Move SimpleExport to libardour, add Lua bindings

This allows to export a session from the commandline tool

```Lua
AudioEngine:set_backend("None (Dummy)", "", "")
s = load_session ("/path/to/session", "snapshot")
assert (s);
e = s:simple_export()
assert (e:check_outputs ())
e:run_export ()
e = nil
```

libs/ardour/ardour/lua_api.h

@@ -256,6 +256,11 @@ namespace ARDOUR { namespace LuaAPI {
 	 */
 	int timecode_to_sample_lua (lua_State *L);
 
+	/** create a \ref SimpleExport Object
+	 * for the current session
+	 */
+	int simple_export (lua_State* L);
+
 	/**
 	 * Delay execution until next prcess cycle starts.
 	 * @param n_cycles process-cycles to wait for.

libs/ardour/ardour/simple_export.h

@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2022 Robin Gareus <robin@gareus.org>
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _ardour_simple_export_h_
+#define _ardour_simple_export_h_
+
+#include "ardour/libardour_visibility.h"
+#include "ardour/session_handle.h"
+#include "ardour/types.h"
+
+namespace ARDOUR
+{
+class ExportHandler;
+class ExportStatus;
+class ExportProfileManager;
+
+/** Base class for audio export
+ *
+ * This allows one to export audio from the session's
+ * master bus using a given export-preset.
+ */
+class LIBARDOUR_API SimpleExport : public ARDOUR::SessionHandlePtr
+{
+public:
+	SimpleExport ();
+	virtual ~SimpleExport () {}
+
+	void set_session (ARDOUR::Session*);
+	bool run_export ();
+
+	void set_name (std::string const&);
+	void set_folder (std::string const&);
+	void set_range (samplepos_t, samplepos_t);
+	bool set_preset (std::string const&);
+
+	std::string preset_uuid () const;
+	std::string folder () const;
+	bool        check_outputs () const;
+
+protected:
+	boost::shared_ptr<ARDOUR::ExportHandler>        _handler;
+	boost::shared_ptr<ARDOUR::ExportStatus>         _status;
+	boost::shared_ptr<ARDOUR::ExportProfileManager> _manager;
+
+private:
+	std::string _name;
+	std::string _folder;
+	std::string _pset_id;
+	samplepos_t _start;
+	samplepos_t _end;
+};
+
+}
+
+#endif

libs/ardour/lua_api.cc

@@ -37,6 +37,7 @@
 #include "ardour/plugin_manager.h"
 #include "ardour/readable.h"
 #include "ardour/region_factory.h"
+#include "ardour/simple_export.h"
 #include "ardour/source_factory.h"
 
 #include "LuaBridge/LuaBridge.h"
@@ -534,6 +535,16 @@ ARDOUR::LuaAPI::wait_for_process_callback (size_t n_cycles, int64_t timeout_ms)
 	return true;
 }
 
+int
+ARDOUR::LuaAPI::simple_export (lua_State* L)
+{
+	Session* const s = luabridge::Userdata::get <Session> (L, 1, false);
+	void* ptr = luabridge::UserdataValue<SimpleExport>::place (L);
+	SimpleExport* se = new (ptr) SimpleExport ();
+	se->set_session (s);
+	return 1;
+}
+
 void
 ARDOUR::LuaAPI::segfault ()
 {

libs/ardour/luabindings.cc

@@ -92,6 +92,7 @@
 #include "ardour/session_object.h"
 #include "ardour/session_playlists.h"
 #include "ardour/sidechain.h"
+#include "ardour/simple_export.h"
 #include "ardour/solo_isolate_control.h"
 #include "ardour/solo_safe_control.h"
 #include "ardour/stripable.h"
@@ -1707,6 +1708,15 @@ LuaBindings::common (lua_State* L)
 		.addStaticFunction ("force_zero_latency", &Latent::force_zero_latency)
 		.endClass ()
 
+		.beginClass <SimpleExport> ("SimpleExport")
+		.addFunction ("run_export", &SimpleExport::run_export)
+		.addFunction ("set_name", &SimpleExport::set_name)
+		.addFunction ("set_folder", &SimpleExport::set_folder)
+		.addFunction ("set_range", &SimpleExport::set_range)
+		.addFunction ("set_preset", &SimpleExport::set_preset)
+		.addFunction ("check_outputs", &SimpleExport::check_outputs)
+		.endClass ()
+
 		.deriveWSPtrClass <Automatable, Evoral::ControlSet> ("Automatable")
 		.addCast<Slavable> ("to_slavable")
 		.addFunction ("automation_control", (boost::shared_ptr<AutomationControl>(Automatable::*)(const Evoral::Parameter&, bool))&Automatable::automation_control)
@@ -2878,6 +2888,7 @@ LuaBindings::common (lua_State* L)
 		.addFunction ("vca_manager", &Session::vca_manager_ptr)
 		.addExtCFunction ("timecode_to_sample_lua", ARDOUR::LuaAPI::timecode_to_sample_lua)
 		.addExtCFunction ("sample_to_timecode_lua", ARDOUR::LuaAPI::sample_to_timecode_lua)
+		.addExtCFunction ("simple_export", &ARDOUR::LuaAPI::simple_export)
 		.endClass ()
 
