add visualizer_sample_multiplier config option

doc/bindings

@@ -439,6 +439,9 @@
 #def_key "m"
 #  toggle_media_library_sort_mode
 #
+#def_key "m"
+#  set_visualizer_sample_multiplier
+#
 #def_key "n"
 #  move_sort_order_down
 #

doc/config

@@ -70,6 +70,12 @@
 #visualizer_in_stereo = yes
 #
 ##
+## Multiply received samples by given value. Very
+## useful for proper visualization of quiet music.
+##
+#visualizer_sample_multipler = 1
+#
+##
 ## Note: Below parameter defines how often ncmpcpp
 ## has to "synchronize" visualizer and audio outputs.
 ## 30 seconds is optimal value, but if you experience

doc/ncmpcpp.1

@@ -66,6 +66,9 @@ Path to mpd fifo output. This is needed to make music visualizer work (note that
 .B visualizer_output_name = NAME
 Name of output that provides data for visualizer. Needed to keep sound and visualization in sync.
 .TP
+.B visualizer_sample_multiplier = NUMBER
+Multiply received samples by given value. Very useful for proper visualization of quiet music.
+.TP
 .B visualizer_sync_interval = SECONDS
 Defines interval between syncing visualizer and audio outputs.
 .TP