Version 0.9

Added: Filter type "IIR", which allows to specify a user-defined IIR filter of arbitrary order with custom coefficients.
Improved: For playback devices, the APO is now installed both as GFX (post-mix) and LFX (pre-mix) APO. Normally the filtering happens in GFX, but the command "Stage" allows to select LFX to apply effects based on the number of input channels.
Added: Expression language. The commands "If", "ElseIf", "Else", "EndIf", "Eval" and inline expressions allow to change the filter behaviour based on runtime conditions.
Added: Command "Copy", which copies audio data between channels.
Added: Command "Delay", which delays the audio on the currently selected channels.
Improved: Configuration files are now locked exclusively for writing while reading them.
Improved: There is now a transition (10 ms) from old to new configuration after loading.
Improved: Substantial internal restructuring to improve extensibility and maintainability. Filtering commands now work exactly in the order they were specified.
Fixed: When the microphone input was in stereo but the application requested a mono stream, the audio was heavily distorted.
Fixed: The sine sweep generated by the Benchmark application had floating-point precision issues leading to severe artifacts when certain filters were applied.

filters/IncludeFilterFactory.cpp

@@ -0,0 +1,63 @@
+/*
+	This file is part of EqualizerAPO, a system-wide equalizer.
+	Copyright (C) 2014  Jonas Thedering
+
+	This program is free software; you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation; either version 2 of the License, or
+	(at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License along
+	with this program; if not, write to the Free Software Foundation, Inc.,
+	51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include <Shlwapi.h>
+
+#include "helpers/LogHelper.h"
+#include "helpers/StringHelper.h"
+#include "FilterEngine.h"
+#include "IncludeFilterFactory.h"
+
+using namespace std;
+
+void IncludeFilterFactory::initialize(FilterEngine* engine)
+{
+	this->engine = engine;
+}
+
+vector<IFilter*> IncludeFilterFactory::createFilter(const wstring& configPath, wstring& command, wstring& parameters)
+{
+	if(command == L"Include")
+	{
+		wstring value = parameters;
+		while(value.length() > 0 && iswspace(value[0]))
+			value = value.substr(1);
+
+		wstring includePath;
+		if(PathIsRelativeW(value.c_str()))
+		{
+			wchar_t filePath[MAX_PATH];
+			configPath._Copy_s(filePath, sizeof(filePath)/sizeof(wchar_t), MAX_PATH);
+			if(configPath.size() < MAX_PATH)
+				filePath[configPath.size()] = L'\0';
+			else
+				filePath[MAX_PATH - 1] = L'\0';
+			PathRemoveFileSpecW(filePath);
+			PathAppendW(filePath, value.c_str());
+			includePath = filePath;
+		}
+		else
+			includePath = value;
+
+		engine->loadConfig(includePath);
+		command = L"";
+	}
+
+	return vector<IFilter*>();
+}