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.

helpers/RegistryHelper.h

@@ -0,0 +1,69 @@
+/*
+	This file is part of EqualizerAPO, a system-wide equalizer.
+	Copyright (C) 2012  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.
+*/
+
+#pragma once
+
+#include <string>
+#include <vector>
+#include <stdexcept>
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#define APP_REGPATH L"HKEY_LOCAL_MACHINE\\SOFTWARE\\EqualizerAPO"
+
+class RegistryHelper
+{
+public:
+	static std::wstring readValue(std::wstring key, std::wstring valuename);
+	static unsigned long readDWORDValue(std::wstring key, std::wstring valuename);
+	static void writeValue(std::wstring key, std::wstring valuename, std::wstring value);
+	static void writeMultiValue(std::wstring key, std::wstring valuename, std::wstring value);
+	static void deleteValue(std::wstring key, std::wstring valuename);
+	static void createKey(std::wstring key);
+	static void deleteKey(std::wstring key);
+	static void makeWritable(std::wstring key);
+	static void takeOwnership(std::wstring key);
+	static std::vector<std::wstring> enumSubKeys(std::wstring key);
+	static bool keyExists(std::wstring key);
+	static bool valueExists(std::wstring key, std::wstring valuename);
+	static bool keyEmpty(std::wstring key);
+	static void saveToFile(std::wstring key, std::vector<std::wstring> valuenames, std::wstring filepath);
+	static std::wstring getGuidString(GUID guid);
+	static bool isWindowsVersionAtLeast(unsigned major, unsigned minor);
+	static HKEY openKey(const std::wstring& key, REGSAM samDesired);
+
+private:
+	static std::wstring splitKey(const std::wstring& key, HKEY* rootKey);
+
+	static unsigned long windowsVersion;
+};
+
+class RegistryException
+{
+public:
+	RegistryException(const std::wstring& message):message(message) {}
+
+	std::wstring getMessage()
+	{
+		return message;
+	}
+
+private:
+	std::wstring message;
+};