I've use matlab get the EQ coeffis a,b , and its work correctly, but when I fill in DSP biquad function, the state value always were -1.#INF.

I was using vector biquad. please help me! The dsp chip is sharc dsp 21488.

dsp code:

static float pm coeffs[MAX_BAND_NUM*5];

float dm state[31*2+1];

...

coeffs[0] = 0.7673;//a2; | |

coeffs[1] = -1.7522;//a1; | |

coeffs[2] = 0.2295;//b2; | |

coeffs[3] = -1.7522;//b1; | |

coeffs[4] = 1.5379;//b0; |

....

biquad(pData_in,pData_out,&coeffs[5*i],state,256,1);

matlab figure:

I've solved this. cause biquad function output invalid data, beacause the filter coefficient, cann't fill the coefficient directly, when using minus coefficient a2,a3, -a2,-a3 is ok.

anyway, thank you for answer.