Added "force mono" option to Music and SoundBuffer

Former-commit-id: 1f46d1461a8289a590a71e368f282a955d7d8234

include/Nazara/Audio/Algorithm.inl

@@ -0,0 +1,25 @@
+// Copyright (C) 2013 Jérôme Leclercq
+// This file is part of the "Nazara Engine - Audio module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Core/Error.hpp>
+#include <Nazara/Audio/Debug.hpp>
+
+template<typename T>
+void NzMixToMono(T* input, T* output, unsigned int channelCount, unsigned int frameCount)
+{
+	// Pour éviter l'overflow, on utilise comme accumulateur un type assez grand, (u)int 64 bits pour les entiers, double pour les flottants
+	typedef typename std::conditional<std::is_unsigned<T>::value, nzUInt64, nzInt64>::type BiggestInt;
+    typedef typename std::conditional<std::is_integral<T>::value, BiggestInt, double>::type Biggest;
+
+	for (unsigned int i = 0; i < frameCount; ++i)
+	{
+		Biggest acc = Biggest(0);
+		for (unsigned int j = 0; j < channelCount; ++j)
+			acc += input[i*channelCount + j];
+
+		output[i] = acc/channelCount;
+	}
+}
+
+#include <Nazara/Audio/DebugOff.hpp>