From 1f6686c2a0c8ecd5bdf7ae74c3f4775811197033 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Thu, 5 Mar 2020 20:47:19 +0100
Subject: Separate pre-roll cycle calculation

This is also needed when exporting.
---
 libs/ardour/ardour/session.h   |  2 ++
 libs/ardour/session_process.cc | 38 +++++++++++++++++++++++---------------
 2 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 1ed5413206..63dd516d72 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -1345,6 +1345,8 @@ private:
 	void process_export         (pframes_t);
 	void process_export_fw      (pframes_t);
 
+	samplecnt_t calc_preroll_subcycle (samplecnt_t) const;
+
 	void block_processing() { g_atomic_int_set (&processing_prohibited, 1); }
 	void unblock_processing() { g_atomic_int_set (&processing_prohibited, 0); }
 	bool processing_blocked() const { return g_atomic_int_get (&processing_prohibited); }
diff --git a/libs/ardour/session_process.cc b/libs/ardour/session_process.cc
index fef23107ca..720f1a7129 100644
--- a/libs/ardour/session_process.cc
+++ b/libs/ardour/session_process.cc
@@ -303,6 +303,27 @@ Session::compute_audible_delta (samplepos_t& pos_and_delta) const
 	return true;
 }
 
+samplecnt_t
+Session::calc_preroll_subcycle (samplecnt_t ns) const
+{
+	boost::shared_ptr<RouteList> r = routes.reader ();
+	for (RouteList::const_iterator i = r->begin(); i != r->end(); ++i) {
+		samplecnt_t route_offset = (*i)->playback_latency ();
+		if (_remaining_latency_preroll > route_offset + ns) {
+			/* route will no-roll for complete pre-roll cycle */
+			continue;
+		}
+		if (_remaining_latency_preroll > route_offset) {
+			/* route may need partial no-roll and partial roll from
+			 * (_transport_sample - _remaining_latency_preroll) ..  +ns.
+			 * shorten and split the cycle.
+			 */
+			ns = std::min (ns, (_remaining_latency_preroll - route_offset));
+		}
+	}
+	return ns;
+}
+
 /** Process callback used when the auditioner is not active */
 void
 Session::process_with_events (pframes_t nframes)
@@ -358,21 +379,8 @@ Session::process_with_events (pframes_t nframes)
 			ns = std::min ((samplecnt_t)nframes, _count_in_samples);
 		}
 
-		boost::shared_ptr<RouteList> r = routes.reader ();
-		for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
-			samplecnt_t route_offset = (*i)->playback_latency ();
-			if (_remaining_latency_preroll > route_offset + ns) {
-				/* route will no-roll for complete pre-roll cycle */
-				continue;
-			}
-			if (_remaining_latency_preroll > route_offset) {
-				/* route may need partial no-roll and partial roll from
-				* (_transport_sample - _remaining_latency_preroll) ..  +ns.
-				* shorten and split the cycle.
-				*/
-				ns = std::min (ns, (_remaining_latency_preroll - route_offset));
-			}
-		}
+		/* process until next route in-point */
+		ns = calc_preroll_subcycle (ns);
 
 		if (_count_in_samples > 0) {
 			run_click (_transport_sample - _count_in_samples, ns);
-- 
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