コード例 #1
0
ファイル: Utilities.cpp プロジェクト: e7mac/DSP-Library
//------------------------------------------------------------------------------
void designFirstOrderLowpass(double* dcoefs, double cutoff, double withFs)
// design parametric filter based on input center frequency, gain, Q and sampling rate
{
	double b0, b1, b2, a0, a1, a2;		//storage for continuous-time filter coefs
	double acoefs[6];
    
	//Design lowpass filter here. Filter should be of the form
	//
	//    2
	// b2s  + b1s + b0
	// ---------------
	//    2
	// a2s  + a1s + a0
	//
    // where b2 and a2 are zero (1st order, just keeM_PIng them so the same BLT function can be used)
    //
	// Parameters are cutoff frequency in Hz
    
    b0 = 1;	// design analog filter based on cutoff frequency
    b1 = 0;
    b2 = 0;
    a0 = 1;
    a1 = 1 / cutoff;
    a2 = 0;
	
	acoefs[0] = b0; acoefs[1] = b1; acoefs[2] = b2; // pack the analog coeffs into an array
    acoefs[3] = a0; acoefs[4] = a1; acoefs[5] = a2;
	
    // and apply the bilinear tranform
	bilinearTransform(acoefs, dcoefs, withFs); // inputs the 6 analog coeffs, output the 5 digital coeffs
}
コード例 #2
0
ファイル: Reverb.cpp プロジェクト: hnney/Stanford
//------------------------------------------------------------------------------
void Reverb::designParametric(double* dcoefs, double center, double gain, double qval)
// design parametric filter based on input center frequency, gain, Q and sampling rate
{
	double b0, b1, b2, a0, a1, a2;		//storage for continuous-time filter coefs
	double acoefs[6];
    
	//Design parametric filter here. Filter should be of the form
	//
	//    2
	// b2s  + b1s + b0
	// ---------------
	//    2
	// a2s  + a1s + a0
	//
	// Parameters are center frequency in Hz, gain in dB, and Q.
	
	
	// TODO: design analog filter based on input gain, center frequency and Q
    // Remeber to handle the two cases: boost and cut!
    ///////////////START//////////////////
    float pi = 3.14159;
	float w = 2*pi*center;
    //boost
    if (gain > 0.0)
    {
        b2 = 1/(w*w);
        b1 = gain/(qval*w);
        b0 = 1;
        a2 = 1/(w*w);
        a1 = 1/(qval*w);
        a0 = 1;
    }
    
    //cut
    else
    {
        b2 = 1/(w*w);
        b1 = 1/(qval*w);
        b0 = 1;
        a2 = 1/(w*w);
        a1 = 1/(gain*qval*w);
        a0 = 1;
    }
    
    
    ////////////////END/////////////////////	

    
	// pack the analog coeffs into an array and apply the bilinear tranform
	acoefs[0] = b0; acoefs[1] = b1; acoefs[2] = b2; 
    acoefs[3] = a0; acoefs[4] = a1; acoefs[5] = a2;
	
	// inputs the 6 analog coeffs, output the 5 digital coeffs
	bilinearTransform(acoefs, dcoefs);
	
}
コード例 #3
0
ファイル: Utilities.cpp プロジェクト: e7mac/DSP-Library
//------------------------------------------------------------------------------
void designParametric(double* dcoefs, double center, double gain, double qval, double withFs)
// design parametric filter based on input center frequency, gain, Q and sampling rate
{
	double b0, b1, b2, a0, a1, a2;		//storage for continuous-time filter coefs
	double acoefs[6];
    
	//Design parametric filter here. Filter should be of the form
	//
	//    2
	// b2s  + b1s + b0
	// ---------------
	//    2
	// a2s  + a1s + a0
	//
	// Parameters are center frequency in Hz, gain in dB, and Q.
    
	// design analog filter based on input gain, center frequency and Q
    if (gain > 0.0) { // boost case
        b0 = 1;
        b1 = gain / (qval * center * 2 * M_PI);
        b2 = 1 / (center * center * 4 * M_PI * M_PI);
        a0 = 1;
        a1 = 1 / (qval * center * 2 * M_PI);
        a2 = 1 / (center * center * 4 * M_PI * M_PI);
    } else { // cut case
        b0 = 1;
        b1 = 1 / (qval * center * 2 * M_PI);
        b2 = 1 / (center * center * 4 * M_PI * M_PI);
        a0 = 1;
        a1 = 1 / (qval * gain * center * 2 * M_PI);
        a2 = 1 / (center * center * 4 * M_PI * M_PI);
    }
	
	acoefs[0] = b0; acoefs[1] = b1; acoefs[2] = b2; // pack the analog coeffs into an array
    acoefs[3] = a0; acoefs[4] = a1; acoefs[5] = a2;
	
    // and apply the bilinear tranform
	bilinearTransform(acoefs, dcoefs, withFs); // inputs the 6 analog coeffs, output the 5 digital coeffs
}