From 308d138144dcc3b62646da4f5cd428da5f89b771 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Tue, 7 Jul 2020 04:45:56 +0200
Subject: [PATCH] Fix audible blibs due to inconsistent monitor state -- #8275

It is possible that Route::monitoring_state() returns
  (MonitoringDisk | MonitorSilence)

This lead to various cases where there were is a direct comparison
(ms == MonitoringDisk). DiskReader::run tests for MonitoringDisk
to check if the buffer needs to be zeroed while locating.

Likewise Route::process_output_buffers() also explicitly tests
for both MonitoringDisk and MonitoringDisk.

The issue was likely introduced in fbe80751173ce7 (although
it may have been possible in earlier version when using hardware
monitoring as well).
---
 libs/ardour/ardour/types.h | 2 +-
 libs/ardour/route.cc       | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/libs/ardour/ardour/types.h b/libs/ardour/ardour/types.h
index f8910715a0..06e06d0196 100644
--- a/libs/ardour/ardour/types.h
+++ b/libs/ardour/ardour/types.h
@@ -463,7 +463,7 @@ enum MonitorChoice {
 };
 
 enum MonitorState {
-	MonitoringSilence = 0x1,
+	MonitoringSilence = 0x0,
 	MonitoringInput = 0x2,
 	MonitoringDisk = 0x4,
 	MonitoringCue = 0x6,
diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index 3eac521d7e..cebed69f82 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -6152,10 +6152,10 @@ Route::monitoring_state () const
 
 	if (m != MonitorAuto) {
 
-		MonitorState ms ((MonitorState) 0);
+		MonitorState ms = MonitoringSilence;
 
 		if (m & MonitorInput) {
-			ms = MonitoringInput;
+			ms = MonitorState (ms | MonitoringInput);
 		}
 
 		if (m & MonitorDisk) {