avfilter: fix highshelf zdf coefficients

libavfilter/adynamicequalizer_template.c

@@ -238,7 +238,7 @@ static int fn(filter_channels)(AVFilterContext *ctx, void *arg, int jobnr, int n
                     break;
                 case 2:
                     k = itqfactor;
-                    g = fg / SQRT(gain);
+                    g = fg * SQRT(gain);
 
                     fa[0] = ONE / (ONE + g * (g + k));
                     fa[1] = g * fa[0];

libavfilter/af_biquads.c

@@ -722,7 +722,7 @@ static void convert_dir2zdf(BiquadsContext *s, int sample_rate)
     case treble:
     case highshelf:
         A = ff_exp10(s->gain / 40.);
-        g = tan(M_PI * s->frequency / sample_rate) / sqrt(A);
+        g = tan(M_PI * s->frequency / sample_rate) * sqrt(A);
         k = 1. / Q;
         a[0] = 1. / (1. + g * (g + k));
         a[1] = g * a[0];