8 files changed, 8 insertions, 8 deletions
diff --git a/drumgizmo/output/alsa.cc b/drumgizmo/output/alsa.cc
index 3686656..66a78c0 100644
--- a/drumgizmo/output/alsa.cc
+++ b/drumgizmo/output/alsa.cc
@@ -71,7 +71,7 @@ AlsaOutputEngine::~AlsaOutputEngine()
 	}
 }
 
-bool AlsaOutputEngine::init(Channels channels)
+bool AlsaOutputEngine::init(const Channels& channels)
 {
 	// try to initialize alsa
 	try
diff --git a/drumgizmo/output/alsa.h b/drumgizmo/output/alsa.h
index 4973f0b..a769c54 100644
--- a/drumgizmo/output/alsa.h
+++ b/drumgizmo/output/alsa.h
@@ -42,7 +42,7 @@ public:
 	~AlsaOutputEngine();
 
 	// based on AudioOutputEngine
-	bool init(Channels chan) override;
+	bool init(const Channels& chan) override;
 	void setParm(const std::string& parm, const std::string& value) override;
 	bool start() override;
 	void stop() override;
diff --git a/drumgizmo/output/jackaudio.cc b/drumgizmo/output/jackaudio.cc
index 9f68edd..52e1d41 100644
--- a/drumgizmo/output/jackaudio.cc
+++ b/drumgizmo/output/jackaudio.cc
@@ -43,7 +43,7 @@ JackAudioOutputEngine::~JackAudioOutputEngine()
 	client.remove(*this);
 }
 
-bool JackAudioOutputEngine::init(Channels data)
+bool JackAudioOutputEngine::init(const Channels& data)
 {
 	channels.clear();
 	channels.reserve(data.size());
diff --git a/drumgizmo/output/jackaudio.h b/drumgizmo/output/jackaudio.h
index 24348f6..b71ff8e 100644
--- a/drumgizmo/output/jackaudio.h
+++ b/drumgizmo/output/jackaudio.h
@@ -40,7 +40,7 @@ public:
 	~JackAudioOutputEngine();
 
 	// based on AudioOutputEngine
-	bool init(Channels chan) override;
+	bool init(const Channels& chan) override;
 	void setParm(const std::string& parm, const std::string& value) override;
 	bool start() override;
 	void stop() override;
diff --git a/drumgizmo/output/outputdummy.cc b/drumgizmo/output/outputdummy.cc
index 5899ead..4ff0816 100644
--- a/drumgizmo/output/outputdummy.cc
+++ b/drumgizmo/output/outputdummy.cc
@@ -34,7 +34,7 @@ DummyOutputEngine::~DummyOutputEngine()
 {
 }
 
-bool DummyOutputEngine::init(Channels data)
+bool DummyOutputEngine::init(const Channels& data)
 {
 	return true;
 }
diff --git a/drumgizmo/output/outputdummy.h b/drumgizmo/output/outputdummy.h
index caa9e5f..5a1b2fa 100644
--- a/drumgizmo/output/outputdummy.h
+++ b/drumgizmo/output/outputdummy.h
@@ -35,7 +35,7 @@ public:
 	~DummyOutputEngine();
 
 	// based on AudioOutputEngine
-	bool init(Channels chan) override;
+	bool init(const Channels& chan) override;
 	void setParm(const std::string& parm, const std::string& value) override;
 	bool start() override;
 	void stop() override;
diff --git a/drumgizmo/output/wavfile.cc b/drumgizmo/output/wavfile.cc
index e81fb2d..78f7899 100644
--- a/drumgizmo/output/wavfile.cc
+++ b/drumgizmo/output/wavfile.cc
@@ -50,7 +50,7 @@ WavfileOutputEngine::~WavfileOutputEngine()
 	}
 }
 
-bool WavfileOutputEngine::init(Channels data)
+bool WavfileOutputEngine::init(const Channels& data)
 {
 	channels.clear();
 	channels.resize(data.size()); // value-initialized with null
diff --git a/drumgizmo/output/wavfile.h b/drumgizmo/output/wavfile.h
index 331733b..a0019d3 100644
--- a/drumgizmo/output/wavfile.h
+++ b/drumgizmo/output/wavfile.h
@@ -40,7 +40,7 @@ public:
 	~WavfileOutputEngine();
 
 	// based on AudioOutputEngine
-	bool init(Channels data) override;
+	bool init(const Channels& data) override;
 	void setParm(const std::string& parm, const std::string& value) override;
 	bool start() override;
 	void stop() override;