bessel_I_0        120 libavfilter/asrc_sinc.c     float mult = scale / bessel_I_0(beta), mult1 = 1.f / (.5f * m + rho);
bessel_I_0        127 libavfilter/asrc_sinc.c         sum += h[i] *= bessel_I_0(beta * sqrtf(1.f - y * y)) * mult;