refactoring to prepare for real-time export

* add a threaded TmpFile Writer
* update API calls to that process_export_fw() can be used as
  process_function

The idea is to re-use export infrastructure from normalization:
export to a tmp-file and then encode target formats after that.

6 files changed, 59 insertions, 28 deletions

diff --git a/libs/ardour/ardour/audioengine.h b/libs/ardour/ardour/audioengine.h
index 7bb7aa3a4d..cb5b82d058 100644
--- a/libs/ardour/ardour/audioengine.h
+++ b/libs/ardour/ardour/audioengine.h
@@ -161,7 +161,7 @@ class LIBARDOUR_API AudioEngine : public PortManager, public SessionHandlePtr
 	   (the regular process() call to session->process() is not made)
 	*/
 
-	PBD::Signal1<int, pframes_t> Freewheel;
+	PBD::Signal1<void, pframes_t> Freewheel;
 
 	PBD::Signal0<void> Xrun;
 
diff --git a/libs/ardour/ardour/export_graph_builder.h b/libs/ardour/ardour/export_graph_builder.h
index df02c9eb57..68eb927513 100644
--- a/libs/ardour/ardour/export_graph_builder.h
+++ b/libs/ardour/ardour/export_graph_builder.h
@@ -41,6 +41,7 @@ namespace AudioGrapher {
 	template <typename T> class SndfileWriter;
 	template <typename T> class SilenceTrimmer;
 	template <typename T> class TmpFile;
+	template <typename T> class TmpFileRt;
 	template <typename T> class Threader;
 	template <typename T> class AllocatingProcessContext;
 }
@@ -164,6 +165,7 @@ class LIBARDOUR_API ExportGraphBuilder
 		typedef boost::shared_ptr<AudioGrapher::LoudnessReader> LoudnessReaderPtr;
 		typedef boost::shared_ptr<AudioGrapher::Normalizer> NormalizerPtr;
 		typedef boost::shared_ptr<AudioGrapher::TmpFile<Sample> > TmpFilePtr;
+		typedef boost::shared_ptr<AudioGrapher::TmpFileRt<Sample> > TmpFileRtPtr;
 		typedef boost::shared_ptr<AudioGrapher::Threader<Sample> > ThreaderPtr;
 		typedef boost::shared_ptr<AudioGrapher::AllocatingProcessContext<Sample> > BufferPtr;
 
diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index c6f32bbe07..db80ddcae3 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -704,7 +704,7 @@ class LIBARDOUR_API Session : public PBD::StatefulDestructible, public PBD::Scop
 	boost::shared_ptr<ExportHandler> get_export_handler ();
 	boost::shared_ptr<ExportStatus> get_export_status ();
 
-	int start_audio_export (framepos_t position);
+	int start_audio_export (framepos_t position, bool realtime = false);
 
 	PBD::Signal1<int, framecnt_t> ProcessExport;
 	static PBD::Signal2<void,std::string, std::string> Exported;
@@ -1230,8 +1230,8 @@ class LIBARDOUR_API Session : public PBD::StatefulDestructible, public PBD::Scop
 	void process_without_events (pframes_t);
 	void process_with_events    (pframes_t);
 	void process_audition       (pframes_t);
-	int  process_export         (pframes_t);
-	int  process_export_fw      (pframes_t);
+	void process_export         (pframes_t);
+	void process_export_fw      (pframes_t);
 
 	void block_processing() { g_atomic_int_set (&processing_prohibited, 1); }
 	void unblock_processing() { g_atomic_int_set (&processing_prohibited, 0); }
@@ -1268,6 +1268,7 @@ class LIBARDOUR_API Session : public PBD::StatefulDestructible, public PBD::Scop
 
 	bool _exporting;
 	bool _export_rolling;
+	bool _realtime_export;
 	framepos_t _export_preroll;
 	framepos_t _export_latency;
 
diff --git a/libs/ardour/export_graph_builder.cc b/libs/ardour/export_graph_builder.cc
index 27b2f6948e..49b40a6736 100644
--- a/libs/ardour/export_graph_builder.cc
+++ b/libs/ardour/export_graph_builder.cc
@@ -36,6 +36,7 @@
 #include "audiographer/general/silence_trimmer.h"
 #include "audiographer/general/threader.h"
 #include "audiographer/sndfile/tmp_file.h"
+#include "audiographer/sndfile/tmp_file_rt.h"
 #include "audiographer/sndfile/sndfile_writer.h"
 
