From 697d29cdc2a59c698d2771f1dbec9a726a123843 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Sat, 30 Sep 2017 13:10:17 +0200
Subject: Fix thinko in 8139becb -- route split cycle

Individual Routes cannot split the process-cycle in no_roll(); roll()
by themselves. Each of the calls will flush output buffers (and offset
port-buffers). If a route feeds another route the inputs of the other
route will only see partial data.
---
 libs/ardour/route.cc           | 31 +++----------------------------
 libs/ardour/session_process.cc | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 28 deletions(-)

(limited to 'libs/ardour')

diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index 0aa69e91ec..f411631e9e 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -383,6 +383,8 @@ Route::process_output_buffers (BufferSet& bufs,
 	 */
 	bool run_disk_writer = false;
 	if (_disk_writer && speed != 0) {
+		samplecnt_t latency_preroll = _session.remaining_latency_preroll ();
+		run_disk_writer = latency_preroll < nframes + (_signal_latency + _output->latency ());
 		if (end_sample - _disk_writer->input_latency () < _session.transport_sample ()) {
 			run_disk_writer = true;
 		}
@@ -3728,38 +3730,11 @@ Route::latency_preroll (pframes_t nframes, samplepos_t& start_sample, samplepos_
 		return nframes;
 	}
 
-	samplecnt_t route_offset = playback_latency ();
-
-	if (latency_preroll > route_offset + nframes) {
+	if (latency_preroll > playback_latency ()) {
 		no_roll_unlocked (nframes, start_sample - latency_preroll, end_sample - latency_preroll);
 		return 0;
 	}
 
-	if (latency_preroll > route_offset) {
-
-		samplecnt_t skip = latency_preroll - route_offset;
-		no_roll_unlocked (skip, start_sample - latency_preroll, start_sample - latency_preroll + skip);
-
-		if (nframes == skip) {
-			return 0;
-		}
-
-		Glib::Threads::RWLock::ReaderLock lm (_processor_lock);
-		for (ProcessorList::iterator i = _processors.begin(); i != _processors.end(); ++i) {
-			boost::shared_ptr<IOProcessor> iop = boost::dynamic_pointer_cast<IOProcessor> (*i);
-			if (iop) {
-				iop->increment_port_buffer_offset (skip);
-			}
-		}
-		_input->increment_port_buffer_offset (skip);
-		_output->increment_port_buffer_offset (skip);
-
-		start_sample -= route_offset;
-		end_sample -= route_offset;
-
-		return nframes - skip;
-	}
-
 	start_sample -= latency_preroll;
 	end_sample -= latency_preroll;
 	return nframes;
diff --git a/libs/ardour/session_process.cc b/libs/ardour/session_process.cc
index a7db77c716..32c8f99734 100644
--- a/libs/ardour/session_process.cc
+++ b/libs/ardour/session_process.cc
@@ -311,6 +311,22 @@ 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));
+			}
+		}
+
 		if (_count_in_samples > 0) {
 			run_click (_transport_sample - _count_in_samples, ns);
 			assert (_count_in_samples >= ns);
-- 
cgit v1.2.3