
		 /* MIDI tab */
		 refresh_midi_display ();
	 }

	 if (page_num == latency_tab) {
		 /* latency tab */

		 if (!ARDOUR::AudioEngine::instance()->running()) {

			 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);

			 /* save any existing latency values */

			 uint32_t il = (uint32_t) input_latency.get_value ();
			 uint32_t ol = (uint32_t) input_latency.get_value ();

			 /* reset to zero so that our new test instance of JACK
			    will be clean of any existing latency measures.
			 */

			 input_latency.set_value (0);
			 output_latency.set_value (0);

			 /* reset control */

			 input_latency.set_value (il);
			 output_latency.set_value (ol);

		 } 

		 if (ARDOUR::AudioEngine::instance()->prepare_for_latency_measurement()) {
			 disable_latency_tab ();
		 }

		 enable_latency_tab ();

	 } else {
		 if (lm_running) {
			 ARDOUR::AudioEngine::instance()->stop_latency_detection();
		 }
	 }
 }

 /* latency measurement */

 bool
 EngineControl::check_latency_measurement ()
 {
	 MTDM* mtdm = ARDOUR::AudioEngine::instance()->mtdm ();

	 if (mtdm->resolve () < 0) {
		 lm_results.set_markup (string_compose (results_markup, _("No signal detected ")));
		 return true;
	 }

	 if (mtdm->err () > 0.3) {
		 mtdm->invert ();
		 mtdm->resolve ();
	 }

	 char buf[128];
	 ARDOUR::framecnt_t const sample_rate = ARDOUR::AudioEngine::instance()->sample_rate();

	 if (sample_rate == 0) {
		 lm_results.set_markup (string_compose (results_markup, _("Disconnected from audio engine")));
		 ARDOUR::AudioEngine::instance()->stop_latency_detection ();
		 return false;
	 }

	 uint32_t frames_total = mtdm->del();
	 uint32_t extra = frames_total - ARDOUR::AudioEngine::instance()->latency_signal_delay();

	 snprintf (buf, sizeof (buf), "%u samples / %.3lf ms", extra, extra * 1000.0f/sample_rate);

	 bool solid = true;

	 if (mtdm->err () > 0.2) {
		 strcat (buf, " ");
		 strcat (buf, _("(signal detection error)"));
		 solid = false;
	 }

	 if (mtdm->inv ()) {
		 strcat (buf, " ");
		 strcat (buf, _("(inverted - bad wiring)"));
		 solid = false;
	 }

	 if (solid) {
		 end_latency_detection ();
		 lm_use_button.set_sensitive (true);
		 have_lm_results = true;
        }
	
        lm_results.set_markup (string_compose (results_markup, string_compose (_("Detected roundtrip latency: %1"), buf)));

        return true;
}

void
EngineControl::start_latency_detection ()
{
	ARDOUR::AudioEngine::instance()->set_latency_input_port (lm_input_channel_combo.get_active_text());
	ARDOUR::AudioEngine::instance()->set_latency_output_port (lm_output_channel_combo.get_active_text());

	if (ARDOUR::AudioEngine::instance()->start_latency_detection () == 0) {
		lm_results.set_markup (string_compose (results_markup, _("Detecting ...")));
		latency_timeout = Glib::signal_timeout().connect (mem_fun (*this, &EngineControl::check_latency_measurement), 100);
		lm_measure_label.set_text (_("Cancel"));
		have_lm_results = false;
		lm_use_button.set_sensitive (false);
		lm_input_channel_combo.set_sensitive (false);
		lm_output_channel_combo.set_sensitive (false);
		lm_running = true;
	}
}

void
EngineControl::end_latency_detection ()
{
	latency_timeout.disconnect ();
	ARDOUR::AudioEngine::instance()->stop_latency_detection ();
	lm_measure_label.set_text (_("Measure"));
	if (!have_lm_results) {
		lm_results.set_markup (string_compose (results_markup, _("No measurement results yet")));
	} else {
		lm_use_button.set_sensitive (false);
	}
	lm_input_channel_combo.set_sensitive (true);
	lm_output_channel_combo.set_sensitive (true);
	lm_running = false;
}

void
EngineControl::latency_button_clicked ()
{
	if (!lm_running) {
		start_latency_detection ();
	} else {
		end_latency_detection ();
        }
}

void
EngineControl::use_latency_button_clicked ()
{
        MTDM* mtdm = ARDOUR::AudioEngine::instance()->mtdm ();

	if (!mtdm) {
		return;
	}

	uint32_t frames_total = mtdm->del();
	uint32_t extra = frames_total - ARDOUR::AudioEngine::instance()->latency_signal_delay();
	uint32_t one_way = extra/2;

	input_latency_adjustment.set_value (one_way);
	output_latency_adjustment.set_value (one_way);

	/* back to settings page */

	notebook.set_current_page (0);
}

bool
EngineControl::on_delete_event (GdkEventAny* ev)
{
	if (notebook.get_current_page() == 2) {
		/* currently on latency tab - be sure to clean up */
		end_latency_detection ();
	}
	return ArdourDialog::on_delete_event (ev);
}

void
EngineControl::engine_running ()
{
	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
	assert (backend);

	buffer_size_combo.set_active_text (bufsize_as_string (backend->buffer_size()));
	sample_rate_combo.set_active_text (rate_as_string (backend->sample_rate()));

	buffer_size_combo.set_sensitive (true);
	sample_rate_combo.set_sensitive (true);

	connect_disconnect_button.set_label (string_compose (_("Disconnect from %1"), backend->name()));

	started_at_least_once = true;
}

void
EngineControl::engine_stopped ()
{
	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
	assert (backend);

	buffer_size_combo.set_sensitive (false);
	connect_disconnect_button.set_label (string_compose (_("Connect to %1"), backend->name()));

	sample_rate_combo.set_sensitive (true);
	buffer_size_combo.set_sensitive (true);
}
	
void
EngineControl::connect_disconnect_click() 
{
	if (ARDOUR::AudioEngine::instance()->running()) {
		ARDOUR_UI::instance()->disconnect_from_engine ();
	} else {
		ARDOUR_UI::instance()->reconnect_to_engine ();
	}
}

void
EngineControl::calibrate_latency ()
{
	notebook.set_current_page (latency_tab);
}