 		.beginClass <RegionFactory> ("RegionFactory")

libs/ardour/simple_export.cc

@@ -0,0 +1,214 @@
+/*
+ * Copyright (C) 2022 Robin Gareus <robin@gareus.org>
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <glibmm.h>
+
+#include "ardour/export_channel_configuration.h"
+#include "ardour/export_filename.h"
+#include "ardour/export_preset.h"
+#include "ardour/export_profile_manager.h"
+#include "ardour/export_status.h"
+#include "ardour/export_timespan.h"
+#include "ardour/profile.h"
+#include "ardour/session_directory.h"
+#include "ardour/simple_export.h"
+
+#include "pbd/i18n.h"
+
+using namespace std;
+using namespace ARDOUR;
+using namespace PBD;
+
+SimpleExport::SimpleExport ()
+	: _pset_id ("df340c53-88b5-4342-a1c8-58e0704872ea" /* CD */)
+	, _start (0)
+	, _end (0)
+{
+}
+
+void
+SimpleExport::set_session (ARDOUR::Session* s)
+{
+	SessionHandlePtr::set_session (s);
+	if (!s) {
+		_manager.reset ();
+		return;
+	}
+
+	_handler = _session->get_export_handler ();
+	_status  = _session->get_export_status ();
+
+	/* create manager, by default it is preconfigured to
+	 * - one Timespan (session-range, if set, otherwise empty)
+	 * - one ChannelConfig (master-bus, IFF the session as a master)
+	 */
+	_manager.reset (new ExportProfileManager (*_session, ExportProfileManager::RangeExport));
+
+	/* set formats(s) and export-filename */
+	set_preset (_pset_id);
+}
+
+void
+SimpleExport::set_name (std::string const& name)
+{
+	_name = name;
+}
+
+void
+SimpleExport::set_folder (std::string const& folder)
+{
+	_folder = folder;
+	if (!_folder.empty ()) {
+		g_mkdir_with_parents (_folder.c_str (), 0755);
+	}
+}
+
+void
+SimpleExport::set_range (samplepos_t start, samplepos_t end)
+{
+	_start = start;
+	_end   = end;
+}
+
+bool
+SimpleExport::set_preset (std::string const& pset_uuid)
+{
+	if (!_manager) {
+		return false;
+	}
+
+	ExportProfileManager::PresetList const& psets (_manager->get_presets ());
+	assert (psets.size () > 0);
+	bool rv = false;
+
+	ExportPresetPtr epp = psets.front ();
+	for (auto const& pset : psets) {
+		if (pset->id ().to_s () == pset_uuid) {
+			epp = pset;
+			rv  = true;
+			break;
+		}
+	}
+
+	_pset_id = epp->id ().to_s ();
+	/* Load preset(s) - this sets formats(s) and export-filename */
+	_manager->load_preset (epp);
+	return rv;
+}
+
+std::string
+SimpleExport::preset_uuid () const
+{
+	if (!_manager) {
+		return _pset_id;
+	}
+	return _manager->preset ()->id ().to_s ();
+}
+
+std::string
+SimpleExport::folder () const
+{
+	return _folder;
+}
+
+bool
+SimpleExport::check_outputs () const
+{
+	if (!_manager) {
+		return false;
+	}
+	/* check that master-bus was added */
+	auto cc (_manager->get_channel_configs ());
+	assert (cc.size () == 1);
+	if (cc.front ()->config->get_n_chans () == 0) {
+		return false;
+	}
+	return true;
+}
+
+bool
+SimpleExport::run_export ()
+{
+	if (!_session || !check_outputs ()) {
+		return false;
+	}
+
+	if (_name.empty ()) {
+		_name = _session->snap_name ();
+	}
+
+	if (_folder.empty ()) {
+		_folder = _session->session_directory ().export_path ();
+	}
+
+	Location* srl;
+	if (_start != _end) {
+		; // range already set
+	} else if (NULL != (srl = _session->locations ()->session_range_location ())) {
+		_start = srl->start_sample ();
+		_end   = srl->end_sample ();
+	}
+
+	if (_start >= _end) {
+		return false;
+	}
+
+	/* Setup timespan */
+	auto ts = _manager->get_timespans ();
+	assert (ts.size () == 1);
+	assert (ts.front ()->timespans->size () == 1);
+
+	ts.front ()->timespans->front ()->set_name (_name);
+	ts.front ()->timespans->front ()->set_realtime (false);
+	ts.front ()->timespans->front ()->set_range (_start, _end);
+
+	/* Now update filename(s) for each format */
+	auto fns = _manager->get_filenames ();
+	assert (!fns.empty ());
+
+	auto fms = _manager->get_formats ();
+	for (auto const& fm : fms) {
+		for (auto const& fn : fns) {
+			fn->filename->set_folder (_folder);
+			fn->filename->set_timespan (ts.front ()->timespans->front ());
+			info << string_compose (_("Exporting: '%1'"), fn->filename->get_path (fm->format)) << endmsg;
+		}
+	}
+
+	/* All done, configure the handler */
+	_manager->prepare_for_export ();
+
+	try {
+		if (0 != _handler->do_export ()) {
+			return false;
+		}
+	} catch (std::exception& e) {
+		error << string_compose (_("Export initialization failed: %1"), e.what ()) << endmsg;
+		return false;
+	}
+
+	while (_status->running ()) {
+		GUIIdle ();
+		// TODO only sleep if GUI did not process any events
+		Glib::usleep (10000);
+	}
+
+	_status->finish (TRS_UI);
+
+	return !_status->aborted ();
+}

libs/ardour/wscript

@@ -240,6 +240,7 @@ libardour_sources = [
         'session_time.cc',
         'session_transport.cc',
         'sidechain.cc',
+        'simple_export.cc',
         'slavable.cc',
         'slavable_automation_control.cc',
         'smf_source.cc',