Chris@49: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@0: 
Chris@0: /*
Chris@52:     Sonic Visualiser
Chris@52:     An audio file viewer and annotation editor.
Chris@52:     Centre for Digital Music, Queen Mary, University of London.
Chris@0:     
Chris@52:     This program is free software; you can redistribute it and/or
Chris@52:     modify it under the terms of the GNU General Public License as
Chris@52:     published by the Free Software Foundation; either version 2 of the
Chris@52:     License, or (at your option) any later version.  See the file
Chris@52:     COPYING included with this distribution for more information.
Chris@0: */
Chris@0: 
Chris@0: /*
Chris@0:    This is a modified version of a source file from the 
Chris@0:    Rosegarden MIDI and audio sequencer and notation editor.
Chris@17:    This file copyright 2000-2006 Chris Cannam.
Chris@0: */
Chris@0: 
Chris@0: #ifndef _AUDIO_LEVEL_H_
Chris@0: #define _AUDIO_LEVEL_H_
Chris@0: 
Chris@0: /**
Chris@0:  * AudioLevel converts audio sample levels between various scales:
Chris@0:  *
Chris@0:  *   - dB values (-inf -> 0dB)
Chris@0:  *   - floating-point values (-1.0 -> 1.0) such as used for a
Chris@0:  *     multiplier for gain or in floating-point WAV files
Chris@0:  *   - integer values intended to correspond to pixels on a fader
Chris@0:  *     or vu level scale.
Chris@0:  */
Chris@0: 
Chris@0: class AudioLevel
Chris@0: {
Chris@0: public:
Chris@0: 
Chris@0:     static const float DB_FLOOR;
Chris@0: 
Chris@0:     enum FaderType {
Chris@0: 	     ShortFader = 0, // -40 -> +6  dB
Chris@0:               LongFader = 1, // -70 -> +10 dB
Chris@0:             IEC268Meter = 2, // -70 ->  0  dB
Chris@0:         IEC268LongMeter = 3, // -70 -> +10 dB (0dB aligns with LongFader)
Chris@0: 	   PreviewLevel = 4
Chris@0:     };
Chris@0: 
Chris@0:     static float multiplier_to_dB(float multiplier);
Chris@0:     static float dB_to_multiplier(float dB);
Chris@0: 
Chris@0:     static float fader_to_dB(int level, int maxLevel, FaderType type);
Chris@0:     static int   dB_to_fader(float dB, int maxFaderLevel, FaderType type);
Chris@0: 
Chris@0:     static float fader_to_multiplier(int level, int maxLevel, FaderType type);
Chris@0:     static int   multiplier_to_fader(float multiplier, int maxFaderLevel,
Chris@0: 				     FaderType type);
Chris@0: 
Chris@0:     // fast if "levels" doesn't change often -- for audio segment previews
Chris@0:     static int   multiplier_to_preview(float multiplier, int levels);
Chris@0:     static float preview_to_multiplier(int level, int levels);
Chris@0: };
Chris@0: 
Chris@0: 
Chris@0: #endif
Chris@0: