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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
/*
Sonic Visualiser
An audio file viewer and annotation editor.
Centre for Digital Music, Queen Mary, University of London.
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.
*/
/*
This is a modified version of a source file from the
Rosegarden MIDI and audio sequencer and notation editor.
This file copyright 2000-2006 Chris Cannam.
*/
#ifndef _AUDIO_LEVEL_H_
#define _AUDIO_LEVEL_H_
/**
* AudioLevel converts audio sample levels between various scales:
*
* - dB values (-inf -> 0dB)
* - floating-point values (-1.0 -> 1.0) such as used for a
* multiplier for gain or in floating-point WAV files
* - integer values intended to correspond to pixels on a fader
* or vu level scale.
*/
class AudioLevel
{
public:
static const double 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 double multiplier_to_dB(double multiplier);
static double dB_to_multiplier(double dB);
static double fader_to_dB(int level, int maxLevel, FaderType type);
static int dB_to_fader(double dB, int maxFaderLevel, FaderType type);
static double fader_to_multiplier(int level, int maxLevel, FaderType type);
static int multiplier_to_fader(double multiplier, int maxFaderLevel,
FaderType type);
// fast if "levels" doesn't change often -- for audio segment previews
static int multiplier_to_preview(double multiplier, int levels);
static double preview_to_multiplier(int level, int levels);
};
#endif
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