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//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose:
//
// $NoKeywords: $
//=============================================================================//
#ifndef VOICE_GAIN_H
#define VOICE_GAIN_H
#pragma once
// ----------------------------------------------------------------------- //
// CAutoGain is fed samples and figures out a gain to apply to blocks of samples.
// Right now, this class applies gain one block behind. The assumption is that the blocks are
// small enough that gain settings for one block will usually be right for the next block.
// The ideal way to implement this class would be to have a delay the size of a block
// so it can apply the right gain to the actual block it was calculated for.
// ----------------------------------------------------------------------- //
class CAutoGain
{
public:
CAutoGain();
// maxGain and avgToMaxVal are used to derive the gain amount for each block of samples.
// All samples are scaled by scale.
void Reset(int blockSize, float maxGain, float avgToMaxVal, float scale);
// Process the specified samples and apply gain to them.
void ProcessSamples(
short *pSamples,
int nSamples);
private:
enum {AG_FIX_SHIFT=7};
typedef long AGFixed;
// Parameters affecting the algorithm.
int m_BlockSize; // Derive gain from blocks of this size.
float m_MaxGain;
float m_AvgToMaxVal;
// These are calculated as samples are passed in.
int m_CurBlockOffset;
int m_CurTotal; // Total of sample values in current block.
int m_CurMax; // Highest (absolute) sample value.
float m_Scale; // All samples are scaled by this amount.
float m_CurrentGain; // Gain at sample 0 in this block.
float m_NextGain; // Gain at the last sample in this block.
AGFixed m_FixedCurrentGain; // Fixed-point m_CurrentGain.
AGFixed m_GainMultiplier; // (m_NextGain - m_CurrentGain) / (m_BlockSize - 1).
};
#endif // VOICE_GAIN_H
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