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