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.

parser/StringOperators.cpp

@@ -0,0 +1,56 @@
+/*
+	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 "StringOperators.h"
+
+using namespace std;
+using namespace mup;
+
+void AddOperator::Eval(ptr_val_type& ret, const ptr_val_type *arg, int argc)
+{
+	if(!arg[0]->IsString() && !arg[1]->IsString())
+	{
+		OprtAdd::Eval(ret, arg, argc);
+		return;
+	}
+
+	wstring firstString;
+	if(arg[0]->IsString())
+		firstString = arg[0]->GetString();
+	else
+		firstString = arg[0]->ToString();
+
+	wstring secondString;
+	if(arg[1]->IsString())
+		secondString = arg[1]->GetString();
+	else
+		secondString = arg[1]->ToString();
+
+	*ret = firstString + secondString;
+}
+
+const char_type* AddOperator::GetDesc() const
+{
+	return L"x+y - Concatenation of strings and addition of noncomplex values";
+}
+
+IToken* AddOperator::Clone() const
+{
+	return new AddOperator(*this);
+}