namespace Rosegarden {
const float AudioLevel::DB_FLOOR = -1000.0;
struct FaderDescription
{
FaderDescription(float i_minDb, float i_maxDb, float i_zeroPoint) :
minDb(i_minDb), maxDb(i_maxDb), zeroPoint(i_zeroPoint) { }
float minDb;
float maxDb;
float zeroPoint; // as fraction of total throw
};
static const FaderDescription faderTypes[] = {
FaderDescription(-40.0, +6.0, 0.75), // short
FaderDescription(-70.0, +10.0, 0.80), // long
FaderDescription(-70.0, 0.0, 1.00), // IEC268
FaderDescription(-70.0, +10.0, 0.80), // IEC268 long
FaderDescription(-40.0, 0.0, 1.00), // preview
};
typedef std::vector<float> LevelList;
static std::map<int, LevelList> previewLevelCache;
static const LevelList &getPreviewLevelCache(int levels);
float
AudioLevel::multiplier_to_dB(float multiplier)
{
if (multiplier == 0.0) return DB_FLOOR;
float dB = 10 * log10f(multiplier);
return dB;
}
float
AudioLevel::dB_to_multiplier(float dB)
{
if (dB == DB_FLOOR) return 0.0;
float m = powf(10.0, dB / 10.0);
return m;
}
/* IEC 60-268-18 fader levels. Thanks to Steve Harris. */
static float iec_dB_to_fader(float db)
{
float 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 float iec_fader_to_dB(float def) // Meter deflection %age
{
float 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;
}
float
AudioLevel::fader_to_dB(int level, int maxLevel, FaderType type)
{
if (level == 0) return DB_FLOOR;
if (type == IEC268Meter || type == IEC268LongMeter) {
float maxPercent = iec_dB_to_fader(faderTypes[type].maxDb);
float percent = float(level) * maxPercent / float(maxLevel);
float 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) {
float value = level - zeroLevel;
float scale = float(maxLevel - zeroLevel) /
sqrtf(faderTypes[type].maxDb);
value /= scale;
float dB = powf(value, 2.0);
return dB;
} else {
float value = zeroLevel - level;
float scale = zeroLevel / sqrtf(0.0 - faderTypes[type].minDb);
value /= scale;
float dB = powf(value, 2.0);
return 0.0 - dB;
}
}
}
int
AudioLevel::dB_to_fader(float 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.
float maxPercent = iec_dB_to_fader(faderTypes[type].maxDb);
float percent = iec_dB_to_fader(dB);
int faderLevel = int((maxLevel * percent) / maxPercent + 0.01);
if (faderLevel < 0) faderLevel = 0;
if (faderLevel > maxLevel) faderLevel = maxLevel;
return faderLevel;
} else {
int zeroLevel = int(maxLevel * faderTypes[type].zeroPoint);
if (dB >= 0.0) {
float value = sqrtf(dB);
float scale = (maxLevel - zeroLevel) / sqrtf(faderTypes[type].maxDb);
value *= scale;
int level = int(value + 0.01) + zeroLevel;
if (level > maxLevel) level = maxLevel;
return level;
} else {
dB = 0.0 - dB;
float value = sqrtf(dB);
float scale = zeroLevel / sqrtf(0.0 - faderTypes[type].minDb);
value *= scale;
int level = zeroLevel - int(value + 0.01);
if (level < 0) level = 0;
return level;
}
}
}
float
AudioLevel::fader_to_multiplier(int level, int maxLevel, FaderType type)
{
if (level == 0) return 0.0;
return dB_to_multiplier(fader_to_dB(level, maxLevel, type));
}
int
AudioLevel::multiplier_to_fader(float multiplier, int maxLevel, FaderType type)
{
if (multiplier == 0.0) return 0;
float 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) {
float m = AudioLevel::fader_to_multiplier
(i, levels, AudioLevel::PreviewLevel);
if (levels == 1) m /= 100; // noise
ll.push_back(m);
}
}
return ll;
}
int
AudioLevel::multiplier_to_preview(float m, int 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;
}
float
AudioLevel::preview_to_multiplier(int level, int levels)
{
const LevelList &ll = getPreviewLevelCache(levels);
return ll[level];
}
int AudioLevel::m_panLaw = 0;
float
AudioLevel::panGainLeft(float pan) // Apply panning law to left channel
{
if (m_panLaw == 3) {
// -3dB Panning Law (variant)
//
// This law has the same characteristics as the -3dB law described
// below, except that a channel's gain begins at +3dB and decreases to
// 0dB as the control is moved through the center position. This
// setting must be used with caution, as the increased edge gains could
// introduce clipping.
