annotate base/AudioLevel.cpp @ 1376:d9511f9e04d7 dev/refactor-piper-related

Introduce some POD structs for describing an external server application and the desired libraries to load from it, and disambiguating between empty list request and invalid list request. This allows for overriding PiperVampPluginFactory behaviour for using a PluginScan to populate the list request.

/* -*- 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.
*/

#include "AudioLevel.h"
#include <cmath>
#include <iostream>
#include <map>
#include <vector>
#include <cassert>
#include "system/System.h"

const double AudioLevel::DB_FLOOR = -1000.;

struct FaderDescription
{
    FaderDescription(double _minDb, double _maxDb, double _zeroPoint) :
	minDb(_minDb), maxDb(_maxDb), zeroPoint(_zeroPoint) { }

    double minDb;
    double maxDb;
    double zeroPoint; // as fraction of total throw
};

static const FaderDescription faderTypes[] = {
    FaderDescription(-40.,  +6., 0.75), // short
    FaderDescription(-70., +10., 0.80), // long
    FaderDescription(-70.,   0., 1.00), // IEC268
    FaderDescription(-70., +10., 0.80), // IEC268 long
    FaderDescription(-40.,   0., 1.00), // preview
};

//typedef std::vector<double> LevelList;
//static std::map<int, LevelList> previewLevelCache;
//static const LevelList &getPreviewLevelCache(int levels);

double
AudioLevel::multiplier_to_dB(double multiplier)
{
    if (multiplier == 0.) return DB_FLOOR;
    else if (multiplier < 0.) return multiplier_to_dB(-multiplier);
    double dB = 10 * log10(multiplier);
    return dB;
}

double
AudioLevel::dB_to_multiplier(double dB)
{
    if (dB == DB_FLOOR) return 0.;
    double m = pow(10., dB / 10.);
    return m;
}

/* IEC 60-268-18 fader levels.  Thanks to Steve Harris. */

static double iec_dB_to_fader(double db)
{
    double def = 0.0f; // Meter deflection %age

    if (db < -70.0f) {
        def = 0.0f;
    } else if (db < -60.0f) {
        def = (db + 70.0f) * 0.25f;
    } else if (db < -50.0f) {
        def = (db + 60.0f) * 0.5f + 2.5f; // corrected from 5.0f base, thanks Robin Gareus
    } else if (db < -40.0f) {
        def = (db + 50.0f) * 0.75f + 7.5f;
    } else if (db < -30.0f) {
        def = (db + 40.0f) * 1.5f + 15.0f;
    } else if (db < -20.0f) {
        def = (db + 30.0f) * 2.0f + 30.0f;
    } else {
        def = (db + 20.0f) * 2.5f + 50.0f;
    }

    return def;
}

static double iec_fader_to_dB(double def)  // Meter deflection %age
{
    double db = 0.0f;

    if (def >= 50.0f) {
	db = (def - 50.0f) / 2.5f - 20.0f;
    } else if (def >= 30.0f) {
	db = (def - 30.0f) / 2.0f - 30.0f;
    } else if (def >= 15.0f) {
	db = (def - 15.0f) / 1.5f - 40.0f;
    } else if (def >= 7.5f) {
	db = (def - 7.5f) / 0.75f - 50.0f;
    } else if (def >= 2.5f) {
	db = (def - 2.5f) / 0.5f - 60.0f;
    } else {
	db = (def / 0.25f) - 70.0f;
    }

    return db;
}

double
AudioLevel::fader_to_dB(int level, int maxLevel, FaderType type)
{
    if (level == 0) return DB_FLOOR;

    if (type == IEC268Meter || type == IEC268LongMeter) {

	double maxPercent = iec_dB_to_fader(faderTypes[type].maxDb);
	double percent = double(level) * maxPercent / double(maxLevel);
	double dB = iec_fader_to_dB(percent);
	return dB;

    } else { // scale proportional to sqrt(fabs(dB))

	int zeroLevel = int(maxLevel * faderTypes[type].zeroPoint);
    
	if (level >= zeroLevel) {
	    
	    double value = level - zeroLevel;
	    double scale = (maxLevel - zeroLevel) /
		sqrt(faderTypes[type].maxDb);
	    value /= scale;
	    double dB = pow(value, 2.);
	    return dB;
	    
