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Optimize dBFS/amplitude conversion functions #7535

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Optimize dBFS/amplitude conversion functions #7535

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59217c5
Optimize dBFS <-> amplitude functions
LostRobotMusic Oct 8, 2024
fa357f6
fix mixed tabs and spaces
LostRobotMusic Oct 8, 2024
73fb99a
style
LostRobotMusic Oct 8, 2024
5084306
use std namespace
LostRobotMusic Oct 8, 2024
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46 changes: 27 additions & 19 deletions include/lmms_math.h
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Original file line number Diff line number Diff line change
Expand Up @@ -164,7 +164,32 @@ inline float linearToLogScale(float min, float max, float value)
return std::isnan( result ) ? 0 : result;
}

static inline float fastPow10f(float x)
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{
return expf(2.302585092994046f * x);
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}

static inline float fastLog10f(float x)
{
return logf(x) * 0.4342944819032518f;
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}

//! @brief Converts linear amplitude (>0-1.0) to dBFS scale.
//! @param amp Linear amplitude, where 1.0 = 0dBFS. ** Must be larger than zero! **
//! @return Amplitude in dBFS.
static inline float ampToDbfs(float amp)
{
return fastLog10f(amp) * 20.0f;
}


//! @brief Converts dBFS-scale to linear amplitude with 0dBFS = 1.0
//! @param dbfs The dBFS value to convert. ** Must be a real number - not inf/nan! **
//! @return Linear amplitude
static inline float dbfsToAmp(float dbfs)
{
return fastPow10f(dbfs * 0.05f);
}


//! @brief Converts linear amplitude (0-1.0) to dBFS scale. Handles zeroes as -inf.
Expand All @@ -174,7 +199,7 @@ inline float safeAmpToDbfs(float amp)
{
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return amp == 0.0f
? -INFINITY
: log10f( amp ) * 20.0f;
: ampToDbfs(amp);
}


Expand All @@ -185,27 +210,10 @@ inline float safeDbfsToAmp(float dbfs)
{
return std::isinf( dbfs )
? 0.0f
: std::pow(10.f, dbfs * 0.05f );
: dbfsToAmp(dbfs);
}


//! @brief Converts linear amplitude (>0-1.0) to dBFS scale.
//! @param amp Linear amplitude, where 1.0 = 0dBFS. ** Must be larger than zero! **
//! @return Amplitude in dBFS.
inline float ampToDbfs(float amp)
{
return log10f(amp) * 20.0f;
}


//! @brief Converts dBFS-scale to linear amplitude with 0dBFS = 1.0
//! @param dbfs The dBFS value to convert. ** Must be a real number - not inf/nan! **
//! @return Linear amplitude
inline float dbfsToAmp(float dbfs)
{
return std::pow(10.f, dbfs * 0.05f);
}


//! Returns the linear interpolation of the two values
template<class T, class F>
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