//
return sqrtf(fabsf((100.0 - pan) / 100.0)); // -3dB pan law (variant)
} else if (m_panLaw == 2) {
// -6dB Panning Law
//
// A channel's gain begins at 0dB and decreases to -6dB as the control
// is moved to the center. From there on the signal continues to
// decrease until it is completely attenuated at the opposite edge.
// The 3dB dip in the combined power of both channels when the control
// is centered will cause the extremes to sound louder than the center.
//
return (100.0 - pan) / 200.0;
} else if (m_panLaw == 1) {
// -3dB Panning Law
//
// A channel's gain begins at 0dB and decreases to -3dB as the control
// is centered. From there on the signal continues to decrease until
// it is completely attenuated at the opposite edge. The combined
// power of both channels remains constant throughout the panning
// range, resulting in an apparent constant loudness.
//
return sqrtf(fabsf((100.0 - pan) / 200.0));
} else {
// OdB Panning Law (default)
//
// A channel's gain begins at 0dB and remains at 0dB as the control is
// moved to the the center. From there on the signal decreases
// linearly till it is completely attenuated at the opposite edge.
// Since both channels have a gain of 0dB at the center, the net
// effect is a 3dB boost in apparent loudness when the control is
// centered. This is a basic balance pot.
//
return (pan > 0.0) ? (100.0 - pan) / 100.0 : 1.0;
}
}
float
AudioLevel::panGainRight(float pan) // Apply panning law to right channel
{
if (m_panLaw == 3) {
return sqrtf(fabsf((100.0 + pan) / 100.0)); // -3dB pannig law (variant)
} else if (m_panLaw == 2) {
return (100.0 + pan) / 200.0; // -6dB pan law
} else if (m_panLaw == 1) {
return sqrtf(fabsf((100.0 + pan) / 200.0)); // -3dB panning law
} else {
return (pan < 0.0) ? (100.0 + pan) / 100.0 : 1.0; // 0dB panning law (default)
}
}
}
#include "system/System.h"
const float AudioLevel::DB_FLOOR = -1000.f;
struct FaderDescription
{
FaderDescription(float _minDb, float _maxDb, float _zeroPoint) :
minDb(_minDb), maxDb(_maxDb), zeroPoint(_zeroPoint) { }
float minDb;
float maxDb;
float zeroPoint; // as fraction of total throw
};
static const FaderDescription faderTypes[] = {
FaderDescription(-40.f, +6.f, 0.75f), // short
FaderDescription(-70.f, +10.f, 0.80f), // long
FaderDescription(-70.f, 0.f, 1.00f), // IEC268
FaderDescription(-70.f, +10.f, 0.80f), // IEC268 long
FaderDescription(-40.f, 0.f, 1.00f), // preview
};
//typedef std::vector<float> LevelList;
//static std::map<int, LevelList> previewLevelCache;
//static const LevelList &getPreviewLevelCache(int levels);
float
AudioLevel::multiplier_to_dB(float multiplier)
{
if (multiplier == 0.f) return DB_FLOOR;
else if (multiplier < 0.f) return multiplier_to_dB(-multiplier);
