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Apply Scale to energy, value still needs to be tweaked

This commit is contained in:
Geoffrey Merck 2020-01-29 19:37:35 +01:00
parent 7ffc58daaa
commit 0a06b26748
2 changed files with 3 additions and 11 deletions
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12
ambed/cagc.cpp
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@ -42,7 +42,7 @@ CAGC::CAGC(float initialLeveldB)
if (m_g < 1e-16f)
m_g = 1e-16f;
m_scale = (float)0xFFFF;
m_scale = 32768.0f;
m_bandwidth = 1e-2f; //TODO : Move to parameter ?
m_gMax = pow(10.0f, (initialLeveldB + 10.0f)/20.0f);//+- 10dB Margin, TODO Move margin to constant
m_gMin = pow(10.0f, (initialLeveldB - 10.0f)/20.0f);
@ -62,17 +62,12 @@ void CAGC::Apply(uint8 * voice, int size)
//Get the sample
float _x = (float)(short)MAKEWORD(voice[i+1], voice[i]);
//This AGC tries to smooth energy so it does not exceed 1
//Therefore divide by our max supposed value
//Maybe we could also change y2 prime calculation below, but for now stick with this
_x /= m_scale;
//apply AGC
// apply gain to input sample
float _y = _x * m_g;
// compute output signal energy
float y2 = _y * _y;
float y2 = (_y * _y) / m_scale;
// smooth energy estimate using single-pole low-pass filter
m_y2_prime = (1.0f - m_alpha) * m_y2_prime + m_alpha*y2;
@ -87,9 +82,6 @@ void CAGC::Apply(uint8 * voice, int size)
else if(m_g < m_gMin)
m_g = m_gMin;
// apply output scale
_y *= m_scale;
//write processed sample back
voice[i] = HIBYTE((short)_y);
voice[i+1] = LOBYTE((short)_y);

2
ambed/cagc.h
View File

@ -43,7 +43,7 @@ public:
private:
float m_g; // current gain value
float m_gMax, m_gMin; //gain clamping
float m_scale; // scale value
float m_scale; // scale value for target energy
// gain control loop filter parameters
float m_bandwidth; // bandwidth-time constant