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10l: reverse the biquad coefficients. 

I did not notice that the filter implementation uses a reversed history state.

Signed-off-by: Janne Grunau <janne-ffmpeg@jannau.net>
This commit is contained in:
Justin Ruggles 2011-01-21 20:59:20 +00:00 committed by Janne Grunau
parent 20ac9de3df
commit 98cfadd648
1 changed files with 6 additions and 6 deletions
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12
libavcodec/iirfilter.c
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@ -137,15 +137,15 @@ static int biquad_init_coeffs(void *avc, struct FFIIRFilterCoeffs *c,
if (filt_mode == FF_FILTER_MODE_HIGHPASS) {
c->gain = ((1.0 + cos_w0) / 2.0) / a0;
x0 = (-(1.0 + cos_w0)) / a0;
x1 = ((1.0 + cos_w0) / 2.0) / a0;
x0 = ((1.0 + cos_w0) / 2.0) / a0;
x1 = (-(1.0 + cos_w0)) / a0;
} else { // FF_FILTER_MODE_LOWPASS
c->gain = ((1.0 - cos_w0) / 2.0) / a0;
x0 = (1.0 - cos_w0) / a0;
x1 = ((1.0 - cos_w0) / 2.0) / a0;
x0 = ((1.0 - cos_w0) / 2.0) / a0;
x1 = (1.0 - cos_w0) / a0;
}
c->cy[0] = (2.0 * cos_w0) / a0;
c->cy[1] = (-1.0 + (sin_w0 / 2.0)) / a0;
c->cy[0] = (-1.0 + (sin_w0 / 2.0)) / a0;
c->cy[1] = (2.0 * cos_w0) / a0;
// divide by gain to make the x coeffs integers.
// during filtering, the delay state will include the gain multiplication