quartztext: fix relative font size handling

modules/text_renderer/quartztext.c

@@ -950,7 +950,18 @@ static offscreen_bitmap_t *Compose(int i_text_align,
 
 static int GetFontSize(filter_t *p_filter)
 {
-    return p_filter->fmt_out.video.i_height / DEFAULT_REL_FONT_SIZE;
+    int i_size = 0;
+
+    int i_ratio = var_CreateGetInteger( p_filter, "quartztext-rel-fontsize" );
+    if( i_ratio > 0 )
+        i_size = (int)p_filter->fmt_out.video.i_height / i_ratio;
+
+    if( i_size <= 0 )
+    {
+        msg_Warn( p_filter, "invalid fontsize, using 12" );
+        i_size = 12;
+    }
+    return i_size;
 }
 
 static int RenderYUVA(filter_t *p_filter, subpicture_region_t *p_region,