mirror of https://git.ffmpeg.org/ffmpeg.git
Add a function that can apply an order 2 rational transfer function in-place.
This function will be used in the upcoming AMR-NB floating point decoder for high-pass filtering. Patch by Colin McQuillan ( m.niloc googlemail com ) Originally committed as revision 19649 to svn://svn.ffmpeg.org/ffmpeg/trunk
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@ -93,3 +93,20 @@ void ff_acelp_high_pass_filter(int16_t* out, int hpf_f[2],
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hpf_f[0] = tmp;
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}
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}
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void ff_acelp_apply_order_2_transfer_function(float *buf,
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const float zero_coeffs[2],
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const float pole_coeffs[2],
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float gain, float mem[2], int n)
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{
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int i;
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float tmp;
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for (i = 0; i < n; i++) {
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tmp = gain * buf[i] - pole_coeffs[0] * mem[0] - pole_coeffs[1] * mem[1];
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buf[i] = tmp + zero_coeffs[0] * mem[0] + zero_coeffs[1] * mem[1];
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mem[1] = mem[0];
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mem[0] = tmp;
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}
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}
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@ -81,4 +81,20 @@ void ff_acelp_interpolate(int16_t* out, const int16_t* in,
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void ff_acelp_high_pass_filter(int16_t* out, int hpf_f[2],
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const int16_t* in, int length);
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/**
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* Apply an order 2 rational transfer function in-place.
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*
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* @param samples [in/out]
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* @param zero_coeffs z^-1 and z^-2 coefficients of the numerator
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* @param pole_coeffs z^-1 and z^-2 coefficients of the denominator
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* @param gain scale factor for final output
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* @param mem intermediate values used by filter (should be 0 initially)
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* @param n number of samples
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*/
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void ff_acelp_apply_order_2_transfer_function(float *samples,
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const float zero_coeffs[2],
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const float pole_coeffs[2],
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float gain,
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float mem[2], int n);
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#endif /* AVCODEC_ACELP_FILTERS_H */
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