annotate base/AudioLevel.h @ 0:da6937383da8

initial import
author Chris Cannam
date Tue, 10 Jan 2006 16:33:16 +0000
parents
children d86891498eef
rev   line source
Chris@0 1 /* -*- c-basic-offset: 4 -*- vi:set ts=8 sts=4 sw=4: */
Chris@0 2
Chris@0 3 /*
Chris@0 4 A waveform viewer and audio annotation editor.
Chris@0 5 Chris Cannam, Queen Mary University of London, 2005
Chris@0 6
Chris@0 7 This is experimental software. Not for distribution.
Chris@0 8 */
Chris@0 9
Chris@0 10 /*
Chris@0 11 This is a modified version of a source file from the
Chris@0 12 Rosegarden MIDI and audio sequencer and notation editor.
Chris@0 13 This file copyright 2000-2005 Chris Cannam.
Chris@0 14 */
Chris@0 15
Chris@0 16 #ifndef _AUDIO_LEVEL_H_
Chris@0 17 #define _AUDIO_LEVEL_H_
Chris@0 18
Chris@0 19 /**
Chris@0 20 * AudioLevel converts audio sample levels between various scales:
Chris@0 21 *
Chris@0 22 * - dB values (-inf -> 0dB)
Chris@0 23 * - floating-point values (-1.0 -> 1.0) such as used for a
Chris@0 24 * multiplier for gain or in floating-point WAV files
Chris@0 25 * - integer values intended to correspond to pixels on a fader
Chris@0 26 * or vu level scale.
Chris@0 27 */
Chris@0 28
Chris@0 29 class AudioLevel
Chris@0 30 {
Chris@0 31 public:
Chris@0 32
Chris@0 33 static const float DB_FLOOR;
Chris@0 34
Chris@0 35 enum FaderType {
Chris@0 36 ShortFader = 0, // -40 -> +6 dB
Chris@0 37 LongFader = 1, // -70 -> +10 dB
Chris@0 38 IEC268Meter = 2, // -70 -> 0 dB
Chris@0 39 IEC268LongMeter = 3, // -70 -> +10 dB (0dB aligns with LongFader)
Chris@0 40 PreviewLevel = 4
Chris@0 41 };
Chris@0 42
Chris@0 43 static float multiplier_to_dB(float multiplier);
Chris@0 44 static float dB_to_multiplier(float dB);
Chris@0 45
Chris@0 46 static float fader_to_dB(int level, int maxLevel, FaderType type);
Chris@0 47 static int dB_to_fader(float dB, int maxFaderLevel, FaderType type);
Chris@0 48
Chris@0 49 static float fader_to_multiplier(int level, int maxLevel, FaderType type);
Chris@0 50 static int multiplier_to_fader(float multiplier, int maxFaderLevel,
Chris@0 51 FaderType type);
Chris@0 52
Chris@0 53 // fast if "levels" doesn't change often -- for audio segment previews
Chris@0 54 static int multiplier_to_preview(float multiplier, int levels);
Chris@0 55 static float preview_to_multiplier(int level, int levels);
Chris@0 56 };
Chris@0 57
Chris@0 58
Chris@0 59 #endif
Chris@0 60