From 66c5fe41ee937f2e8b85a4a655aa4d3e6e6fee5b Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Thu, 20 Jul 2017 17:53:56 -0400
Subject: [PATCH] framework for silent-roll-while-slave-syncing

---
 libs/ardour/ardour/disk_reader.h |  3 +++
 libs/ardour/disk_reader.cc       | 18 ++++++++++++--
 libs/ardour/session_process.cc   | 42 ++++----------------------------
 3 files changed, 24 insertions(+), 39 deletions(-)

diff --git a/libs/ardour/ardour/disk_reader.h b/libs/ardour/ardour/disk_reader.h
index faeeaf1f52..c07dbab585 100644
--- a/libs/ardour/ardour/disk_reader.h
+++ b/libs/ardour/ardour/disk_reader.h
@@ -99,6 +99,8 @@ class LIBARDOUR_API DiskReader : public DiskIOProcessor
 
 	static void set_midi_readahead_frames (framecnt_t frames_ahead) { midi_readahead = frames_ahead; }
 
+	static void set_no_disk_output (bool yn);
+
   protected:
 	friend class Track;
 	friend class MidiTrack;
@@ -126,6 +128,7 @@ class LIBARDOUR_API DiskReader : public DiskIOProcessor
 
 	static framecnt_t _chunk_frames;
 	static framecnt_t midi_readahead;
+	static bool       no_disk_output;
 
 	/* The MIDI stuff */
 
diff --git a/libs/ardour/disk_reader.cc b/libs/ardour/disk_reader.cc
index 918761e537..c7221ad90f 100644
--- a/libs/ardour/disk_reader.cc
+++ b/libs/ardour/disk_reader.cc
@@ -44,6 +44,7 @@ PBD::Signal0<void> DiskReader::Underrun;
 Sample* DiskReader::_mixdown_buffer = 0;
 gain_t* DiskReader::_gain_buffer = 0;
 framecnt_t DiskReader::midi_readahead = 4096;
+bool DiskReader::no_disk_output = false;
 
 DiskReader::DiskReader (Session& s, string const & str, DiskIOProcessor::Flag f)
 	: DiskIOProcessor (s, str, f)
@@ -289,7 +290,7 @@ DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
 			}
 		}
 
-		/* if monitoring disk but locating, put silence in the buffers */
+		/* if monitoring disk but locating put silence in the buffers */
 
 		if (still_locating && (ms == MonitoringDisk)) {
 			bufs.silence (playback_distance, 0);
@@ -380,7 +381,7 @@ DiskReader::run (BufferSet& bufs, framepos_t start_frame, framepos_t end_frame,
 
 			chaninfo->buf->increment_read_ptr (playback_distance);
 
-			if ((speed != 0.0) && (ms & MonitoringInput)) {
+			if (!no_disk_output && (speed != 0.0) && (ms & MonitoringInput)) {
 				/* mix the disk signal into the input signal (already in bufs) */
 				mix_buffers_no_gain (output.data(), disk_signal, speed == 0.0 ? nframes : playback_distance);
 			}
@@ -1465,3 +1466,16 @@ DiskReader::refill_midi ()
 
 	return ret;
 }
+
+void
+DiskReader::set_no_disk_output (bool yn)
+{
+	/* this MUST be called as part of the process call tree, before any
+	   disk readers are invoked. We use it when the session needs the
+	   transport (and thus effective read position for DiskReaders) to keep
+	   advancing as part of syncing up with a transport master, but we
+	   don't want any actual disk output yet because we are still not
+	   synced.
+	*/
+	no_disk_output = yn;
+}
diff --git a/libs/ardour/session_process.cc b/libs/ardour/session_process.cc
index 19a6b64720..9229372b43 100644
--- a/libs/ardour/session_process.cc
+++ b/libs/ardour/session_process.cc
@@ -32,6 +32,7 @@
 #include "ardour/butler.h"
 #include "ardour/cycle_timer.h"
 #include "ardour/debug.h"
+#include "ardour/disk_reader.h"
 #include "ardour/graph.h"
 #include "ardour/port.h"
 #include "ardour/process_thread.h"
@@ -235,43 +236,10 @@ Session::process_routes (pframes_t nframes, bool& need_butler)
 int
 Session::silent_process_routes (pframes_t nframes, bool& need_butler)
 {
-	boost::shared_ptr<RouteList> r = routes.reader ();
-
-	const framepos_t start_frame = _transport_frame;
-	const framepos_t end_frame = _transport_frame + lrintf(nframes * _transport_speed);
-
-	VCAList v = _vca_manager->vcas ();
-	for (VCAList::const_iterator i = v.begin(); i != v.end(); ++i) {
-		(*i)->automation_run (start_frame, nframes);
-	}
-
-	_global_locate_pending = locate_pending();
-
-	if (_process_graph) {
-		_process_graph->silent_process_routes (nframes, start_frame, end_frame, need_butler);
-	} else {
-		for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
-
-			int ret;
-
-			if ((*i)->is_auditioner()) {
-				continue;
-			}
-
-			bool b = false;
-
-			if ((ret = (*i)->silent_roll (nframes, start_frame, end_frame, b)) < 0) {
-				stop_transport ();
-				return -1;
-			}
-
-			if (b) {
-				need_butler = true;
-			}
-		}
-	}
-
-	return 0;
+	DiskReader::set_no_disk_output (true);
+	int ret = process_routes (nframes, need_butler);
+	DiskReader::set_no_disk_output (false);
+	return ret;
 }
 
 void
-- 
2.30.2