filter/ReplayGain: remove FilterPlugin instance, add explicit constructor

src/filter/FilterRegistry.cxx

@@ -28,7 +28,6 @@ static const FilterPlugin *const filter_plugins[] = {
 	&route_filter_plugin,
 	&normalize_filter_plugin,
 	&volume_filter_plugin,
-	&replay_gain_filter_plugin,
 	nullptr,
 };
 

src/filter/FilterRegistry.hxx

@@ -36,7 +36,6 @@ extern const FilterPlugin convert_filter_plugin;
 extern const FilterPlugin route_filter_plugin;
 extern const FilterPlugin normalize_filter_plugin;
 extern const FilterPlugin volume_filter_plugin;
-extern const FilterPlugin replay_gain_filter_plugin;
 
 gcc_pure
 const FilterPlugin *

src/filter/plugins/ReplayGainFilterPlugin.cxx

@@ -19,9 +19,7 @@
 
 #include "config.h"
 #include "ReplayGainFilterPlugin.hxx"
-#include "filter/FilterPlugin.hxx"
 #include "filter/FilterInternal.hxx"
-#include "filter/FilterRegistry.hxx"
 #include "AudioFormat.hxx"
 #include "ReplayGainInfo.hxx"
 #include "ReplayGainGlobal.hxx"
@@ -163,8 +161,8 @@ ReplayGainFilter::Update()
 		pv.SetVolume(volume);
 }
 
-static PreparedFilter *
-replay_gain_filter_init(gcc_unused const ConfigBlock &block)
+PreparedFilter *
+NewReplayGainFilter()
 {
 	return new PreparedReplayGainFilter();
 }
@@ -183,11 +181,6 @@ ReplayGainFilter::FilterPCM(ConstBuffer<void> src)
 		: pv.Apply(src);
 }
 
-const FilterPlugin replay_gain_filter_plugin = {
-	"replay_gain",
-	replay_gain_filter_init,
-};
-
 void
 replay_gain_filter_set_mixer(PreparedFilter &_filter, Mixer *mixer,
 			     unsigned base)

src/filter/plugins/ReplayGainFilterPlugin.hxx

@@ -27,6 +27,9 @@ class PreparedFilter;
 class Mixer;
 struct ReplayGainInfo;
 
+PreparedFilter *
+NewReplayGainFilter();
+
 /**
  * Enables or disables the hardware mixer for applying replay gain.
  *

src/output/Init.cxx

@@ -216,14 +216,12 @@ audio_output_setup(EventLoop &event_loop, AudioOutput &ao,
 		block.GetBlockValue("replay_gain_handler", "software");
 
 	if (strcmp(replay_gain_handler, "none") != 0) {
-		ao.prepared_replay_gain_filter = filter_new(&replay_gain_filter_plugin,
-							    block);
+		ao.prepared_replay_gain_filter = NewReplayGainFilter();
 		assert(ao.prepared_replay_gain_filter != nullptr);
 
 		ao.replay_gain_serial = 0;
 
-		ao.prepared_other_replay_gain_filter = filter_new(&replay_gain_filter_plugin,
-								  block);
+		ao.prepared_other_replay_gain_filter = NewReplayGainFilter();
 		assert(ao.prepared_other_replay_gain_filter != nullptr);
 
 		ao.other_replay_gain_serial = 0;