	} else {
	    
	    double value = zeroLevel - level;
	    double scale = zeroLevel / sqrt(0. - faderTypes[type].minDb);
	    value /= scale;
	    double dB = pow(value, 2.);
	    return 0. - dB;
	}
    }
}


int
AudioLevel::dB_to_fader(double dB, int maxLevel, FaderType type)
{
    if (dB == DB_FLOOR) return 0;

    if (type == IEC268Meter || type == IEC268LongMeter) {

	// The IEC scale gives a "percentage travel" for a given dB
	// level, but it reaches 100% at 0dB.  So we want to treat the
	// result not as a percentage, but as a scale between 0 and
	// whatever the "percentage" for our (possibly >0dB) max dB is.
	
	double maxPercent = iec_dB_to_fader(faderTypes[type].maxDb);
	double percent = iec_dB_to_fader(dB);
	int faderLevel = int((maxLevel * percent) / maxPercent + 0.01f);
	
	if (faderLevel < 0) faderLevel = 0;
	if (faderLevel > maxLevel) faderLevel = maxLevel;
	return faderLevel;

    } else {

	int zeroLevel = int(maxLevel * faderTypes[type].zeroPoint);

	if (dB >= 0.) {
	    
            if (faderTypes[type].maxDb <= 0.) {
                
                return maxLevel;

            } else {

                double value = sqrt(dB);
                double scale = (maxLevel - zeroLevel) / sqrt(faderTypes[type].maxDb);
                value *= scale;
                int level = int(value + 0.01f) + zeroLevel;
                if (level > maxLevel) level = maxLevel;
                return level;
            }
	    
	} else {

	    dB = 0. - dB;
	    double value = sqrt(dB);
	    double scale = zeroLevel / sqrt(0. - faderTypes[type].minDb);
	    value *= scale;
	    int level = zeroLevel - int(value + 0.01f);
	    if (level < 0) level = 0;
	    return level;
	}
    }
}

	
double
AudioLevel::fader_to_multiplier(int level, int maxLevel, FaderType type)
{
    if (level == 0) return 0.;
    return dB_to_multiplier(fader_to_dB(level, maxLevel, type));
}

int
AudioLevel::multiplier_to_fader(double multiplier, int maxLevel, FaderType type)
{
    if (multiplier == 0.) return 0;
    double dB = multiplier_to_dB(multiplier);
    int fader = dB_to_fader(dB, maxLevel, type);
    return fader;
}

/*
const LevelList &
getPreviewLevelCache(int levels)
{
    LevelList &ll = previewLevelCache[levels];
    if (ll.empty()) {
	for (int i = 0; i <= levels; ++i) {
	    double m = AudioLevel::fader_to_multiplier
		(i + levels/4, levels + levels/4, AudioLevel::PreviewLevel);
	    if (levels == 1) m /= 100; // noise
	    ll.push_back(m);
	}
    }
    return ll;
}
*/

int
AudioLevel::multiplier_to_preview(double m, int levels)
{
    assert(levels > 0);
    return multiplier_to_fader(m, levels, PreviewLevel);

    /* The original multiplier_to_preview which follows is not thread-safe.

    if (m < 0.) return -multiplier_to_preview(-m, levels);

    const LevelList &ll = getPreviewLevelCache(levels);
    int result = -1;

    int lo = 0, hi = levels;

    // binary search
    int level = -1;
    while (result < 0) {
	int newlevel = (lo + hi) / 2;
	if (newlevel == level ||
	    newlevel == 0 ||
	    newlevel == levels) {
	    result = newlevel;
	    break;
	}
	level = newlevel;
	if (ll[level] >= m) {
	    hi = level;
	} else if (ll[level+1] >= m) {
	    result = level;
	} else {
	    lo = level;
	}
    }
		   
    return result;

    */
}

double
AudioLevel::preview_to_multiplier(int level, int levels)
{
    assert(levels > 0);
    return fader_to_multiplier(level, levels, PreviewLevel);
/*
    if (level < 0) return -preview_to_multiplier(-level, levels);
    const LevelList &ll = getPreviewLevelCache(levels);
    return ll[level];
*/
}