From 604fc35e167e139cbb1f6fb8130ce4fa778af4a0 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Thu, 17 Oct 2019 17:34:00 -0600
Subject: [PATCH] clear RTMidiBuffer before re-rendering into it

---
 libs/ardour/midi_playlist.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libs/ardour/midi_playlist.cc b/libs/ardour/midi_playlist.cc
index ae9c0bbf13..5b66a0fe0d 100644
--- a/libs/ardour/midi_playlist.cc
+++ b/libs/ardour/midi_playlist.cc
@@ -500,6 +500,7 @@ MidiPlaylist::render (RTMidiBuffer& dst, MidiChannelFilter* filter)
 	if (regs.size() == 1) {
 		tgt = &dst;
 		wpr.acquire ();
+		dst.clear ();
 	} else {
 		tgt = &evlist;
 	}
@@ -526,6 +527,7 @@ MidiPlaylist::render (RTMidiBuffer& dst, MidiChannelFilter* filter)
 		/* Copy ordered events from event list to dst. */
 
 		wpr.acquire ();
+		dst.clear ();
 
 		for (Evoral::EventList<samplepos_t>::iterator e = evlist.begin(); e != evlist.end(); ++e) {
 			Evoral::Event<samplepos_t>* ev (*e);