avfilter/af_anequalizer: Avoid loss of precision when calculating nyquist frequency

Fixes: CID1351398
Fixes: CID1351400
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavfilter/af_anequalizer.c

@@ -610,7 +610,7 @@ static int config_input(AVFilterLink *inlink)
         }
 
         if (s->filters[s->nb_filters].freq < 0 ||
-            s->filters[s->nb_filters].freq > inlink->sample_rate / 2)
+            s->filters[s->nb_filters].freq > inlink->sample_rate / 2.0)
             s->filters[s->nb_filters].ignore = 1;
 
         if (s->filters[s->nb_filters].channel < 0 ||
@@ -645,7 +645,7 @@ static int process_command(AVFilterContext *ctx, const char *cmd, const char *ar
         if (filter < 0 || filter >= s->nb_filters)
             return AVERROR(EINVAL);
 
-        if (freq < 0 || freq > inlink->sample_rate / 2)
+        if (freq < 0 || freq > inlink->sample_rate / 2.0)
             return AVERROR(EINVAL);
 
         s->filters[filter].freq  = freq;