 #include "ardour/audioengine.h"
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 67f43dc470..9ab82c7106 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -213,6 +213,7 @@ Session::Session (AudioEngine &eng,
 	, post_export_position (0)
 	, _exporting (false)
 	, _export_rolling (false)
+	, _realtime_export (false)
 	, _export_preroll (0)
 	, _export_latency (0)
 	, _pre_export_mmc_enabled (false)
diff --git a/libs/ardour/session_export.cc b/libs/ardour/session_export.cc
index 1dee1f8d3c..84342fa3d9 100644
--- a/libs/ardour/session_export.cc
+++ b/libs/ardour/session_export.cc
@@ -104,13 +104,20 @@ Session::pre_export ()
 
 /** Called for each range that is being exported */
 int
-Session::start_audio_export (framepos_t position)
+Session::start_audio_export (framepos_t position, bool realtime)
 {
 	if (!_exporting) {
 		pre_export ();
 	}
 
-	_export_preroll = Config->get_export_preroll() * nominal_frame_rate ();
+	_realtime_export = realtime;
+
+	if (realtime) {
+		_export_preroll = nominal_frame_rate ();
+	} else {
+		_export_preroll = Config->get_export_preroll() * nominal_frame_rate ();
+	}
+
 	if (_export_preroll == 0) {
 		// must be > 0 so that transport is started in sync.
 		_export_preroll = 1;
@@ -170,12 +177,19 @@ Session::start_audio_export (framepos_t position)
 		return -1;
 	}
 
-	_engine.Freewheel.connect_same_thread (export_freewheel_connection, boost::bind (&Session::process_export_fw, this, _1));
-	_export_rolling = true;
-	return _engine.freewheel (true);
+	if (_realtime_export) {
+		Glib::Threads::Mutex::Lock lm (AudioEngine::instance()->process_lock ());
+		_export_rolling = true;
+		process_function = &Session::process_export_fw;
+		return 0;
+	} else {
+		_engine.Freewheel.connect_same_thread (export_freewheel_connection, boost::bind (&Session::process_export_fw, this, _1));
+		_export_rolling = true;
+		return _engine.freewheel (true);
+	}
 }
 
-int
+void
 Session::process_export (pframes_t nframes)
 {
 	if (_export_rolling && export_status->stop) {
@@ -201,26 +215,27 @@ Session::process_export (pframes_t nframes)
 	} catch (std::exception & e) {
 		error << string_compose (_("Export ended unexpectedly: %1"), e.what()) << endmsg;
 		export_status->abort (true);
-		return -1;
 	}
-
-	return 0;
 }
 
-int
+void
 Session::process_export_fw (pframes_t nframes)
 {
 	if (_export_preroll > 0) {
 
-		_engine.main_thread()->get_buffers ();
+		if (!_realtime_export) {
+			_engine.main_thread()->get_buffers ();
+		}
 		fail_roll (nframes);
-		_engine.main_thread()->drop_buffers ();
+		if (!_realtime_export) {
+			_engine.main_thread()->drop_buffers ();
+		}
 
 		_export_preroll -= std::min ((framepos_t)nframes, _export_preroll);
 
 		if (_export_preroll > 0) {
 			// clear out buffers (reverb tails etc).
-			return 0;
+			return;
 		}
 
 		set_transport_speed (1.0, 0, false);
@@ -228,29 +243,36 @@ Session::process_export_fw (pframes_t nframes)
 		g_atomic_int_set (&_butler->should_do_transport_work, 0);
 		post_transport ();
 
-		return 0;
+		return;
 	}
 
 	if (_export_latency > 0) {
 		framepos_t remain = std::min ((framepos_t)nframes, _export_latency);
 
-		_engine.main_thread()->get_buffers ();
+		if (!_realtime_export) {
+			_engine.main_thread()->get_buffers ();
+		}
 		process_without_events (remain);
-		_engine.main_thread()->drop_buffers ();
+		if (!_realtime_export) {
+			_engine.main_thread()->drop_buffers ();
+		}
 
 		_export_latency -= remain;
 		nframes -= remain;
 
 		if (nframes == 0) {
-			return 0;
+			return;
 		}
 	}
-
-	_engine.main_thread()->get_buffers ();
+	if (!_realtime_export) {
+		_engine.main_thread()->get_buffers ();
+	}
 	process_export (nframes);
-	_engine.main_thread()->drop_buffers ();
+	if (!_realtime_export) {
+		_engine.main_thread()->drop_buffers ();
+	}
 
-	return 0;
+	return;
 }
 
 int
@@ -279,9 +301,13 @@ Session::finalize_audio_export ()
 
 	/* Clean up */
 
-	_engine.freewheel (false);
-
-	export_freewheel_connection.disconnect();
+	if (_realtime_export) {
+		Glib::Threads::Mutex::Lock lm (AudioEngine::instance()->process_lock ());
+		process_function = &Session::process_with_events;
+	} else {
+		_engine.freewheel (false);
+		export_freewheel_connection.disconnect();
+	}
 
 	_mmc->enable_send (_pre_export_mmc_enabled);