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// FrameRate.h
//
/////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2002 David Ward
//
/////////////////////////////////////////////////////////////////////////////
#ifndef __FrameRate_h__
#define __FrameRate_h__
#include "MSVC_Unannoy.h"
// keeps track of framerate
// computes the Steps parameter
// computes RXmax - which controls the maximum rate of zooming in
const double LN2= log(2);
class CFrameRate {
public:
CFrameRate() ;
~CFrameRate() {};
const double Rxmax() const {return m_dRXmax;}
const int Steps() const {return m_iSteps;}
const double Framerate() const {return m_dFr;}
void Reset(unsigned long Time);
void NewFrame(unsigned long Time);
// TODO: These two shouldn't be the same thing:
void SetBitrate(double TargetRate);
void SetMaxBitrate(double MaxRate);
private:
double m_dFr;
double m_dMaxbitrate; // the maximum rate of entering information
double m_dRXmax; // the maximum zoomin per frame
int m_iFrames,m_iTime,m_iTime2,m_iSamples;
int m_iSteps; // the 'Steps' parameter. See djw thesis.
};
inline CFrameRate::CFrameRate() {
// maxbitrate should be user-defined and/or adaptive. Currently it is not.
#if defined(_WIN32_WCE)
m_dMaxbitrate=5;
#else
m_dMaxbitrate=5.5;
#endif
m_dRXmax=2; // only a transient effect
m_iFrames=0;
m_iSamples=1;
// we dont know the framerate yet - play it safe by setting it high
m_dFr=1<<5;
// start off very slow until we have sampled framerate adequately
m_iSteps=2000;
m_iTime=0; // Hmmm, User must reset framerate before starting.
}
inline void CFrameRate::NewFrame(unsigned long Time)
// compute framerate if we have sampled enough frames
{
m_iFrames++;
if (m_iFrames==m_iSamples) {
m_iTime2=Time;
if (m_iTime2-m_iTime < 50)
m_iSamples++; // increase sample size
else if (m_iTime2-m_iTime > 80) {
m_iSamples--;
if (m_iSamples <2)
m_iSamples=2;
}
if (m_iTime2-m_iTime) {
m_dFr=m_iFrames*1000.0/(m_iTime2-m_iTime);
m_iTime=m_iTime2;
m_iFrames=0;
}
m_dRXmax=exp(m_dMaxbitrate*LN2/m_dFr);
m_iSteps=m_iSteps/2+(int)(-log(0.2)*m_dFr/LN2/m_dMaxbitrate)/2;
// dchar debug[256];
// _stprintf(debug,TEXT("fr %f Steps %d samples %d time2 %d rxmax %f\n"),fr,Steps,samples,time2,RXmax);
// OutputDebugString(debug);
}
}
inline void CFrameRate::Reset(unsigned long Time)
{
m_iFrames=0;
m_iTime=Time;
}
inline void CFrameRate::SetBitrate(double TargetRate)
{
m_dMaxbitrate = TargetRate;
}
inline void CFrameRate::SetMaxBitrate(double MaxRate)
{
m_dMaxbitrate = MaxRate;
}
#endif /* #ifndef __FrameRate_h__ */
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