From 776d8590f92e2f3774e1283f3b9be44e58263ef8 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Sun, 20 Aug 2023 09:18:25 -0600
Subject: [PATCH] fix crash when opening a session created before the
 midnam-channel GUI property existed

---
 gtk2_ardour/piano_roll_header.cc | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/gtk2_ardour/piano_roll_header.cc b/gtk2_ardour/piano_roll_header.cc
index 70629e1e4b..4a72fbccfe 100644
--- a/gtk2_ardour/piano_roll_header.cc
+++ b/gtk2_ardour/piano_roll_header.cc
@@ -471,16 +471,20 @@ PianoRollHeader::get_note_name (int note)
 
 	if (mtv) {
 		string chn = mtv->gui_property (X_("midnam-channel"));
-		int midnam_channel;
 
-		sscanf (chn.c_str(), "%*s %d", &midnam_channel);
-		midnam_channel--;
+		if (!chn.empty()) {
 
-		name = mtv->route()->instrument_info ().get_note_name (
-			0,               //bank
-			0,               //program
-			midnam_channel,  //channel
-			note);           //note
+			int midnam_channel;
+
+			sscanf (chn.c_str(), "%*s %d", &midnam_channel);
+			midnam_channel--;
+
+			name = mtv->route()->instrument_info ().get_note_name (
+				0,               //bank
+				0,               //program
+				midnam_channel,  //channel
+				note);           //note
+		}
 	}
 
 	int oct_rel = note % 12;