C++ Breakpoint::setFrequency方法代码示例

//.........这里部分代码省略.........
//! than that will produce frequency oscillations for the remainder of
//! the Partial, in the case of a single bad frequency (as is common
//! at the onset of a tone). Any damping factor less then one will 
//! converge eventually, .5 or less will converge without oscillating.
//! Use the damping argument to control the damping of the correction.
//!	Specify 1 for no damping.
//!
//! \pre		The two Breakpoints are assumed to be consecutive in
//!				a Partial.
//! \param		bp0	The earlier Breakpoint.
//! \param		bp1	The later Breakpoint.
//! \param		dt The time (in seconds) between bp0 and bp1.
//! \param		damping The fraction of the amount of phase error that will
//!				be corrected (.5 or less will prevent frequency oscilation 
//!				due to burst errors in phase). 
//! \param		maxFixPct The maximum amount of frequency adjustment
//!				that can be made to the frequency of bp1, expressed
//!				as a precentage of the unmodified frequency of bp1.
//!				If the necessary amount of frequency adjustment exceeds
//!				this amount, then the phase will not be matched, 
//!				but will be updated as well to be consistent with
//!				the frequencies. (default is 0.2%)
//
void matchPhaseFwd( Breakpoint & bp0, Breakpoint & bp1,
				    double dt, double damping, double maxFixPct )
{
	double travel = phaseTravel( bp0, bp1, dt );
    
    if ( ! BreakpointUtils::isNonNull( bp1 ) )
    {
        // if bp1 is null, just compute a new phase,
        // no need to match it.
        bp1.setPhase( wrapPi( bp0.phase() + travel ) );
    }
    else if ( ! BreakpointUtils::isNonNull( bp0 ) )
    {
        // if bp0 is null, and bp1 is not, then bp0
        // should be a phase reset Breakpoint during
        // rendering, so compute a new phase for
        // bp0 that achieves bp1's phase.
        bp0.setPhase( wrapPi( bp1.phase() - travel ) ) ;
    } 
    else
    {
        // invariant:
        // neither bp0 nor bp1 is null
        //
        // modify frequecies to match phases as nearly as possible
        double err = wrapPi( bp1.phase() - ( bp0.phase() + travel ) );
        
        //  The most common kinds of errors are local (or burst) errors in 
        //  frequency and phase. These errors are best corrected by correcting
        //  less than half the detected error at any time. Correcting more
        //  than that will produce frequency oscillations for the remainder of
        //  the Partial, in the case of a single bad frequency (as is common
        //  at the onset of a tone). Any damping factor less then one will 
        //  converge eventually, .5 or less will converge without oscillating.
        //  #define DAMPING .5
        travel += damping * err;
        
        double f0 = bp0.frequency();
        double ftgt = ( travel / ( Pi * dt ) ) - f0;
        
        #ifdef Loris_Debug
        debugger << "matchPhaseFwd: correcting " << bp1.frequency() << " to " << ftgt 
                 << " (phase " << wrapPi( bp1.phase() ) << "), ";
        #endif
        
        //	If the target is not a null breakpoint, may need to 
        //	clamp the amount of frequency modification.
        //
        //  Actually, should probably always clamp the amount
        //  of modulation, should never have arbitrarily large
        //  frequency adjustments. 
        //
        //  Really, should never call this function if bp1
        //  is a null Breakpoint, because we don't care about 
        //  those phases in Loris. 
        if ( true ) //  bp1.amplitude() != 0. )
        {	
            if ( ftgt > bp1.frequency() * ( 1 + (maxFixPct*.01) ) )
            {
                ftgt = bp1.frequency() * ( 1 + (maxFixPct*.01) );
            }
            else if ( ftgt < bp1.frequency() * ( 1 - (maxFixPct*.01) ) )
            {
                ftgt = bp1.frequency() * ( 1 - (maxFixPct*.01) );
            }
        }
        bp1.setFrequency( ftgt );
        
        //	Recompute the phase according to the new frequency.
        double phi = wrapPi( bp0.phase() + phaseTravel( bp0, bp1, dt ) );
        bp1.setPhase( phi );

        #ifdef Loris_Debug
        debugger << "achieved " << ftgt << " (phase " << phi << ")" << endl;
        #endif
    }
}