From 33af0b0d3daabbbefdc8c09bf8f19b821b2fc137 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Thu, 26 Oct 2017 15:15:05 -0400
Subject: [PATCH] optimization for track with zero audio channels should not
 short-circuit MIDI disk reading

---
 libs/ardour/disk_reader.cc | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/libs/ardour/disk_reader.cc b/libs/ardour/disk_reader.cc
index 98643f8ebd..dd6c3ee09d 100644
--- a/libs/ardour/disk_reader.cc
+++ b/libs/ardour/disk_reader.cc
@@ -251,11 +251,6 @@ DiskReader::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_samp
 		}
 	}
 
-	if (c->empty()) {
-		/* do nothing */
-		return;
-	}
-
 	if ((speed == 0.0) && (ms == MonitoringDisk)) {
 		/* no channels, or stopped. Don't accidentally pass any data
 		 * from disk into our outputs (e.g. via interpolation)
@@ -263,6 +258,14 @@ DiskReader::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_samp
 		return;
 	}
 
+	BufferSet& scratch_bufs (_session.get_scratch_buffers (bufs.count()));
+	const bool still_locating = _session.global_locate_pending();
+
+	if (c->empty()) {
+		/* do nothing with audio */
+		goto midi;
+	}
+
 	if (speed != 1.0f && speed != -1.0f) {
 		interpolation.set_speed (speed);
 		disk_samples_to_consume = interpolation.distance (nframes);
@@ -273,8 +276,6 @@ DiskReader::run (BufferSet& bufs, samplepos_t start_sample, samplepos_t end_samp
 		disk_samples_to_consume = nframes;
 	}
 
-	BufferSet& scratch_bufs (_session.get_scratch_buffers (bufs.count()));
-	const bool still_locating = _session.global_locate_pending();
 
 	if (!result_required || ((ms & MonitoringDisk) == 0) || still_locating || _no_disk_output) {