BIQUAD_FILTER     257 libavfilter/af_biquads.c BIQUAD_FILTER(s32, int32_t, INT32_MIN, INT32_MAX, 1)
BIQUAD_FILTER     258 libavfilter/af_biquads.c BIQUAD_FILTER(flt, float,   -1., 1., 0)
BIQUAD_FILTER     259 libavfilter/af_biquads.c BIQUAD_FILTER(dbl, double,  -1., 1., 0)