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diff --git a/src/base/AudioLevel.h b/src/base/AudioLevel.h
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+// -*- c-basic-offset: 4 -*-
+
+/*
+    Rosegarden
+    A sequencer and musical notation editor.
+
+    This program is Copyright 2000-2008
+        Guillaume Laurent   <[email protected]>,
+        Chris Cannam        <[email protected]>,
+        Richard Bown        <[email protected]>
+
+    The moral right of the authors to claim authorship of this work
+    has been asserted.
+
+    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.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#ifndef _AUDIO_LEVEL_H_
+#define _AUDIO_LEVEL_H_
+
+namespace Rosegarden {
+
+/**
+ * We need to represent audio levels in three different ways: as dB
+ * values; as a floating-point multiplier for gain; and as an integer
+ * on a scale for fader position and vu level.  This class does the
+ * necessary conversions.
+ */
+
+class AudioLevel
+{
+public:
+
+    static const float DB_FLOOR;
+
+    enum FaderType {
+             ShortFader = 0, // -40 -> +6  dB
+              LongFader = 1, // -70 -> +10 dB
+            IEC268Meter = 2, // -70 ->  0  dB
+        IEC268LongMeter = 3, // -70 -> +10 dB (0dB aligns with LongFader)
+           PreviewLevel = 4
+    };
+
+    static float multiplier_to_dB(float multiplier);
+    static float dB_to_multiplier(float dB);
+
+    static float fader_to_dB(int level, int maxLevel, FaderType type);
+    static int   dB_to_fader(float dB, int maxFaderLevel, FaderType type);
+
+    static float fader_to_multiplier(int level, int maxLevel, FaderType type);
+    static int   multiplier_to_fader(float multiplier, int maxFaderLevel,
+                                     FaderType type);
+
+    // fast if "levels" doesn't change often -- for audio segment previews
+    static int   multiplier_to_preview(float multiplier, int levels);
+    static float preview_to_multiplier(int level, int levels);
+};
+
+}
+
+#endif
+
+