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141 lines
3.2 KiB
C++
141 lines
3.2 KiB
C++
/*
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* AGC.cpp
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* -------
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* Purpose: Automatic Gain Control
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* Notes : Ugh... This should really be removed at some point.
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* Authors: Olivier Lapicque
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* OpenMPT Devs
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* The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
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*/
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#include "stdafx.h"
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#include "../sounddsp/AGC.h"
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OPENMPT_NAMESPACE_BEGIN
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//////////////////////////////////////////////////////////////////////////////////
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// Automatic Gain Control
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#ifndef NO_AGC
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#define AGC_PRECISION 10
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#define AGC_UNITY (1 << AGC_PRECISION)
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// Limiter
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#define MIXING_LIMITMAX (0x08100000)
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#define MIXING_LIMITMIN (-MIXING_LIMITMAX)
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static UINT ProcessAGC(int *pBuffer, int *pRearBuffer, std::size_t nSamples, std::size_t nChannels, int nAGC)
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{
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if(nChannels == 1)
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{
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while(nSamples--)
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{
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int val = (int)(((int64)*pBuffer * (int32)nAGC) >> AGC_PRECISION);
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if(val < MIXING_LIMITMIN || val > MIXING_LIMITMAX) nAGC--;
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*pBuffer = val;
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pBuffer++;
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}
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} else
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{
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if(nChannels == 2)
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{
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while(nSamples--)
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{
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int fl = (int)(((int64)pBuffer[0] * (int32)nAGC) >> AGC_PRECISION);
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int fr = (int)(((int64)pBuffer[1] * (int32)nAGC) >> AGC_PRECISION);
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bool dec = false;
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dec = dec || (fl < MIXING_LIMITMIN || fl > MIXING_LIMITMAX);
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dec = dec || (fr < MIXING_LIMITMIN || fr > MIXING_LIMITMAX);
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if(dec) nAGC--;
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pBuffer[0] = fl;
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pBuffer[1] = fr;
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pBuffer += 2;
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}
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} else if(nChannels == 4)
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{
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while(nSamples--)
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{
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int fl = (int)(((int64)pBuffer[0] * (int32)nAGC) >> AGC_PRECISION);
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int fr = (int)(((int64)pBuffer[1] * (int32)nAGC) >> AGC_PRECISION);
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int rl = (int)(((int64)pRearBuffer[0] * (int32)nAGC) >> AGC_PRECISION);
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int rr = (int)(((int64)pRearBuffer[1] * (int32)nAGC) >> AGC_PRECISION);
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bool dec = false;
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dec = dec || (fl < MIXING_LIMITMIN || fl > MIXING_LIMITMAX);
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dec = dec || (fr < MIXING_LIMITMIN || fr > MIXING_LIMITMAX);
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dec = dec || (rl < MIXING_LIMITMIN || rl > MIXING_LIMITMAX);
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dec = dec || (rr < MIXING_LIMITMIN || rr > MIXING_LIMITMAX);
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if(dec) nAGC--;
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pBuffer[0] = fl;
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pBuffer[1] = fr;
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pRearBuffer[0] = rl;
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pRearBuffer[1] = rr;
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pBuffer += 2;
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pRearBuffer += 2;
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}
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}
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}
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return nAGC;
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}
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CAGC::CAGC()
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{
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Initialize(true, 44100);
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}
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void CAGC::Process(int *MixSoundBuffer, int *RearSoundBuffer, std::size_t count, std::size_t nChannels)
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{
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UINT agc = ProcessAGC(MixSoundBuffer, RearSoundBuffer, count, nChannels, m_nAGC);
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// Some kind custom law, so that the AGC stays quite stable, but slowly
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// goes back up if the sound level stays below a level inversely proportional
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// to the AGC level. (J'me comprends)
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if((agc >= m_nAGC) && (m_nAGC < AGC_UNITY))
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{
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m_nAGCRecoverCount += count;
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if(m_nAGCRecoverCount >= m_Timeout)
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{
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m_nAGCRecoverCount = 0;
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m_nAGC++;
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}
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} else
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{
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m_nAGC = agc;
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m_nAGCRecoverCount = 0;
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}
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}
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void CAGC::Adjust(UINT oldVol, UINT newVol)
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{
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m_nAGC = m_nAGC * oldVol / newVol;
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if (m_nAGC > AGC_UNITY) m_nAGC = AGC_UNITY;
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}
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void CAGC::Initialize(bool bReset, DWORD MixingFreq)
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{
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if(bReset)
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{
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m_nAGC = AGC_UNITY;
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m_nAGCRecoverCount = 0;
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}
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m_Timeout = (MixingFreq >> (AGC_PRECISION-8)) >> 1;
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}
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#else
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MPT_MSVC_WORKAROUND_LNK4221(AGC)
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#endif // NO_AGC
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OPENMPT_NAMESPACE_END
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